Stuttering at Spa?

[cantfind1]

Question for all of you that have done Spa.

Coming out of Stavelot and running along Courbe Paul Frere towards blanchimont in 4th gear foot flat to the floor the car is stuttering, change into 5th foot flat to floor and it will then hesitate again.

Only doing it on this particular stretch?

I was thinking fuel starvation but with just under half a tank i was still getting it to occur occasionally.

Any thoughts?? anyone else experienced this?

[_Nathan_]

I got that in exactly that place, assume was fuel starvation, with me went away if I filled up.

[shimmy]

I got that in exactly that place, assume was fuel starvation, with me went away if I filled up.


had it once there (but only when car was older)

also at Sears (Snetterton) and Coppice (Donny) but once again only when car was over 50k miles :smokin:

[_Nathan_]

My lovely motor car only has 41k on it now :-)

[cantfind1]

Ah good to know, well not good, but at least its a common fault.

I have already replaced my fuel pump, filter and pressure regulator, so I think it s time to look for some sort of upgraded pump.

Seems the OEM one, even when new, is not up to the job, must be something to do with long sweeping turns?

[shimmy]

My lovely motor car only has 41k on it now :-)


ill tel you what "my motor" has on Tuesday :whistle:

[_Nathan_]

Cantfind1 - consider using the oem as a riser to a litre swirl pot then a proper pump from there.

You clocking it then shim :whistle:

[cantfind1]

[quote=_Nathan_;69407]Cantfind1 - consider using the oem as a riser to a litre swirl pot then a proper pump from there.

Yeah have thought about the swirl pot idea, any clues as to where to find out about this setup? Or who can do it?

[shimmy]

Cantfind1 - consider using the oem as a riser to a litre swirl pot then a proper pump from there.

You clocking it then shim :whistle:

no, just hammering it:smokin:

[_Nathan_]

Any race shop mate, Simpsons, steels, intersport, thorny etc etc. I would use Simpsons personally but a lot depends on geography.

[cantfind1]

Cheers Nathan, will talk to simpsons they owe me a favour!

[northernjim]

could it not just be the fuel pick up line in the tank having been dislodged??

might be worth looking at before buying a pot and extra pump:beer:

[shane@mbtech]

I had it when down to just over 1/4 tank, only seemed to get it coming out of sharp corner with slight incline.

Tried to leave half tank minimum and had no issues.

If others are suffering I reckon its poor baffle design.

[daniel]

no stuttering, and no remap.:thumbs:

[cantfind1]

Have found my solution!! Well CA found it.

http://www.ca-automotive.co.uk/single_prod-cHJvZF9pZD0yOTE5JmNhcl9tYWtlPWJtdyZjYXJfdHlwZT1lND ZtJmNhdF9pZD0zJmNvbXBfaWQ9OA==.html

I already have a spare pump so the cost for me will be reduced quite a bit.

But this is a pretty good solution to a problem that most of us have. And its OEM!!

[cantfind1]

no stuttering, and no remap.:thumbs:


Nothing to do with remap mate, its because in long sweeping right hand curves with low fuel quantity the pump on the right hand side is unable to suck fuel. simples.

[shimmy]

Good find

If you have a spare pump (like me) what else would you need and are you gonna buy the kit or just find the bits?

[azrael]

A nessecity I would say.

I remember Simpsons telling me the fuel system was a crap design for exactly this reason.

Can happen with anything from between 1/2 down to 1/4

[cantfind1]

Good find

If you have a spare pump (like me) what else would you need and are you gonna buy the kit or just find the bits?

Already spoken to Roy from CA, told him I have the pump already and he said he will sort out the rest of the bits for me.

Give him a call tomorrow Shim tell him you heard it from me.

[cantfind1]

A nessecity I would say.

I remember Simpsons telling me the fuel system was a crap design for exactly this reason.

Can happen with anything from between 1/2 down to 1/4

Completely agree!

I was getting it from just below 1/2.

Obviously depends how hard you are pushing it.

Can t wait to get this sorted as it was my biggest problem at the mo.

[azrael]

Completely agree!

I was getting it from just below 1/2.

Obviously depends how hard you are pushing it.

Can t wait to get this sorted as it was my biggest problem at the mo.

Be interested to hear your feedback. Have had lots of probs too. (Should learn my lines :) )

How much is fitting?

[shimmy]

Makes you wonder if the HG or oveheating issues could have been caused by lack of fuel on these types of corners

[cantfind1]

Makes you wonder if the HG or oveheating issues could have been caused by lack of fuel on these types of corners


Lots of things make me wonder.

I tend to put it down to wheel alignment rather than my shit driving!

But yes you make a good point hence why I replaced my pump, filter and regulator a while back and will soon be fitting one of these!

http://www.horsepowerfreaks.com/partdetails/HPF/Fuel/Fuel_Pump_Install_Kits/E46_M3_Walbro_In_Tank/16889

You guys owe me a drink for all this info! haha

[DuncanR]

Lots of things make me wonder.

I tend to put it down to wheel alignment rather than my shit driving!

But yes you make a good point hence why I replaced my pump, filter and regulator a while back and will soon be fitting one of these!

http://www.horsepowerfreaks.com/partdetails/HPF/Fuel/Fuel_Pump_Install_Kits/E46_M3_Walbro_In_Tank/16889

You guys owe me a drink for all this info! haha

Is there a UK supplier of those mate ?

[cantfind1]

No mate but they will ship here. just give them a bell they are very helpful.:thumbs:

[azrael]

No mate but they will ship here. just give them a bell they are very helpful.:thumbs:

What is your final solution, the second link or both links?

[cantfind1]

think I will do both to be honest, as i already have the oem pumps, so reduces the cost a lot.

[mattCSLnut]

Lots of things make me wonder.

I tend to put it down to wheel alignment rather than my shit driving!

But yes you make a good point hence why I replaced my pump, filter and regulator a while back and will soon be fitting one of these!

http://www.horsepowerfreaks.com/partdetails/HPF/Fuel/Fuel_Pump_Install_Kits/E46_M3_Walbro_In_Tank/16889

You guys owe me a drink for all this info! haha

THANX for all you info mate :thumbs: I've been having this same problem, mainly @ Brands Hatch, coming out of Clearways (180 degree right hander turn before the pit straight ) with just under half a tank of GO-GO juice and I've been getting the same misfiring in 4th & 5th + it did it again @ Bedford the other day although admittedly I was below a 1/4 of a tank of fuel. Strangely it doesn't happen @ the Ring but I guess it's because it's a flowing circuit without any 180 degree turns.
He's my appreciation :beer: token, to be cashed in near future :thumbs:

[The Gorilla]

Hi,

I have found this thread fascinating.

To address any problem you need to undestand the
cause.

The standard E46 petrol Tank pick up operates
from one side of the tank.

ie] the fuel pump is having to 'suck' the fuel
as opposed to 'push' it from one side only.

Thus when the pipe that the fuel is sucked up
to the fuel pump is not below the fuel
level, then air enters the fuel pump, fuel
pressure drops and the spluttering on
heavy cornering on 1/4 tank can and does
occur.

As the standard fuel pump is rated for 5 bar then
its only issue is fuel supply and what its pick
up is, ie] what distance away from the pump
will it still suck up fuel.

So, if you had a short length of rubber fuel hose
fitted to the bottom of the existing fuel pick
up, then a 'T' fitting, and then another length of fuel hose
to the other side of the tank, which would be no more
that about 1.0 mtr in length, you would ensure that
the fuel pump was always able to suck up fuel,
which is the cause of the problem.

Although this is all internal to the tank, access via
the existing pump set up would be quite easy, and
you have to remove this to fit the CA solution
anyway..

The CA fix just creates another part that can go
wrong, adds more weight !!!!!! and the same
results can be acheived a lot simplier and a whole
lot cheaper.

Regards,

The Gorilla.

[shimmy]

So Gorilla you are basically saying keep the OEM set up but increase the chances of continuous fuel pick up by lengthening the pick up pipe and give it two outlets, one either side of the tank

Nice and simple but surely if either of these open ends is pulling air, you will have spluttering!

[The Gorilla]

Hi

Shimmy- if you dual feed a pump that 'sucks'
then it should always pull fuel, so long
as one of the feeds is always constantly fed.

The reason being that as fuel is heavier than
air, the pump has to suck the lighter air
through the heavier density fuel, of the constant
supply.

That is why its important to have some hose away from
the 'T' in both directions, so that if one of the feeds is exposed
to air, then its easier for the pump to keep sucking from
the constant feed, than to suck the lighter air in 'through'
the heavier fuel.

Regards,

The Gorilla.

[AlexGTT]

My head is starting to hurt with all this thinking.;)

Good info Gorilla.:smokin:

[shimmy]

Sorry not convinced

Gonna try it with some straws and Stella tonight!

[karbonkid]

Sounds easier to ensure enough fuel is in tank.

[The Gorilla]

Hi,

Two Straws and Stella will get you pissed,
nothing else.

Sounds like a plan though.

Have one straw, short distance, which then has a 'T'
for two feeds from the 'T' into your Stella.

Sticking two straws straight into the ''Shimisters
Stella sucker'' will not prove the point.

Start sucking up your Stella with both feeds
well into the amber juice, and while still
sucking at an even rate just pull one feed
out, you should still be on the way to getting
well pissed, not spluttering and coughing as usual !!!


Regards,

The Gorilla.

[glendog74]

Sounds easier to ensure enough fuel is in tank.

:thumbs:

[AlexGTT]

Sounds easier to ensure enough fuel is in tank.

That's far too easy.:clown:;):hahaha:

[shane@mbtech]

Hi,

Two Straws and Stella will get you pissed,
nothing else.

Sounds like a plan though.

Have one straw, short distance, which then has a 'T'
for two feeds from the 'T' into your Stella.

Sticking two straws straight into the ''Shimisters
Stella sucker'' will not prove the point.

Start sucking up your Stella with both feeds
well into the amber juice, and while still
sucking at an even rate just pull one feed
out, you should still be on the way to getting
well pissed, not spluttering and coughing as usual !!!


Regards,

The Gorilla.


I know what you mean fellow ape.

Some good info and theoretically it should work, an easy try to be honest.

The drawbacks of using full tank of juice is the handling characteristics of the car, 1/4 tank is much faster than full tank. And to be fair if you guys didnt want to be quick why modify in the first place;).


I only ever had it happen below 1/4 tank, so I never let it drop below from halfway between 1/4 and 1/2, seemed to cure my issues.

[shimmy]

http://www.abcteach.com/free/k/kilogramscale2rgb.jpg

[RolyGTIR]

Sorry not convinced

Gonna try it with some straws and Stella tonight!

Nothing like a pint of wife beater!!! :thumbs:

Might take several pints to fully test this :smt030

[shane@mbtech]

http://www.abcteach.com/free/k/kilogramscale2rgb.jpg

Fuck me your sharp you Shimmy.

Whats heavier? A ton of bricks or a ton of feathers?

[glendog74]

Fuck me your sharp you Shimmy.

Whats heavier? A ton of bricks or a ton of feathers?

W..w..w..what's h..heavier?

Shh..Shh...Shimmy in...O..Oc...October 2009 or Shh..Shh...Shimmy in..Oc..October 2010?

[shimmy]

Fuck me your sharp you Shimmy.

Whats heavier? A ton of bricks or a ton of feathers?



dont start that one, i did that one on the kids last week and still trying to convince them they are the same.......driving me mad :bigcry:

[shane@mbtech]

dont start that one, i did that one on the kids last week and still trying to convince them they are the same.......driving me mad :bigcry:

Ha.:hahaha:

[cantfind1]

Hi,

I have found this thread fascinating.

To address any problem you need to undestand the
cause.

The standard E46 petrol Tank pick up operates
from one side of the tank.

ie] the fuel pump is having to 'suck' the fuel
as opposed to 'push' it from one side only.

Thus when the pipe that the fuel is sucked up
to the fuel pump is not below the fuel
level, then air enters the fuel pump, fuel
pressure drops and the spluttering on
heavy cornering on 1/4 tank can and does
occur.

As the standard fuel pump is rated for 5 bar then
its only issue is fuel supply and what its pick
up is, ie] what distance away from the pump
will it still suck up fuel.

So, if you had a short length of rubber fuel hose
fitted to the bottom of the existing fuel pick
up, then a 'T' fitting, and then another length of fuel hose
to the other side of the tank, which would be no more
that about 1.0 mtr in length, you would ensure that
the fuel pump was always able to suck up fuel,
which is the cause of the problem.

Although this is all internal to the tank, access via
the existing pump set up would be quite easy, and
you have to remove this to fit the CA solution
anyway..

The CA fix just creates another part that can go
wrong, adds more weight !!!!!! and the same
results can be acheived a lot simplier and a whole
lot cheaper.

Regards,

The Gorilla.

Yes well put, however the fundamental floor in your plan is that the crap oem pump is not strong enough to suck fuel through lengths of hose around the tank hence why you install a second pump in place of the sender unit on the left hand side to push fuel to the right hand pump.

Hardly any extra weight as you are replacing the other unit with the same thing any way, it just has a pump in it which weighs grams!

The oem pump degrades over time and does not produce enough flow anyway, hence why i am going with the walbro conversion for piece of mind.

If you want to be tight the just do the walbro conversion and let it suck fuel through pipes from the left and right side of the tank.

[The Gorilla]

Hi,

The Standard E46 fuel Pump is fine for what were
talking about.

It pumps 5.5 bar at 350mm so no problems.

If changing the pump though, then a Bosch 044 would
be my choice.

Bosch 044 Pump 120.00
Adjustable Fuel Reg 100.00
Sytec Filtre Pre Pump 60.00
Rubber Hose & Fittings 25.00

About as good as any Road / Track car will ever need
and a long way shy of the CA fix.

But as I said the hose alone is a simple easy fix for
a Car that does some Track days.

Regards,

The Gorilla.

[billy-m3cutters]

Very interstingn thread guys and very helpful indeed especially for those who do regular track days.

I would suggest this to be a sticky in a trackday section.


Well done cantfind1;)

[DuncanR]

Sorry not convinced

Gonna try it with some straws and Stella tonight!

Be careful not to injure Stella Shim ...

[DuncanR]

dont start that one, i did that one on the kids last week and still trying to convince them they are the same.......driving me mad :bigcry:

What you need to find mate is a 6 foot tall fookin wood pigeon !!!:hahaha:

[Bealo]

Good thread and good read :thumbs:

[cantfind1]

Hi,

The Standard E46 fuel Pump is fine for what were
talking about.

It pumps 5.5 bar at 350mm so no problems.

If changing the pump though, then a Bosch 044 would
be my choice.

Bosch 044 Pump 120.00
Adjustable Fuel Reg 100.00
Sytec Filtre Pre Pump 60.00
Rubber Hose & Fittings 25.00

About as good as any Road / Track car will ever need
and a long way shy of the CA fix.

But as I said the hose alone is a simple easy fix for
a Car that does some Track days.

Regards,

The Gorilla.


As I said if you want to be tight then yes you can do it this way, however the oem pump is definitely not up to the job, especially the old ones most of us have in our cars. They may pump that pressure when new, but they have been proven to be losing up to 10 psi at high rpm as they age.

Hey you are only risking engine damage that's all! So yeah go cheap.

I am not saying buy the CA kit, to be fair it's expensive however it is the best solution, but yes you can do this yourself with a bit of effort.

[The Gorilla]

Hi,

Cantfind1- the oem pump is up to the job.

The OEM fuel pump is pumping at over the 5 bar fuel pressure
required, its the fuel regulator that
determines the 5 bar fuel pressure delivery.

So a 10 psi drop in a OEM pump already pumping
at 6 bar +, which the OEM pump is, would not
make any difference.

''Tight'' and ''cheap'' do not enter into it.

Regards,

The Gorilla.

[cantfind1]

The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.

M3 pumps loosing pressure/flow over time is well documented now.

I have found this out the hard way.

If you are tracking your car at regular intervals or revving the engine hard constantly the fuel pump needs replacing as a matter of course.

Then adding some sort of fuel pick up or second pump is a must for sweeping right handers.

[The Gorilla]

Hi,

Quote-

''The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.''

Please explain, how do you know its the pump thats
faulty if its measured after the fuel pressure regulator ?


Regards,

The Gorilla,

[cantfind1]

Hi,

Quote-

''The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.''

Please explain, how do you know its the pump thats
faulty if its measured after the fuel pressure regulator ?


Regards,

The Gorilla,

Because it produces the correct 5 bar at normal rpm's.

It's not until I started pushing the car constantly ie on track that the oem fuel pump started showing its weakness.

Plus my regulator was new.

Any more questions?

[shane@mbtech]

Because it produces the correct 5 bar at normal rpm's.

It's not until I started pushing the car constantly ie on track that the oem fuel pump started showing its weakness.

Plus my regulator was new.

Any more questions?

Why would pump pressure drop just because revs increase?

The pump should pump constant pressure should it not, whether at 1000rpm or 8000rpm?

The regulator controls the pressure. I concur that a weak pump would lose pressure whether it was measured after the reg or not.

The reg regulates pressure, but if at say 7000rpm the pressure needs to remain constant, then the regulator will be trying to keep pressure at say 5bar, but the pump would have to work harder due to the amount of fuel being used, in order to maintain a constant pressure. A weak pump would mean a slight drop in fuel pressure.

I think a weak pump is only part of the issue, a poor designed tank setup is another.

I never had any issues in straightline driving, just out of sharp corners on 1/4 tank.

This to me says poor pickup design rather than faulty pump, in my case.

[The Gorilla]

Hi,

Cantfind1- as Laswy says. the electric fuel pump
is constant, it has nothing to with engine rpm.

That is very reason there is a fuel regulatro.

You can only test a fuel pumps true pressure rating, when
its off the car, and there are no other factors like-

Faulty Fuel regulator-
Clogged fuel filtre-
Obstructed fuel lines-
Fuel line connectors seeping-
Fuel injector seals split or pershied-

So while your own experinces may have been
very costly, there are many items that
can impact fuel pressure.

Regards,

The Gorilla.

[cantfind1]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:

[shane@mbtech]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:


I know ~I answered my own question, ;)

I was discussing. I like discussions such as these, very good and informative.

[cantfind1]

I agree!:thumbs:

[The Gorilla]

Hi,

If an engine requires 5 Bar fuel pressure at 200 GPH
then revs do not enter into it.

Going faster or slower does not alter the
delivery of fuel made by the pump, whereas
the engine may burn more or less fuel, if
its delivered at 5 Bar, there will always be
enough fuel.

There are no problems on long straights at WOT
pulling 7500/8000 rpm.

The only issue is when the pump is starved of fuel
and can not make the 5 Bar required, due to the
factor of G forces on longer radius bends washing
fuel away for prolonged periods from the pick up.

This has nothing to do with the pump.

Regards,

Thje Gorilla.

[cantfind1]

Hi,

If an engine requires 5 Bar fuel pressure at 200 GPH
then revs do not enter into it.

Going faster or slower does not alter the
delivery of fuel made by the pump, whereas
the engine may burn more or less fuel, if
its delivered at 5 Bar, there will always be
enough fuel.

There are no problems on long straights at WOT
pulling 7500/8000 rpm.

The only issue is when the pump is starved of fuel
and can not make the 5 Bar required, due to the
factor of G forces on longer radius bends washing
fuel away for prolonged periods from the pick up.

This has nothing to do with the pump.

Regards,

Thje Gorilla.


Yes people do have problems on long straights pulling 7000-8000 rpm and no sometimes the oem fuel pumps are not producing enough flow to give the required 5 bar. But you do not need 5 bar of pressure at low rpm!! Have you ever driven your car with a pressure gauge attached to see what happens??

5 bar is not required by the engine at low rpm the requirement for fuel to the engine increases with rpm therefore you have less flow back to the tank, this in turn affects the siphon system and makes it less efficient in cornering.

I am not going to argue the point anymore with you as it is tiresome Gorilla.

[The Gorilla]

Hi,

Cantfind1 - your correct that it is tiresome.

There is no flow back from the rail on a s54.

Regards,

The Gorilla.

[azrael]

I am not going to argue the point anymore with you as it is tiresome Gorilla.

I thought it was a discussion, no need to argue here :thumbs:

[glendog74]

Tiresome :hahaha:

[shimmy]

I love all our technical discussions ESP when NZ_M3 and The Gorilla are involved.

Trouble is I am not clever enough to understand who is right everytime :bigcry:

[cantfind1]

Hi,

Cantfind1 - your correct that it is tiresome.

There is no flow back from the rail on a s54.

Regards,

The Gorilla.

BMW seems to think otherwise.
Check pipe number 3 in the diagram.
http://www.realoem.com/bmw/showparts.do?model=BL92&mospid=47621&btnr=16_0484&hg=16&fg=15

http://www.realoem.com/bmw/diagrams/e/w/131.png

[_Nathan_]

That doesn't come back from the rail though which was the point being made - go and look at the rail on your car, it just stops at the front of the engine.

http://www.realoem.com/bmw/showparts.do?model=BL96&mospid=50641&btnr=13_0909&hg=13&fg=15

[cantfind1]

yes true, didn t read that bit but the point is it flows back to the tank to the siphon system and if you haven t got much flow back then the siphon system will be less efficient.

[cslnutta]

BMW seems to think otherwise.
Check pipe number 3 in the diagram.
http://www.realoem.com/bmw/showparts.do?model=BL92&mospid=47621&btnr=16_0484&hg=16&fg=15

http://www.realoem.com/bmw/diagrams/e/w/131.png

Please keep this going guys, this is getting very interesting:thumbs:

You guys are obviously very knowledgeable, please continue to bless us mere simpletons with your plethora of info!

Fascinating stuff

[DuncanR]

I love all our technical discussions ESP when NZ_M3 and The Gorilla are involved.

Trouble is I am not clever enough to understand who is right everytime :bigcry:

+46 of us !!! :hahaha:

[shimmy]

ignoring the fuel starvation on RHD crners at 1/4 tank fuel, i think the fuel system is the root cause of the high temps at 100% throttle on hot days that i and others have experienced. Even FLOW got a bit at ZOLDER.

could the fuel at 100% THROTTLE be running short and running the engine lean and therefore hotter thus affecting oil temps and eventually water temps?

[shane@mbtech]

ignoring the fuel starvation on RHD crners at 1/4 tank fuel, i think the fuel system is the root cause of the high temps at 100% throttle on hot days that i and others have experienced. Even FLOW got a bit at ZOLDER.

could the fuel at 100% THROTTLE be running short and running the engine lean and therefore hotter thus affecting oil temps and eventually water temps?

I had zero issues Shimmy and I stayed out for approx 10 laps on the trot at full throttle. My oil temp and coolant temps ran far lower than yours did. Yours has a new engine, which for me points to external cause.

I had the fuel starvation at 1/4 tank of fuel too.

Unless you need a new fuel pump I doubt it is that. Have you tried a new fuel pump or even a fuel filter?

Other possibilities....... radiator
oil cooler
sticking stat(oil too)
restriction in cooling system

[AlexGTT]

I had zero issues Shimmy and I stayed out for approx 10 laps on the trot at full throttle. My oil temp and coolant temps ran far lower than yours did. Yours has a new engine, which for me points to external cause.

I had the fuel starvation at 1/4 tank of fuel too.

Unless you need a new fuel pump I doubt it is that. Have you tried a new fuel pump or even a fuel filter?

Other possibilities....... radiator
oil cooler
sticking stat(oil too)
restriction in cooling system

Shane, I'm totally convinced the issue is radiator. I had a similar slight rising temps at a very hot Donny the other day. However, oil temps stayed beautifully under control. That didn't happen before the bigger oil cooler went in. The oil temps would rise with water temps with the standard oil cooler.

The issue is, I'm sure, old stuffed up water rads. Not just external blockages (flies and shite between the fins, etc.) but internal build up which reduces the efficiency of the rad. 99% of the time the heat generation is handled but on track with compounding heat build up @100% throttle on a hot day and the heat gradually overtakes the rads ability to extract the heat.

If it was a fuel issue the lambda's and knock sensors would be going nuts and the ecu would pull things back timing wise, etc. Hence why the engine stutters on genuine 1/4 tank and less with fuel starvation.

I'm changing the radiator for a new oem asap.

[shane@mbtech]

Shane, I'm totally convinced the issue is radiator. I had a similar slight rising temps at a very hot Donny the other day. However, oil temps stayed beautifully under control. That didn't happen before the bigger oil cooler went in. The oil temps would rise with water temps with the standard oil cooler.

The issue is, I'm sure, old stuffed up water rads. Not just external blockages (flies and shite between the fins, etc.) but internal build up which reduces the efficiency of the rad. 99% of the time the heat generation is handled but on track with compounding heat build up @100% throttle on a hot day and the heat gradually overtakes the rads ability to extract the heat.

If it was a fuel issue the lambda's and knock sensors would be going nuts and the ecu would pull things back timing wise, etc. Hence why the engine stutters on genuine 1/4 tank and less with fuel starvation.

I'm changing the radiator for a new oem asap.

Thats my thoughts too Alex, but I dont have the rising oil/coolant temps. I will wait until I do.

Forte do a great coolant degreaser type product, used it only today on a car which had a failed water seal dumping all oil into water, and vice versa. Works a treat, its worth a try before taking off rad, esp for people who have to pay to get rad changed.

[shimmy]

Do it Alex but I'm sure it won't help.

My money is on the fuel or ecu and I'm my heart everything is saying that the car is running lean at full throttle.

I'm pretty sure I can check this easily with my Rev App or maybe someone has a GT1 that I can plug in. Theory states that the pressure should not drop as you hit 100% throttle.

Here is a good item from dragsters

http://www.automotiveu.com/SolvingOverheating.htm

[shane@mbtech]

Do it Alex but I'm sure it won't help.

My money is on the fuel or ecu and I'm my heart everything is saying that the car is running lean at full throttle.

I'm pretty sure I can check this easily with my Rev App or maybe someone has a GT1 that I can plug in. Theory states that the pressure should not drop as you hit 100% throttle.

Here is a good item from dragsters

http://www.automotiveu.com/SolvingOverheating.htm

If it was running that lean that the car overheats, it would blow up in my opinion.

Have you ever changed fuel filter?.

[shimmy]

If it was running that lean that the car overheats, it would blow up in my opinion.

Have you ever changed fuel filter?.

Can't remember.

I think I might change fuel filter and regulator and I have a spare fuel pump to try as well.

How hard is it to swap out filter and regulator?

[AlexGTT]

Shim, you are correct and fuel mixture does have a significant effect on engine temps. However, when you look at the extremely high state of tune with the E46 motor, I would expect to see holed pistons and more extreme damage and not just raised temps. Believe me, I've seem less highly tuned motors grenade themselves after just a few seconds of unchecked lean running at 100% throttle at near max rpm.

[AlexGTT]

Ah ha, snap Shane!

[shimmy]

Shim, you are correct and fuel mixture does have a significant effect on engine temps. However, when you look at the extremely high state of tune with the E46 motor, I would expect to see holed pistons and more extreme damage and not just raised temps. Believe me, I've seem less highly tuned motors grenade themselves after just a few seconds of unchecked lean running at 100% throttle at near max rpm.

I wonder if Roland can ask the right man at BmW if slight lean running at 100% throttle on hot days could just raise engine temps enough to push oil temps up.

I believe S54 was designed to run slightly lean at full throttle for emissions

[shane@mbtech]

Can't remember.

I think I might change fuel filter and regulator and I have a spare fuel pump to try as well.

How hard is it to swap out filter and regulator?

Near side under car about 1ft behind wheel. Remove the covers held in by 8mm bolts. Couple of pipes to disconnect.

BMW say they are for life- complete bollocks when you see the state of some fuel filters we change, turn them upside down and they run out black.

[shane@mbtech]

I wonder if Roland can ask the right man at BmW if slight lean running at 100% throttle on hot days could just raise engine temps enough to push oil temps up.

I believe S54 was designed to run slightly lean at full throttle for emissions

If it was because it was running lean, then it would be pulling timing loads and it would feel really slow,

[AlexGTT]

I wonder if Roland can ask the right man at BmW if slight lean running at 100% throttle on hot days could just raise engine temps enough to push oil temps up.

I believe S54 was designed to run slightly lean at full throttle for emissions

If you speak Ant, my CSL was slightly rich at wot max revs when on the rollers 4 years ago. Was mapped to adjust it out on mine.

[shane@mbtech]

Another thought popped in my head, do you run normal unleaded or super?

I used the 98 at spa, what did you use?

[AlexGTT]

If it was because it was running lean, then it would be pulling timing loads and it would feel really slow,

Exactly Shane, my thoughts as well.

[AlexGTT]

Another thought popped in my head, do you run normal unleaded or super?

I used the 98 at spa, what did you use?

Always super in mine and I'm sure Shim does as well.

[shimmy]

always super 98 or 99

[shimmy]

• Wide open throttle depletes intake manifold vacuum at the tip of the fuel injectors and in the fuel pressure regulator vacuum chamber. The spring closes the restriction valve to raise fuel pressure available to the fuel injectors. This maintains pressure differential (fuel flow through) for the fuel injectors.



From BmW sheets! I wonder if the fuel pressure isn't allowed to raise itself!

Take a look at this

http://www.unofficialbmw.com/images/m3engineelectronic2.pdf

[cantfind1]

For you guys running standard ecu maps that also have changed your back box and/or Cats you will be running lean at WOT and top end rpm....

The standard ecu map does not have a wide enough range of fuel adaptations to cope with the extra flow from the exhaust ie car runs lean at certain points through rpm range...

Wether or not this is enough to cause that much extra heat who knows, but yes it will cause extra heat!

However this lean running is not lean enough to cause damage as car will retard timing...only if it hears detonation though! To see if it is retarding timing plug in a GT1 and go for a drive while looking at the instant ignition timings screen...

Best get your car on a good dyno for a quick check of the AFR's Shimmy, or install an AFR guage which is more accurate and see what it's doing. You can also run the GT1 on the dyno to see the ignition timings...very interesting to see what the ecu is doing with them and how fast it changes the timings in each cylinder!!!

I have found that the AFR for the S54 should be in a range of between 12/1 or 13/1 mine run a steady 12.5/1 from about 2500 rpm...

[shimmy]

For you guys running standard ecu maps that also have changed your back box and/or Cats you will be running lean at WOT and top end rpm....

The standard ecu map does not have a wide enough range of fuel adaptations to cope with the extra flow from the exhaust ie car runs lean at certain points through rpm range...

Wether or not this is enough to cause that much extra heat who knows, but yes it will cause extra heat!

However this lean running is not lean enough to cause damage as car will retard timing...only if it hears detonation though! To see if it is retarding timing plug in a GT1 and go for a drive while looking at the instant ignition timings screen...

Best get your car on a good dyno for a quick check of the AFR's Shimmy, or install an AFR guage which is more accurate and see what it's doing. You can also run the GT1 on the dyno to see the ignition timings...very interesting to see what the ecu is doing with them and how fast it changes the timings in each cylinder!!!

I have found that the AFR for the S54 should be in a range of between 12/1 or 13/1 mine run a steady 12.5/1 from about 2500 rpm...

as ive had my car thru loads of years and situations i know however that it has nothing to do with remap, nothing to do with exhaust (only item changed at some points was to 100 cell cats)

I will do some checks however and see what i can pick up

[cantfind1]

• Wide open throttle depletes intake manifold vacuum at the tip of the fuel injectors and in the fuel pressure regulator vacuum chamber. The spring closes the restriction valve to raise fuel pressure available to the fuel injectors. This maintains pressure differential (fuel flow through) for the fuel injectors.



From BmW sheets! I wonder if the fuel pressure isn't allowed to raise itself!

Take a look at this

http://www.unofficialbmw.com/images/m3engineelectronic2.pdf


You mean you think you have a problem with your pressure regulator, possibly a weak spring not closing the return line restriction?

Easy to check mate attach a fuel pressure tester to the rail and take it for a drive or on the dyno and see what pressure its maintaining at the fuel rail. Obviously ur looking for 5 Bar...

[shimmy]

You mean you think you have a problem with your pressure regulator, possibly a weak spring not closing the return line restriction?

Easy to check mate attach a fuel pressure tester to the rail and take it for a drive or on the dyno and see what pressure its maintaining at the fuel rail. Obviously ur looking for 5 Bar...


There are a large amount of E46M3 owners, especially in States, that seem to have high temps on track at 100% throttle on hot days. Nobody sems to have really cured it and most hide it with increased oil coolers (i can see that might work) but id rather solve it tbh.

I think that its something simple and to do with the age of the cars (something wearing out).

I think my APP does fuel pressure reading from the OBD so ill try that first this weekend and see what it records.

[cantfind1]

Cool let me know how you get on.....I think you may be right something is wearing the question is what......I think it may be old radiators.....old oil coolers becoming less efficient with age....

[shimmy]

Cool let me know how you get on.....I think you may be right something is wearing the question is what......I think it may be old radiators.....old oil coolers becoming less efficient with age....

My oil system is 100% new with engine change so not that and countless US cars have had new rads or aftermarket rads with no improvement.

It's gonna be a little more obscure than that and simply o fix, I betcha

[shane@mbtech]

My oil system is 100% new with engine change so not that and countless US cars have had new rads or aftermarket rads with no improvement.

It's gonna be a little more obscure than that and simply o fix, I betcha

try a fuel filter Shimmy, and if no joy, change the pump.

Ive got a tank here, I might disect it and see if I can fit baffles, to stop the fuel surge issues.

[alexk]

ignoring the fuel starvation on RHD crners at 1/4 tank fuel, i think the fuel system is the root cause of the high temps at 100% throttle on hot days that i and others have experienced. Even FLOW got a bit at ZOLDER.

could the fuel at 100% THROTTLE be running short and running the engine lean and therefore hotter thus affecting oil temps and eventually water temps?

Christoforos from Cyprus resolved the temp issue when he re-mapped the ECU with the factory map.
The car was re-mapped.

So what stats do we want to see with the GT1 guys ?
I can do a test.

[83SY]

I got that in exactly that place, assume was fuel starvation, with me went away if I filled up.

+1 keep it min 3/4 tank

[ac427]

What is the recommended pump these days?

Has anyone used an HRC fuel pump?

Is the Bosch 044 too large to fit?

[Mike R]

What is the recommended pump these days?

Has anyone used an HRC fuel pump?

Is the Bosch 044 too large to fit?

The 044 is an external pump, the CSL uses an internal pump.

You would have to make a "surge tank" that the OEM pump feeds to and the the 044 takes the fuel from the surge tank to the fuel rail.....

[cantfind1]

Careful fitting aftermarket pumps, whether internal or external. You will change the fuel flow, normally will require remap if you fit a higher flowing pump.