Stuttering at Spa?

[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...