Need some info on Air/Fuel Peak Recall on ESS 625

[bvrider1]

I am trying to troubleshoot an issue. 2nd and 3rd gear pulls at highway speeds over 70 mph wide open will show hesitation on top end.

New plugs installed last week. Can someone provide what their peak recall is for air/fuel on their P3 Guage? I would like to get a base line.

Thank you!

[Patrón]

Originally Posted by bvrider1

I am trying to troubleshoot an issue. 2nd and 3rd gear pulls at highway speeds over 70 mph wide open will show hesitation on top end.

New plugs installed last week. Can someone provide what their peak recall is for air/fuel on their P3 Guage? I would like to get a base line.

Thank you!

are you on the 'stock' pullies and what octane are you using? my first recommendation was going to be plugs.

are you 100% certain the manifold is seated correctly and your bypass valve is working correctly?

[bvrider1]

I am on the stock pully running 93

Good call on the manifold seating. I will need to verify that. So you are saying at high boost I could be generating a leak , which would make make me run more lean? I like that theory.

Can you help me understand how to troubleshoot the bypass valve?

Originally Posted by Patrón

are you on the 'stock' pullies and what octane are you using? my first recommendation was going to be plugs.

are you 100% certain the manifold is seated correctly and your bypass valve is working correctly?

[bvrider1]

If the manifold was leaking I should run into a rich condition. I am not seeing that based on the p3 guage. I am running lean.

[BPMSport]

Originally Posted by bvrider1

If the manifold was leaking I should run into a rich condition. I am not seeing that based on the p3 guage. I am running lean.

Looking at the peak measurement doesn't give you anything useful, unless the peak measurement is taken during a full throttle window, which it is not.

When you let off the throttle, the injectors will turn off, so the AIR fuel ratio will raise from whatever it was prior to the throttle lift (likely 12-14.7 depending on whether you were cruising or full throttle), up to a full lean condition when the injectors turn off. 19ish is simply the last sample that your P3 read before the oxygen sensors couldn't read any leaner. Whenever the gauge freezes at a number, or goes to a high number, the injectors are off. This means absolutely nothing with regard to how the car is operating and doesn't mean that it's running lean in any respect.

If you want to measure the air fuel ratio, then measure or watch the gauge on a 3rd or 4th gear pull while you are at full throttle. This will indicate the air fuel ratio under load, and you will likely see around 12.2 at the top of the tach which is a solid AFR for an FI M3 with safety in mind.

If you see it richer than that, then perhaps the belt may be slipping, or the manifold couplers or bypass valve is leaking, which would cause the mixture to go overly rich as there isn't enough air to match the injected fuel for the boost level it's expecting.

Hope this helps.

[bvrider1]

Thanks for the explanation Mike. It makes sense now on your explanation of the lean condition. I have a new tensioner that I plan on putting on. Hoping that would help if there is belt slip.

Originally Posted by BPMSport

Looking at the peak measurement doesn't give you anything useful, unless the peak measurement is taken during a full throttle window, which it is not.

When you let off the throttle, the injectors will turn off, so the AIR fuel ratio will raise from whatever it was prior to the throttle lift (likely 12-14.7 depending on whether you were cruising or full throttle), up to a full lean condition when the injectors turn off. 19ish is simply the last sample that your P3 read before the oxygen sensors couldn't read any leaner. Whenever the gauge freezes at a number, or goes to a high number, the injectors are off. This means absolutely nothing with regard to how the car is operating and doesn't mean that it's running lean in any respect.

If you want to measure the air fuel ratio, then measure or watch the gauge on a 3rd or 4th gear pull while you are at full throttle. This will indicate the air fuel ratio under load, and you will likely see around 12.2 at the top of the tach which is a solid AFR for an FI M3 with safety in mind.

If you see it richer than that, then perhaps the belt may be slipping, or the manifold couplers or bypass valve is leaking, which would cause the mixture to go overly rich as there isn't enough are to match the injected fuel for the boost level it's expecting.

Hope this helps.

[Patrón]

Originally Posted by bvrider1

If the manifold was leaking I should run into a rich condition. I am not seeing that based on the p3 guage. I am running lean.

i was basing my response on your post. i didn't see where you stated you were running lean.

I'd also like to comment on P3 'peak' numbers. it's missleading to read the boost peak. to truly see the boost numbers you have to video or datalog the boost, i believe the gear changes (dct) and traction control affect the peak boost reading recall on the p3.

[bvrider1]

OK guys. Here are some new findings. After the idler pulley was swapped out I also swapped out the pulley with another spare 625 pulley. The combination of the two worked out and it pulls very nice on the BPM tune.

[Iyzmi]

Originally Posted by bvrider1

OK guys. Here are some new findings. After the idler pulley was swapped out I also swapped out the pulley with another spare 625 pulley. The combination of the two worked out and it pulls very nice on the BPM tune.

You swapped your 96.5mm pulley with another 96.5mm pulley?

[bvrider1]

Yes. I had a spare and wanted to rule out any slipping issues.

Originally Posted by Iyzmi

You swapped your 96.5mm pulley with another 96.5mm pulley?

[bvrider1]

I replaced the Belt Tensioner Pulley and the 96.5 pulley

[Iyzmi]

Originally Posted by bvrider1

I replaced the Belt Tensioner Pulley and the 96.5 pulley

Were either of these pulleys loose or visibly worn? I'm not sure how swapping these pulleys would have made any difference. A new belt tensioner would make more sense to me, though a buddy of mine just swapped his while chasing a low peak boost issue and it didn't help.

[bvrider1]

The 96.5 was out of round. It was dinged up enough. I should have swapped it out sooner but it never came to mind.

Originally Posted by Iyzmi

Were either of these pulleys loose or visibly worn? I'm not sure how swapping these pulleys would have made any difference. A new belt tensioner would make more sense to me, though a buddy of mine just swapped his while chasing a low peak boost issue and it didn't help.

[BPMSport]

Originally Posted by bvrider1

OK guys. Here are some new findings. After the idler pulley was swapped out I also swapped out the pulley with another spare 625 pulley. The combination of the two worked out and it pulls very nice on the BPM tune.

Fantastic! Glad you got it sorted out

[bvrider1]

Sad to report back but the hesitation is getting worse. The out of round pulley gave me a placebo feeling. With temps coming back down I thought the car would pull better. It is a 6k-7k rpm range. It's a higher mileage m3 so I have new ignition coils that will be here on on the 23rd.

I will post back on how the car runs after new ignition coils are in. Just to recap new plugs have been installed. Next is are the coils. If that fails I have to look at fuel delivery.

[bvrider1]

On the plus side I can get it to show on a steady 2nd gear roll . Still hesitation from 6-7k. Can't wait for the new ignition coils to come in. Hope that fixes it.

[bvrider1]

Today I installed new ignition coils and It really did help. The car idles smoother and the hesitation is gone. My car is an 08 and the ignition coils were also stamped 08. I went with the FCP kit. Hope this posts helps others.