Lean afr during wot

Haedenjames

Haedenjames

Greenie N00B Member
Iv been battling this weird issue where afr ramps up to mid to high 12s during wot then back down. I also have the infamous hesitation/backfire after shifting form 2nd to 3rd while at wot. When this occurs afrs ramp up to the 13s right after the hesitation. I’m on e25 and fully tuned my tuner says it’s not the tune and he suspects a sticking bpv however I blocked it off and no change. I pressure tested the system from the maf housing back with 23psi and no leaks. Brand new 02 sensor maf sensor and maf o ring. Brand new spark plugs as well. Here are some logs. Anyone ever seen this before my tuner is convinced it’s a hardware issue nothing to do with the tune and I’m stuck at a loss.
 

Attachments

Instructions:
1. Post a picture of your engine bay, intake side.
2. Also post what your intake actually is and what airflow straightener it has (a pic of the intake with the filter off, looking inside will work)
3. Post an idle log (HOT engine please, preferably after you arrive at work or have been driving twice as long as it takes the coolant temp to get to normal).

If you get the idle log with the hood open, I'll need to know if your radiator fan is on or if it's windy while you have the hood up, though I'm reasonably sure I'm already going to recommend that you get one of these:

https://www.treadstoneperformance.com/honeycomb-maf-mass-air-meter-airflow-straightener/p103828

Having one has saved many a people from headache shit like what you've got going on, even though several tuners say you don't need them.

I run one myself, in fact, and have a spare:
6KyHBau.jpg

gvbsI9t.jpg
 
Enki said:
Instructions:
1. Post a picture of your engine bay, intake side.
2. Also post what your intake actually is and what airflow straightener it has (a pic of the intake with the filter off, looking inside will work)
3. Post an idle log (HOT engine please, preferably after you arrive at work or have been driving twice as long as it takes the coolant temp to get to normal).

If you get the idle log with the hood open, I'll need to know if your radiator fan is on or if it's windy while you have the hood up, though I'm reasonably sure I'm already going to recommend that you get one of these:

https://www.treadstoneperformance.com/honeycomb-maf-mass-air-meter-airflow-straightener/p103828

Having one has saved many a people from headache shit like what you've got going on, even though several tuners say you don't need them.

I run one myself, in fact, and have a spare:
6KyHBau.jpg

gvbsI9t.jpg
Click to expand...
Here is the log there was no wind ac is off and hood is down. Here’s the pics also. I ordered that straightener can I put it right in front of the corksport straightener? I have a 3.5 inch corksport intake also.
 

Attachments

  • idle log ac off.csv
    idle log ac off.csv
    9 KB · Views: 5
  • 2236935A-D56A-463E-B5DB-EED21EF0E29D.jpeg
    2236935A-D56A-463E-B5DB-EED21EF0E29D.jpeg
    1.1 MB · Views: 18
  • E6D044CB-407E-47D6-AF40-04A893D7924B.jpeg
    E6D044CB-407E-47D6-AF40-04A893D7924B.jpeg
    1.6 MB · Views: 15
It will probably stick out a bit but that shouldn't be too much of a problem. Just make sure you gently squeeze the areas that stick out far enough to prevent you from installing it, so it collapses down and does a snug press fit like thing. On mine you can see where I fucked up and squeezed too much, but even with that, it's only in there by friction and hasn't moved in years.

gvbsI9t.jpg
 
Enki said:
It will probably stick out a bit but that shouldn't be too much of a problem. Just make sure you gently squeeze the areas that stick out far enough to prevent you from installing it, so it collapses down and does a snug press fit like thing. On mine you can see where I fucked up and squeezed too much, but even with that, it's only in there by friction and hasn't moved in years.

gvbsI9t.jpg
Click to expand...
Based on what I sent you does that look like my issue?
 
Well there was no wind. Maybe turn the AC on (to force the radiator fan to run) and see if the AFRs or MAFv changes erratically?
 
Enki practically saved my life suggesting the honeycomb for my 4" intake. STFT would peg and hold at +25 when the fans kicked on. Now the ecu properly adjusts and STFT comes back down. The car doesn't drive like absolute dog shit now with the AC on! Thanks @Enki

Sent from tapioca
 
Straightener in my CS MAF housing came loose and was moving...had to re silicone it in place, shit I might just remove it now and toss this honeycomb in after reading this thread
 
Awafrican said:
Straightener in my CS MAF housing came loose and was moving...had to re silicone it in place, shit I might just remove it now and toss this honeycomb in after reading this thread
Click to expand...
same thing happened to me a few years back, also with the cs maf housing. I thought my intake manifold had a damn hole in it with how high the LTFT ended up getting before I discovered it was the straightener. Superglued it back and no issues since, probably will upgrade to a honeycomb when I get a bigger intake.
 
Enki said:
You have issues with just having the AC on....Imagine 100x more wind coming through the engine bay and ask yourself that question again.
Click to expand...
Here’s an update. The honey comb fixed weird fuel trims and cruising afr. However it did not fix my lean at wot issue. Car still has 0 kr but it does still spike at wot then comes back down.
 
You must log in or register to reply here.
Back
Top