Problem Solved! Was Due to Incorrect MAF Scaling!


Ok, i am coming here as last resort...

As the title says i have this rich idle that will idle anywhere from 13.5-14.0...

Cruising around i get the same afr at a constant speed...

All i want is my afr to be at 14.7 like it used to be

Things i have tried and please don't tell me/ post replies to recheck. I have rechecked all of these things countless of times.....

• Boost Leak Test
  • Has been done 4 times now same results... Not even a whisper
  • Did one earlier today and i put the PSI up to like 17.....
• Replaced all my intercool piping to stock along with changing my BOV
• Changed Spark Plugs
• Reflashed to all different tunes i had through out the past year...
• Unplug the Battery
• Change my Injector Scalings/latencies all around
• Clean Maf Sensor
• Change my Idle RPM..
• Tried Leaning out my high octane AFR Maps
• Tried switching to tephra's V7 (Made it even richer on accel)
• I forget the rest of things...

I have one check engine light and its because of the rear 02 sensor since no cat...

Mods Done to My Car:

• Buschur Racing Intake
• AMS Front Mount
• Walbro 255 LP
• Presicion 880's
• AMS Fuel Rail
• HKS SSQ BOV
• FULL 3 inch Exhaust
• Test Pipe
• All New Throttle Body Seals

I'm sure there are some other minor things modded but can't think of them..
I have tried everything i can think of and have been searching the forums for weeks.... Any help i will appreciate it.

Kevin

 

What are u using to keep an eye on the afr? If your using a aem wideband check the sensor it might be going out and causing crazy readings. When mine went it would not read when covered in a rag of gas it stayed at full lean, but with the car running it would show weird results like yours except mine started reading leaner instead of richer

 

Thanks for the reply, I am currently using the Innovate LC-1. I tried recalibrating it and still the same. Also tried using a friends AEM and same results.

 

Check to make sure you havnt developed an exhaust leak recently that will throw off the wideband, but not actually change the afr's

 

I checked a while back i'm thinking this is my last reason to why it's rich. I will report back with this answer in the morning! Thank You!

 

Did this problem start completly out of nowhere gradually over time or did it happen after a mod/retune? Is this idle A/F Ratio constant in both open and closed loops? What does your front O2 Sensor Data look like?

 

^^+1^^ could be your front O2 sensor gone or going bad.

 

An exhaust leak pre sensor will cause leaner readings not richer so this shouldn be the ops problem.

 

Check the vac line and fuel pressure regulator... do a fuel line pressure check... at idle... someone here should know the idle pressure of the fuel system.

 

The A/f Raftio is constant, Except sometimes when i first turn my car on the A/F Ratio will sit at like 14.7-15.0. Then as soon as i tap the gas it changes down to 13.5-14.0. This occurs on cold and warm starts.

Front 02 looks good, no CEL and fuel trims are all in the 2% range.

If my Fuel Pressure was bad wouldn't that produce lean effects?

 

The fuel pressure for almost every vehicle is right around 42-43psi and yes lower pressure would cause leaner readings. Not a bad idea to check tho it might have gotten higher at idle if there's a problem with the regulator and its not opening properly

 

Ok, After taking 2 months of my god damn time to find the problem. I finally decided to play with my MAF Settings today. I adjusted my MAF Scaling table just by a few numbers, reflashed ecu, Started Car. AND BAM 14.7 - 15.0 Idle A/F Ratio.. I hope this will help others that stumble across the same problem.

Thanks For Everyone's input as well!

Kevin

 

Im thinking its gotta be some type of mechanical or electrical issue.... that has been my experience when you can't figure it out with tuning etc.. and all of the sudden something just goes wrong.

 

^ what scaling did you use?

 

Sweet! MAF Scaling makes sense...did u just have a retune done by a shop? I'm curious about the scaling used also...