Alright Guys I Need Some Help....And Fast...
Alright Guys I Need Some Help....And Fast... Well for awhile now my car has been throwing two codes a p0171 and p0174. Both are lean codes, I am currently running a diablo sport tune(i know it's junk) and a GMS MAF. I tried running the car with out both and the code came back.....I check my MAF for dirt....and I cleaned it anyway...but the code keeps comming back....to add the insult to injury I am running a Autometer Narrow band A/F gauge and I can just watch the car go from Stoich jump to lean and then go back to Stoich....I've heard of people changing their O2's but I don't wanna take out the money just yet $80/each isn't that cheap for something that isn't going to fix it...any ideas people? I need help.....
Staging Lane
Joined: Jan 2006
Posts: 64
Likes: 0
It's probably one of those aftermarket MAF's with the resistor soldered in.
It change's the voltage the PCM reads causing it to lean it out,where the real "power" is found in those. The diablo does the same thing in it's programming,only the correct way by changing associated table's in the PCM.
Take either one out of the equation and by itself they shouldn't cause a problem.
Throw the MAF in the trash IMO,use a stocker unless you HAVE to have an oversized for CFM.
It change's the voltage the PCM reads causing it to lean it out,where the real "power" is found in those. The diablo does the same thing in it's programming,only the correct way by changing associated table's in the PCM.
Take either one out of the equation and by itself they shouldn't cause a problem.
Throw the MAF in the trash IMO,use a stocker unless you HAVE to have an oversized for CFM.
It does it even with the stock MAF....so I have no idea....also I unprogramed the car and the codes came back...the codes come up with the computer un-tuned and the stock MAF....thats why I'm out of ideas...
10 Second Club
Joined: Apr 2002
Posts: 1,755
Likes: 2
From: Cincinnati, Ohio
Because it is happening on both banks the car is most likely truly running lean. When the car is idling the O2's should switch back and forth under 200mv and over 800mv occasionally. If it is staying biased on the lean side (under 400mv) maybe you've got a vacuum leak. Can you get access to freeze frame data to see the running conditions when the codes occurred?
It's usually stays below 400mv....does that mean I do possibly have a vacuum leak? And as for freeze framing data....I don't have a true data logger...I used the handheld....
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try increasing the PE power enrichment on your diablo a few %. or the injector slope. search the slope bc i cant remember wich way you change the injector slope to account for the maf's bs... dont do anything do dramatic on the diablo
10 Second Club
Joined: Apr 2002
Posts: 1,755
Likes: 2
From: Cincinnati, Ohio
Originally Posted by Zero4488
alright guys thanks for the help....but one last question...if it is a vacuum leak...any ideas where to start to look for it?
I replaced the fuel pump...haven't check the fuel pressure yet....ummm....I can't hear any hissing....I really just wanna take the car to ECS and get it tuned and sell the diablo...I'm sick of it....btw...what is a good data logger? I want to get one to monitor my car....