some weird thing is happening with my car that ive never seen before. 2010 LNF.

been trying to chase down the cause of a random intermittent P0101 code ive been throwing as of late. it comes and goes and obviously when it throws the code the car runs like complete crap with no boost but then while driving itll just fix itself and runs nice and boosts perfectly fine and hard.

what i now notice is that on my rpd at start up and idle the afr is just stuck. it does not fluctuate like it normally does its just stuck at 14.7. on my interceptor the lambda is also just stuck without fluctuating. just stuck at 1.00. fuel pressure on the rpd moves a bit but its in very small numbers, also not doing its usual 300-600 or so sweep just stuck at around the 450s. boost gauge is also reading alot less vacuum than the usual 20 i see. ALOT less. enough that it tells me there has to be a leak somewhere but something thatll cause the much of a change on the gauge would be pretty obvious id say. but wait theres more!

once i start driving, after awhile, all of sudden all of the readings start doing their thing again! afr swings around, lambda swings around, fuel pressure swings around, and vacuum drops to 20. all is well. when i park the car and start it back up itll do all the stuff i said before again. just stuck! if i pull the maf connector at idle the car would idle pretty much the same but then when i connect it and i look inside the car all of the readings are moving. i dont even know...

maf is fairly new and clean, no oil in the intake. top map sensor has no oil on it and looks good. bottom map looks good too. those are just physical inspections. is there a way to actually test these sensors to see if theres an internal issue or what not? or their wiring? not throwing any map codes but i did however throw a code a few times a very long time ago but never again. something about iat and iat 2 numbers not being within spec of each other or something. forgot the code number.

ive flashed different tunes to rule out any setting issues but problem is still there regardless of tune. disconnected battery for awhile and same thing. im not sure what else to do. everything ive searched about P0101 points to boost leak this and boost leak that but when the car decides to actually behave the thing pulls like a freight train!

definitely not ruling out the possibility of the maf being bad even if its only a few months old i just dont want to buy a new one only for the problem to still be there. do 3 bar maps usually go bad? i wanna test all 3 sensors and their wiring. what should i be looking for?

 

So the stable AFR on start up is normal, the car is in open loop going off your base tables. This is the same thing as unplugging the maf, there are a few tables the ECU relies on incase of a MAF failure the car will still run without increasing. So I'm going to say your MAF is very likely just fine. Now it's possible the airflow is more or less than the ECU expects to see and throws the P0101, I would perform a boost leak test through the intake of the turbo and check everything with a leak detector (you can get a can of cheap natural gas leak detector at any hardware store, comes with a brush in can so you can easily apply). I've had boost leaks found this way that I didn't know about and had no issue hitting full boost, one major culprit would be your 3 bar map sensors, they are notorious for leaking so giggle them a bit while under pressure.

When you say you tried different tunes are they all off the same base tune?

If they are try a stock GMStg1 tune and see what happens (just change the fuel pulse width for e85, and don't go crazy on pulls as I'm going to assume the WGDC is much lower with the 7163).

I did a quick search of the service manual I have and couldn't find the MAF/MAP test for function procedure, if I have more time later today I'll see if I can find it.

 

thanks for the reply!

so i just installed a powell V3 separator about a week ago and while i had everything off i swapped the map sensors around for a test, retightend all of the couplers, boost leak tested and even compression tested. when i started the car initially after install i threw the code again while driving so i swapped back to the original prelim tune and im not sure what i did before but i havent got a single code since. im gonna try another file and see if i can get the code to pop again just to be able to rule out any actual hardware being at fault.

on another note, the car is smoking at idle like it never was before since the install of the separator. ive had a similar smoke problem before when the fresh air inlet was bad. its an oil smoke/smell and only at idle not under accelaration. im thinking either that line is screwed again or maybe i have the whole separator routed wrong because it was FOR SURE not smoking like that 3 seconds before i installed the damn thing lol

hot compression test was 150, 140, 145, 150 which has me alittle worried about cyl 2 and 3.

 

What does the MAF look like on a log? If it is a +29% look at your intake for a leak. Also if you have any fittings loose on the oil separator that will also result in a boost leak.

 

I just had a similar issue. STFT would spike to 29.7 and throw my LTFT out of wack so bad the car ran like garbage. Car would smoke because it was throwing too much fuel at it. Id get a p0101 and sometimes a lean at idle code. It was my 02 sensor.