mountainman

So... I have been fighting trying to get my 04 LQ9 to run properly. Have aftermarket stand alone harness and computer. Motor will start..stumble and die. If I put my foot on the gas pedal it will run, rev up, and if you hold your foot on the gas pedal it will run for as long as you want. take your foot off the gas and it stumbles and stalls.
So I was doing a heat cycle figuring that maybe it needs to "learn". Because sometimes it will run for 15-20 seconds stumbling around 300 rpm. I had my scanner plugged in watching the values as I was bringing it up to temp. AS SOON AS THE COMPUTER TRIED TO TURN THE FANS ON, at 196, the stft went crazy into the negatives (-15-25) and threw a running rich code on both banks? I've had the rear O2s deleted, but my scanner reads a value of .445v and 99.4% for both of them (bank one and bank two) does that seem right?

IDEAS??????

Russ K

iTrader: (1)

That means your fueling is very rich. What mods, cam specs? If your using Hp Tuner's, I can look at your tune/log. Is your fuel pressure higher that stock? Larger injectors?

Russ Kemp

mountainman

Completely stock LQ9 from a 2004 cadillac escalade. DBW, only mod is headers and a cold air intake. Supplier used HP tuners, but supplier wont give me a copy of the tune used, so I can only scan and guess

mountainman

Its in front of a turbo 400 using a dakota digital VSS

murphinator

iTrader: (2)

at that point its going from open loop to closed loop and trimming fuel like crazy because its rich , in open loop its not looking at the 02's and doesnt trim..

mountainman

I've had the rear O2s deleted, but my scanner reads a value of .445v and 99.4% for both of them (bank one and bank two) does that seem right?

mountainman

So its taking absolutely no info from the o2's until 196 degrees?

murphinator

iTrader: (2)

rear (downstream ) 02's are only to monitor emmisions , its the front (upstream) that monitor and in unison with the pcm maintain stoich.

I havent used my tuning software since my tuning laptop power outlet broke so I cant offer to look at your tune and my thought process regarding tuning is not as sharp as it was when using it regularly but the first change I would suggest is getting a tuner yourself or get friendly with someone local that has one so your not so tied at the hip to your tuner that you cant do anything without him that has to be a helpless feeling.