# Rich fuel mix



## Red Devil (Dec 31, 2006)

HI
I have big problems with my -06. It starts to go rich on the fuel mix and after a while the O2 sensors gets sooty and thats when i get a code. The problem often appear when it is cold and rainy. Drove for two months this summer without problems after the change of O2 sensors and new MAF + new computer. The mecs did not have a clue what to do so they started changing things that where plausible. This however did not solve the problem and now the car leave a smoke trail and the idle is irregular again. The only mod is American Racing headers and a short shift. Now I´m starting to think that it could be some temp sensor problem and that the computer gets the idea that the car i cold and needs a richer mix (as when you make a cold start)

Anybody recognize this or similar problems? Please write if you have some experience of the same kind. 
Regards Tomas


----------



## 87GN06GTO07IRL (Aug 10, 2009)

Did you get a tune after the header install?


----------



## mtjoy (May 3, 2007)

What codes are you getting? Has your car been tuned? Are you running an aftermarket CAI? What MAF are you running? Is it a stock replacement or an aftermarket one?

I had an issue with my MAF calibration after a tune and it basically created an unmetered air situation where the ECM thought there was more air coming in than actually was. As such the ECM would richen up the AFR and it would throw a lean code on each bank.

I did the same as you and started changing sensors and the MAF to no avail. I finally took a close look at my tune (w/ hp tuners) and found the MAF calibration was off. Corrected this and it resolved the situation.

You may went to check for air leaks around your CAI and intake manifold. With the car running spray down the CAI, throttle body, and intake manifold with carb cleaner and see if the idle changes. If it does then wherever you are spraying the carb cleaner is where you have an air leak. Also check your vacuum lines.


----------



## Red Devil (Dec 31, 2006)

*Thanks*



mtjoy said:


> What codes are you getting? Has your car been tuned? Are you running an aftermarket CAI? What MAF are you running? Is it a stock replacement or an aftermarket one?
> 
> I had an issue with my MAF calibration after a tune and it basically created an unmetered air situation where the ECM thought there was more air coming in than actually was. As such the ECM would richen up the AFR and it would throw a lean code on each bank.
> 
> ...


Thank you for the advise. 
When I put on the Headers I did a HPtune. The tuner got it to go nice after that but the problem returns after some time. Then we did a new tune and all was perfect a couple of months. It is not showing any codes when it is starting do go rich but after some time it will indicate problems with the O2 sensors (they stopp functioning due to to much clogging)
The mechs have been checking the air intake for leaks but found nothing. The first tune hade a CAI added but since then I have the normal air intake (with a tune) Now there is no tune only a complete new data box. I´v been thinking that there is a problem with the temp sensor or the thermostat?
But I,m lost now. Took it for a ride on the freeway when the weather was nice and it was working all right and no codes. When it is cold weather and rainy it seems that this problem comes back but i´m not shure. Will this give you any new ideas?
Regards Tomas


----------



## Poncho Dan (Jun 30, 2009)

Red Devil said:


> Thank you for the advise.
> When I put on the Headers I did a HPtune. The tuner got it to go nice after that but the problem returns after some time. Then we did a new tune and all was perfect a couple of months. It is not showing any codes when it is starting do go rich but after some time it will indicate problems with the O2 sensors (they stopp functioning due to to much clogging)
> The mechs have been checking the air intake for leaks but found nothing. The first tune hade a CAI added but since then I have the normal air intake (with a tune)* Now there is no tune only a complete new data box.* I´v been thinking that there is a problem with the temp sensor or the thermostat?
> But I,m lost now. Took it for a ride on the freeway when the weather was nice and it was working all right and no codes. When it is cold weather and rainy it seems that this problem comes back but i´m not shure. Will this give you any new ideas?
> Regards Tomas


You need a retune with a new ECM, and don't go back to the original hack who did it the first time... it sounds like they either tuned you using LTFTs (stock O2 signal) instead of a wideband, or they didn't disable VE lookups when calibrating your MAF.


----------



## jpalamar (Jul 22, 2008)

You have a bad tune.


----------



## Red Devil (Dec 31, 2006)

Thank´s a lot you guys 
I´m going to try a new tune.
By the way do you think a Procharger fit with the standard program that follows the kit will help?
Tomas


----------



## jpalamar (Jul 22, 2008)

I really think you should get it retuned properly, especially if you go FI.


----------



## Red Devil (Dec 31, 2006)

Thanks again!
A little uppdate. When I took the car for a ride some days ago it was raining and cold out.
The car started all right but as soon as I started to go faster and pulled the throttle more it started so smoke grey smoke like a battleship laying out cover....
I did not get it to go well at all that day. Did some full throttle acc from 2000 to 4000 revs but it did not help. 
Next time I whent out it was sunny and warmer and dry tarmac. Guess what? the car was spinning happy and no smoke! Strange indeed.
By the way. There is no tune att all in the car after the change of data box. It is the original GM programming in the box so it makes me think that it is something different that goes on. 
Regards Tomas


----------

