Hi! New here, and some questions...of course

[Randi]

Hi! I've been lurking on this site for awhile. I usually come to search for answers to my Tahoe questions. You guys seem to know alot :thumbsup: I wanted to register so I could see the pictures of all your trucks. Nice! I have an 03 Tahoe LT. We haven't done much too it, just air intake, exhaust, and some tires/wheels (20's with 305 on the tires) I also have a few questions I couldn't find answers to, so here goes...

We put a new K&N intake on as soon as we bought it, and a few weeks later we added a Flowmaster exhaust. As soon as we did that the engine light came on. My husband took it to Auto Zone and got the codes. It had something to do with Oxygen/Fuel mixture?? Has anyone had this happen? What do I ned to do to get that engine light off?

My other question is about using E85. We have a station here that sells it, and I thought I would give it a try. I'd like to try and be less dependent on foreign oil . Is it OK to use it with the after market air intake and exhaust? I wouldn't think there would be a problem, but want to check so I don't mess anything up. I love my Tahoe too much to do that!

TIA!

 

[HitandRunDriver]

Welcome to the forum!

I had the same thing happen with my engine light after I had my magnaflow exhaust installed. I think your ECU isnt used to having the exhaust on yet due to less backpressure in the engine. My light turned off within a couple days, i think it should eventually adjust the air/fuel mixture.

As for E85, you need to be sure your engine is compatible with it (FlexFuel) but having the intake and exhaust arent going to mess anything up. One thing though, although E85 is cheaper and better for the environment, ethanol is not as volatile as gasoline so your gas mileage will take a hit of around 10%....someone correct me if i'm wrong here

 

[Randi]

Thanks! The engine light has been on since about Oct. we thought that once the weather warmed up it would go off (we were also having a problem with the car shaking when i was stopped at a light. once the engine warmed up it would stop) Someone told me to get it calibrated. Do you think that would help??

 

[MadMedwyn]

Hopefully it's something as simple as your mass airflow sensor. Its the electrical piece thats located on your intake tube near your filter. Pull that out and spray some CRC MAF cleaner on it. There's a good chance that may do the trick, and it cant hurt.

 

[Randi]

We did that too. It did help the shaking a little bit.

 

[MadMedwyn]

Hmm the next easiest thing is to clean the throttle body. They make throttle body cleaner so you just have to take off your intake tubing to get to your tb. Spray some of that cleaner in it and wipe as far as you can reach while someone is in the truck with the gas pedal down to keep it wide open.

That might help the shaking but I doubt it'll shut off the check-engine light.

 

[Randi]

Thanks! I'll have Dh give that a try!

 

[Gordo]

you know it could just be the gas cap too but if you took it to autozone and they said it was the oxygen/fuel mixture then i dont know I say the gas cap because I have a cousing with an 03 or something tahoe he had the issues where the service engine light came on for few months. He kept changing pluggs and wires and oil very ofter ahead of schedule it would fix the problem or so he thought so we got the codes read and it was just the gas cap. But the truck would vibrate at idle and felt very heavy when driving around. after he change the cap and poured some 44k in the tank he was good to go again and no problems since. You will probably spend $30.00 on doing this with the gas cap and the 44k but its worth a shot. Or take it back to autozone to get the code read and see if that could be it.

 

[Randi]

I think I'll take it back to Autozone today. If it is the gas cap, is it just because it is loose? I'll try the small repairs first, and then move on to the big ones! What about calibration? Someone that had a Tahoe a few years ago told me that he had to calibrate something after their intake/exhaust was installed. It doesn't sound like anyone here has had to do that though.

 

[Gordo]

It could just be that its loose but if you have had the light on since october its probably just a bad cap. did you take it to autozone today what did they say?

 

[Randi]

Yeah I took it in and got 5 codes back. 3 for oxygen sensors that are bad, and 2 for a lean fuel mixture. Now I'm really wishing it was that gas cap. $30 is a lot better than $240!!