Ok, I have a friend's 01 Tahoe with 114k miles on the 5.3. Anyway the throttle body needed to be cleaned badly because it was sticking. I said I would do that and some other maintenance things while I had it installing the lowering kit. I took the TB off and cleaned it, bypassed the coolant line to the TB, descreened the MAF, and trimmed the EGR tube. We assembled everything and poured Seafoam in the gas tank, then a half a can through the vacuum line off the master cylinder. Anyway, after the Seafoam it started to smoke like crazy meaning it had a whole lot of carbon and gunk that needed cleaning out. Since then it would ping and rattle under acceleration, that has been cleared up. Now it doesn't idle, and feels like it has a miss. I do plan on swapping the plugs after I Seafoam it again, what can I do about the idle? The SES light is on and the code says it has a misfire and an idle circuit or idle control valve problem. Is it possible when we removed the TB some how I jarred or managed to accidentally damage the sensor that controls idle? Please help, I have to give the truck back tomorrow and want it fixed.

 

That's most likely your problem, I've heard a lot of horror stories about damaging your MAF when descreening plus not much of an improvement...

 

I too have heard a lot of horror stories about damaging MAF when descreening plus minimal improvement for the risk. That element is rather fragile.

 

i would say the MAF is the problem....i would never run seafoam through anything either though, i just dont trust the stuff

 

I doubt it is the MAF but I will swap with one that I know is good. I have descreened every MAF I have owned since 00 when I read it added HP because it added a couple degrees of timing. I have never had an issue. I would say I have done about 30 of them and all my friend's have done them as well. None of them has ever caused an issue. As far as Seafoam goes, there again I have probably done 10 cars and have recommended it to several people. So I have first hand experience with 15-20 vehicles that have been Seafoamed and never had an issue. Why is it you don't trust Seafoam 454? To those that said descreening the MAF was the problem, what symptoms made you think it was the MAF and where have you heard about all these issues?

 

Im sure just the plugs are shot. If it is the MAF then you should be able to unplug it and the vehicle will run fine.

 

I've read about it. It spooked me enuff I didn't pursue it. And someone told me about it. GM had to do it for a reason. I didn't know it gained power thru addin timing, I thought it was thru increased airflow (CFM).

Then why didn't plugs create a problem before? But even so, if they're original, they shoulda been replaced awhile ago.

 

https://www.performancetrucks.net/fo...ght=maf+screen
https://www.performancetrucks.net/fo...=desreened+maf

 

Well, I have another MAF on my wife's Yukon that is descreened but works perfectly. I am going to swap them out today when I get off and swap the plugs as well. I am going to Seafoam it again because it cleaned up a whole lot. I did the Deep Creep in the intake, TB cleaner (not carb cleaner), Seafoam through the tank and vacuum system. I have some NGK TR55 plugs to toss in, just as a refresher what is the best gap to run them at was it .38 or .40 it has been awhile and I forgot

 

Descreening the MAF does NOT add timing! Theory is it smooths out airflow but I wouldn't advise doing it. my $ is that when you try a new MAF it idles smoothly again