98 T/A....bought about 6-7 months ago. 104,XXX miles. Lid, headers, full exhaust, and thats really it. AIR and EGR deleted. (and new bosch O2's)

Codes po171/174 just started showing. Thought I initially found the problem with the PCV tubing. It was AFU! Repaired everything, rerouted, reinstalled. Cleared the codes with a hand held and drove off. A few cycles later "SES light". I found a faulty repair in the job I did to begin with. Fixed it, and drove off. I've been chasing this problem and I'm going crazy. The car just doesn't seem to have much mid range. WOT is fine. Idle sometimes sinks down to about 500 rpms too. I installed a new air filter and cleaned the maf. Still keeps showing up. I havent checked my fuel pressure yet. I also haven't checked for exhaust leaks yet either. I did take the maf off the car, fired up the engine and put my hand over the throttlebody, letting it almost die. I heard obsolutely NO vacuum leaks....My friend is going to log fuel trims for me this weekend.

Btw, I've read every thread on google about this...most threads never finished, others had simpler solutions

 

For those that don't want to look up the codes it is lean both banks. Even though you cleaned the MAF it could still be out of calibration. The problem has to affect both banks and the pcm is adding 25% extra fuel and still seeing a lean condition. Check fuel pressure underload (driving down the road)

 

You could have bad intake gaskets. Maybe spray some carb cleaner on the sides of the intake while it is running and see if the idle changes..

 

Spray around the intake and watch the fuel trims. Alot of times you can barely tell the idle change but you will see it on the trims immediately if you have a leak. Do it from a cold start and watch it as it warms up.

 

this^

 

Alright I will try this first thing Sat morning. A friend of mine thats going to HPtune it this weekend also suggested that "maybe" the original tune can't compensate for the much colder intake air (average 35-55 degrees F) lately. I didn't have this problem when it was warm outside. You guys think thats legit too?

With that being said, we all know what cold weather does to seals/gaskets/orings...so it very well could be the intake gasket

 

Also, Since I'm buying the credits for HPtuners, would there be an reason why I couldn't delete the MAF before, during, or after the tuning process? I've been reading that 98's are 50/50 about running just MAP with SD

 

Ok, tomorrow is tune day.

Today, I took out the IAC. It was sticky. I cleaned it and let it dry. Put a new gasket on it and reinstalled it. I also noticed that one of the ports for the already deleted EGR, one of the caps that was used to cap off both sides of the TB wasn't there. Capped it off and took it for a drive.

Idled great, mid range felt alot better, and WOT was stupid fun!!!

I really hope tomorrow goes good. Gotta do a TQ converter on Turbhoes tranny before all the fun starts

 

egr port on tb? what the hell?

 

Sorry, TB bypass is what I ment not EGR. Its been a 28 hour day....I had watch last night and haven't been to bed yet

 

Well, my buddy's torque converter took too long and didn't get to do anything to my car

 

I work at a dealer here in jax chevy we have been having issues on the trucks with the intake gaskets leaking due to the cold weather we have done alot of these fuel trims will be high and then level off as it warms up. if you want I have a scanner you could come by and i could hook it up and check it out for you. problem is they leak at the botom which is hard to detect

 

EVERYBODY has been having issues with intake gaskets leaking. Between the GM's and the Ford's we keep a couple on the lot with intake gasket problems.
But.. it's easy money and it helps pay the bills. God bless these new and improved designs we have now!

 

Thanks for offering up some help! I'm borrowing a MAF from another member on here today and I'm gonna try a put some miles on it. I changed out all my plugs yesterday and changed out the PCV valve just for the hell of it. Now when you say on the bottom, you talking about the back or front? Could you pm me your name and #. If this other MAF isn't going to do the trick, I will give you a call. Thanks!

 

New MAF did the trick!!

 

[QUOTE=DynoDR;14371164]EVERYBODY has been having issues with intake gaskets leaking. Between the GM's and the Ford's we keep a couple on the lot with intake gasket problems.
But.. it's easy money and it helps pay the bills. God bless these new and improved designs we have now! [/QUOTE
I miss the fords I made so much money extracting spark plugs out of the 3v motors it isnt even funny best 100 dollar tool i have ever bought now its sits lonley in the tool box

 

[QUOTE=Predator T/A;14374347]You got that right! Pulled 5 out of 8 a DIY'r broke last week and a had to insert a few on the old 4.6 in a GT and a V10 Expedition.

Pulling 6.0 Diesel heads tomorrow... I COULD live without that one!

Junkie.. Good to hear you got it fixed!

 

Thanks DynoDR. So far so great!!! Man the car feels so much better...more fun too lol! Also just started treating my gas with Lucas injector cleaner. With the new plugs, maf, and cleaner, I'm trying to squeeze out another 2-3 mpg's