Ok last week I compeltely redid my exhaust. 2.5" mandrel all the way around,Pacesetter LT's, Removed Cats, dual in/dual out single stainless muffler,and LT1 fans. I had a some exhaust leaks but had them taken care of. Spent about 5 hours tuning but Im still having a problem. After I crank the truck and let it sit for say 5 minutes in park it starts to idle REALLY choppy almost dying and it keeps doing ti untill I get it in drive and take off. What could this be? Is there a possibility that is is 02 related? Thanks for the help!

 

There is no good way to answer this unless you do some data logging of what is going on at idle. There's just not enough information here to make a call.

Are you sure all the leaks are fixed?

 

I have a high idle due to exhaust leaks, suck some atf fluid in the intake and look for smoke coming out other than at the tailpipe. Pritty sure all the leaks arent taken care of.

 

Ok I know I dont have any exhaust leaks except a tiny tiny one where the EGR block off plate goes on the Pacestter LT's. RIght when I crank it up and untill it starts to idle low and sputter the idle will jump to almost 3k rpms for a sec then drop back down and repeat untill it starts to sputter. Im gonna be doing some tuning tonite so hopefully I can figure it out.

 

idk how tiny of a leak at the egr plate that your talking about... but i was trying to figure out why i was idleing high for a while and it was bc my egr had a tiny leak like you describe... possibly that might be it. Is it making a noise? the plate i mean, like is it buzzing?

what is your idle speed set at right now? 600rpms?

 

Im finding out exhaust leaks are tricky mother ******* even tiny ones can influence performance more than youd think. I recently got some thermal weld compound from car quest. Its like a metal putty I used it to seal the egr block off I had made and it did a good job. Once the stuff is heated and cures the only way your getting it off is with a grinder.

might give it a shot on the leak

 

HMM! What is it called? Forst off to actually think that those two bolts were gonna seal that EGR spot is a GD joke-of course you can use some kind of compound but why even include the bolts! lol The best thing to do is cut it off and weld it which is what I will do eventually. Ok looks like I found my problem. Last weekend me and CRAZYCUTER4.8 tune my truck-speed density etc...(ok well CRAZYCUTER4.8 did the tuning but I did the driving! ) Come to find out we didnt spend enough time on the MAF tables and it a little off. I found this out by unhooking the MAF and it runs,idle,all around better. I could feel a noticable SOTP difference-so the MAF is a little off! Tonite we are gonna fix it though. Thanks for the help though! Its always good to know its something a few key strokes can fix! But I do want to know about the stuff you sealed you EGR plate with!

 

thermo weld from car quest cost about $3.50 anybody should have it though

 

Well ****! When I thought my MAF tables where just off real bad and that was the fix I was wrong. The MAF tables were off but I a little later when I had the MAF off and let it sit in park it started to do the same thing.(rev to like 3k and go back down rev to 3k and go back down over and over untill it eventually starts to lad up and idle real rough) So I started to check all my header bolts and one was a little loose so I tightned it but the EGR plate bolts where really loose so i tightned them-I didnt end up even using any type of weld/sealer. So we start we crank it and start to scan it-the idle problem was fixed after a minute or so and the LTFT B1 and B2 were now basiclly the same. Before B2 would be at like 22 and B1 would be at -6 .So we found the problem! Not exactly. So I drive around for a few hours logging and stopping to reflash ever so often but the last time we stop to reflash the same **** starts to happen(revs to 3k and drops and repeats-then starts to load up and wants to die-also LTFT B2 was way off again). So it seems that the 02 is acting up working and not working on its own time. I had been running 100/93 octane mix for about 6 months now and I know that hasnt helped the 02's. So I dropped it off to the dealership this morning to have my 02's swapped under warranty! ! I hope that is the problem becuase ti sure seems like it could be doesnt it? Then on the way to work this morning my air condition stopped working-it is still blowing just hot air so we will see what the problem is-it never fails!

 

Have you logged your Short Term Idle Trims (STIT) and your Long Term Idle Trims (LTIT's)? Are they near zero or are they more than +or-2? Might be an issue there.

Do you notice that the problems seem to happen as the e-fans are cycling? If the idle is set too low the fans kicking on will drop the idle even more. Then you may make the PCM start trying to correct the low idle and have even more problems.

Any of this seem to apply?