Bryan 02TA

Ok, my buddies took off my Longtubes and replaced with stock manifolds and catalytic converters. They also took off my jantzer tb and put a 99 stock tb on the car. I don't have any exhaust from the catalytic converters back right now, have to get the y pipe and catback welded on. Anyways, after all this the car runs absolutely horrible.

If i get on the gas in any gear it just pops and bucks and just sounds bad. It will rev up but it almost sounds like the car is backfiring the entire time. Absolutely no power at all. When the car isn't in gear at idle it sounds fine, i can rev it up and it doesn't backfire or sound nasty at all, only when the engine is under a load.

My car is an 02 and i put the 99 tb on it, i know they are a little different and my cable is loose, but i'm sure that wouldn't cause this problem. I'm not throwing any codes either except for the normal ones (no rear o2's or AIR). Car ran fine this way before the LT's and TB came off. Please help

yak

iTrader: (15)

my guess is the the PCM is saying WTF.... The tb may may a large impact on the matter but, I am by no means an LS1 expert.

DravenMyers

What do you mean by the wire is loose? I would try install the your other tb and if it works ok and test & check 02 sensors to see if their ok. If you cant figure it out just take to your local LS1 specialist and have them diagnose it for you.Then just do repairs your self.

ruck98

iTrader: (1)

its probaly the pcm it dosent know what to read it going crazy when the pcm screws up that it retards your timing

01TAFlyer

iTrader: (4)

Sounds like a loose wire or plug, but you also might try resetting the pcm, to reset the fuel trims.

Bryan 02TA

well the 98-99 throttle bodies are different b/c of the cam lobe. It makes the throttle cable loose so if i hit the gas at WOT i won't get the full 100% WOT. I either need to get the 2000+ throttle body or the cam lobe off one.

I guess i could reset the pcm. I have a predator, should i just reinstall my stock tune or should i reset the pcm completely? Also, how do i reset it if that's what i need to do?

01TAFlyer

iTrader: (4)

All resetting the pcm does is reset all learned values, such as fuel tables, and trims. Im sure there are more, but those are the main things. That is all it did for me. But anyways, it shouldn't have any effect on the tuning done with your predator.

Bryan 02TA

alrighty, i'll reset the pcm today, i just don't know how to do it?

Bryan 02TA

ok, i turned the key on and unplugged the 2 pcm fuses under the hood, then turned the key off and waited 10 minutes to plug them back in. If that is the correct way to reset the pcm, it didn't work. Lemme know if that is how you do it and if i have any more options?

01TAFlyer

iTrader: (4)

I turned the key to on, removed the fuses and then left it for ten minutes (with the key still in the ignition) You may not notice any difference, I did but you never know, just something else to try. Did you check your plugs and wires yet?

Bryan 02TA

that's basically what i did, i could tell it did something b/c my idles was weird at first startup.

anybody else have any suggestions, i need to fix this badly.

flippincamaro

iTrader: (23)

disconnect the positive side of the battery for a lil while. see what that does that is how i always reset mine

01TAFlyer

iTrader: (4)

If the idle was screwed up at first, then you did it right. If nothing changes after 3-4 driving cycles, then that is not the issue.

DravenMyers

How can you reset the computer by disconecting the battery? that only works on the obd 1 system not on obd 2 which comes on all 96 and newer vehicles

flippincamaro

iTrader: (23)

Okay then how come all the shops i talk to and my computer programmer says to disconnect the battery for 15-30 mins to reset and it clears codes. ive done this several times on newer cars and works great just the computer relearns idle and fuel trims.

Bryan 02TA

ok, just tried a different throttle body off on 01 car, that didn't help any either. i am at a loss here, i have no idea what could cause this. It feels and sounds like a misfire but i'm not getting a misfire code. DAMN!!!

gwj

10 minutes of power disconnect (battery) usually will reset the codes. The capacitors will usually drain w/o power by then, at least that's been my experience w/my car. Question: I guess I missed something, are you putting your car back to stock to sell it? I've seen a couple 'a posts lately where folks have removed mods and had a hard time getting the car (engine) to run correctly.

gwj

I'm trying to think this out...you put the stock exhaust manifolds back on, IF you have deleted AIR and EGR, fine, but have you plugged/blanked off the the inlets for the stock system? Sorry if this sounds assinine, just trying to dig the details, see if there is an air leak somewhere.

DravenMyers

I did not a obd2 computer could reset idle and fuel trim adj. by disconcecting it.I do know for sure that you cant reset codes by disc. the battery you have to use a scanner to clear the codes.I think you might be confuesing the obd 1 & obd 2 systems they both have diff plug inserts.I will do more research about it being able to reset the settings for air & fuel.

Bryan 02TA

yeah i plugged the EGR and AIR back up. And yes i'm putting it back to stock to sell it. I don't know what it could be. What is the difference in resetting the pcm and flashing it? If there is a difference, maybe i should flash it?