Driveability Issue after LT and exhaust install; *Update*

[BigSkySN95]

I just finished putting BBK LT's, O/R H-pipe, and Magnapacks on my '95 GT which only had a ebay CAI, 65mm TB, 14 degrees of timing and underdrive pulleys before. The car ran great when I parked it but now I have a nasty stumble just off idle and if I'm cruising along in a tall gear at lower RPMs and step down on the loud pedal. Do you think I need a tune already or could it be something else? I changed spark plugs, wires, cap and rotor last year when I cleaned my MAF and IAC.

 

[94IVGT]

Re: Driveability Issue after LT and exhaust install

a tune would be a nice investment, but with the new mods it wouldnt be necessary to need one. sounds like you may have another problem.

 

[94Pro-5.0]

Re: Driveability Issue after LT and exhaust install

check your ground cables and vaccum lines.

 

[BigSkySN95]

Re: Driveability Issue after LT and exhaust install

I didn't see any ground or vacuum lines get disconnected but I'll double check. The idle is a bit rougher too, I think I'll go through the whole idle surge remedy first and at the same time check for vacuum lines or grounds. Any tips on where to look for vacuum lines that can easily get disconnected?

 

[ryclef331]

Re: Driveability Issue after LT and exhaust install

There is no way you need a tune right now. Not with those mods. Adding an exhaust isn't going to affect the car that much.

 

[Blck945.0]

Re: Driveability Issue after LT and exhaust install

Did you disconnect the battery and let the memory clear? When I did mine I disconnected the battery to let the memory clear and the car ran rough for about a day and a half until it adjusted. Now the only problem with the car is when I first start it and try to drive it, if I don't let the car warm up a little it runs like hell (surging idle and wants to stall) until it warms up. I'm guessing it's the O2 sensors not warming up fully when it runs like shit, when I first start it since they are moved farther down in the header. But if I let it warm up a bit it runs great.

 

[BigSkySN95]

Re: Driveability Issue after LT and exhaust install

I did notice that it runs better when it is fully warmed up and I had the battery disconnected for 3 months so memory shouldn't be a problem. The idle quality isn't as good as before, much rougher and surging. It also seems to have less power than before, you really have to bring the revs up to turn the tires over and getting sideways on dry pavement is much harder.

 

[Blck945.0]

Re: Driveability Issue after LT and exhaust install

I'd check to make sure that the vacuum lines behind the smog pump have a good connection (I disconnected mine when installing the LT's) and that none of them are burnt or hanging down on the header. I'd also check to make sure none of the header bolts backed out. I kinda noticed a loss in power on the low end but nothing like your describing.

 

[BigSkySN95]

Learned a valuable lesson on this project. If you drop a spark plug on the ground, don't reuse it even if it looks good. The porcelain had 2 vertical cracks on it and was misfiring. I didn't see them after I drop the plug but now that they are black I sure can see them. The car runs like a top now and idles almost as good as the 5.4 in my pickup.