blakern

iTrader: (9)

I got me a 95 Z28 back in Febuary to daily drive. Its got about 77k on it. It seemed to have an intake gasket oil leak so this past weekend I pulled the intake off replaced the gaskets and also changed the plugs and wires. The car ran fine before I tore into it but not so good now. The car seems to have a slight miss at idle and a miss under load. The miss under load is usually when the cars in overdrive with the converter locked up, give it a little gas and it misses as it accelerates. From 1500-2000rpms. Over 2000rpms it seems fine.

I did a few searches and found that a few other people have had simular problems but the threads just end with no solution?? When I pulled the coolant lines out of the throttle body some coolant might have ran down on the OPTI.

I work @ a shop and we scaned it and no codes, no missfires reported, all sensors seemed to be working correctly, couldnt find any vacum leaks,,,,

What should I do?? Pull the water pump, check the OPTI for leaks??
This is really frusterating...
Please help me,, PLEASE..

IronOutlaw

iTrader: (4)

crank the car up at night and check for arcing of the plug wires. sometimes its hard to see so look close. i dont think its the opti. check small things first.

blakern

iTrader: (9)

i guess i dont know what you mean 4 sure.

IronOutlaw

iTrader: (4)

do what? all im saying is you may have a wire to close to the header/manifold. i was using stop plug wires on my car with headers and found that they had gotten too hot and were arcing, causing my miss underload, in overdrive just like you have. i couldnt see the arcing from far back and had to look very close to the heads of the wires to see the arcing.

blakern

iTrader: (9)

was ur car missing @ idle also?? Its almost dark.. Im going to put it up on my lift now. I hope ur right.

IronOutlaw

iTrader: (4)

no miss at idle. just lugging in overdrive and way up high in the rpms. i bought oxygen sensors, a coil, and oxygen sensor extensions before i found out it was the wires. before i just popped the hood and looked under there and say no arcing so i just ruled that out. about a week ago i looked very close and had 4 wires arcing on the spark plugs and i could BARELY see it.

blakern

iTrader: (9)

im looking... What does it look like?? I should see a faint spark leaving the plugs/wires??

IronOutlaw

iTrader: (4)

just a little light sparking up is what mine looked like. any kind of spark that shouldnt be there. mine was very faint and i had to look close to see it and it was pitch black outside.

blakern

iTrader: (9)

dang man i couldnt see anything. I have stock manifolds so you cant really see the top of the plugs very well. I'll keep checking. Lets say they are arcing, if i pull the plug wires off will the boots have like little burn marks on them??

blakern

iTrader: (9)

Any other ideas from you LT1 experts. Im really getting tired of this, ive spent the last 4days under this thing and really miss spending time wit my family..

ThoR294

iTrader: (6)

make sure you have no vacuum leaks, hook up a gauge and make sure its alright. make sure your wires are on the right plugs also

OddballLt1

iTrader: (1)

I had a problem like this with my 96, ended up being the MAF. It had a bad miss at idle and also low in the rpm band. I swapped sensor and it is fine now. Try unplugging the sensor and see how it idles and runs, if its better then before, then it should be the MAF

blakern

iTrader: (9)

We checked for vacuum leaks and couldnt find any. We also monitored the MAF and it seemed to be working fine, but im going to unplug it this mourning and see how it drives on the way to work.

blakern

iTrader: (9)

well I unpluged the MAF and it didnt change anything. Once it warms up it still has the same unconstant miss under load in OD with the converter locked, between 1200-1800rpm. Still idles crappy as well.

Anyother sugestions??

One of our mechanics mentioned that my new plug wires are touching, and that they might be crossfiring?? Anyone ever had this problem? I ordered some wire loom to cover each plug wire but I think that the factory wires were touching eachother in places and I didnt have any problems then.

sweet-94z28

iTrader: (30)

I had the same issue after doing my intake. It turned out to be that my PCV hose was cracked and it had a slight vacuum leak. A few months later, it came back so I put a new set of plug wires on it and now it is smooth. I bet you are getting a crossfire because on mine, you could see the wires glowing with a spark charge at night.

con_fuse9

Car would buck at 5000rpm, every now and then - mostly when the engine was hot. Felt like traction control kicking in - or maybe fuel cutoff (I thought, or hoped, that it was just my tack too slow and that it was really happening at 5800rpm). It started getting worse - down at about 4000rpm....

1) Only happened under load
2) Only happened when engine was hot.
3) Only happened at higher rpm.
4) Fuel pressure O.K. - and O2 sensor O.K. (From scan tool). So it wasn't fuel issue. Besides, when cold, the motor is supposed to run rich and the fuel issue would be worse.
5) So its air or spark... probably not air....

Bottom line, my ignition system wasn't putting out the required power. It was a combination of things.

1) Spark plugs - some of the double platinum spark plugs had lost the platinum on the ground strap. This made the gap close to .070 - that's a big gap to jump - note the stock ignition system jumped this gap just fine most of the time... Don't ever use double platinums and expect them to last 50,000miles.
2) Corrosion on the ignition wires - especially the coil wire.
3) I also replaced the ignition coil. It was O.K. when I Ohmed it out, it just looked 'melted'. When I got the new one it didn't look much better. Probably could have cleaned the old one (the terminals).
4) Reassembled with contact grease.

That was at 70,000 miles. It has now started again at 120,000 this time I have the cash to put in a full MSD system (digital 6), new wires, new plugs, new coil etc.

I'm just seeing if I can get some headers while I'm at it.

blakern

iTrader: (9)

Well I spent another evening under this LT1 of mine. I pulled off each plug wire and checked them for burns and then covered each pull wire with wire loom. So im pretty sure the wires are not crossfiring. Its missing really bad now when in OD, almost to the point where it has to down shift to 3rd to accelerate. One thing that I did notice was a little coolant on the swaybar?? But I cant tell where it came from..

Please someone help me..

Any ideas????

blakern

iTrader: (9)

Haha, you sux. It took me 3 different nights but SHES ARCING!!!!!!!!!

Shes arcing from the coil, plugs, cap, everywhere. Whats causing this??? I dont think their getting hot. I have stock exhaust manifolds and taylor 8mm wires. If theres alittle coolant in the OPTI could this cause ARCING????

ThoR294

iTrader: (6)

bad wires. poor routing of the wires

blakern

iTrader: (9)

My wires are brand new. I could see getting one bad wire, but I have many spots acring. I wish I could just try putting my old wires on but I broke 2 or 3 of them.

What would you consider poor routing of the wires? I routed them the only way I could see 2 without them getting burnt or caught in the belt.