Hello all, hope I have info that will help point me in the right direction. So here we go, 2 weeks ago, we did plugs and wires on a buddies 96Z. Got done the car ran great. Fast-forward 1 week, he drives it to work, car runs great, gets in to it to go home, and bam hella misfires check engine light.

So we figure it has to be something with the plugs and wires, checked them all, and no issue. No arching, all are on the right plug ect ect.

We are going to test the opti, and the coil next, am I missing anything, or is that about it?

Also the smell of fuel is quite abundant, at the exhaust (more than normal) and it is quite poppy (more than normal for SLP1).

 

Burnt wires. Pull ALL boots and check them as well as the wires themselves. Any brittleness, replace. You have to feel and not just look sometimes the burnt area is where you can not visually see it.

 

going to pull them all off, will advise how it goes.

 

If you have an enhanced OBDII scan tool, it will tell you which cylinders are misfiring.

 

Hey All, thanks for the replies.

This is my ride, is it still possible for the wires to be burned? I have Taylor FMJ wires?? They are practically brand new, or thinking closer to the boot area? The misfire is very appearent at idle but as you roll threw the throttle under load it jumps in and out of the misfire, and if you try and stab through it falls flat on it's face. Just a little more info.

 

If you don't have a scan tool, and everyone should have at least a code reader, go to Autozone and have them pull any codes.

Yes, the boots that go on the plugs can burn. When the engine is cold, pull the boots off and look at them.

 

A friend of mine has a scan tool that I'm going to borrow tomorrow.

 

Ok, so the codes that pulled were; p0100, p0122, & p0300. This car ran perfect the first couple of days that we had the tune up done. What did I do?

 

unplug the maf and see if it makes a difference. no difference- the sensor is bad or the pigtail/wiring has a problem. Your tps is low as well so you need to play with the throttle stop screw or slot the sensor. I would fix those codes and then address p0300 since it may be related to the previous 2 codes.

 

Johnnyb is correct with code P0100 being MAF problem, code P0122 being TPS voltage low, and P0300 means multiple random misfires. Correcting the first two might fix the P0300. I've seen a lot of posts about the P0300, but it seems as if no one ever posts what their particular fix was. In my case, when I've had the P0300, it's been the plug wires.

 

OK, so while running the car I unplugged the MAF and there was no change whatsoever? what is supposed to happen when i unplug it? also a friend had an extra maf that we swapped over and there is no change in the misfire either. could the plug going into the maf be bad? if so, how do i fix it?

 

If I unplug the maf on my car it wont start or run; it dies right away.
If my memory serves me correct, there should be a pink wire going to the maf pigtail that should be getting 12v. you may want to check that (search to make sure thats the correct wire first though ) search "p0100" and you should be able to come up with it. Hope that helps

 

So i changed out the MAF pigtail with an extra that i had and it runs the exact same way? Now i have changed both the maf and pigtail. Plus I am Getting 12v to the pink wire. My car starts up and runs with the MAF unplugged.

 

Does it still have P0100?

Did you check the TPS voltage? P0122 sets when the TPS voltage drops below 0.20V. It has to be in the range of 0.20-0.90V at closed throttel for the PCM to set the baseline 0% thorttle position reference. With the voltmeter across the blue and black wires, key on engine off, measure the closed throttle voltage, then slowly rotate the throttle and watch for a smooth increase in voltage to WOT. There should be no spikes or dropouts as you rotate the throttle, and the WOT voltage should be about 4V above the closed throttle voltage.

As was mentioned earlier, if you have access to a scanner with "GM enhanced parameters", you can scan the misfire count by individual cylinder. That will tell you if its a truly random misfire, or mainly in one or two cylinders.

 

OK, a little update. So i pulled all the plugs, and most of them are oilish and smell like gas on the drivers side and the passenger side are white in color? Could i have a bad cat? The only reason i think its a cat is because the misfire is sooo bad it can barely be driven and the exhaust just sounds clogged, I bought this car completey stock and in desparate need of a tune up. So i changed wires, plugs, fuel filter, did a Moroso CAI and lm1. My thinking was with all the "new" flow and power the cat couldnt handle it. Or am I just talking out of nowhere?