So, almost all the repairs on my 94 TA are done. Started it the other day after getting the opti and what not hooked up, and it started fine. fired right up, sounded good. Last night, after wiring up the new foglights, we went to start it, and it would not start. eventually, I got it started, and it is running like crap. it has a terrible misfire. here's the low down:

What we replaced and what with:

Replaced the "bad" GM Opti with a new Duralast Gold.
Replaced factory GM wires with new Summit Racing 8.0 mm wires.
Replaced all eight original plugs with new NGKs.
Replaced the original ICM with a new CarQuest one.
Replaced the original coil with a new MSD coil.
Replaced the two year old CarQuest alternator under warranty
Replaced the two year old Interstate battery under warranty.
New AC Delco waterpump (yes we got the o-ring on)
New Duralast thermostat
New GM thermostat housing
Replaced torn Gm elbow with a TrickFlow aluminum intake elbow
Replaced cracked GM intake box with a TrickFlow cold air intake

Other unrelated stuff:
New eBay foglamps with halos
New GM fender
Repaired front cover

At this point, I'm at a complete loss as to where to go from here. The original problem with the car was that it was becoming very hard to start, would run rough when first started, missed badly for the first minute or two of running, then would clear up and run strong. One day, it stalled on me going down the road at about 35 mph, then would not restart. It was raining that day. Also found that the thermostat gasket had been leaking and fluid was getting on the opti. This led to the opti diagnosis and all this work we just put into it.

Now, it again doesn't want to start, and misses very badly once it does start. Sometimes, it won't start at all, no matter how long or how many times you crank it. when this happens, it smells terribly of fuel. When it does start, it will not stall, but never clears up either, it continuously misses. we found last night that if you unplugged the harness from the second injector back on the passenger side, it doesn't change anything, while unplugging any other injectors cause the engine to stumble even more. Today, I swapped that injector (which looked pretty dirty when i pulled it) and the first injector (which looked extremely clean when i pulled it) on the passenger side, in hopes of finding the injector to be bad. It changed nothing. unplugging the second injector back still doesn't affect the engine while unplugging any of the others does.

I also hooked my fuel pressure gauge up to the rail. results were as follows:
initial pressure on hook up after sitting all night: 0 psi
pressure on key on, engine off: 41 psi initially, but slowly dropped as i let it sit for a minute. dropped to 37ish after about 3 minutes.
at idle: 38 psi.

Before, the only code that the car ever threw was something about the EGR system, but it did that for a long time before I ever started having problems. Now, the MIL is not coming on, though it does light up during system check on start up, despite the obvious miss.

The only other mods to the car that I can think of mechanically are the high stall converter, a hollowed cat, and a magnaflow muffler.

At this point, I'm stuck thinking towards bad wiring to that injector, or a bad cylinder on the engine. any other thoughts? The gas in the car is 8 month old premium, but it wasn't old when i parked the car for the winter when all this started happening. also, i started the car up and moved it a few times over the winter, and it fired right up and ran great when it was like 0 degrees out.

Thanks guys!

 

update: other injector connectors are pulsing ground. this one has no ground....

 

and another update: the ground wire seems old and sketchy (go figure) for cylinder number four. voltage changes slightly depending on position of the wire. also, cylinder number six is also experiencing the same problem with the injector. possibly a head gasket??? there is no evidence of it in the oil though. any other thoughts?

 

Here is a picture of a plug from each bank. The whitened one is from cylinder number one. It seems to be running fine. the blackened one is from cylinder four. it is the one we were questioning. Also did compression testing, and all cylinders came up around 150 psi.

 

If you can't make a stock setup run a swap is WAY WAY WAY beyond you.

I would take a look at the plug wire on the dead cylinder, bet you melted it.

Many of your parts choices are really bad, wouldn't surprise really anyone here if the module crapped out already.

 

ok, the ls swap was meant to be humorous. can you expand upon the bad choices?

 

we checked all of the wires: none are melted. also, all cylinders have spark.

 

Last update of the night. We swapped the old ICM back into the car (I thought I had replaced it just as precautionary maintenance since we were replacing everything else). I will have CarQuest warranty it for me on Tuesday and try a brand new one.

 

just as a suggestion, when swapping injectors swap them to the opposite bank. The PCM does not make individual corrections per cyl but by bank. If a injector is causing a lean or rich condition in a cyl swapping it to a different cyl in same bank looks the same to the PCM. Also, if it smells rich have you checked the coolant temp reading seen by the PCM? Different sensor than what is used to display on the gauge. That can effect the fueling...I'd check that injector harness and maybe do a leakdown test on that cyl fouling the plug.

 

I will try swapping the injectors to the other side tomorrow. I appreciate the advice. I have not checked the the reading on the PCM yet because my personal scanner only works with OBDII. Tuesday I will bring the Determinator home from work and scan the system if I haven't resolved the problem yet. Also, a leak down test is on my list to try tomorrow, as well as unwrapping the injector wires on cylinders four and six to check for weak points and running new wires if necessary.

 

problem solved: four and six had gotten crossed. I noticed it this morning and managed to wiggle my arm in there and swap them. my buddy had previously been doing everything with the plugs and wires because he has much thinner arms. Now that everything is firing in the right order, she fires right up instantly and has no misses. i feel stupid, but lesson learned: personally double check everything. Thanks for the input guys!

 

I love it when the fixes are simple.

Always start with the basics!

 

I think everyone dismissed that because you had said it started up fine once. Otherwise that should be first thing to check since plug wire wire routing is so tough on these.

 

glad we had a happy ending here.

 

Was there any backfiring when the wires were crossed? Doesn't stand to reason two affected cylinders would keep the engine from running.

 

now that its running. do your self a favor and sell it and buy a LS car

 

Yes, that way you can be an even faster keyboard racer

 

we had pulled the wires back off of the plug side to reorganize them after the test start because they were going to rub on a pulley. it was the FIRST thing I asked my friend, and he assured me they were on correctly. so I ha moved on.

 

Can anyone expand on my "really bad" parts choices that 96capricemgr mentioned earlier? If I made bad choices I'd like to know what they were and why they were bad so that I don't make the same or similar mistakes in the future.

 

Questionable opti, icm, and coil. You're really gambling with an aftermarket distributor.