Hi, this has had me stumped all day so any help is greatly appreciated:
Bought a 94 Z28 with 120k, auto trans, and an aftermarket intake on it (AZ Special). Ran great on the test drive, bought it for 900 and drove it home. It started raining on the way back and the engine began to misfire, revs jumping everywhere at idle, and bog down, it stalled twice at idle. Got it to my house, replaced the optispark, plugs, wires, cap and rotor, and the water pump and thermostat while I was in there.

It ran fine for a day, now the engine randomly cuts out. It goes from a beautiful 5.7l roar to NOTHING, like someone slammed a carb shut. It doesnt mis, chug, bog or give any indication its going to happen. from 2000 rpm to dead in a second flat. It does it uphill, downhill, idle, highway, anywhere. After it dies it then won't start for about 20 minutes, itll crank hard but doesnt seem to get any fuel, sometimes itll catch for a second and if I give it gas itll rev up and usually stay running for another 15 minutes(if I shift to neutral and keep the rpm above 2500 at every stop light I seem to avoid stalling as much).

Thinking fuel delivery I replaced the fuel filter, the pump is definitely strong, I don't have a pressure gauge but I get fuel spraying out of the schrader valve when I press it. I think if it were low pressure itd mis or choke or anything besides going to dead. If anything it stalls more often since I changed the filter. Oh and changing all the spark stuff fixed the misfires and stuttering, but not the stalls.
any thoughts?

Ill be pulling the codes in a couple hours, but it doesnt always trigger the ses, sometimes itll trip the check gauges, sometimes the ses, sometimes nothing. Wtf?
thanks

 

hopfully the trouble codes will tell u what it is. ignition module can do that. what kind of opti did u use it should have come with cap and rotor?

 

ugh, now its not tripping any dummy lights and AZ said there weren't any codes(may just be their cruddy reader). The one code I did pull was a misfire one or something but that was before I replaced the opti so it prlly actually was. The distro box isn't here but I want to say it was summit. Had some water from the exhaust but only after I put in that dry gas stuff(side note: is that a waste of money?). As for exhaust water I havent lost any coolant, my oil isn't in any way milky and there isn't any abnormal amount of visible exhaust(a little vapor for the first minute). Another thing I noticed this time is my oil pressure gauge read a little under 80 at idle, but stayed there when I turned the car off and barely moved uner throttle so i think it may be stuck... I just want my beast healthy!

 

Im going through a simmilar problem with my 94 Z (look at the thread below yours called "MAF problem?"). Do u smell gas when it stalls or see white smoke??

 

i had a problem simular car would run fine till i got a few miles from home then either die or not start. i would go home get truck and body to pull me and the car would start run fine all the way home. had a friend at the parts store tell me to change the ignition module. that was it. not saying this is your problem but it sounds simular. i think the sumitt optis are rebuilt and in either case not the highest quality opti. ive had a gm high performance for 90k miles and no probem and have a msd in the camaro i have now, so far no problem. again im not saying u got a bad opti but i have read on here of a lower quality opti lasting a month.
ps also read on here that its a good idea to seal the cap with some high temp gold or blue rtv to keep water out.

 

rwing o2 sensors maybe? just changed mine, got 5 more mpg. mine was idling a little high nothing like whats going on with u. if it would keep running would sound like a radical cam.

 

alright, ill take this weekend and investigate all these possibilities. I'll report my findings then*grumbles angrily and stomps off to find the keys to the acura*. thanks guys.

 

I am having this same issue and was wondering if you ever got the problem fixed? Thanks

 

I never did resolve it, no. It's been sitting in my garage. Im sorry to hear the same has happened to you. I can tell you what didn't fix it: optispark distributer, spark plugs + wires, ignition coil, injector cleaning(on the machine at the shop), and computer replacement.

best of luck!

 

did you replace the coil only or the ignition modual with it?