Car is a '93 Z28, stock, looking towards maximum reliability more so than maximum performance (I feel the car is plenty fast out of the box for a street car).

I developed some sort of ignition related issue going to the corner store this morning. Came out of work to find we had a decent rain while I was in the office, was running great on my way home from work. Left the house about an hour later, didn't get 1/4 mile away before it sputtered and died. Got it fired up enough to make it into the parking lot, and that's pretty much all she wrote. I found out if I floor it, and crank for about 10-15 secs, it will fire and sound like it's running on 4 cylinders for a second, then die. Wouldn't rev past 3K. I let it sit for about 30mins, was able to fire it again, and barely kept it running with my foot to the floor, sounded like 2 more cylinders started firing, but wouldn't run any lower than about 2K RPMS. Only DTC12 showing (I know that means normal operation). I yanked the airbox, and elbow, reseated the ignition module/coil wire/coil connectors, and reconnected the temp sensor by the water pump. It fired up, was idling around 300rpm. I shut it down to put all the parts back together, and it was back to only firing for a second with my foot to the floor. Yanked the temp sensor plug again, no difference. I didn't feel like dealing with it anymore in the parking lot, and had it towed home.

I'll be looking at it closer tomorrow to see what's really going on. The car has a nearly new (less than 1000 miles) Delco opti, and MSD 8.5mm wires. Other than that, the car is stock. I'm thinking I might be dealing with a bad coil, or ignition module, but I know better than to jump to conclusions without troubleshooting.

Now, my concern. I'm planning on taking the car on a 5,000 mile cross country trip in a couple months to northern Michigan, and back here to Phoenix. I'm a bit worried about ignition system failure out in the middle of nowhere, Missouri or Illinois. If it turns out to be coil and/or ignition module, should I just replace them (remounted away from the engine), and not worry about it? If it turns out to be opti related, is switching to the Delteq or Northstar setup really any more reliable? The price of either really isn't a concern to me, as having the car die in the middle of nowhere will easily cost me more than either once towing and garage costs are factored in.

 

hmm you say the opti is fairly new? it wouldnt be ther first time one went after only 1K miles. but that does sound like the culprit. I would also make sure the ignition module is good, you can take that to advance or auto zone and they can test it. if its not the module then its time for another opti. your options arent cheap. since the optical sensor on the opti prolly went out you need to buy a new opti no mater what. there are some very good optis out there Dynatech (sp) has one MSD has one but prolly the best bet for reliability would be to buy another delco opti, try to return yours defective, and they go coil per cylinder. the ltcc setup is nice but damn expensive your prooly going to spend between 800 and 1000 to get the new opti, coils etc. if I was worried and was low on cash I would just by two opti's and bring tools to chance it out on the road. Is your water pump leaking?

 

Water pump was changed out at the same time the opti was, doesn't appear to be leaking now (nor am I losing coolant).

 

So after letting the car sit for about 10 hours , it just fired right up. It was obviously flooded, but once the fuel was cleared out, it ran OK.

I tried reconnecting the temp sensor by the water pump, and it wouldn't start again. Unplugged the sensor, took a bit of cranking to clear the cylinders, but it did fire back up. Shut it down and started it a few times to make sure, and it's good. It's back to idling around 400-500 again, although I don't have the induction bits back on yet (figured it's a good time to delete the silencer).

So I can eliminate failure of the opti/coil/ICM. It must be mositure related. Is it OK to spray water around the engine to try and track down the problem area? I was planning on getting a few gallons of distilled water, and using spray bottles, but then knowing that distilled water isn't electrically conductive, should I be using tap water? I live in an apartment, so using a garden hose isn't an option.

 

It sounds like the coolant sensor is bad. If the sensor is faulty, that can easily be the culprit in your car flooding and not starting.

 

heh...oops, forgot to mention that the coolant sensor had been disconnected since I got the car due to being bad. I just mentioned it, as I tried reconnecting it since I was in that area anyways, and it was worth a shot. Haven't yet had a chance to get to the parts store to replace it. I'm planning on taking a day off work tomorrow to fetch some parts, coolant sensor being one of them.

 

If you have a multimeter handy, you can test it and confirm: http://shbox.com/1/4th_gen_tech2.html#ect

 

I wouldnt count out the ICM just yet. its very very common to have an ICM "come back to life" so to speak. heat causes it to fail but after some time it cools and runs fine again till it heats up. keep an eye on it.

 

If you have the stock elbow, make sure that pointless tube is attached. I had simular problems, thought it was the opti unti I saw it (the tube) hanging, prior owner decided a clamp wasn't required...any way it's an easy and cheap check.

 

The pointless tube? Do you mean the silencer?