nw92vert

Yesterday the engine died after running about 10 minutes when it was idling as I was in traffic. It restarted after a short crank and then died hard and would not restart. It cranked fine but didn't seem to even try to fire. I had it towed home for $100. When I got home after work I tried it again and it fired right up! I drove it directly into my garage and restarted it, again just fine. This time I let it warm up while idling (I've had very intermittent surging, hesitations and even stalls when engine is hot) and it finally starting running less smoothly and finally died again. It wouldn't restart. But this time there was a Code 41 - EST problem. So I read up on it (Helms) and it says that an intermittent problem is probably due to connections. So I checked and wiggled and disconnected what I could on the Coil Driver as well as slightly disconnected and reconnected each of the 4 connectors on the ECM.
Now it fires right up with a high idle and posts a Code 22 - TPS problem. I just replaced the TPS last weekend and drove it for about 30 minutes total before it all went to hell yesterday morning. I just now got through fully removing each of the ECM connectors to make sure all the pins are straight and the wires soundly seated. I also just removed and reinstalled the replacement TPS. All to no avail.
I had the ECM replaced a few months ago. I have to wonder if it has crapped out, if the wiring harness is having troubles, or if the TPS I just put in was not of the best quality and I need a new one.
Its a '92 LT1 6-speed roadster.

Please help. I know some of you guys have probably been here and done this before and I sure would appreciate any suggestions.


- Glenn

Jack_leg

It’s a possible the ignition module being tricky on you. Most of them go out and no more use can got out of them when they fail. None the less, I have dealt with some that were intermittent and were a pain the ever-loving-arss.

Stay with your helms, I would, but I’m waiting on the mail to arrive. I will be pondering on you problem.

jfb

Your engine quitting problem is typical of a spark module failing at operating temperature and working again after cool off. I'd replace the spark module.
Code 22 sets when the engine idling, the TPS voltage falls below 0.2 volts for longer than 3 seconds. A poor electrical connection from the ECM to the top of the TPS, or a mis adjusted idle position on the TPS can cause this problem. With the engine running you should measure close to 5 volts on the top of the TPS (verifying a good connection to the ECM) and adjust the TPS for 0.54 volts out +/- .08 volts with the throttle closed. The manual also says that if you cannot adjust the TPS for 0.54 volts, then you need a new TPS.

nw92vert

When you say Spark Module do you mean the Opti-Spark?

jfb

I was thinking in terms of my 87 which has a spark module in the distributor, but still , the optispark has to have a spark module that switches current to the primary of the spark coil/s.

Jack_leg

I didn’t mean that, but JFB may or may not. I’m talking about the ignition module on the passenger side on the front of the head. About 6” or so below the valve cover. That little bas_turd has left me stranded twice now.

It may not be the cause though; I think you can get it tested at the parts store. I didn’t get it tested last time because: I had already bought it from that store 3 years ago, and 2 it did the exact same thing last time it went out.

The OPTI-Spark causes some bad things to go down as well, but I haven’t had to deal with that just yet. I know it cost 5 times as much at one time when I was checking prices.

Here is what I'm thinking:
http://www.partsamerica.com/ProductD...pe=194&ptset=A

bogus

The "spark" module (Ignition Control Module) in this case is on the coil, not the optispark... I don't view the opti as being a "module" it's a component.

I agree, this smells of a bad ignition module. This unit is essentially a couple of amplifying transisters that power the coil.

Also, check the harness itself. They have a tendency to wear over time. Ecklers sells the harness pigtails needed to replace the coil and ICM ends.

In general, the 1992 harness is very durable. Sure, ends will fail, but the wiring is of good quality.

nw92vert

I see in Mid-America's catalog a Test Harness kit that includes harnesses for the TPS, O2, IAC, Coolant Temp, Knock and MAP sensors.
It seems like a wise investment if they're any good. And they supposedly come with instructions for usage with a digital volt meter.

Does anyone have any experience with these? If good I think they'll help me get to the root of my woes...


- Glenn

bogus

I think those test harnesses are a good idea.