First post be gentle.

I have had my 94 Z28 for about 8 months and have had my share of problems. I have fixed most of them but I am still a young mechanic.
Recently, I will be driving and after some warm-up time it seems to enter a limp mode where rpm plummets to 500 or less. I throw it into neutral and give some gas and most of the time it returns to normal. But if it does stall it will normally start up immediately. However, twice when it stalled I had a no start condition. But when I returned to it 1-2 days later she fired right up.

It’s not throwing any codes.

Tested fuel pump and 45psi @ WOT

Found that there was no spark during the 2nd no start

Replaced ICM on a hunch

Started driving with more confidence that I had fixed the issue, but the limp mode just happened again. I’m going to see if the coil is any good and maybe poke around for a bad ground. But I’m stuck guessing. Please HELP. I love that car but it’s driving me insane. I have dealt with bad OPTI (2 in fact) and I pray that isn’t in your suggestions.

 

Not poking fun at your post. Merely lightening things up a little. I feel your frustration.

1994 Z/28 LT1
K/N Cold Air
Magnaflow catback
Jegs Performance OPTI + wires

I have issues with anyone needing 2 distributors in just 8 months. First question, did the engine ever run good since you got it?

2 distributors and you're using a Jegs unit. That's a big

You say no codes but do you actually mean "no SES"? There's a difference. Some codes do not set an SES.

2 more. You said that "it goes into limp mode" after it warms up. Are we to assume that it runs good until it warms up?

If so have you tried forcing it to stay in open loop after it warms up by disconnecting an O2 to see how it runs then? Warm up problems are usually either a closed loop control problem or an electrical item breaking down after it warms up.

The last item is my previous LT1. On real humid mornings, it would never start. After the day wore on, sun came out and temperatures rose. Started with no problem. Got an idea about that too, but that's later.

Note to self: That was really weird!!!!!!!

 

This seems to be a completely random event. It will run good (and has since I have had it) and the limp/stall just seems to come out of no where.

I did scan for codes before and none were to be found.

as for being stuck in open loop, the second time this happened to me I thought something similar. I let the car run in the driveway for about 1 hr. Then I took it for a drive. No problems

as for the 2 distributors, an MSD unit failed on me

 

Just an update.

I decided to take a look at the opti since that is where my trouble has been in the past. When I got the hub pulled off and got a better look I saw a small coolant leak, as well as an oil leak.

I personally wasn't the one who replaced to opti the last 2 times and had no idea the leak was present. It would have been nice of them to tell me about it though.

Oh well no use crying over spilled oil. Got a Felpro kit for the timing cover. not looking forward to dropping the oil pan though.

Thanks for the input