Speed sensor?

[Osseobob]

Update…..

replaced the spark plugs.

test drove and same issue. Except that I no longer have the VSS code.

Here is the funny thing 

When I clear the code it seems to run out fine while the engine is cold but after around 5 miles and things warm up the issue returns. I can clear the code and restart the car and the issue is immediately back. let the car sit and cool down clear the code, car runs good until things warm up again.

the only code coming up now is E042c and h. This code is for the ignition.

I did install a NGK coil pack last year.

I’m beginning to think that either the coil pack or the ignition module is bad.

any thoughts?

 

[DAVES89]

Take the ignition module off your 1989 and install it on the 1990 and take it for a ride. Classic ignition module/coil pack. Second thought would be a failing crank sensor..

[Nailhed66]

In my experience, a persistent EO42 will put the car in default spark mode and the engine is running on 4 cylinders. Limp mode is drivable, but rough. EO42 is indicating a communication problem between ICM and ECM. In my case the ICM itself was not the problem. Replacing the 14 pin connector and splicing in a new length of wires ultimately solved the issue. Process of elimination, start with the ICM and work your way back was my method.

[Ronnie]

I wouldn't rule out the spark plug wires. They are likely source for this problem when the engine is at low RPM and under load, but I don't think they would set a code.

[2seater]

Swapping the entire ignition module from a known good operating car is a good idea. Eliminate what you can. There are tests on this site for the crank sensor as well. One other item I have noted on two front engine harnesses is problems with the insulation on the wires. I alluded to this on my LN3 + S/C thread and that seems to be peculiar to the '90 and newer engines. The short harness is wound through the front of the engine which ties the cam sensor, crank sensor and ICM together with the eight-pin plug from the firewall connected right behind the power steering pump as viewed from the front of the engine. This harness is not on earlier cars and might be considered if all else fails.

[Osseobob]

Hopefully my last update!

Yes, I determined that the speed sensor was faulty but not the reason for the engine problem. In my last update I explained that when I went to remove the spark plug wire from the coil pack the coil tip for number 4 wire came off and was still inside of the plug wire. Obviously the coil pack must now be replaced. By the way this coil pack was less than a year old. I used to think that NGK was quality stuff but not no more! So I figured I’m not sure if this was the original problem so just to be safe I ordered a new ignition module as well. I installed both devices today and couldn’t wait to test drive my car. drove it a total of 25 miles and it ran like a dream. This is the first time since I purchased the car last spring that the check engine light is off. And yes I have learned how to use the diagnostic in the dashboard and it really is amazing that they had this technology back then. For the record I no longer have the 89 because of financial issues back in 2017. I missed the car so much that is why I purchased the 1990 vert. however I really do miss the CRT. 

I am so excited to be back in the saddle (so to speak)

I love this car!

Glad I didn’t drive it off a cliff!

[Ronnie]

Sounds like you might have it fixed. I hope you will continue to hang around.

[Padgett]

Major problem with the CRT is that it was not sunlight readable so NG in a convertible.