Check Engine codes jumping around

[azactor]

I need help...After having the engine rebuilt, I’ve had the check engine light come on for different things. I’ve had my mechanic use a scan tool and it gets to a certain point then shuts the testing down. Here are the things I’ve already done:
- spark plugs

- coils

- coil clips and wires

- fuel injectors

- crank sensor



The check engine light keeps coming on and I can feel the misfire all the time. The codes seem to keep jumping from either:
- a misfire in one cylinder

- a misfire in a different cylinder

- crank position sensor (I’ve replaced it 3 times and it makes no difference)



The only thing me and friends can think of is that it’s either something in the wiring harness (not worth fixing) or something with the ECU/PCM. I’m sick of dumping money into it and it not fixing the problem, but I need to the car to run correctly.

 

[gkomo]

Have you ever had your ECU home through by a company like ECUExchange?

Assuming it wasn’t doing this prior to the engine rebuild?

 

[spikedbat]

I'm having a similar problem to you I believe. My CEL comes on at times flash or stays on then goes off etc.
So after getting the codes pulled I've got a code 98. Long story short I learned something new today after being a foxbody owner for 25 years and I'm bringing my original back to life. The EEC-IV has internal components that fail from age. The capacitors leak. Corrode the PCB of the computer and cause voltage errors with the sensors or just don't allow the sensors to run at the correct voltage. I have 3 EEC-IV's that I'm going to rebuild now that I know this. I recently bought a 93GT and it came with a spare EEC. I just opened it up and checked and sure enough the caps were corroded but I had to look close with a scope to see. I'm going to rebuild the EEC-IV. It's worth opening yours up and checking if they've been replaced or not.

Email me if you need help.

 

[DadLife0724]

Plus one on pulling the brain and busting it open. Could save you alot of money. You can throw parts at it all day and it won't make a bit of difference if the comp is bad.