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Misfires at cruise, short video and a log attached

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Jungy

15+ Year Contributor
97
2
Nov 2, 2006
Saint Cloud, Minnesota
I'm still getting really bad misfires and hesitation under 3k rpm and need help figuring out what the problem is because I've done 3 weeks of trouble shooting so far. This is what I've done so far to no avail:

replaced plugs
replaced wires
swapped out coils
swapped out ign transistors
ran the car in both SD and w/ a 2g maf
added grounds from the neg batt terminal to the sensor grounds and block
Swapped out CAS'
ensured base timing was correct and also that the CAS wasn't 180 out
checked 6 bolt swap wiring
checked all injectors at idle

YouTube - DSM problems

I'm running Bosch 1600's and was recommended to try stockers but I don't have stock injectors to test with, I forgot to mention that I'm running e85, but I tried lowering the base fuel press to 30 psi to get my injector pulsewidths up and still the same issue. I also checked my mechanical timing and everything is correct. Do you think it could still be injectors? Any other suggestions?
 

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Hello, I don't have alot of experience with E85 but I did notice that in your log your combined fuel trim seems really sluggish. I am just going off of the way my ecu reacts and my fuel trims are constantly cycling around 0. Have you double checked your setting in ecmlink. Also, have you tested for boost leaks. I was having a similar problem with my 1g but as soon as I would go into boost it would fix itself then hit boost cut. I did a boost leak check and found a bad intake manifold gasket. Just a suggestion.
 
Tested the CAS wiring
Checked the wb wiring to ECU
Gapped the plugs countless different ways

What I've noticed are the symptoms are a lot worse when the car has been running for a short period of time and get a lot better when the car has been running for a while. Also the tach jitters/jumps when held at a steady rpm. Could this be a poor solder connection at the socket on the ecu?
 
Well I socketed the 2nd EPROM I had and still the same issues. I sat down with the multimeter and buzzed out the ecu and everything with the socket and ic1 & ic2 checked out good. I ran new coils signal wires (Br-R & B-L) from the ecu to the power transistor and also cut and added a new ground from the PT to the batt neg and now the car will barely start and die right away, backfire really loud when forced to stay running by giving it some throttle, and the tach is all over the place jumping around.

Today I ran new power wires to the coil and PT and wired the coil outputs directly to the PT bypassing the engine speed connector and still runs like total crap. the power wire to the PT was really corroded under the shielding. Could adding all these new wires killed my PT in the process?
 
Car wont even start now and nothing has changed. Ordered up a new PT and also found out i need a new CLT sensor ### link is getting no temp readings from it. I'm honestly debating throwing in a CDI and going COP and eliminating the PT and firing the CDI directly from the ecu.
 
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