big_mama
Probationary Member
- 9
- 0
- Aug 3, 2020
-
Luxembourg,
Europe
Hi dsm tuners, a Mitsubishi companion here that needs your help. I thought I would write here on this forum because I think here are the most people with knowledge of these older Mitsu engines, and because I am totally lost here. First of, I don't have an Eclipse, but a Mitsubishi Sapporo (Europe) aka Galant Sigma (States) E16a from 1988. Technology wise the engines should be very similar to the 1G Eclipse. It's a 4G64 SOHC however.
So, my problem is the engine has terrible misfires, especially noticeable in the 2000-3000rpm range. It also fails to start 1-2 times when cold or stalls after a few seconds. The idle is also very rough, especially cold. After narrowing down the possible reasons, I guess the engine is simply running much too rich (--> black sparks).
The things that I have done so far:
* I checked all the sensors (as far a I could) that the ECU needs to calculate the mixture, including air flow, air temp, air pressure sensors, engine coolant temp sensor, throttle body position sensor and mixture regulator resistor. I also checked all the lines from the sensors to the ECU, swapped the ECU and swapped the MAF unit. So on the electrical side I don't know if there is anything more I can do, seems to be all fine.
* Compression wise I did a simple dry compression test with the following results (168, 170, 175, 170 psi). It should be 170, so 3 is a little high (hmm ). Vacuum is constant at around -10psi at idle.
* Fuel pressure regulator is new. I also tried new injectors (cheap Chinese ones though).
* I checked the EGR valve and cleaned it, and I changed the PCV with a new one.
* Coil, distributor cap, sparks (tried BPR7ES-U11 and BPR6ES) and cables are all new.
* Double checked timing belt alignment, and set idle ignition timing.
* Cleaned the throttle body and checked for intake leaks.
* The car doesn't have a cat, so no O2-sensor either. It also has no knocking-sensor that could go mad.
And now I don't know what I can do anymore. Unfortunately I am far from an expert when it comes to engines, so maybe it's just a totally stupid thing that I missed, but I don't know what to look for, or how to approach this. So please, any help is very appreciated. What could cause it to run so rich?
So, my problem is the engine has terrible misfires, especially noticeable in the 2000-3000rpm range. It also fails to start 1-2 times when cold or stalls after a few seconds. The idle is also very rough, especially cold. After narrowing down the possible reasons, I guess the engine is simply running much too rich (--> black sparks).
The things that I have done so far:
* I checked all the sensors (as far a I could) that the ECU needs to calculate the mixture, including air flow, air temp, air pressure sensors, engine coolant temp sensor, throttle body position sensor and mixture regulator resistor. I also checked all the lines from the sensors to the ECU, swapped the ECU and swapped the MAF unit. So on the electrical side I don't know if there is anything more I can do, seems to be all fine.
* Compression wise I did a simple dry compression test with the following results (168, 170, 175, 170 psi). It should be 170, so 3 is a little high (hmm ). Vacuum is constant at around -10psi at idle.
* Fuel pressure regulator is new. I also tried new injectors (cheap Chinese ones though).
* I checked the EGR valve and cleaned it, and I changed the PCV with a new one.
* Coil, distributor cap, sparks (tried BPR7ES-U11 and BPR6ES) and cables are all new.
* Double checked timing belt alignment, and set idle ignition timing.
* Cleaned the throttle body and checked for intake leaks.
* The car doesn't have a cat, so no O2-sensor either. It also has no knocking-sensor that could go mad.
And now I don't know what I can do anymore. Unfortunately I am far from an expert when it comes to engines, so maybe it's just a totally stupid thing that I missed, but I don't know what to look for, or how to approach this. So please, any help is very appreciated. What could cause it to run so rich?
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