The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support Fuel Injector Clinic

1G new CAS pigtail -RPM still cutting out

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

codym

10+ Year Contributor
636
7
Dec 28, 2011
Amarillo, Texas
I'm having a bit of trouble here...


My CAS connecter was old, broken, and the rpm wire came out of the plug.

I got a pigtail, and a green top CAS sensor to test if the sensor was bad as well.

Last night I soldered in the new pigtail, and couldn't get it to start for about a half an hour. After it finally started, the rpm on my tach was 2-300 RPM - but the RPM reading on my SAFC was reading mid 500's.

I swapped out the CAS with no changes.

After some hard praying last night, I woke up this morning to verify all connections again. I started it up and again, idling around 2-300 on the tach, mid 500 on the SAFC.

After idling a couple minutes, it suddenly woke up and idled perfect around 900 on both the tach and SAFC.

I drove the car to work and it only cut out when I first pulled out of the parking lot. After leaving work, it started up and ran fine for about 2 miles, and than again the tach started cutting out, falling down and than jumping back up, but with no change in RPM reading on the SAFC.


I have verified my wiring is good, and no essential connectors are unplugged.


I'm at a complete loss as to what could be causing the RPM on the tach to drop, even after swapping the CAS with no differences between the green/black top.
 
Last edited:
Also, a bad coil or the wiring between the transistor, coil, and plugs could result in the power transistor not generating the tach signal, or generating a half signal. A half RPM signal sounds like 1 of the 2 channels/coils is misfiring
 
The RPM signal for the tachometer comes from the power transistor unit. If you haven't already, you might consider having a hard look at that.

http://www.dsmtuners.com/forums/articles-electrical-wiring/229419-how-test-power-transistors.html
\


I tested and replaced the power transistor, so far the RPM signal has been consistent, and the car was running fine..



But now I'm having a different issue..

I had the car off for a few minutes while I went into the store, came back out and started her up. Idle on the tach was showing ~ 1000 RPM, while the RPM on the SAFC was around 600, when I attempted to back out it puttered miserably , and died.

The SAFC was also showing" 0 hz" of airflow, while before it was sitting at 24hz at idle. The SAFC is the one thing in my car I didn't wire in myself, I'm contemplating just uninstalling it, but I am unsure of what was done to put it in.


I am still getting a dim green light from the MAF-T at idle, and solid green light above 20% throttle - which would indicate there is a MAF signal. I tried leaning out the base/idle knob with no changes in the AFR, so I turned it back to the settings I had written down from the last log.

I have checked and double checked every connector, wire, bolt, sensor, etc. Nothing is unplugged, all my soldered connections have continuity, & I have no leaks pre or post MAF.
 
Last edited:
Another day of troubleshooting, and I was still unable to find anything causing my issue.

I checked the wiring from the gm maf to the dsm maf connector, which I had to solder because the connectors weren't the same, all have continuity.


The only thing I have not checked is the wiring of the SAFC, which I am removing this morning.

I find it a bit strange that it's showing 0hz airflow, but the translator is getting a signal from the gm maf.
So that means somewhere between the translator, the dsm maf wiring, the safc, and the ecu - the maf signal is getting lost.


I'm going to have a poke around at the safc wiring, and see what happens when I remove it.
 
Figured I'd update, I removed the SAFC, when I did I noticed that the maf wire was melted a bit, most likely causing the afc to read 0hz of airflow...

Great, but now I'm having problems with the tach jumping and it's missing again..
So I'm just gonna check things off and find this problem one by one.. :toobad:


As of today I have done the following in the last few weeks since the issue has started.

- New plugs (BPR6ES @ .044") and wires
- New transistor - cleaned connector
- Cleaned coil pack connector
- Removed safc and wired maf signal correctly
- Verfied grounds on Intake, Trans, Ecu and firewall.
- Verified no blown fuses including ign. & MPI
- Replaced cam sensor and soldered pigtail.
- Grounded ignition and set base idle.*


I took out the ECU when I removed the safc and verified all the caps looked good, no odd colors or smells. I know every issue can't be caught by the naked eye, but I do plan on getting my ecu linked and knocked this summer so if anything is wrong hopefully they'll find it.

Sometimes it starts right up, idles fine and won't mess up till I drive for 5-10 minutes. After it's warm is when it consistently gets worse it seems like.

* I didn't adjust ignition timing because I don't have a timing light, nor do I know anyone that does to use. I did buy alligator clips though. :applause:


Next step is going to be replacing the coil pack, it is one of the items that have not been replaced since I've had the car(just over a year now) and I'm not sure when it was last done, looks a littly dingy..
I hope a new coil pack fixes this problem for good.
 
Last edited:
I was checking the spark plugs yesterday to see if they were fouling from all the misfiring, when I pulled the plug wires off 1 & 4 the wires came completely apart from the boot. I'm sure that wasn't helping my issue.

Got new wires on yesterday and the issue is still persisting.

I removed the current coil pack, and it looks a little rough. This was my coil from ye' ole 7 bolt, and in all honesty I've never cleaned it even throughout the 6 bolt swap
You must be logged in to view this image or video.


I noticed that one of the wires leading to the 2/3 coil looks to be in bad shape.
You must be logged in to view this image or video.





I took the coils off the bracket today and cleaned everything with electrical contact cleaner. Just about everything was covered in oil and grease, including where the power splits to the coils :nono:

Took of the ground , which was covered as well. After I cleaned it and the bracket, I sanded the grounding plate a little to remove who knows how many years of surface gunk.


Got the coil re installed and let the car idle for 6-7 minutes.
Wasn't missing and idle had leveled around 900, I took her out 3 miles and back, cruising around and it didn't miss a single beat.


Guess we shall see :ninja:
 
Last edited:
I think I might have solved the issue, I drove around town today running some errands, about 25 miles total and she was running pretty solid. Wasn't missing, good idle. Went out and bought a timing light and set ignition timing at 5° BTDC, first time using a timing light :D

New coil is still coming in Monday , hopefully I can just keep it as a spare :thumb:
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top