CEL on, Bouncy Tach, HELP!

[kid325e]

I consider myself pretty knowledgable with the M20 so this has me stumped.

Car has been driving well for the last couple of weeks, first problem i've ever had with it that i've been stumped on.

Long story short, I drove the car to work this morning just fine. No issues whatsoever. The tach wasn't reading right and either bouncing around 2500-4000 RPM and 0 when idling. Did a whole days work, came to pull the car out of the lot and the CEL was on the it was having trouble even holding an idle. It would surge, almost die, than surge again, until it eventually fell on it's face and died.

Stomp Code reveals a lot of different faults related to Grounds, and Fuel System but still not enough for me to pinpoint what's going on.

I have all weekend to delve into it and see if I can get it running right. Once the CEL turns off the car runs great. This has got me wanting to just ditch the E30 this weekend and get the 2002 project done to drive to and from work next week. Hoping to get some good insight on this one.

Thanks for your time guys,
Paolo

[jlevie]

My first suspicion would be a bad CPS, bad engine harness, or a flaky DME.

[kid325e]

After a stomp test I got code 1263 which refers to the EVAP Valve. Anyone have any insight? Have a good chunk of the day to work on it tomorrow and would love ideas.


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[kid325e]

I swapped in a known good 173 ecu, the one that came out of the car was a 524 for what it's worth.


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[FLG]

Jim already pointed you in the correct direction.

As he said, harness, cps, or dme

Do a search for testing cps, simple check Is to check if it ohms out correctly. 540 ohms or so iirc. Won't always tell you if it's working but it's a good base line. Replace it with a dealer one, only.

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[kid325e]

Just an update for you guys.

First thing I did this morning was check the main relays (the three that sit under the plastic cover), I keep spares (brand new ones) in my garage. Although the Main Relay had been replaced most recently it was the culprit. I swapped it and everything cleared right up. Car started right up, etc. etc. Been driving it all morning. Thoughts?