Engine is running bad and shows check engine lite, but only has a code 12? Isn't that the Passed-Self test code? It will present 12, 12 , 12, and than repeat. I hope I my ECU didn't crap out? Someone make me feel stupid and point out whats wrong. Thanks.

Sorry, I can't make you feel stupid...but I have heard that some codes have trouble staying in the ECM memory. Maybe you should disconnect the ECM to clear it, and try again.

12 is the code that indicates the system is working. Whatever is causing your problem doesn't have a sensor to send a trouble code to the ECM. However, sometimes the Coolant Temperature Sensor will fail without setting a code. Usually you get a very rich exhaust smell with this situation. I don't ever recall hearing of one failing and causing a lean burn.

quote Originally posted by fierofool: 12 is the code that indicates the system is working. Whatever is causing your problem doesn't have a sensor to send a trouble code to the ECM. However, sometimes the Coolant Temperature Sensor will fail without setting a code. Usually you get a very rich exhaust smell with this situation. I don't ever recall hearing of one failing and causing a lean burn.

Damn, that's what I what I thought -good self test. Nuts. I'll check the coolant sensor and clear the ECU. The damn thing was running great, even with the stock chip and all major the mods. I jacked up to dump the break-in oil and put new oil, and tighten an exhaust leak. And now this, dang I almost ready for the dyno for chip burn. Always sumthing.
Thanks guys.

FLASHING check engine light? = ECM problems.

If it is flashing key on engine running.

HMM.. I'LL HAVE TO LOOK AGAIN, THANKS.

quote Originally posted by phonedawgz: FLASHING check engine light? = ECM problems. If it is flashing key on engine running.

The code 12 actually means "no ignition reference signal". It's normal to get that code when checking for trouble codes (while the engine is off), because the ignition system isn't firing (i.e. the distributer isn't turning). If you get that code while the engine is running, it means the ECM isn't getting a reference signal from the distributer. And thus, the ECM can't control the ignition timing, which would explain why the engine runs crappy.

But he said 12 12 12 , meaning he is reading the flashes. IE jumpered and no scanner.
When you jumper to check codes it always flashes code 12. What you need is a scan tool/cable/laptop. if the Check Engine Light is on when running you have a problem. You would need to scan it to see the code as it is there and not setting for whatever reason. if it is flashing fast and NOT jumpered while key on, you have a bad chip or ECM.
But don't dyno with the light on, depending on the code it may be in "limp home mode" may hurt the engine, but won't give you good dyno results.

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