IS THE ECM BAD?
Thread Starter
Instructor
Joined: Jun 2003
Posts: 128
Likes: 0
From: tampa fl
IS THE ECM BAD?
It's been a while had to go to work to pay the bills. Anyway the starter went out Friday and while I was replacing it I hit the knock sensor plug and the brittle plastic crumbled, well I tried to make it stay on (no luck), so out of frustration I left it disconnected and low and behold I picked up 2 miles to the gallon. The knock sensor was replaced a month ago. Up until now the best I could get on Average was 18 mpg now it's 20 mpg. I have been wondering about the ECM for long time is there a way to check it or is it best to replace it if so Autozone offers a standard one and Bosch any thoughts on what would be best.
Thanks
Rocky :flag :confused:
Thanks
Rocky :flag :confused:
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: IS THE ECM BAD? (ROCKY85)
Absent a scanner, does the Check Engine Light work? Will it flash a Code 12 when you ground the diagnostic link? Do the MPG and Range Displays work? If these items are ok, the ECM is probably working as it should. A 2 mpg increase is negligible, but if you feel the knock sensor was retarding timing, you need a scan to verify it and even it is, that doesn't mean the sensor or the ECM is at fault. The engine could be pinging or there could be an engine noise setting it off, or the wire could be picking up interference and sending false signals to the module.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 128
Likes: 0
From: tampa fl
Re: IS THE ECM BAD? (ROCKY85)
Since I don't really understand all the functions of the ECM, I thought that it may not be working properly, could the ECM be retarding spark when it should not?
Thread Starter
Instructor
Joined: Jun 2003
Posts: 128
Likes: 0
From: tampa fl
Re: IS THE ECM BAD? (ROCKY85)
Strange you should ask but the MPG and Range cleared itself and started over again 2 weeks ago and took forever to give an average (we are talking days on daily driver)
Thanks
Rocky
Thanks
Rocky
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: IS THE ECM BAD? (ROCKY85)
Strange you should ask but the MPG and Range cleared itself and started over again 2 weeks ago
The fact that ANYTHING changed with the disconnecting of the knock sensor, proves the ECM is sensing and reacting. The sensor can and will pick up and report "false" knock counts. The ECM will react to these by retarding the ignition to reduce/prevent, what it has been programmed to perceive as knock. Retarding the timing, hurts performance. No knock sensor, no false (or real) knock counts. No knock counts, no retarding of the timing, and improved performance and mileage. All this is no guarantee that the ECM is working perfectly, but nothing you've said raises the suspicion that it isn't. All the evidence poimts to NO ECM problems. You sound like a good candidate for a factory service manual. Good luck, and...
RACE ON!!!
Thread Starter
Instructor
Joined: Jun 2003
Posts: 128
Likes: 0
From: tampa fl
Re: IS THE ECM BAD? (ROCKY85)
No the battery wasn't disconnnected, this occured when my wife was driving the car. If you have seen my previous posts this car has undergone a major resurrection due to the poorly maintained condition it was in when we purchased it , every sensor has been replaced and all wiring has been restored to the factory condition with the exception of the cooling fan which has an adjustable thermostat to compensate for the excessive heat we have in the summer months, so it turns on sooner.
Thanks
Rocky
Thanks
Rocky
