89 ecm problem
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Intermediate
Joined: Aug 2009
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89 ecm problem
Car just died on highway with no warning. Took ten minutes and started up. Before it died the fuel average readout started to fluctuate all the way to 42mpg and read 551 miles to empty.Also the temp started to climb a bit when it normally runs about 188-190.Could this be the ECM failing. No codes were thrown and it started right back up again later with no issues.Noticed the fuel average out of whack the week before too but not all the time.
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
I'd be more inclined to suspect a wiring issue, especially a ground problem. Check the ground connections on the side of the block above the oil filter. I think '89 also has some grounds on the top bell housing bolt on the driver's side. It's under the windshield wiper motor. Good luck getting to that one. You probably need to pull out the distributor.
The ECM sends the injector pulse width to the dashboard. The dashboard uses that info plus the MPH calculation to determine what the mileage is. That also affects the range calculation, which is mileage vs. amount of fuel in the tank.
The ECM sends the injector pulse width to the dashboard. The dashboard uses that info plus the MPH calculation to determine what the mileage is. That also affects the range calculation, which is mileage vs. amount of fuel in the tank.
Thread Starter
Intermediate
Joined: Aug 2009
Posts: 37
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Yea,that was the first thing I checked.Because I put an engine in about 2 years ago so I thought a connection came loose.Once I got it started I made it home but it broke down the same way on the wife a week before.Test drove it after she got stuck and the only issue was the fuel mileage fluctuation.But cut out twice on me like that on Sunday.Drove with the scanner hooked up and everything seemed fine.The ECM's are cheap enough from Ecklers I may just get one and pray.Thanks
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
You may have two problems that seem related but are not.
If it's overheating I would suspect a lean mixture. Check the datalog. The trick is to catch the problem while datalogging. The problem with datalogging is that there is way too much information and it's tough to sort through it all to detect a problem. I found that importing it into an Excel spreadsheet and graphing various parameters was helpful.
Dying when hot can be an ignition module issue. If they get too hot they shut down. Usually caused by either no thermal grease underneath or dielectric grease was used by mistake.
I did have an ECM problem a few years ago. I would be driving along and the engine would just stop running randomly. It would come back in a few seconds. Rebuilt ECM fixed it.
If it's overheating I would suspect a lean mixture. Check the datalog. The trick is to catch the problem while datalogging. The problem with datalogging is that there is way too much information and it's tough to sort through it all to detect a problem. I found that importing it into an Excel spreadsheet and graphing various parameters was helpful.
Dying when hot can be an ignition module issue. If they get too hot they shut down. Usually caused by either no thermal grease underneath or dielectric grease was used by mistake.
I did have an ECM problem a few years ago. I would be driving along and the engine would just stop running randomly. It would come back in a few seconds. Rebuilt ECM fixed it.
Last edited by Cliff Harris; May 16, 2013 at 12:40 AM.
Thread Starter
Intermediate
Joined: Aug 2009
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I did the have the ignition module go bad once but it threw a code and also would not start again once it died. This time if it sits for a few it starts back up. Also ran in the driveway for half hour with no issues. Going to try again tonight on the highway and see what happens
Le Mans Master
Joined: Aug 2007
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From: WV
I did the have the ignition module go bad once but it threw a code and also would not start again once it died. This time if it sits for a few it starts back up. Also ran in the driveway for half hour with no issues. Going to try again tonight on the highway and see what happens
Ignition control modules can do exactly what yours is doing, it can shut off and start right back up, die and not start for a half hour, or die an not start again until there changed...WW
