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ECM; IDENTIFICATION
Topic Started: May 22 2011, 01:14 PM (2,519 Views)
edd
New Member
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need to replace the ECM on my 1991 geo metro 3cly m/t
ECM= A3 3-MT-FED 33920-61B6 2 112000-1252
Does ALL the numbers need to be the same on the replacement ECM?
does any one have one
thanks
Edited by edd, May 23 2011, 09:03 PM.
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dayle1960
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Fastest Hampster EVER

Yes they have to be the same. If not you will put one in to a 5spd when it was for an auto. That would cost a lot of $$$ because of a minor mistake.
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sitka53
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not for sure on this but the ECM in my 1990 vert looks as if it was replaced with one from a junk yard it has writen on it in that yellow paint pen stuff they mark parts with all the time (1991 auto) and it seems to work ok not sure what the whole story is behind this or even if what it says on the ECM is correct
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Good bye


My 91 has no egr and has a vacuum and mechanical advance distributor. If you install the incorrect ecm it may be for a car with computer controlled advance and this will cause untold detonation problems. An XFI computer for the same year will look for EGR and will want to control the timing--- Beware.
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edd
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The problem is this; for the past 6mths. when driving on highway car runs great then like a switch goes off the engine won't run past 1/4 to 1/2 throttle, won't run over 45 mph. Then like a switch goes on it runs great. This would happen every 3 or 4 days. Occasionally the check engine light would come on for a short time then go out. The code would be for o2 sensor. The o2 sensor tested ok but I installed a new. No change. Now this problem happens daily. Now it also won't run past 1/8 throttle. I've found if I pull fuse and reset ecm 6-10 times problem goes away but comes right back. I tried to test the TPS, the repair manual I have shows the TPS having 4 pins but mine only has 3. I also checked for mv with a DVOM on the single wire to the o2 sensor but there is no voltage. This is why I'm assuming a problem with the ECM. The 91' 3cly metro has 175,000 miles. I rebuilt the motor, tune up, new fuel filter, new vacuum lines @ 165,000 miles. Also cleaned all grounds.
Any thoughts.....
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Memphis metro


Check your exhaust pressure out of the tailpipe. May not be the problem but its worth taking a look at to see if maybe you have a restriction in your exhaust.
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dayle1960
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You might have a dead cat in your exhaust system. Or maybe a banana in the tail pipe. EGD might be right. Keep plugging away and you will find the problem. Narrow down the culprits. Engine, wiring, exhaust, ghosts. I vote for the exhaust.
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Good bye


Sure sounds like the honeycomb rolling around inside your cat. Sometimes it lines up and the car runs good and then it moves around and plugs up the outlet.
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edd
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Exhaust is not plugged.
keep thoughts coming
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Memphis metro


Put a fuel pressure gauge on it and check the fuel pressure.
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dayle1960
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Are there any chopped wires underneath the dash? Sounds like a wiring issue. Is the 02 sensor dead or dying? I know you checked it, but if it is dying then maybe you need to replace it. Another fellow is having the same issue as you. Might want to follow his thread. http://geometroforum.com/topic/4291608/

Could be the ignition switch? Just throwing that one out there.
Edited by dayle1960, May 25 2011, 07:36 PM.
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edd
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the wiring under dash and under hood looks good. I don't think it is the ignition switch as the motor keeps running, just won't take any throttle. I did install a new o2 sensor but made no difference. There is no o2 input to the ecm, as there is no voltage on the o2 sensor wire. Charging voltage is good at 14v. I do need to check fuel pressure when problem acts up.
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edd
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finally got back home. Checked fuel pressure , sometimes 23psi sometimes 5psi. Removed fuel tank and found fuel pump pick-up screen plugged and tank full of sand. Cleaned tank, installed new filter, pump and screen problem fixed. When I got this car 2 years ago the gas tank filler tube was rotted off which allowed sand and dirt to enter tank. Thanks for all your reply's
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vr4


Thank you for updating the thread. Too many times someone asks for help then never posts a fix.
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Scoobs
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:D

i actually have an ecm sitting in my garage i pulled out of a 1991 5 speed. car was totaled front end. impact, both motor and trans worked when pulled, just the tire/frame]drivers side was mashed.
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