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85 2M4 Misfire, help would be appreciated (Page 1/3) |
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Klyde7_2M4
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OCT 04, 09:58 AM
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I have been searching through the forums of this place on misfires for months, and no matter what I've done my car still misfires, it is an irratic misfire
The tach still bounces, I'm pretty sure it's when the missfires occur, not before, I've had the new icm tested and it passed
What I've done
Wires, plugs, cap, rotor, icm, pickup coil
Fuel pump, fuel filter
Timing
New 02 sensor
Also have played around with the plug gap
If I think of anything else I'll post
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Klyde7_2M4
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OCT 04, 09:59 AM
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Just remembered more Important info
The car missfires during idle and trying to maintain speed, car shudders
Acceleration is 100% okay
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Klyde7_2M4
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OCT 04, 11:13 AM
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Did have low fuel pressure from older pump, replaced pump, to a OEM pump and reads 90 psi (aware that is a **** ton and I know it should be around 9-13) that's just the pump with the ignition on, no idea how to test it with car running
Tested with a 20 psi gauge first, that completely blew it out of the water and it broke, put a nicer gauge on it and that's how I got the 90 psi (・o・)
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Gall757
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OCT 05, 05:10 PM
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If you really are producing 90 psi with that pump, it's dangerous. Get another one.
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Patrick
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OCT 05, 05:24 PM
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quote | Originally posted by Gall757:
If you really are producing 90 psi with that pump, it's dangerous. Get another one.
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Agreed. Trying to troubleshoot an engine issue while it's running 90 psi fuel pressure when it's supposed to be 9-13 psi is pointless... if not downright dangerous.[This message has been edited by Patrick (edited 10-05-2021).]
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buddycraigg
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OCT 08, 08:36 PM
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quote | Originally posted by Patrick:
Agreed. Trying to troubleshoot an engine issue while it's running 90 psi fuel pressure when it's supposed to be 9-13 psi is pointless... if not downright dangerous.
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I second that. I am not talking to you when you have 90 PSI on a 4 cylinder engine.
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NY_FIERO
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OCT 14, 03:12 PM
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The year was 1998... i had a silver 2.5 with the isuzu 5 speed. I had the same symptoms.. I went to a junk-yeard... pulled the ecm from a buick (whatever it was) with a 2.5. Put it in and it ran flawlessly. It seems strange but true.. the buick was even an auto.... [This message has been edited by NY_FIERO (edited 10-14-2021).]
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NY_FIERO
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OCT 14, 03:49 PM
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And yes... resolve the fuel pressure issue first... are you certain you're not talking 9.0 lbs? not 90???
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RWDPLZ
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OCT 14, 05:58 PM
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Replace fuel pump with proper one, then replace coolant temp sensor for the ECM (there are 3, usually the one in the thermostat housing), and rebuild/clean the TBI.
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Forrest
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OCT 18, 02:45 PM
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Could it be a faulty fuel pressure regulator? Get them on ebay...they are cheap. $20 as opposed to $87 from the parts stores.
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