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Help! Intermittent Misfire

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Old 05-12-17, 09:22 AM
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9Dragnfly2
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Default Help! Intermittent Misfire

In advance: sorry if the post is to long! I have a 92 SC400 with about 210,XXX miles. For about a year and a half I've been having intermittent misfires. It started maybe this time last year but wasn't very noticeable. When it first happened I was sitting at a traffic light and the car bucked for a few seconds and that was it. As the weeks progressed it became worse. It would happen multiple times a day and sometimes misfire the entire day. It happens under load, and idling. When it started to happen I noticed a strong odor…not like raw fuel but something else and would cause your eyes to water if you stand behind it. I replaced the plugs again. I decided to buy another vehicle while trying to diagnose the SC. On day while in class I decided to use our Snap On Solus ultra (toyota/Lexus OBD1 adapter) since the CEL was on and scanner read "no communication". Tried paper clip method also and light did not flash either. We've spent the entire day trying to diagnose the misfire. Previously to this problem I've replace fuel pump because it died (Jan 2016)…plugs, cap, rotor, and could after timing job (march 2016). I Parked the car in the back of my driveway for a few months driving it once a week maybe. Some days it'll run fine and others it'll run like crap. Last week I replaced the injectors with Reman Denso ones and still does it. Before changing wires I pulled each on individually to see if one did not change idle or stall…all but 4 & 6 would make changes the way it ran. So yesterday decided to replaced the wires and that did not help either. So far I'm completely lost and tired of it. Owned the car 3 yrs. and has been a money pit and still needs a lot more work done but I don't want to get rid of it. If any suggestions or have had the same problem please help I would greatly appreciate it.

Last edited by 9Dragnfly2; 05-12-17 at 12:15 PM.
Old 05-12-17, 12:34 PM
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scsexy
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i'd check the ecu and plugs/wires
Old 05-12-17, 01:08 PM
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jimbosr1
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ecu all day long!
Old 05-12-17, 08:44 PM
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Ghoulie
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ecu or the coil packs, also called igniters. my sc400 had one fail and half the cylinders would not fire. ran like ***, had no power, bucked like a mule, gas odor out the back, and the exhaust glowed red at night.
Old 05-13-17, 09:47 AM
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9Dragnfly2
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Originally Posted by Ghoulie
ecu or the coil packs, also called igniters. my sc400 had one fail and half the cylinders would not fire. ran like ***, had no power, bucked like a mule, gas odor out the back, and the exhaust glowed red at night.

Yah been trying to avoid the ECU but maybe my problem…I will also do some research to see if there is anyway to test both igniters.
Old 05-13-17, 04:55 PM
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dogwisper
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Originally Posted by scsexy
i'd check the ecu and plugs/wires
I agree with ecu. The no communication and no CEL light normally points to faulty ecu. You can physically open it up and see if capacitors are leaking and scarring the board. As previous poster indicated it's most likely ecu.
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