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djratlif

'92 Misfire/Skip issue

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My 1992 SE started to skip and misfire while driving to work last Thursday. I shifted into neutral and gave it some throttle, seemed to smooth out and made it to work. After work it ran like normal, no skip no problems until Saturday morning on my way to work again. This happened in the past while I was using the vehicle as a lot truck/beater but it went away by itself. (This is what I call my hands off approach to vehicle repair) The misfire is throughout the RPM range and I can't pinpoint a cylinder after pulling plug wires one by one. I have put a new cap/rotor and plugs/wires on less than 5k miles ago. I am going to do a fuel pressure test to make sure it is being fed enough but for some reason I feel it is electrical. I tested the coil's primary and secondary resistances and the primary is only 0.72 ohms. The specs in the chiltons are between .80 and 1.00, does this sound like it could be the issue? The secondary resistance fell into specs. Any help would be appreciated, D

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have you checked for any codes yet? would be the first step. What plugs are you using? gap correct?

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I have not checked the codes yet, inexperienced with the OBD I system having grown up with OBD II mostly. As for the plugs and gaps, I am running NGK V-Power plugs and the gaps are between .030 and .035 on them.

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I recently discovered there is a very delicate, oh lets say (because I don't know what it's called) timing wheel / disc under a little dust cover inside your distributor, after you remove the cap, take off the rotor, there are two philips head screws holding tight a little round cover, remove those and very gently and without touching perhaps, inspect that disc with all the little slots in it, if that has any dust or foreign debris it will cause the laser in that little box to read incorrectly, it seems to me it works like a cd player laser, it scans those little rectangular holes and translates into binary code for on / off signals, for what I got no clue but it looks important.

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Thanks gv280z I will do this right now and see if anything looks dirty or out of place.

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All good under the rotor and cover, the disc is clean and looks to be in place. I'll keep updating when more information arises. Thanks again, D

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.72 vs .80 would most likely be within the accuracy range of your meter unless it's very nice (fluke?). If you've taken care of spark I'd move to fuel and then look for a vacuum leak.

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You can check codes without an OBD reader. Box is under the passenger seat, read the blinking lights. You can google the procedure and codes or you can download the FSM here in the Garage section (suggested)

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he has a 92, no fsm here for it, but the 94 manual is probably the same

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Hey DJ I think I've still got a functional ignition module I can send you, put it in little bubble mailer probably cost a buck to send to you, it could be that you have a failing module. PM me your addy or a post office box and I'll get it out to you no charge.

 

Oh yeah, forgot I've got a coil too! It's yours, no worries, Just let me know.

Edited by gv280z

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he has a 92, no fsm here for it, but the 94 manual is probably the same

92/94 years different style? Might be different, just my thoughts

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Haven't read the codes yet still however I did perform a fuel pressure test and check vacuum hoses. The vacuum hoses on the rig were all messed up, looks like a young kid got in and did work without knowing what they were doing. The fuel pressure regulator was not even hooked up along with the other vacuum hoses being routed wrong. I fixed all the vacuum issues and still the same problems. The pressure regulator and pump seem to be working as the pressure reads 36-39 psi and around 47-50 with the regulator unplugged.

 

 

Hey DJ I think I've still got a functional ignition module I can send you, put it in little bubble mailer probably cost a buck to send to you, it could be that you have a failing module. PM me your addy or a post office box and I'll get it out to you no charge.

Oh yeah, forgot I've got a coil too! It's yours, no worries, Just let me know.

 

Thanks, I appreciate the offer. I want to diag it a little further before I throw parts at it. I will definitely be contacting you if I find out the coil is shot or ignition module. I have a cheap Harbor Freight meter so I'll bring it to a buddy with a Fluke for a better reading to see if it really falls out of spec. I'll also have my module tested as well to see if that could be the issue.

 

Thanks again for the help guys, have a few more things to check now before I resort to a "professional" mechanic. Around here its hard to find a decent shop without a month waiting list.

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Well the problem is gone now, the plug wire got pushed up into the boot too far causing it to seat wrong. The tech I had work on it is a Chevy guy but did it in his spare time. Only had to buy lunch and some beers for my stupid oversight. Thanks again for the help guys, really good group of people here.

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Sounds like you either need new plug wires, or if they are new they are defective. But glad it's fixed.

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