Had some lovely stumbling/misfiring/engine cutting out entirely today. Threw a P1300, then P0300 for misfires (obviously) and the car would not fire up and run reliably again until it had cooled off for a bit. Drove about 50 miles at ~45, did it again. Drove ~70 miles at 65, did it again and worse, taking longer to cool down and run right. Fluids are good, plugs are unfouled, belts are tight and in known adequate condition, battery just tested good (after the first time), alternator is new. When it's not misfiring, I still have full rev range, no hesitations, no noticeable power loss. I don't think it's an intermittent short just because then harsh road bumps would trigger it.
I figure it's either the coil or the ignitor, my bet's on the coil because it's never been changed and I've had some frankly shitty wires and plugs and lots of fouling over the past 200K from all the burning oil. This would also explain the occasional summertime stumble as idle fell below 500 RPMs or shut the car off when it was 90+ degrees and I was stopped in traffic on black asphalt in the sun.
What says the collective wisdom, though?
(And do you REALLY need to rotate cylinder 1 to TDC when you remove the dizzy to get at the coil? How much of a pain is it to just pull out the coil itself?)
Replaced the coil. Primary terminal resistance of the old one was about an ohm...not .07 (or thereabouts). High-tension terminal was bent all to hell and blackened, so that can't have been doing any good. It IS very possible to get off the coil without taking out the entire distributor...the gasket gets in the way but by making one small cut down toward the bottom you can lift the piece that goes over the coil out of the way and put it back afterward with no loss in sealing effectiveness.
Car still threw a P1300 and died after some driving-while-warm, though. I've electrical-taped up a small insulation abrasion in the black wire on the external connector (made that one years ago for StreetDyno/HomeDyno wiring) and the battery cable is disconnected, I figure I can let the PCM re-learn how much advance it needs to run the hard way, but if this doesn't resolve the issue what else is there to check?
There are a number of threads on here on driveability issues that all point to the distributor as a whole. Also its a crap shoot with an aftermarket one too.
My experience with ignition coils is if either side is NOT zero or infinite, its still good. As you found the low side is usually a 1-2 ohms while the HT side is 10-15 K ohms. These numbers are typical for almost ANY ignition coil. BUT....BUT... heat can be a factor in a coil being OK one moment and then dead the next. Since there are a few coils of different sorts as well as heat affected electronics, there can be more than one item failing or about to fail to give you fits. 15 year old electrical parts can easily fail at any time, but the Japanese stuff is still incredibly good quality.
i recently replaced the distributor (napa), rotor (napa), bought NGK wires(ebay), and plugs (ebay good deals), timing belt kit (napa). I have zero codes.
I'm confused, I didn't think the 4/7AFE (4A-GE in your case) engine had ignition coils. Thought it was distributor cap, rotor, and spark plug wires.
I have never had an issue like you describe, but generally a misfire is one of a few things: bad spark, fuel problems, or sensor error.
Spark could be cap, rotor, wires, spark plug, or loose/bad connection on a wire. Would yank the cap off and look for signs of carbon trails, cracks, excess wear, etc. Look at the rotor too. Replace if worn. Sounds like you replaced wires and plugs already.
I have not heard of a fuel problem related to heat. The generic answer is check your fuel filter, but that doesn't fit the bill here I think.
I don't think the 4/7AFE engines have MAF sensors. Does the 4A-GE? MAF sensors can cause some really bizarre problems. A front O2 sensor may cause the engine to run poorly, but I think it would give a CEL code for an O2 sensor problem too.
Have newish wires, newish plugs, newish cap and rotor. (Less than 5K on 'em.) Front O2 sensor is....well, it's not newish, but it's within 10 or 15K of having been replaced. Standard 100K lifespan part. Fuel filter was checked/replaced maybe 20K ago after having been let go for embarassingly long. It's not the wires, I wiggled them and ran my fingers down them while the engine was running. Nothing stumbled, nothing shocked me. It's not the cap or rotor, those look fine when I had them apart yesterday. I doubt it's the plugs but it wouldn't hurt to check them out tomorrow. No MAF sensor, it's a MAP sensor, and I checked and cleaned both IATs although they're likely unrelated.
The coil is internal to the distributor, as is the capacitor or I guess what you'd think of as the condenser. The igniter module (at least what I THINK is the igniter) sits directly below the bracket that holds the DLC1 diagnostic connector. Tomorrow I'm going to pop open the dizzy again and check for insulation breaks in the internal wiring and verify the coil resistance is to Chilton's 96-97 7A spec...it's possible the parts store may have given me a bad part. Honestly I kind of hope they did, as it'll be cheap and easy to remedy as opposed to a $150 distributor.
The heat-related part of it is what really has me scratching my head.
....The cap is fine and only a couple months old. I don't need a new cap because I already have one, and RockAuto has Beck/Arnley caps for about $13. I'm looking at entire distributors at this point.
Final guess: check your EGR system. I talked to my Dad, who had a similar issue on his smog-equipped 80's Toyota pickup. The truck would start to have slight, intermittent hesitation once it warmed up (albeit, he remember this taking about 15minutes to start).
The tube between the intake and EGR was full of crap. Ended up cleaning the interconnecting tubes and replacing the VSV valve. Took 3 different mechanics to correctly diagnose. Just a thought.
Checked plug gap and condition, everything looked fine in there or at least what I consider normal for an oil-burner and what's produced perfectly normal combustion across the past many miles. Cap is OK, rotor is OK, new coil had about an ohm across primary--considering the probes themselves were about .5 and the book says .3-.5...NOT .07 as I initially thought. So odds are the old coil was OK too. I'm an idiot but I know that.
There's no discernable shaft play on the distributor and the interior looks relatively clean, no visible wiring breaks/issues/missing insulation etc. The condensor doesn't really do much but RF suppression as I understand it, so that's not a likely point of replacement. The resistance for the pickup coil checks out OK so it seems electrically OK and mechanically OK as well.
The one thing that I still need to check in the distributor is the gap between the rotor and the secondary of the coil. The old coil had a bashed-in secondary...I don't know why it would have been that way, how it would've gotten that way, or how long it'd been like that, but I'm thinking it didn't happen for no reason.
Checked and cleaned the EGR system (as much as feasible) maybe 10-20K ago but it was nasty as hell so it wouldn't hurt to do it again...but you'd think that'd be a P0401 EGR code.
Maybe it's the ignitor, but the Chilton guide claims there's no external one for the 96-97...despite RockAuto listing one and me being pretty damn sure I see it bolted beneath the diagnostic connector.
You are good enough to find the problem. It seems You almost have done whatever was necassary about electric system . IMO check the Knock sensor even you don't have code for that. probably you know the knock sensor is a little strange animal.
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P1300 likely the coil?
How much of a pain is it to just pull out the coil itself?)
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