'94 drivability problem

My car has an intermittent issue with losing spark (I'm sure of that much). Sometimes it stumbles for a short portion of warm-up, running on 2 cyl. Other times, it won't start at all (thank mother nature and timing for spring motorcycle weather). It acts like the coil is breathing its last breath. Does anyone know a test to decipher between an intermittently bad coil and an intermittently bad ignitor? I'd rather not start throwing expensive parts at a problem and hope I'm a good guess. For that matter, does anybody have a working, used coil that I can borrow/have/buy for testing? Ignitor? I would be gratly appreciative to any help with cheap parts or good tests to isolate the problem.

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Originally Posted by boisking

My car has an intermittent issue with losing spark (I'm sure of that much). Sometimes it stumbles for a short portion of warm-up, running on 2 cyl. Other times, it won't start at all (thank mother nature and timing for spring motorcycle weather). It acts like the coil is breathing its last breath. Does anyone know a test to decipher between an intermittently bad coil and an intermittently bad ignitor? I'd rather not start throwing expensive parts at a problem and hope I'm a good guess. For that matter, does anybody have a working, used coil that I can borrow/have/buy for testing? Ignitor? I would be gratly appreciative to any help with cheap parts or good tests to isolate the problem.

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Coil/igniter are one in the same on 94-97's ;) I might have a spare lying around, I can look for it tomorrow and if I find it, I'll bring it out Wed if you're going to be there.

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Originally Posted by Adam Payrot

Coil/igniter are one in the same on 94-97's ;) I might have a spare lying around, I can look for it tomorrow and if I find it, I'll bring it out Wed if you're going to be there.

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According to Todd (looking up the parts with his mazdaspeed account) and the guy at O'reiley's, they are not the same. Nor are they the same price. If you can prove me wrong, though, it might save me some guesswork. I'll be there on Wednesday. Thanks, dude.

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Originally Posted by boisking

and the guy at O'reiley's

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Hah, I had a guy at Autozone insisting that I didn't need anything but 1157 bulbs for my Miata tails... don't trust them with anything. :rolleyes:

As for Todd... well, use your own judgement :D

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Originally Posted by boisking

My car has an intermittent issue with losing spark (I'm sure of that much). Sometimes it stumbles for a short portion of warm-up, running on 2 cyl. Other times, it won't start at all (thank mother nature and timing for spring motorcycle weather). It acts like the coil is breathing its last breath. Does anyone know a test to decipher between an intermittently bad coil and an intermittently bad ignitor? I'd rather not start throwing expensive parts at a problem and hope I'm a good guess. For that matter, does anybody have a working, used coil that I can borrow/have/buy for testing? Ignitor? I would be gratly appreciative to any help with cheap parts or good tests to isolate the problem.

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I had a similar problem and it turned out that I had water down in the spark plug holes. Don't know if you've washed your engine lately, but the first time it happened to me the problem didn't pop up until a day or two after I had been to the car wash - very odd, but that's all it was.

Just a thought...

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Originally Posted by boisking

According to Todd (looking up the parts with his mazdaspeed account) and the guy at O'reiley's, they are not the same. Nor are they the same price. If you can prove me wrong, though, it might save me some guesswork. I'll be there on Wednesday. Thanks, dude.

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Check this...

I can find a lot more examples that say the same. 90-93 had them separate, 94-97 had them combined.

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Originally Posted by Adam Payrot

Check this...

I can find a lot more examples that say the same. 90-93 had them separate, 94-97 had them combined.

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Good enough for me. Thanks, man. I know that the coils are getting steady power, but is there a test to see if they are getting good signal from the ECM? No water in the plug wires.

I'm sure there is a range for the resistance that should be seen at the connectors, but I don't know of any other way to test the signal. I never had luck with the resistance values when I had one of my coils blew; they were "good" according to the readings. I pulled a plug, plugged it into the wire and sat it on the valve cover while turning the engine over; no spark meant bad coil. I learned not to trust those readings after that.

This is what we were looking at from Mazdaspeed... It is supposed to be just for a '94, and it lists the Ignition Coil & Igniter together as BPE8–18–10XA, but then also lists just the Igniter Set alone as B61P–18–251. I should have noticed that the part number starts with B6. Looking at the 1992 sheet, the number is the same. Perhaps Mazda screwed up the when they made the PDF. :confused:

Don't forget... a bad CAS can make the spark do crazy things.

RJ

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Originally Posted by channelmaniac

Don't forget... a bad CAS can make the spark do crazy things.

RJ

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What kinds of symptoms are we talking about here?

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Originally Posted by channelmaniac

Don't forget... a bad CAS can make the spark do crazy things.

RJ

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Good call.
Recently I helped a buddy with a Corolla that had all the same symptoms. Everything pointed to a bad coil. Replaced coil only to find out that wasn't the problem. It was the CAS crank angle sensor (known as crankshaft position sensor on Toyota) but its the same sensor, just a different name.

Definitely worth checking out.

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Originally Posted by MadMonkey

Hah, I had a guy at Autozone insisting that I didn't need anything but 1157 bulbs for my Miata tails... don't trust them with anything. :rolleyes:

As for Todd... well, use your own judgement :D

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So I walked into Autozone and asked the nice young man in the red shirt if they had a vacuum gauge. He looked at me with a puzzled look on his face and said: "Vacuum gauge? What does that do?"

I almost left immediately, but instead said (slowly) "Measures vacuum"

He said, I'll have to ask...

The *other* guy said "if we have them, they'll be right over there." So the first guy walks over and starts looking at the endcap stocked with spark plugs.

I walked over to the *next* aisle, where the vacuum gauge was hanging next to the fuel pressure gauge and some other diagnostic stuff and said - "I'll take this one..."

Sheesh!

Hehe... When ever the parts dope asks my father-in-law for year, make, and model when he has asked for something by part number, he always tells them the part number is for rear rotors for 1941 ford pick-up. I was with him when he did it once at NAPA... Very entertaining! We watched the guy try to find it in the computer, then ask the guy next to him to look, then they got the manager. It took them 10 minutes to get somebody smart enough to tell us that a 1941 Ford couldn't possible have disc brakes. We had to take them outside to show them the hot-rodded truck before they were willing to look for the part by the part number provided when we walked in. :rolleyes:

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Originally Posted by cam76034

Good call.
Recently I helped a buddy with a Corolla that had all the same symptoms. Everything pointed to a bad coil. Replaced coil only to find out that wasn't the problem. It was the CAS crank angle sensor (known as crankshaft position sensor on Toyota) but its the same sensor, just a different name.

Definitely worth checking out.

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Any test(s) that you know of to determine whether the CAS is still good?

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Originally Posted by boisking

Any test(s) that you know of to determine whether the CAS is still good?

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Sure... it starts with getting someone to distract Wags while you "borrow" his for testing. ;)

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Originally Posted by boisking

Any test(s) that you know of to determine whether the CAS is still good?

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Sure don't, short of replacing it with a known working unit. I would look at the connection there, clean the contacts and reconnect. Maybe channelmaniac knows a better way.

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Originally Posted by Titus

Sure... it starts with getting someone to distract Wags while you "borrow" his for testing. ;)

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I like the way you think, good sir! ::Banana::

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Originally Posted by Titus

Sure... it starts with getting someone to distract Wags while you "borrow" his for testing. ;)

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Originally Posted by boisking

I like the way you think, good sir! ::Banana::

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Ahhh..... nice try you ::Clown::'s . Unfortunately, Bo is forgetting that we swapped coils from my car last summer when we were trying to diagnose the rough idle problem, to find out that there was a hole in the intake pipe. His car wouldn't start with my coils connected. My coil pack and his coil pack have different part #'s.

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Originally Posted by johnwag

Ahhh..... nice try you ::Clown::'s . Unfortunately, Bo is forgetting that we swapped coils from my car last summer when we were trying to diagnose the rough idle problem, to find out that there was a hole in the intake pipe. His car wouldn't start with my coils connected. My coil pack and his coil pack have different part #'s.

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Yeah, I believe there is a 4th wire on the 94-95's that runs to the tach (and something else I would imagine). The 96-97 coils are 3-wire and don't need that 4th wire. You can put the 94-95's in a 96-97, but not vice-versa.

I'm about to head over to my "storage" and see if I can find that extra coil. It came off my 94, so no worries on compatibility for Bo.

There's no real way to test an intermittent CAS... unless you have an oscilloscope to watch the signals... and provided you know what you are looking for on the signals...

Best way is to swap 'em.

RJ

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Originally Posted by Adam Payrot

I'm about to head over to my "storage" and see if I can find that extra coil. It came off my 94, so no worries on compatibility for Bo.

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My hero ::Horse::

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Originally Posted by channelmaniac

unless you have an oscilloscope to watch the signals... and provided you know what you are looking for on the signals...
RJ

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On a (probably) unrelated note - anyone have a 'scope? I'm trying to chase the gremlins out of my newly rebuilt motor, and I'd like to verify that my injectors appear to be getting the correct pulses.

It's only running on 2 or 3 cylinders at the moment, but we seem to have fuel, air, and spark - so I guess we're down to quantity and timing of the elements now...

Are you sure the plug wires are connected correctly?

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Originally Posted by Titus

Are you sure the plug wires are connected correctly?

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If the question was for me - yes. I've even tried swapping wires with a known good set - though my Magnecores are relatively new. I've tried swapping 1&4 wires at the coil, as #1 runs great, 4 not all.

I'll start a new thread with the gory details...

Well, Adam's coil was not compatible. It was newer than he thought. I also had a cold ride to work today, since the car wouldn't start. I am ready for some ideas. Tests?

Car was running great for a few days, but decided not to start after work today. Of course, after testing for spark (none) and diconnecting/reconnecting connectors, she started. Contact surfaces in the connectors looked good to me. Wiring harness has no areas that I have found where anything is worn through. I am wondering if my wire shaking and connector adjusting revealed the problem or if it is coincidence.

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Originally Posted by boisking

Car was running great for a few days, but decided not to start after work today. Of course, after testing for spark (none) and diconnecting/reconnecting connectors, she started. Contact surfaces in the connectors looked good to me. Wiring harness has no areas that I have found where anything is worn through. I am wondering if my wire shaking and connector adjusting revealed the problem or if it is coincidence.

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NEED MORE INFO!

What connectors?

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Originally Posted by channelmaniac

NEED MORE INFO!

What connectors?

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Conectors for CAS and coils. Also, based on a tip from trackdog, I messed with the o2 sensor wires (Gary says a shorted o2 sensor wire has caused his car to cut spark, by shorting out the ignition/engine control fuse). None of the wires were loose or decaying, or anything like that. The copper contact points of the connectors were not corroded. Almost shiny, even. I also removed a small portion of the black stuff that bundles the wiring harness to the CAS and verified that the wire casing is still pliable. I am assuming that it is coincidence, with the car starting after messing with wires. I bet that there is a part going bad (still guessing CAS or coil).

Well, today my intermittent problem reared its ugly head again. This time, the symptoms were more severe. After work, It wouldn't start...nothing new. I have a trunk full of tools because of this problem. I get the car to start by just unplugging various wires, shaking the harness in various places, and cycling the ignition switch from OFF to RUN, not start, vigorously. There was no scientific method to this. I don't even remember what I did. I got approximately the distance of 2 blocks from my workplace (on 190 service road) and it stalled while driving. This is the first time I have experienced this. I get out and repeat the earlier "fix" method...and it starts again. I am planning on meeting the guys in McKinney for a movie, so I go east to 75, then north on central. As I approach Allen (just before Bethany ST), she stalls again. I coast across three lanes of traffic, across a bridge, and lose momentum 30 yards before the exit ramp. I am now sitting still on the shoulder of Central Expressway at 230-245 in the afternoon. Pretty heavy traffic traveling 65-75 MPH. "I like my odds" I think to myself as I hop over the passenger door and walk to the front of my car to try to repeat the SWAG fix aforementioned. No workie. I call for backup after 20 minutes of tinkering (I wanted to tinker anywhere except there). My brother, of course, is up to the door sills of his jeep in muddy water, and had to quit having fun to help me out. 40 minutes later, he arrives and pulls me to the nearest parking lot. Out come the tools. It is time to get down to the nitty-gritty. I start pulling everything out to inspect. All the plugs in the general area of the coil/cas are pulled and reinstalled. I apply my test light to all the connectors to make sure there is power coming out of the ECM. Good power signal, no start. I pull out the CAS, then disassemble it. I accidentally bend the little star thingy inside it, then bend it back. Then, I notice something that reminded me of Gary. The o2 sensor wires he had mentioned to me received another look. One was seperated. I swear it was not seperated when I pulled and shook on the wires back at work. It must have been barely hanging on by a single strand or something. I reassemble and reinstall the CAS, splice a new section of wire into the o2 sensor pigtail, and reinstall the wiring harness (I had begun to remove the engine harness from the rear of the head for more detailed inspection). It is running again......for now. My CAS currently has no rear cover on it (partial re-assembly for testing purposes). My timing is guestimated at somewhere between 0 and 20 degrees BTDC. I am just going to drive it and see if this problem reappears, but I hope that fixed it. I can handle looking dumb for not finding a broken wire sooner, if it saves me a few hundred bones in parts. Sorry for the long story. Bean, I assume you changed my signature for me. I like it, so I'll leave it alone.