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Uniquely desultory
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7,558 Posts
Discussion Starter #1
Alternate title: "car heals itself."

I hate it when they heal themselves. Aren't supposed to do that.

About 3 weeks ago I charge the battery and took it for a spin, first time in almost a year. I'm thinking, 'oh hell yes, I dig this car.' All I needed was to weld in a new CAT. So a week later I try to start it again. Nothing, just grinding that is. I put some starter fluid in the airways, still nothing. So I consult the E30 no start guide protocol, pretty sure it's no spark but I give it one quick test - disconnected a spark plug, put some #12 multi strand in the socket, hooked a jumper cable to ground, this so I could shoot for a spark while grinding it (my buddy out of town). It cranked over a few times, no spark, suddenly it not only sparked, it started up. Hooked the plug back up, it ran great. This car is still incredibly fast, even with 450K.

I welded in a CAT, passed smog, paid for tags, it ran great for a weak. Then started a lurching miss, with a check engine light flash, on the way home Saturday night. The miss was so sudden and thorough seemed it had to be electric. Just a few times though.

Last night I was driving home and it really started missing. Then would hit 2, 3 seconds no power at all, suddenly starting back up. I pulled over, it died, wouldn't start. I missed with the spark plug wires, pushing them in at the distributor and tugged on the TPS wire back and forth. The latter as the miss was reminiscent somewhat of one on my other, now totaled E30, when the wire to the CPS strayed up to contact one of the pulleys, wearing off insulation, and grounding intermittantly (going to look at that in detail today).

Anyway, twice I got it to start back up after a full stall by messing with those items. I made it a block from home and it stalled again. This time I first tried plug wires - no start - then moved the CPS wire back and forth - no start. So then I pulled out a piece of wire in the trunk and tried the first accidental electro shock thing, hooked it to a spark plug socket, sure enough, after some grinding and no spark, suddenly the spark jumped and it started.

I'm going to look at a bunch of things, but who knows, I was hoping this might ring a bell with someone.
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #2
I may, emphasize *may* have caught a lucky break. I had a spare ECU that I had tested for good operation years ago. I put it in and went for a 5 mile freeway test drive. It was perfect except for one brief cut out stutter, complete with 'check engine' light coming on for a nano second. Much better than the last 5 miles I drove before that. But that one stutter worries me.

I inspected the Crankshaft position sensor. Looks good, the wire not pinched like my other one had been.
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #3
Who knows, maybe someone will read this someday and I will have found (at some point) the answer to this puzzle.

It wasn't the ECU. It occurred to me (Duh) to hook the old one back up (still screwed to glovebox lid) and see how it performed. Worked just as good as the replacement. For about 20 - 30 minutes. Unexpectedly stalled at one point but started up. After the next stop, it started, I stalled it in low gear, would not start for love nor money. Pushed it out of the way of other cars in the parking lot, 10 minutes later it did start. Got 1/4 mile away it stalled at speed, no amount of roll starting did the trick. While sitting, I hooked the replacement ECU up again - nothing.

I tried my trick of jump the spark plug gap, thinking this did some magic, but no spark was available. My searching indicates that a dying coil can perform intermittantly in this manner. One guy said as soon as his got warm it would cut out. Said it passed all the tests while at rest.
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #4
Jeez, not the coil. The phrase 'unfindable electronic gremlin' keeps coming to mind. Ouch.
 

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D'oh, You Kids!
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29,358 Posts
That sure points to a failing CPS. I had one that acted like that for a week or so until it completely stranded me. I put in a new one and haven't had a bit of trouble since.
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #6
I had been under the impression that I put in a new CPS some years back but upon looking at my excel spread sheet record I see that I got one from Pick n Pull off a rig with an odo reading of 108k about 5 years ago. And who knows, an odo reading of 108k on 26 year old car might not be realistic. That would be 4k a year.

I know one thing, when this first starting cutting out several days back it was very reminsicent of the difficulties I had on my other rig when the CPS cable had some of it's insulation removed from contacting a pulley and was shorting out. IOW, not a stuttering misfire but complete loss of engine power.

I'm getting a bit wary of replacing parts will nilly but this might be it.
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #7
I put in a new CPS, this during a phase when it wouldn't start - no change. I found a schematic showing which leads to the CPU harness should be ground - they all check out. Somewhere there is a funky connection. A week ago it started right up - went out for 2 mile spin, ran great. Has started every day since. Went on a longer errand last night, maybe 5 miles. Ran like a champ the whole time. And me holding my breath.
 

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Nick's Toys
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1,289 Posts
I am going out on a limb here, but have you ever checked FP at this point ?
If you don't have a gauge, just a quick spray test.
Once you eliminate fuel as the culprit then it could be 2 things:
Loose wire or one shorting out when going round a corner or over a bump
Electronic component failing from heat or dried out capacitor.
These gremlins sure are fun to find :(
 

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Uniquely desultory
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7,558 Posts
Discussion Starter #9
Every time it hasn't run it had no spark. Then somehow spark returns.

What I don't know, does the ECU turn off spark if it detects no fuel delivery?

The gremlin thing is scaring me. One wonders how many of the E30s I used to pick over at boneyards landed there because of such a gremlin.
 
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