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Are my plug wires bad and if so would that cause stalling after the car is hot?

38K views 301 replies 27 participants last post by  chairmankaga 
#1 ·
My car wants to die after a while. It'll start strong, idle smoothly, rev freely, run fine. After a while, though, it'll start to miss. It'll chug a bit. It'll probably die. I ran it at idle in the garage this past Sunday and regardless of where I set the idle it would eventually start missing to the degree that my digital rev meter was freaking out and bouncing all over the range.

The battery is new, the coil is new, the ignition amp is new, all of the sensors are new, the wiring to connect them is new, the plugs are new, the injectors have been serviced and flow cleanly, the electricity to fire them is consistent and adequate, the fuel pump is new, the fuel pressure regulator is new and confirmed to be at spec, the AFM checks out and the mix is good (if a tad rich). I've literally gone through every component and either checked/confirmed it's good or replaced it, if not.

All that's left is the plug wires, and they're $150 or so. I don't know if the plug wires on my car are original, but they are old. However, the resistance readings are all withing spec when cold. I can't seem to be able to determine if they lose conductivity or if the resistance goes wonky when they get hot. I assume MAYBE that's what's happening?

Thoughts? Every time I drive the car for more than about 15 minutes, as soon as I come to an idle stop it'll die and take several minutes to restart. Let me tell you, when that happens at an intersection at a major highway, it's not good. Not good at all.
 
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#142 ·
Sigh. I wonder if this engine doesn't just want to die.
Dive into it again last night, looking for the leak. Checking the timing belt and cam timing. Ignition timing. Injectors. Fuel supply. Vacuum hoses. Everything in the L Jet tuneup guide. Didn't find much aside from a slightly loose plenum hose clamp. Fired it up and after a few seconds not only did it still suffer catastrophically low vacuum and began stalling, after about 30 seconds it began pouring out acrid white smoke from somewhere in the engine bay. I couldn't tell exactly where as I shut the thing down as fast as I could. I gave it a few minutes to make sure it wasn't actually on fire.
At this point I assume something is truly, badly wrong with it.


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#144 · (Edited)
Not really. No. This was more of an oily smell.
There's no evidence of a blown head gasket - no milkshake, no external leaks, no mess in the cylinders. But it does seem like it's in the head(s).
Looks like I'll be methodically tearing down at least the fuel and ignition system if not more. Whee.

Thoughts - the engine didn't seem to be running long enough to generate the heat to burn anything externally, like spilled oil on the exhaust or anything like that. From experience that'll take a minute or two at least! So the smoke must've come from inside the engine. So how was it getting out? It definitely wasn't from the throttle body or AFM. It seemed to be more under the plenum.

I also dipped the new injector seals in oil prior to installing them, although I can't imagine there was enough oil on them to generate that amount of smoke. But maybe?

Wondering if one of the intake tubes isn't the leak culprit, and the smoke WAS the oil on the injector seals?

All speculation at this point.
 
#148 ·
No, no backfiring or popping. Vacuum is still extremely low - 10-12" - and as before even breathing on the throttle causes an immediate stall. It did run long enough to confirm the distributor retard works and timing is OK, although a bit advanced (more on the P/F line rather than the R, although this is probably because it hadn't run long enough for the idle to drop).
 
#150 ·
Yeah, seems there was some residual lubricant on the injector seals that was smoking. However, I've still found no obvious culprits. None of the seals were pinched. The injectors do not leak. The timing marks on the cams are still perfectly aligned and belt tension is fine. None of the hoses have hidden tears. I was going to put some air into the plenum and listen for the whistle but I accidentally knocked over my compressor and broke the outlet valve. Then I dropped my torque wrench and broke that, too. Thankfully that's a Craftsman and Sears confirmed via phone they will replace it for free.

It's holding fuel pressure, at least.

So I'm still at a loss regarding the vacuum. It's still stalling instantly if I even breathe on the throttle. You can watch the vacuum go from a measly 12-15" to 0 when I do.
 
#151 ·
Yeah. Almost certainly leaking injector seal(s). Buttoned back up and purring.
Went ahead and replaced with FPR with a brand new Bosch piece. The pressure continued to randomly drop to 0 with no external leaks or from the injectors. So far so good.


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#155 ·
Plug wires and coil connected. Distributor is on the mark with 1 at tdc. Cam marks line up. Grounds connected. Spark being made. Injectors pulsing. Fuel pressure good. Cranking. Just no ignition anymore. At least before it would run, albeit briefly.
Maybe time to call in the expert. I need a break from his car.


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#156 ·
I wish you could get another known-good AFM to test by substitution. I wish somebody could loan you one, and I sure would myself if I had one. I'd ship it to you tomorrow...

And before you plugged in that AFM, I would ring out the wires in the connector itself to ensure they make good contact.

As I look back over all 11 pages of this post, the AFM and the ECU are two major items that have not yet been ruled out, correct?
 
#157 ·
I think I'm getting known-good AFM and ECU to test out in the next few days. I checked the continuity of wiring from the AFM and all of the sensors to the ECU harness just last year, with no issues.

I'm not convinced I didn't damage something when I was reinstalling the fuel rail though. Even when the injector seals were leaking so badly, the car would start and run, albeit not for very long or very well. Now it won't even start. I'm going to take a few days break from it, go back through all of the systems and make a checklist, then try again soon. Need to replace my noid light that my old neighbor moved away with. Plugs are getting juice, though. I did confirm that.
 
#160 · (Edited)
Oh, yeah, I keep getting side tracked by the guys with problems with their 164s. Sorry. Get you confused with a guy that had trouble with his 164.

Never mind. Hope you get this figured out, as both of the GTV6s I drove were fun, esp the 86, best of that bunch.
 
#161 ·
At this point I think I have to assume there's something very wrong internally. All of the injectors leads check out with the noid light. Fuel pressure is good. Spark is good. Timing marks are all aligned. Belt has tension. Starter cranks easily. Battery is good and fully charged. Etc.

Cranking the engine now produces a mechanical clanging sound, but ONLY when the injectors and plug wires are connected. When I had everything unplugged to try the noid light and check compression, no clanging. Reattach everything, clanging.

I feel like I'm out of my depth. Contacted a local mechanic who's appeared in this thread but right now I have literally no free time to deal with it. Maybe in early May...

Frustrated and alarmed. I'm hoping it's something simple and dumb that I've overlooked but I have this feeling in my gut that's not the case. This might be it.


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#162 · (Edited)
Mr. Chairman, can you pull the distributor cap off, pull the rotor and see if the keyway is stripped? Have you watched the rotation of the distributor shaft lately as the engine cranks, and verified the rotor's at the right spot, firing number 1 at TDC?

Random spark firing might give you that kind of sound. Mike's car had some bad gas in the bottom of the tank last summer, after sitting here for awhile, and when we went to start it up, I could have sworn the cam belt had slipped and it had low compression, and it made unusual noise when cranking. We did a tune up (it was due), torqued the heads, verified the timing, fresh gas and fuel system preserver, and after a couple of pops it started and ran like a champ.

I know I'm asking a lot of you at this point! I'm beginning to believe in the demon-possessed supernatural as far as this motor's concerned...
 

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#163 ·
You nailed it. I'd recently replaced the rotor and I guess when installing it I chipped the plastic/Bakelite/whatever it is and opened up the keyway. I suppose the rotor was sort of wobbling. Swapped the old one back in. I got excited thinking I'd solved the start/stall as well, but alas. It does start now, and easily. Idles smoothly. Then dies.
Plan to try swapping the AFM for a known good one, maybe this weekend if I can get my hands in it.


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