Whelp, I'm getting pissed. My car has recently developed some kind of miss around 2250-2500 rpm and over, and I'm getting tired of it. The actual miss is pretty intermittent, but the tach jumps around in that rpm range (without the actual rpms noticeably changing) alot, and everyso often it will miss while doing it. The tach will bounce around in that rpm range in both drive and overdrive (and all gears then I assume), and while just in neutral just holding it in that rpm range too. However the actual miss has only occured in OD cruising. Voltage as read at the dash guage is solid during the missing, so it's not battery/alternator cutting out or something.

Now I've changed the cap, rotor, coil, and HEI module on the distrib with no luck. Thought for sure one of those was the culprit. I inspected the plug wires, all looked good. Read the resistance across them and they were all right in range with each other, with very little measured resistance. So I think they're good. I've checked the battery/tach wire connections to the distrib as best I could, they seem fine (they run down where I can't see them anymore pretty quickly, could be something down on that end). I pulled a plug on each side of the engine, coloring was good. They're not very old, but I'll change them if I don't find this soon anyway.

I'm drawing a complete blank on what to check now, anyone have any ideas? The wiring in the car is a slight hackjob, could that cause a specific miss like this? I ask because I was having a slight hot starting problem that turned out to be a corroded positive battery connection. When I fixed that the miss/tach skipping briefly went away. It returned immediatly after I took apart my distrib to fix a sticking advance problem. That is why I suspected something on the distrib itself initially as well. Now I'm leaning toward a wiring problem since I changed every component on/in the distrib. The car has no other funny side effects, no hard starting, etc that would give me any clues...

The car's setup is a ex-TPI car now with a Holley 3310 carb, MSD Pro-Billet Distrib, etc. Can't think of what else to check.

BTW, to check to see if it's a wiring problem with the wiring through the ignition switch, or something similar prior to the hot battery lead running to the distrib, is there any reason why I couldn't temporarily run a straight hot lead from the battery to the distrib on a new wire to bypass all the ignition switch setup and all stock wiring there and check if the miss goes away? That is my next step if there's nothing that would hurt...

If anyone sees something I've missed, or has a good method to try to troubleshoot something like this, any help would be appreciated.

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray


[This message has been edited by Ray87Z (edited November 06, 2001).]

 

The ignition pickup is likely the problem- it's around the distributor shaft in the base of the distributor housing. Having a known-good junkyard distributor is always a good idea for tracking down if the problem is "under the cap" or elsewhere.

Either that or the secondary voltage is leaking back into the primary side somehow (bad ignition components).

Yes, you can run a hot lead stright to the battery to test if the stock wiring/power supply to the distributor is bad.


[This message has been edited by Damon (edited November 06, 2001).]

 

The ignition pickup huh. That's the whole assembly down with the star shaped magnet junk right? Any idea what a replacement unit would run? I do have a partial spare distributor, that part is there and should still be good (an Accell Blueprint unit). Is that part interchangeable between all HEI distribs, or would you think it will have to be the specific part from MSD? Is the whole star shaped magnent assembly all part of the whole thing, or is the ignition pickup seperate and below that? I'll take a look at it tomorrow and see what I think I guess. Maybe I can use the Accel parts I've got on the MSD...

------------------
Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray