Timing light isn't entirely regular...

[GrimJack]

I haven't run into this before.

My car seems to have picked up a bit of a stumble at idle. I figured it might be timing related, so I threw my light on there to check. It's an inductive pickup, which is new to me, my old light was one of the inline jobs.

The issue is, that I don't appear to get a perfectly steady flash from the light. It's reasonably steady, but it misses every now and again - maybe 20% of the time.

Could this be an indicator that the cylinder isn't firing all the time, causing my stumble? Or do inductive pickups just not work 100% like the inline ones?

 

[cwapface]

Try it on a different plug wire to see if it fires 100% of the time

 

[jetjock]

What cwapface said. And remember, the Supra uses DIS with waste spark. The waste firing has different characteristics than the true so if you have a cheap light it may not be responding well to it. That's sometimes an issue with poorly made inductive pickups. Try cleaning the laminations on the pickup and when not using it leave it open if it has that ability. That way if it gets dropped you won't damage it. Otherwise, place a piece of cardboard between the jaws during storage.

This is also where an ignition anaylzer can really help, either the cheapie digital type or a scope. If you're willing to learn how to interpert the data an analyzer can tell you a great deal of information, everything from plug/wire condition right down to the A/F mixture in individual cylinders.

 

[bluemax]

I've noticed the same thing when I time my car.
It looks a little odd. But I just go with the flow.
I use an inductive timing light too.

 

[miggles]

me too.i just wiggle on the inductive wire and pull it taught then i get the light constantly.i figure its the tension leads too skinny to fit snuggly in the clamp.

 

[Supra Blues]

My inductive light does the same thing.

I don't have a miss, idles perfect, but everyone once in a while it won't flash.

 

[lagged]

same here!

 

[GrimJack]

Ok, thanks for the input, everyone. I'll chalk this up to the light then, and the stumble up to the fact that my motor is awfully tired. Time to get on that new shortblock...

 

[billspreston01]

I had the same problem when I timed my engine, I had no clue what it was, but I adjusted the clamp on the #1 wire and it seemed to go away. Actually...I think it was blinking but just not in time with the mark. It was timed at 10 degrees, but every few blinks (every 5 or so) it would show like 15 degrees or 7 degrees and weird things like that...any ideas?? haha...maybe it was just the light being retarded, but it stopped (I think) after I put a new cps cap and seal on. hmmm

 

[miggles]

put it down to one of the little quirks of the supra.Its a mystery thats not supposed to be solved.:biglaugh:

 

[GrimJack]

BTW, just to keep everyone in the loop - I found the cause of my stumble at idle. 20psi on a Toyota head gasket through a 57trim CT26 obviously doesn't let the head gasket survive for very long.