intermittant spark

alexander · Post by **alexander** » Fri Jan 25, 2008 4:39 am

hi all,
i have a new installation, but it is not yet running properly.
symptoms:
*car has been able to rev right out cleanly to red line, but punctuated with an intermittent on/off miss.
*this is new since the MJ so i am discounting a fuel issue
*after being quite driveable yesterday, it is now hesitating so badly it is not.
*when i put a timing light on any of the (4) leads, you can see the ignition cutting out
under any sort of load, even in the garage. this seems to be the crux of it.
*oddly, one lead from each of the coil packs causes the timing light to flash
twice as fast as the other lead from the same coil pack!
*these symptoms are the same with the mj plugged in, or not.

thoughts?
regards
alexander

david jenkins · Post by **david jenkins** » Fri Jan 25, 2008 9:00 am

Alexander,

I've had very similar symptoms to you regarding 2 plugs showing a good flash, while the other 2 don't. Does your timing light have a sensor that clips over the plug lead? The type that has an arrow indicating which way to put it on the lead?

If so, could you try an experiment? On the leads that give a bad flash, try putting the sensor on in the other direction.

If it works, I'll tell you why!

David

alexander · Post by **alexander** » Fri Jan 25, 2008 10:10 am

hi david, well that certainly is the case!
and i have just been reading the earlier thread in which you raised this exact issue. so i think i will just buy another, decent quality, timing light and work on the other problem in other ways.

that said, the additional complication i am seeing is this: by changing the orientation of the inductive pickup, i can indeed get a regular flash on each lead, but for one lead on each coil, that regular flash is (visually) twice the rate of the flash on the other lead from that coil. if i swap the leads between 1 & 4, and 2 & 3, makes no difference, so it is not a cylinder issue.

i suppose it is still the POS timing light at fault - it is hard to imagine how there could be more impulses going down one HT lead from a coil, than the other lead from the same coil.

and one thing remains also: even with a regular flash, the light is going out intermittently when i rev the motor, and that coincides with the engine faltering. so there is a gremlin in there somewhere.

for the record, the brand of light i have is "trisco". it was the only one available in a number of autoparts shops near me - strange in a world awash with products from 100,000 chinese factories. anyhow, i would definitely NOT recommend this brand.

regards
alexander.

david jenkins · Post by **david jenkins** » Fri Jan 25, 2008 12:43 pm

Strange that your results with a timing light are similar to mine (1 lead twice as much flash as the other). In my case the strobe gave silly results, but the engine ran properly regardless!

In the end I decided to ignore the strobe... it was easier that way...

David

alexander · Post by **alexander** » Fri Jan 25, 2008 1:44 pm

david,
i actually didnt pick up from the other thread that you were seeing the double speed flash too,
so i wonder whether it is something to do with the coil, or we just had the same crap
timing light!

anyhow, i am going to buy another one, and we will then see.

david jenkins · Post by **david jenkins** » Fri Jan 25, 2008 3:20 pm

Alexander,

Don't forget that double flash is normal! The system fires on both the compression AND the exhaust stroke.

The half-speed flash is the one to worry about...

David

alexander · Post by **alexander** » Mon Feb 25, 2008 3:05 am

original problem solved: what seemed like intermittent & momentary loss of ignition, was in fact a problem in the molex connector, causing intermittent & momentary reversion to limp mode. at 4000rpm ish, that feels like the ignition cutting out.

solution was to push the pins firmly back into the molex plug.