Coil test

[wahoo50]

Have read where resistance across coil towers should be 11-12.5, mine is 17.2-17.4. Should this be a problem? Car is popping under boost.

 

[mikestertwo]

Have read where resistance across coil towers should be 11-12.5, mine is 17.2-17.4. Should this be a problem? Car is popping under boost.

Do all the coils read 17.2-17.4? Is it an aftermarket coil pack?

 

[wahoo50]

Yes, 1st pair reads 17.4 ohms, 2nd 17.25, third 17.4. It appears to be aftermarket, I see nothing signifying Delco. Thanks for the reply.

 

[mikestertwo]

If they all read the same I would say that is normal for that coil pack.

 

[DailyDrifter]

Is it popping from the exhaust or intake? Was the coilpack hot when you ohm'd it?

 

[wahoo50]

Coil pac was not hot. Have since replaced it with a new Delco, also replaced the ignition module (Delco), have 8.5mm wires, resistance is almost perfect. Is backfiring out the tailpipe. Fuel pressure stays up there, have Red Armstrong twins.

In searching for the problem, it appeared to be missing on one cyl., sometime, removed the plug, looks OK, gonna go back with a new set of NGK's.

Boost peaks at 17 lbs., usually run 28 lbs., which is no problem for my setup.

Help anybody?

 

[captflash]

I had a similiar problem but in reading the threads I regapped my plugs from .035 to .032 and it stopped. The info on this said that under high boost that the spark could be blown out at .035. Good luck.

 

[DailyDrifter]

I would gap the plugs at 30. Your backfiring from the exhaust indicates a rich misfire. You could be blowing the spark out due to plug gap, or too much fuel (which will also put out spark, and possibly cause knock). If the problem is in one cylinder it could be internal, best way is to do a leakdown test, NOT a compression test, LEAKDOWN :wink:. What are your o2 readings? Misfires can be tricky, a rich misfire will probably show up as a lean o2 number because there is still unused oxygen in the misfire mixture.

I would start by tightening the gap first, if the problem is still there do a leakdown test. In a wastespark system you have one coil firing 2 cylinders, so if it's only affecting one cylinder I would'nt be chasing a ignition problem. BTW your old coil resistance seems a bit high, around 12-13 is the norm.