Hey guys I got a problem Im having some trouble tracking down. I have been tuning the car up lately increasing the boost and dialing in the AFR. Anyways the car was still running 2" pipe on the hot side of the intercooler so upgraded that to 2.5" and ever since then the car has a misfire above 20psi. As soon the turbo spools in 3rd the car starts misfiring and bucking until I let off. The fuel is low 11s, timing is still low around 12* so I figured it was blowing out the spark. Check plugs and regapped them to .024". Didn't fix the problem, pulled some more timing up top and nothing changed. Im still thinking its blowing out spark so tmrw Ill try lowering the boost back down a couple psi and see if that helps any. Im still on the stock coil pack maybe thats not strong enough at this power level.

The car is pushing a little over 400bhp.

try a .020 gap. if still, try .015, if no change then stop there with the gapping trials. it's something else.

Ill try that this week. I turned the boost down to about 19-20psi and its pulling fine.

Originally posted by SilvrEclips
Im still on the stock coil pack maybe thats not strong enough at this power level. The car is pushing a little over 400bhp.

Curious. I lost the stock coil pack (and the MSD coil pack) at a little over 500whp at 24lbs on a bw366 with 10.5 comp (as I recollect). I ended up using the Screamin' Deamon coil for another 5lbs to 567whp. My plug gap at that time was .018.

So it is possible, but it seems a little low for a power threshold. Maybe the coil is getting weak? I take it you're running a 3 bar. It is possible that she is malfuntioning. I did have a 3 bar that would only go to the mid 20's.

Originally posted by bullettdsm

Originally posted by SilvrEclips Im still on the stock coil pack maybe thats not strong enough at this power level. The car is pushing a little over 400bhp.

Curious. I lost the stock coil pack (and the MSD coil pack) at a little over 500whp at 24lbs on a bw366 with 10.5 comp (as I recollect). I ended up using the Screamin' Deamon coil for another 5lbs to 567whp. My plug gap at that time was .018. So it is possible, but it seems a little low for a power threshold. Maybe the coil is getting weak? I take it you're running a 3 bar. It is possible that she is malfuntioning. I did have a 3 bar that would only go to the mid 20's.

yea, after what bullett said, don't go to .015 as i said earlier. start at .018 if .020 doesnt do it. small steps.

What is your dwell settings?

Dwell settings

Cranking dwell 10ms
Running dwell 3.0ms
Minimum discharge 0.5ms

Bring your dwell up just a bit more. You should be able to run about 4.0 msec's of dwell. With the gap down to .18 you should get to 19 to 24psi.

Ok I will give that a try. Im running the 4g63 igniter if that makes a difference.

Just another data point for you. When I started raising my boost, I would get a misfire at peak boost. Increasing my dwell eliminated the misfire, without reducing spark plug gap. I am using 4.5 ms on internal Fairchild ignition drivers.

Corbin
'95 ESI-T

Now with more power and fewer leaks



Humble servant of the Wiki

Increase running dwell up to 4.0ms with the plugs gapped at .024 still. Boost is up to 23psi and not blowing out spark yet. That seems to have helped. Ill probably up it a couple more psi when I get the car tuned a little more. Thanks guys

sweet