Greetings. I am finally tuning the setup I've had in the works for over a year and we've run into an issue. My tuner is competent and knows what hes doing at the levels we are currently shooing for (lowest boost possible with current springs) roughly 18psi.

We've tuned through all the gears for the most part however we have run into an issue around 6500 rpm doing WOT runs in 3rd and 4th there there is breakup and a loss of acceleration. We think this is resulting from one of two issues and here is where we are trying to get input.

A little more background is in order however. We originally tuned the motor to break it in and see if there were issues with a PFC setup. We had an issue with breakup then which my builder attributed to fouled plugs from the original tune. We swapped the plugs out and the problem went away. However shortly after we brought it back in for a couple follow-up issues and to switch to an AEM Series II from TriPoint.

Now we have started the process again with the AEM and with brand new plugs (installed not a week ago with maybe 300 miles on the tune there is breakup again). Now we are running stock NGK plugs which I understand aren't great for the setup but should handle it at least for a few months before fouling.

We think there are two potential issues for the breakup. Either

A. We need colder plugs even at low boost (keep in mind I'm saying low boost relative to what the car was designed for). I'm looking at either Autolite 11s or NGK 11s and posted on an autolite thread for opinions. If I can run autolite I'm not concerned as they are like $3/ea but the NGKs are going to cost me substantially more money when they inevitably foul from idling or something dumb I'll do.

or

B. My meth nozzle is too large and I'm actually drowning out the engine from fuel/boost juice.

Considering this is my first car running in this case boost juice I don't have a lot of experience and I'd hate to throw in my set of NGK 11s only to fuel them out in a few days/weeks if thats not the real issue.

Thoughts?

 

Which ignition system ?

 

Using lugwids AEM coil setup, not yet on direct fire.

 

ignition dwell period insufficient for the coils at that load .. go direct fire.. push dwell up to 5ms or there abouts

if you currently have settings at 5ms with wastespark then the ecu is terminating the charge period early to fit all the events in

 

I've run 22psi on a 35R with these coils in wastespark with a PFC with methanol injection without issue. Wastespark/dwell isn't necessarily the issue.

Uleepera, you have a PM.

 

Responded to pm a couple days ago, issue is still occurring. Bumping the thread.

 

On a side note, I ordered Autolite AR3932X plugs to try out although we've almost ruled out plugs as the issue.

 

Have you looked into simple things such as measuring continuity of the spark plug wires? I'm sure you're using Ludwig's harness which is correct but you should also measure the grounds at each point going back to the battery. Are EGT's available?

 

[QUOTE]Sadly I wouldn't qualify that as simple for me I'm learning as I go with a lot of this.

We may have actually identified an issue here as the ground one one end was supposed to connect to connect to the battery and it is apparently connected to the chassis. We are going to move it today and see if that does anything

Yes they are.

We are also checking the dwell to make sure it is set at 4.5ms

 

Pretty sure the issue has been resolved. 99% of the thanks to Ludwig. The issue seems to be that the battery ground was actually mounted to the chassis instead of the battery. After I moved it today we did about 2 hours of highway pulls through the RPM ranges with no breakup at all. ::KNOCK ON WOOD::.

Also sorted out a lot of my idle issues although I've got a bit more to do for that.

Man this issue was haunting us for like a month!

Thanks again Ludwig!

 

Good to hear. I recently had to help someone else out with a similar issue. These coils are great but the can be finicky if the grounds are not checked after install. Chris knows his stuff with these coils!