I have an issue that I need feedback on.

I am running a meth+pump (92oct) mix on a daily driver tune set at 28psi with 30psi spikes. If I run through the gears starting in 1st or 2nd and then rip through 4th all is good. If I tip in to 3rd/4th on a roll on around 4-4.5K rpm I experience a "pop" (sounds like off throttle backfire). This does not happen all the time but, puzzles me when it does.

Plugs checked for gap - no obvious flameout (HKS twinpower installed)
Meth sprayers checked for flow - tested flow is excellent (AMS kit)
AFR is in the 11.0-11.4 range

Any feedback?

 

Does the meth system open up or ramp up quickly, it sounds like you just have too much fuel when you roll onto the throttle. Maybe too much meth too fast or too much Accel Fuel or a combo of both. You should do some fuel testing and see whats going on, if your fuel looks good I would start checking for misfires and go from there. The AEM with stock coils and Meth at high boost can cause misfires becuase the stock coils don't seem to recharge or dwell as good.

 

The meth system has two sprayers. One sprayer hits at 4psi and the other hits around 14psi. I am on the rich side for meth as I know you can lean out the mix a little with meth. When the second sprayer hits I am in the 10s a/f for a bit. I wil make some adjustments and log. As far as spark I do have the HKS twin power installed so I will just swap plugs and regap to address any spark issue as I am fairly certain I am getting good spark.

Thanks for the feedback....

 

Unless you are dwelling the stock coils differents the DLI made very little difference when I tested it. It helped but it wasn't enough help for high boost in the situation I had. If you are in the 10s when the 2nd sprayer hit and you do not have a progressive style controler I would say it is a combo of these things causing your backfire problem.

 

What would you suggest to address the spark issue?

The car dips in the low 10s high 9s initially and then hovers in the 11.2 range. I might target a 11.5-11.8 with a high 10 dip to address the issue from a fueling perspective.

 

I do it and I have no meth kit. But good luck!

 

tune 0psi to 3psi map at 4-4.5K. or below 0psi. It probably needs to be a bit leaner. or advance a bit of time. what is your tip-toe throttle afr at4-4.5K? what's your gap at?

I've noticed that it does drop down to 10afr for a sec before it rises up to 13afr for a milisec then down to 11.5 on my car.

 

My AEM gauge only reads to 10 a/f so I know that I am hitting 9s.

My gap is at .024 with 8 heat range plugs.

I threw in a little hot sause to add a safety fator while leaning it out but, I am convince it is not igniting due to too rich conditions.

What kind of timing are you seeing in the 4500-5200 range?

Where is your on boost timing transition?

Care to share a print screen of your timing table?

 

I can't share my map. but you could share your datalog with us.

but 9's super freaky rich.

i would go change the plugs again. it maybe fouled already.

I had this happened to me before, but it wasn't dipping to 9's. 9's is something I've never experienced before while driving. it's either your aem is pulling timing on its own on fail safe settings or your timing transition is wrong.

 

I have been playing with the transition and focusing there. I will log and share.