revolve40

I recently installed FVD’s MAF kit (spec’d for 93 octane, cat bypass, and LWFW) and didn’t like the fact that it was pinging heavily at WOT lower in the RPM band. This is not a thread to discuss the pros/cons of MAF conversion etc. - there are other places to do that.

I found the attached vacuum leak (new male-to-male connector on the way).

Could this alone be the cause of my pinging issue? Or is it more likely that the 93 octane I’m getting locally is not “up to task”?

C24FUN

I have a MAF intake (not the FVD kit but the earlier Autothority MAF) which I installed 10+ years ago. I have a similar experience with pinging when I am heavy on the throttle at lower RPM (under 2500) and the air temperature is high (> 28-30 deg.C). I always run 94 Octane and have no other engine mods other than a Cup primary muffler bypass. When I first noticed this, years back, the general consensus was that the chip that came with the MAF kit had modified (advanced) the ignition timing in an effort to up the horsepower, and had pushed the advance into a range that leads to pre-ignition under the conditions I described. I have compensated by staying light on the throttle at low RPM on hot days. 😊

As far as the air leak goes, I have no useful info. I would certainly fix it and see what difference it makes, if any.

Cheers!

Jim G.

BGMS_964

It's certainly possible. You're allowing unmetered air into the engine. The DME doesn't know that this extra air is being introduced therefore it doesn't schedule a corresponding increase in fuel. The result is a leaner A/F mixture and lean mixtures are more likely to detonate.

revolve40

Thanks, all. Yes, the FVD chip certainly advances the timing and could be more aggressive than the Steve Wong chip I've been running without issue (also tuned for 93). I'm wondering if the MAF, being far more sensitive than the AFM, is impacted more significantly by vacuum leaks such as the one I posted than is the AFM. Will fix and report back.