Ok, so ever since I swapped over to OLF, I've been getting some pretty bad backfiring. It only happens when I go WOT and let up around 6k rpm. In first gear, it's really freacking loud, in 3rd it sounds more like a stutter or a hesitation with some popping.

help please.

 

That doesn't sound right.. It might be tuning or some other setting (ignition cut instead of fuel cut, etc..) but I'd need more info about the setup of the car to suggest anything..

 

Mods: Intake, 3" exhaust dp to muffler no cat, port and polished cylinder head with 1mm oversized valves dual springs and titanium retainers, utec (obviously) w/o map sensor (I haven't hooked it up yet), ebc set at 22-24 psi, bov vta and an LM1 wideband.

I was out playing with it just now, and had something similar happen again. This time in 2nd, the pop wasn't as loud, but definitely there. It was accompanied by urching of the car. About 90 seconds later, I tried to hammer it again and ended up with a stutter (almost like ignition cut on the launch rev limiter) followed by a dead pedal (just like with fuel cut). The log showed 3 counts of knock at 0% load immediately after. I will post the log in a second.

Thanks for the help Jack, if you can figure this out, you will be my god.

 

Here's the log. Both acceleration points (the 100% tps records) are in there.

 

I just noticed that the second time I accelerated at 5241 rpm, for some reason the mod. timing went back to ECU. This shouldn't be happening since I have a value in there.

AFR's were between 11.5 and 12.1 on 91 oct. I know it's a little lean, but I was running close to that before the OLF upgrade.

 

It sounds like the P0300 misfire but I have seen resonance at that exact RPM which sometimes is picked up as knock.. Weird.. You may have a minor problem with the UTEC, I would try reflashing the firmware and re-enter your settings, and then reload your map..

 

excuse my ignorance, what is OLF?

 

Open Loop Fueling.

And, there is no such thing as a dumb question

 

Thanks Jack, I'll try that tonight and report back what i find, if anything.

 

Alright, I'm still having the same problem. I backed timing off and started dumping in more fuel, and part of the problem seems to have disappeared at lower RPM.

I just made a 2nd gear pull to redline that was nice and clean, shifted to 3rd and I get some popping. Not quite as bad as the backfiring that I was experiencing, but popping out of the tail pipe none the less (I'm beginning to just think that's normal).

However, after shifting into 3rd and continuing on, I get a loud pop and a fuel cut like cut at about 5500 rpm. I double checked in my parameters, and in the OLF settings, I have the MAF fuel cut set to 0 for turning it off. I did not log any knock what so ever.

I did notice something strange in the log. I'm using an EBC for boost control, so my boost column in the log always reads 'ECU'. But, during my 2-3 shift and right at and a few log lines after my cut it read LCM. WTF does LCM mean and should I even be concerned with it?

 

I would think you have a serious leak going on somewhere. I suggest to pressure test your car immediately and try to find the leak.

 

I'll check it out. Thanks.

 

I was never able to disable the MAF fuel cut with the UTEC for some reason. Whenever I hit 24psi, bam, fuel cut. None of the instructions worked properly to prevent this from happening. I eventually just flashed the ECU to get rid of the fuel cut.

Not sure what LCM is though. I have never seen that one. I took a look through all my old logs and never had LCM show up. I keep thinking Lowest Common Multiple for some reason

 

pdx evo, did you ever try moving up the maf hz fuel cut up from 1700 to maybe 2500hz? That surely would have fixed your fuel cut problems. LCM is launch control, that will explain the bangs that occur after you step on the clutch and you let off the throttle.

 

Moved it all over and it didnt change anything. UTEC always was a bit off on the electronics though, so it wouldnt surprise me if something wasnt getting pathed properly in the layout.