Built CA sudden backfire.

[Leve1One]

My AVC-R reads about 480-500mmHg @ idle, which hasn't changed ever since I cranked her for the first time... The backfire doesn't occur when I release the throttle, it happens at WOT or anytime the boost hits the "limiter". It is TP insensitive. I don't know if you understand what I'm trying to say...

It just backfires anytime the boost levels get high enough and it doesn't matter whether I am full throttle or half throttle.. as long as boost builds up, it WILL backfire.

Anyways, here's a picture of my S13 Help get this beauty back on road! :P

[float_6969]

I know we've covered this, but it sounds like either a weak ignition, or a limiter. Did it start to get colder when this started? Are you sure you don't have a boost/ MAFS limit programmed into the Nistune?

[Leve1One]

Perfectly sure. Checked twice and re-flashed the tune I had that worked. TPS voltage is within service manual limits...

[float_6969]

The only solution at this point is to set it on fire. I'm sorry for your loss

[Leve1One]

While it definitely sounds like a proper solution, I think i'll pass. :P

[Sideways s12]

not sure if this was covered but try running colder plugs and see if it goes away I was having the same problem with the wifes dsm everytime you got into boost it would sputter and backfire we changed to colder plugs and it runs perfect...

[Leve1One]

It started backfiring with BCPR7ES gapped at 0.6mm. Initially I thought that the plugs were the culprit, so the first thing I did was to go for the BCR8ES gapped at 0.6mm. No difference whatsoever. Also, IK22's and PFR7A. Same thing.

[boost_boy]

It started backfiring with BCPR7ES gapped at 0.6mm. Initially I thought that the plugs were the culprit, so the first thing I did was to go for the BCR8ES gapped at 0.6mm. No difference whatsoever. Also, IK22's and PFR7A. Same thing.

Hmmm, now that I know your choice of spark plug, can I ask why are you running such a cold plug? The BCPR6ES-11s are more than efficient for your application. Colder plugs have been giving me nightmares when it comes to tuning this motor and I live in a very tropical environment. The 7s fouled easier and were causing the car to flame too much. I've never used the 8s as there was no need for the 7s.

[Leve1One]

Sure, I went for colder plugs since -at least supposedly- help in higher boost applications. Bear in mind that when the motor worked fine, it would pull nearly 30psi (and I am not making this number up :P )

Granted, I never had an issue with the stock BCPR6ES-11 even when left at 1.1mm gap but that was prior to rebuilding the CA. At first I went with BCPR7ES which turned out to be a bit more "reliable" on dyno when we tuned it. I had spark blowout at 1.1mm gap with the 7's, so setting it at 0.6mm made it go away and worked perfectly.

Now the 8's came only as a test to see if the whole backfiring issue was caused by the plugs, no other reason. I can switch back to my 7's at any point.

Summers here tend to shoot to 105 degrees and even more (rarely though).

[boost_boy]

I would go back to the 6s and only switch to 7s in extreme boost applications (upwards of 30 psi).