Backfiring

**Dan** · 09-04-2016, 02:56 PM

Got the car out of the garage. Stalled it and restarted it and it backfired then ran. Got it on the road, drove fine. I get back to the house and let it idle. Idles good, no backfiring. Seems to have a slight miss that's off and on. Let it run for couple minutes at idle and shut it off. Go to restart it 30 minutes later and backfires twice through the intake I assume.
Video of it idling

Seems to be backfiring out the map sensor. Thoughts? LE2 heads and cam if it matters. 24x, so don't blame the opti. Timing chain went back on as it came off. Don't blame the pink intake

Thoughts?

**BALLSS** · 09-04-2016, 03:19 PM

back fire through intake generally means a timing issue (like Opti installed wrong). IDK what particulars there are on the 24x ignition..perhaps something there to look into.

coming out the MAP is likely it was the path of least resistance, especially if you don't have the orange rubber boot that goes over the MAP nipple (don't see it in our pic)

you can get those nipples at the Harley parts dept for a few $

**Dan** · 09-04-2016, 03:20 PM

Yeah. My friend and I are thinking it has to do with that seal missing. Replacing it later then I'll restart it and see what happens

**Dan** · 09-04-2016, 07:08 PM

Replaced map. It's backfiring out the exhaust now. Pulled #1 plug just to take a look at it. Wasn't fouled out. Put it back it and ran it. Ran for about 30 seconds before another gun shot.
I'm going to check fuel pressure when the key is on and see what I'm getting..

Could it be that it's just dumping way too much fuel?

**Catmaigne** · 09-04-2016, 07:27 PM

Quadruple check all of your wiring. I remember my friend's car doing that when he hooked his plug wires up wrong. Did you remember to swap cylinders 7-4 and 2-3 because of gen 1 firing order?

**Dan** · 09-04-2016, 07:29 PM

I pinned the harness to BP automotives instructions. I assume that already has the firing order swapped.

**Dan** · 09-06-2016, 02:49 PM

Bump.
Is it possible it's tune related?
Fuel pump? I still have the stock 111k mile pump in with 36 lb injectors.

**harner** · 09-06-2016, 03:02 PM

Is this a 0 mile build? I ask, because my 24x car did this with a BP Automotive harness. Turned out to be the fuel injector harness was backwards as it wasn't labelled. Flipped it around and connected them properly and no more gun shots out the exhaust.
@Dan

**Dan** · 09-06-2016, 03:05 PM

I repinned the harness. So I'm using the stock harness.

New heads and new cam. Bottom end is still stock.

**Dan** · 09-06-2016, 06:11 PM

Could it possibly be the octane if the fuel has dropped since it sat for close to a year? Lower octane fuel causing detention. I didn't put stabilizer in