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Backfiring
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
https://youtu.be/5jk_IsKuFik
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 :)
http://uploads.tapatalk-cdn.com/2016...3e678fc056.jpg
http://uploads.tapatalk-cdn.com/2016...dffd4382e6.jpg
Thoughts?
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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 $
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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
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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?
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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?
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I pinned the harness to BP automotives instructions. I assume that already has the firing order swapped.
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Bump.
Is it possible it's tune related?
Fuel pump? I still have the stock 111k mile pump in with 36 lb injectors.
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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
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I repinned the harness. So I'm using the stock harness.
New heads and new cam. Bottom end is still stock.
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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
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Is it pronounced gun shot backfires?
Edit: To add more to that, when I first got my car back running I would have some serious backfiring at random. Was running very rich etc. About burned the car down but my tuner's tech found that my coils were not connected correctly. Harness was correct but the physical coils were not plugged in right order wise.
Follow your harness, verify its going to each coil correctly and then double check that each coil is going to its correct cylinder. IDK how you have em mounted but its not OEM like LS1s so you could have messed that up.
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Yes it's gun shot backfires.
I have the coils mounted like LS.. Should they not be like that?
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http://uploads.tapatalk-cdn.com/2016...a575c2d744.jpg
I have the coils mounted to the valve covers in a line.
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If you take the big plug into each coil pack harness, and trace it out to each coil, they each fire for their respective cylinders, correct?
Really doesn't matter how you mount em
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I'll have to check that out tomorrow and report back to you
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Other than, if we assume you did everything right, I would say its tune related.
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Def double check wiring to make sure injector/coil are firing to the correct cylinder. If that lines up, check the tune to confirm firing order.
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I thought you couldn't change firing order in the tune? @MoeHorsePower did the tune for me
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You can't change actual firing order in the tune AFAIK, only cylinder bank assignment. The computer always uses the same firing order and GM used those computers on both Gen 1 and Gen 3 by swapping pins in the wiring harness.
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If it's a 24x you change the injector bank, torque head are already swapped, let me know if you found the problem
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1&5 look like they have more carbon/oil suggesting those cyl are either not firing or have a weaker spark
how many miles on the plugs?
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Half a mile and idle. I'm replacing those two coils
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1/2 mi, ouch
coil is suspect for those cyl. you could swap coils to another cyl to see if problem migrates to those cyl or just lay the plug against the head and crank motor to see if you get spark
but those two plugs never saw spark if they are that fouled in 1/2 mi of use
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I literally drive it around the block twice and then let it idle
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Replaced the two coils and new plugs.
Backfired as it cranked. Ran for about 20 seconds before it backfired again. It's backfiring out the intake again.
I'm going to go over the wiring again and see if I missed anything.
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Also I should note it only seems to backfire at idle. Out of all the times it has done it I don't believe it has done it with the foot on the pedal.
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If its a new coil and plugs, something is goofy with your wiring IMO.
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I'll go over it again and I hope I messed up somewhere.
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How aggressive is the new cam and how close is the tune?
No horrible vac leaks, or stuck injectors?
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223/231 .557/.571 110 Lsa is the cam
Moe did a mail order for me.
No vacuum leaks.
Couldn't tell you about the injectors. I'll check that out.
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Injectors 1 and 6 were backwards. Wow that took 5 seconds to find
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Went over the harness three times and nothing else is wrong. I'm going to trace the coil wires now too.
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So.. Purple wire was going to cylinder 7. Purple wire is ignition coil 1..
Well I'll be damned it's all reversed
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Holy fuck i got it lord jesus i am happy
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Congrats, happy you found it.
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Glad you found the problem. Bet you feel good today eh?
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I feel great. Thank you everybody for the suggestions and help.
Still trying to figure out how the clutch is holding and why I have no tach. The pcm is reading rpm
