Is this misfire?

[Paintballaa5]

Hey guys I think might be a misfire going on during idle.
No CEL's thrown, and it performs fine during all driving conditions. I'm just not sure if this is something I should be worried about. I've attached a video, and you can hear small little pops in the exhaust. They aren't super loud and they aren't consistant. It's just kinda random.

New BPR7ES's, and NGK 7mm wires.

Any help is appreciated!

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[renovatdkitchen]

I had something somewhat similar and it was because my ISC wasnt dialed in. Might not be the same in this case, but just wanted to chime in with my solving that sound

 

[Paintballaa5]

Thanks, i'll look into that. Although I did just go through the steps properly adjusting the BISS.

 

[007jimmy]

When did you start to notice the pops? Are you running rich at idle?

 

[Afizzle]

might be the bpr7es

try 6es, they run better for more mildy modded dsms

 

[1Gina2G]

I'd like to know this too, i get this on my new build with 7Es plugs, can this really be from the plugs themselves??

 

[WOTDSM]

That's not a misfire, just small backfire.

In my experience, it's caused by the gap of the plug, not the plug itself. My 1G did this when I was running E85 with a .010 plug gap.

Make sure you're gapped around .028 if you're using pump gas.

 

[Bojangles465]

I had the same problem, but unfortunately I don't know what was really wrong, I fixed it by replacing the ecu, adjusting the tps, adjusting the throttle body stop screw, adjusting the biss and replacing coil packs and plug wires

 

[Paintballaa5]

It was doing it with the BPR6's before I switched to 7's. Gap is .028.
I've got an almost perfect idle afr so it's not rich.

Maybe it could have something to do with leaky throttle body shaft seals? Possibly getting inconsistent airflow?

 

[007jimmy]

It was doing it with the BPR6's before I switched to 7's. Gap is .028.
I've got an almost perfect idle afr so it's not rich.

Maybe it could have something to do with leaky throttle body shaft seals? Possibly getting inconsistent airflow?

Boost/vacuum leaks will cause a difference in airflow metering. Are you listening to the popping with the cutout open?

 

[Paintballaa5]

Boost/vacuum leaks will cause a difference in airflow metering. Are you listening to the popping with the cutout open?

It was recorded with the cutout open, because it's more audible. But it's still there when it's closed.

 

[007jimmy]

Well it sounds like extra unburnt fuel crackling in the exhaust. Fix all boost/vacuum leaks, check timing and verify fuel pressure. Then go from there. Its more like a small backfire then a misfire as someone already stated.

 

[Bojangles465]

So is it idling good now?

 

[Paintballaa5]

All boost leaks are taken care of besides the throttle body seals and BISS screw. Haven't got a chance to get to them.

But yes, it idles great.

 

[WOTDSM]

All boost leaks are taken care of besides the throttle body seals and BISS screw. Haven't got a chance to get to them.

But yes, it idles great.

That could do it!

Fix those and you should be good and your car should run a lot better. I recommend sending your tb out to throttlebodys.com for the bore/rebuild service. Awesome mod!

 

[Paintballaa5]

Well it seems the problems been narrowed down. Anyone else have this problem before replacing tb shaft seals?
Thanks for the advice guys!

 

[WOTDSM]

A very unlikely scenario is a fuel injector issue.

Stock 450s? Any engine management utilities?

I know when injector dead time is off from what the ECU wants it can cause a small backfire at idle.

 

[Paintballaa5]

A very unlikely scenario is a fuel injector issue.

Stock 450s? Any engine management utilities?

I know when injector dead time is off from what the ECU wants it can cause a small backfire at idle.

No, i'm using 880's and link. My dead time is 375, which put my combined fuel trims at ~0. I can post up a log if that will be helpful?

I had to clip out the pull at the end for it to fit.

 

[WOTDSM]

Aha. I think we have our answer.

What brand? Pte?

If that's the case you should be at 420 for your deadtimes. That is the most likely culprit. If your trims are off after deadtimes adjust, manipulate airflow. But your airflow is going to be off until you fix those boost leaks. So the problem is the dead times which are out of whack because airflow is off because of the boost leaks.

 

[Paintballaa5]

Aha. I think we have our answer.

What brand? Pte?

If that's the case you should be at 420 for your deadtimes. That is the most likely culprit. If your trims are off after deadtimes adjust, manipulate airflow. But your airflow is going to be off until you fix those boost leaks. So the problem is the dead times which are out of whack because airflow is off because of the boost leaks.

Yes PTE. Wow! That makes perfect sense. Thank you so much. I was under the impression the dead time chart for different injectors was just a reference and it should be close to that. I'll order up some shaft seals and get those fixed as soon as I can.