2G Spark plug blowout or ?

[roadtrip_69]

All,

There's a few articles related to this topic but haven't seen anything recent. Just wanted a concise answer if possible.

Issue has been a backfire (power drops and it pops and bangs out the exhaust) at higher boost levels. Sometimes its starts as low as 24psi and other times its pretty consistent at 26/27 psi. It feels exactly like fuel cut, as if there was still a load/boost limiter setup. But I have removed that via Ecuflash. (within the tune I have set)

I have tried both copper ngks and iridium ngks but I have not gone lower than .28 in gap. As I, in my mind would be expecting to be getting misfire codes instead of a "fuel cut" feeling. If it was just the plugs blowing out. Also of note not getting hardly any if any knock. Regardless of rpm/boost level.

I do also have meth injection setup and I have considered maybe its what is blowing out the spark itself being set too aggressively, but its a progressive setup. Starts at 10 PSI and goes full go around 30 (though i cant get to 30 currently as it cuts out before then)

Running the DSM68HTA V3 (and trying to set boost at 30 psi as I've done what research I have been able to come across and that seems to be the mark most use to get the most out of the turbo)

Prior to the new turbo, i was experiencing the same thing with the tdh05 20g i was running, but it would always kick in around 23-24psi and that turbo had a bad issue with surge when letting off the throttle at high boost as well so figured it was just out of its efficiency range. The latter has gone away since upgrading to the 68HTA at least.

I've also already replaced the ignition modules, and wires with NGK's. Logs only show when I let off the throttle AFTER it happens, dropping injector pulse width to minimal. No knock, afr's are high 10's/low 11's right about where I have things set.

If its NOT spark blow out, what else could it be?

Any ideas? Troubleshooting ideas?

I did just switch out my iridium's back to some bp7es cooper . set to .26 but haven't driven as of yet. And plugs when I removed them look perfect, not wet, not white, no oil just normal combustion signs.

So extremely frustrated. Up and until the issue it runs great, pulls like it should. Will break traction in 3rd gear at high rpm (before I just replaced the front struts)

 

[BLACK'98DSM]

Have you tried decreasing the plug gap?

 

[roadtrip_69]

Have you tried decreasing the plug gap?

I did drop it down to .26. And rechecked the gap on the existing plugs and they were some how at .30 and I know i gapped them to .28 when I put them in... so not sure what that means.

Going to test the new gap next time I'm merging onto the highway ...

 

[jdxnc]

Go down to .020 gap and try again. That's a big enough jump to determine once and for all if it's blowout. Next step is new plug wires. They can look perfect but be arcing out.

 

[roadtrip_69]

Go down to .020 gap and try again. That's a big enough jump to determine once and for all if it's blowout. Next step is new plug wires. They can look perfect but be arcing out.

What's the negative impact on such a narrow gap? But I'll try out the .26 see if there's any improvement and then I'll drop them way down just to see if it does anything. I'd expect to get a couple extra psi without the issue if it's on the right track?

 

[jdxnc]

What's the negative impact on such a narrow gap? But I'll try out the .26 see if there's any improvement and then I'll drop them way down just to see if it does anything. I'd expect to get a couple extra psi without the issue if it's on the right track?

You might see harder cold starts. When you're trying to rule out something like bad plugs, a big jump makes the issue more apparent if it's the cause. I wouldn't bother with .026, go right to .020, it will either go away or not and you have your answer.

 

[diambo4life]

You might see harder cold starts. When you're trying to rule out something like bad plugs, a big jump makes the issue more apparent if it's the cause. I wouldn't bother with .026, go right to .020, it will either go away or not and you have your answer.

100% agree.

 

[1990TSIAWDTALON]

I run .018" on 8's and really no cold start issues and the motor seems very happy. Just for comparison.

 

[jed344]

Most our car are using 8's and we have ran gaps all the way down to .013. Personally anything over .017 acts fairly well, when you go smaller idle really suffers and starting. Your plug gap now is what i would consider very large. I start at .024 on stock cars personally. Car that are making some jam its extremely common to be under .020. I will also add be sure your grounds are good. We found adding a extra ground off the head also helped to stretch the stock ignitions further. The ignition is like a welder, If the motor is grounded badly it will struggle.

 

[roadtrip_69]

Thanks everyone. I believe that is/ was the problem. Just going from .30 (thought was .28 but my grap tool was old might have been off a little) down to .26 has fixed the problem up to 27/28 psi. Holds 26 all the way up the rpm range.. but I adjusted my boost controller while I was troubleshooting so if I fixed it, it wouldn't over boost to 40 psi or something .

Adjusted it up a couple ticks to see if I can hit that 30 psi mark I'm aiming for.

I'll probably regap the plugs down a little more... but..

Unfortunately now I have a bigger issue...(as soon as I figure this one out..now this.)

My damn first gear is out. Started popping out at random on take off, maybe one out of 10-15 shifts the last few weeks but now it's pretty much every single (attempted) shift.

It doesn't grind going into gear.. just pops right out. Sigh. Anyone know what the highest possible cause of that is?

according to the alldata it's "most" likely the fork or hub/slider. Anyway to confirm without tearing it all apart? I know parts are hard to come by.....

 

[jdxnc]

Make sure the shifter bushings on the trans and shifter base aren't all worn out and now allowing the selector arm on the transmission to not travel far enough for full engagement. Sounds like you're not getting full engagement of the slider ring.

 

[diambo4life]

Most our car are using 8's and we have ran gaps all the way down to .013. Personally anything over .017 acts fairly well, when you go smaller idle really suffers and starting. Your plug gap now is what i would consider very large. I start at .024 on stock cars personally. Car that are making some jam its extremely common to be under .020. I will also add be sure your grounds are good. We found adding a extra ground off the head also helped to stretch the stock ignitions further. The ignition is like a welder, If the motor is grounded badly it will struggle.

100% about proper grounds. Stock ignition can go quite far.