Backfire out the wastegate?

[Shades]

... is that due to too much fuel?

[swalltr207jg]

could be...

[deadly_sleeper]

what are you A/F ratios when it's happening?

[1st Gen]

Yikes!
Timing maybe?

[323driver]

Too much fuel that finishes burning in the exhaust and WG. Your EGTs are high I suppose?

[Shades]

Well this only happened when I upped the boost on the wastegate. A lot of pow pow bang bang, sounded like an old Batman show. I'm thinking too much fuel that the MS needs to be more sensitive, change some lag times.

My A/F's were good... 11.8's while on boost. My timing should be good cause I don't get bangs when I down the boost. The spool is much quicker, as in it gets to full boost faster now so I'm thinking sensitivity on the MS.

[Lex]

If I remember correctly you have the standard 2.5Bar map sensor in there. So we might have set a boost cut at around 20-21psi since that's where the sensor maxes out at and that's exactly what it would sound like.

EDIT: We can take the boost cut off, but I don't recommend going too much above the 21psi point and there is a risk of a runaway (oh noes) turbo/boost condition that won't be stopped without the cut. It would be called overboost protection in Megatune.

Something like this:



I can look at it on Monday

[Shades]

It's funny tho, it wasn't anywhere near 20psi when the backfiring started... maybe 10psi or more.

[Lex]

Hmm maybe something else. Can you reproduce the event all the time?

[Shades]

Yup... almost every time I stepped on the pedal. I'll try again tonight when I get home.

I love the feeling of this setting cause the boost hits a lot harder, or as in the wastegate keeps shut longer.

[Lex]

So it backfires now with the new setting but boost does not get to 20psi before it backfires? Also, what if you lean into the throttle slowly?

[Shades]

I'm thinking I have to gap my spark plugs smaller... it's probably having a misfire at high boost. It pops around 10-15psi... and only happens when I give it the beans.

I also had some popping tonight at my normal setting... gonna pull the plugs tomorrow and have a look.

[Lex]

Plugs or plug wires have done this for me. Jon drop me a line with when you'll be by on Monday.