Big POP

[xharlequinx]

hey everyone,
I just had my 1991 tsi AWD dyno tuned with these mods: DSM link, Gm maf/ blowthrough, fmic, garrett 60 trim, t3 netics manifold, 264/272 hks cams weisco pistons and rods, running at 21 psi. I haven't been launching it at all, but have been going WOT through 2nd and 3rd a good 12 times in the past 2 days. All of the sudden the car starts to smell like that horrible burn/smoke all of us dsmers know about. I drive the car easy for 20 minutes and the smell goes away. On the way home I go WOT one more time in 2nd gear and at around 6000rpms I hear a big POP! I thought it was just the blowthrough pipe off of the gm maf coming off again. No big deal but when I keep driving I'm still holding boost... So wtf was that popping noise!?
OTHER SYMPTOMS:
(I also just went to 12 psi and shifted to 3rd and looked out my rearview mirror to see greyish blue smoke. I hope I'm just running rich and I didn't blow n e thing. Then when I drive at lower rpms in 1st gear the car studders a bit.) n e help would be greatly appreciated.

 

[xharlequinx]

well I checked under the hood for any leaks or cuppler issues but everything seems to be strong and intact... myb the car was just a little hot from 6 pulls I did 2nd to 3rd.
so long as I didn't spin a bearing or mess up my internals I'm happy.

 

[dsmdragon]

wow you might have fried your piston rings bro. If you know what blue smoke means coming out the back of your car then you know you are burning oil or you have a really bad leak. The pop might have been from a back fire in the downpipe OR a vlave sticking open for a split second to long. try turning down the boost and drive it around for awhile. BACK to where it was before like 10 or 8..... Your car might not be able to handle 12 just yet

 

[tyger1]

the bluish smoke can also be a blown head gasket!!

 

[dsmdragon]

also 2 to 3 pull in 2nd to 3rd might have heated a lot of sh*t up and made some bad but not series problems... was it just a pop! or like pop pop popopopppp let me know

 

[xharlequinx]

it was just a quick pop.... it sounded IDENTICAL to one of the cupplers popping a pipe loose off of my frontmount. Just one loud pop. But the unusual part was it still obtained boost. THat same day the pipe from the gm maf popped off but all I did was refasten it tighter and that problem was solved.
I mean I've been boosting it at 21 all day and yesterday and it's been fine. Along with that my car has always run a bit rich which could just b why the smoke is that color. I used to think it was something like a blown head gasket or frying a ring but it was just rich.

 

[xharlequinx]

my oil level is a bit higher than usual also but it's not super high where it would be a threat to the car's well being.
I mean it just came off the mustang dyno yesterday so everything is the way it was when it did the decent runs that it did.

 

[tyger1]

drain your oil and check the viscosity of it. if you blew your head gasket it will be thinner than usual with coolant mixed in it

 

[dsmdragon]

If it was just one pop and not a couple then that might rule out the valves might have been a back fire in your downpipe. You should see why your oil presure is up a little and you might find the reason. If the car is just running like sh*t then lower your boost bro and see if it helps any for now. If the problem keeps up like in a week or so you might want to start checking your internals for problems or leaks. piston rings might be your last place to look if you don't find it from doing your easier inspections.. this might be a good time to replace some gaskets to.. j/k

 

[xharlequinx]

thanks for the advice on that. I will check the oil. But my ride wasn't really running bad at all. I have 0 knock at 21psi. so the big pop just shocks me since it wasn't one of the cupplers popping off one of the intake pipes.
I have a 4 bolt rear end too, I I don't think the rear end or the axles could have gone if I just did a pull from 2 to 3rd

 

[MyÜberFastGSX]

It could have been a bad misfire. Or something on the road.
Thats best case scenario.

Worst case scenario:
a) You jacked up the rings and you're burning oil now.
b) could stretched the head studs and have oil leaking in that way.

Hope for the best but expect the worst. Then you'll always be happy.

 

[xharlequinx]

I couldn't agree more... but I think its safe to say that this will always be the mentality of dsmtuners once u reach a certain level in performance and tuning.


I was actually thinking it was a misfire because when the car was dyno tuned it had a bad batch of gas in it. My plugs are just ngk bpr7's and I was told to bring the gap smaller or just to buy the EIX bpr7's, because the bad gas and the spark plugs could be causing the misfire.
What I'm thinking is that just to be safe, the dyno shop kept the car a bit rich just to prevent serious detonation. And now that I have a GOOD batch of gas in the car, it's running more rich.
When I start the car up to warm up, it bogs a lot from 2k down to 1300rpms and then it goes back up to 2k and does it again and again. This is usually a common symptom to runnnig rich.
I just took it for a drive and other than the bogging when it's warming up, it's performing PERFECTLY. All I can think is that it's rich from the tune, and myyyyb I need new plugs which could both explain a LOUD misfire.