2G Boost Spike when car shifts!

[tom1995tsi]

My boost spikes from 16 to about 18-20 when the A/T shifts does anyone else have this problem? Is there any way i can fix it? I was thinking about buying an external o2 dump but i want to know why it does this?

Thanks

-Tom

 

[saw wave analog]

yeah mine is spiking to 24psi and fuelcutting me right now. it sucks. o2 dump would help a lot but i dont know if i want to deal with the noise.. im loud enough as it is, a dump is guarenteed to make every cop in a 5 mile radius know you are racing

 

[98TalonTSi]

I had a bad spike problem in the cold last winter from 18 to 25 on shift. When I ported my manifold and got an external wastegate and Hallman, no more spike problem.
YOu can go external and just route it back into the exhast 18" after the initial DP bend.
Mike

 

[tom1995tsi]

I like the sound of an external dump, i have a joe p mbc its not too bad i guess. Do you guys think that with a b16g, stock injectors, and a walbro 255 that a spike from 18-20 between shifts could blow my car or a head gasket? Im running around 15-17 it creeps a small bit.

 

[Denji]

I think you should be okay so long as it just spikes and doesnt maintain that much boost. I'm sure you will hear both sides..

 

[DSMJim]

I think you should be okay so long as it just spikes and doesnt maintain that much boost. I'm sure you will hear both sides..

See this thread http://www.dsmtuners.com/forums/showthread.php?t=144308

Hellotbone just swapped his 2G A/T to a 6bolt manual. Why? Beacuse he spun a rod bearing in the 2G motor. His boost was also spiking to 24psi between shifts. This is because your torque converter loads the motor down pretty hard on shifts thus creating a lot of extra boost. You will have knock ever time this happens and your boost spikes like that. It's probablly just a matter time if your spiking high enough before something lets go. Knock is an engine killer, it pounds the bearings, pistons and everything else into paper weights pretty quickly.

 

[tom1995tsi]

It sucks i dont have any way of logging knock with my datalogger, what would be the best way to find out knock?

 

[98TalonTSi]

If timing is being pulled, than you're starting to knock.
I don't have any spike anymore, once I went with the external gate.
I'm not turning this into a 6bolt manual to a 7bolt auto argument, but I don't think this guys motor blew just because of a spike and knock. There's something more. I do have a little knock on shift, but nothing to worry about at all. It's just a matter of messing with a few settings till it clears up.
I also have a WB02 and DSMLink, so I can "clearly" see what's going on at the top end.
Mike

 

[tom1995tsi]

I dont understand timing i am logging with a palm pilot would you mind explaining? Also i think im getting a dsm chip that will change my factory boost gauge into a knock gauge not sure yet though.

 

[98TalonTSi]

http://auto.howstuffworks.com/ignition-system.htm
Read that. Because turbos compress that air even more, we are more prone to pre-ignition or detonation. That's why we typically have lower compession pistons.
Mike

 

[saw wave analog]

*update*


well last night i spent 3 hours porting the ungodly hell out of my already somewhat ported o2 sensor housing.. i took it to the point where i actually drilled through the outer wall in a couple places, but a couple fill welds and some polishing later all i have to say is WOW.. what a difference.. i am not creeping at ALL now, not even a tiny bit, and my boost isnt spiking in the slightest on shifts anymore either.. and that is something that the car has done since the t25. i am now getting a rock solid 17 psi and i love it if you are running a stock o2 housing, hog the holy shit out of it and that will cure your problem if your car is anything like mine

 

[DSMJim]

I'm not turning this into a 6bolt manual to a 7bolt auto argument, but I don't think this guys motor blew just because of a spike and knock. There's something more.

No it was because he was creeping so bad during shifts to like 24psi that it was knocking like crazy. Remember that knock pulverises bearings like your fist into a peanutbutter sandwich. If your have some knock for an extended period of time, your eventually going to run into a bearing problem. Now 10-20 counts isn't gonna do it, but we have a feeling he was havinig a lot more then that.

He decided that when changing the motor which he had to do that he wwould just swap in a manual trans too for the hell of it.

 

[98TalonTSi]

No it was because he was creeping so bad during shifts to like 24psi that it was knocking like crazy. Remember that knock pulverises bearings like your fist into a peanutbutter sandwich. If your have some knock for an extended period of time, your eventually going to run into a bearing problem. Now 10-20 counts isn't gonna do it, but we have a feeling he was havinig a lot more then that.

He decided that when changing the motor which he had to do that he wwould just swap in a manual trans too for the hell of it.

I hear ya.....but there's got to be a tremendous amount of knock when spiking for that split second and it's got to be done constantly. Oh well, hope he has more luck with the 6 bolt/MT

saw wave analog: Glad to hear that it all worked out for you.
Mike

 

[Eclipsei95cl]

I am having the same exact problem. I would creep to 25psi all the time and CEL would flash indicating knock(dsmlink) so what I did was just took my boost controller off and just hooked up to the external gate. Its only 14 psi but at least im not hittin knock. Still gata work some bugs out, tuning etc. then ill raise the boost again.

 

[tom1995tsi]

Ima get an external dump o2 housing 2.5" SS that should help it out a bit.

 

[98TalonTSi]

No it won't...I'll post some stuff from the masters at DSMLink about spike and creep.
MIke