Overboosting??

[CuseTownGti]

So 3 days after moving up to the 3inch turboback im running into some problems. Car was running good up till sunday when i really tried getting on it. up till then i kinda babied it cause of wet conditions and bald tires. Basically when ever i try to go above 4500 the car starts to buck or almost hiccup in and out of boost. now my old exhaust was super restricitve as it was ment for a N/A VR6. i gained 15whp just from removing the resonator and placing in a testipe. Now with the 3inch with no cat and a muffler thats pretty much a 4-5inch tube with some sound deading in it the car wants to haul some serious ass but then starts the "hiccups". Is it possible i freed up so much back pressure the car is hitting a higher boost without turning up the boost? i don't have a boost gauge yet cause im seriously broke. i bought stu's exhuast months ago and just came up with the money to get it installed this past weekand. So you guys think if i dial back the boost i will be ok? Remember ,i have a RR FPR,upgraded in-line fuel pump, FMU with stock injectors for the tune. Not the best for high HP, but its been extremely reliable.

Oh and if anyone has a boost guage for sale let me know:(

p.s. car only does this after hitting the intial kick of boost, drives fine out of boost and no codes,

[turbosnow]

Get bigger injectors...but first a boost and air fuel gauge.....if you are leaning out enough to make the car buck you definitely want to back off. It is probably more a question of the turbo spooling up quicker than expected rather than the actual boost level reached, which should be fairly constant. Turnign the boost down may help as the car wouldn;t lean out with less air, but those stock injectors scare the hell out of me.

[VWTUNING]

I would consider calling EIP as well since they installed the kit. I think Brent hass a boost guage you can borrow as its not installed in the cabby yet... (you'll have to ask him)

[B4passatglx]

Straight out of the Turbo Bible: "Maximum Boost"

Overboost: Tailpipe - "The tailpipe can frequently cause an overboost problem. Often the wastegate depends on an increment of backpressure in the tailpipe to function properly. This problem occurs when something in the exhaust pipe fails and reduces backpressure I.E. a rust hole."

Maybe the upgrade to a bigger exhaust and the deletion of the CAT and resonator dropped the backpressure and caused this problem. Not sure though.

I don't know if this applies since you have a dump tube thats not re-routed back into the exhaust

[evolveVW]

sounds like its leaning out. My car does something similar when it hits the boost cut off.

[turbosnow]

Straight out of the Turbo Bible: "Maximum Boost"

Overboost: Tailpipe - "The tailpipe can frequently cause an overboost problem. Often the wastegate depends on an increment of backpressure in the tailpipe to function properly. This problem occurs when something in the exhaust pipe fails and reduces backpressure I.E. a rust hole."

Maybe the upgrade to a bigger exhaust and the deletion of the CAT and resonator dropped the backpressure and caused this problem. Not sure though.

I don't know if this applies since you have a dump tube thats not re-routed back into the exhaust


IIRC the EIP kit has an external wastegate, so there's not really much need for backpressure to push the actuator arm.

[BUNNYLOVE]

You almost definetly are running more boost with the less restrictive exhaust. I can't believe you don't have a boost gauge atleast dude. I have one you can use..
Check your vaccum hoses too, your wastegate hose may have came off.

[CuseTownGti]

thanks for the replies, yea,yea i copped out on not getting a boost guage when i should of gotten one asap, but i haven't had an interior since august and im not a fan of column pods.... as far as injectors go, i wanted to go with the bosch green tops but they're not "drop ins" with the mk4 vr, it would require me to switch to a mk3 manifold and a short runner

btw, How sensitive are the manual boost tee's, i have the turbosmart one, i.e. a quarterturn will notch it down approx. "x" psi?

[customfabvw]

hey brian, you are most definitely hitting higher boost. alot more, and it will hit harder too. you just freed up a good amount of horse power and your turbo is gonna spool up fast becuase there is no restriction! let me know!

[boostin20v]

btw, How sensitive are the manual boost tee's, i have the turbosmart one, i.e. a quarterturn will notch it down approx. "x" psi?

ya...its not that simple. really need a boost guage to see the change.

[VWTUNING]

dude you can borrow my boost guage from the golf for a while if you need it, get one on there an see whats up!

im moving it anyway so its no big deal, let me know (might be out there tomorrow night)

[CuseTownGti]

ya...its not that simple. really need a boost guage to see the change.

i know,its just i hate having a car that doesn't run right and driving the jetta coupe is a love/hate thing, so the vr being down has me anxious, i tried turning down the boost just to see if it would help, tried a 4thgear pass but nothing changed. could only turn the boost knob about 1.5 turns before it wouldnt turn anymore.did this .5 increments and made short additional passes. thanks to everyone who is offering to lend me a gauge to see whats up. I'm actually making good money this week at work, VA hospital=federal wage, but then after i blow my money on a boost gauge and hopefully find a windeband then i won't have work for another week and end broke living paycheck to paycheck.

God bless all you guys/gals with project cars i get way to flustered and my patience goes out the door

[evolveVW]

Trust me.. most of us go through the same thing all the time.

[RichB]

Would doing any VAG-COM logging help Brian out???

[customfabvw]

hey brian, just bring it over here to my shop!

[CuseTownGti]

im sure a vag-com could only do good Rich...hey Matt i'll give ya a call when i get out of work

[RichB]

im sure a vag-com could only do good Rich...hey Matt i'll give ya a call when i get out of work

We can do some research on what to log and do some data logging if you want... just let me know.

[gump1119]

Hey. I'm having the same exact problem in my GTI. 2.0L 8V Garrett Stage II Turbo Kit from ATP.

When it was first installed, the car ran fine and revved/boosted to redline no problem. Now though, at about 4500 rpms it dies, starts to buck, has no power, and the CEL light starts to flash. If anyone knows what might have caused this, please let me know. I go to school in colorado and only get to drive my car every few months and it sucks coming home to a broken car, so I wanna fix it. I'll be home in a week though so expect to see me around 'cuse here and there.

BTW: Where/when does everyone go on Erie nowadays?

[johnouellette]

You've got to be lean with stock injectors, a simple test would be to put some 93 with a big octane booster and take it for a ride. If it runs better your lean.

If it doesn't run better you could try putting the cat back on.

[customfabvw]

i fixed it all up, problem is gone!

[RichB]

i fixed it all up, problem is gone!

Dang nab it! Stop teasing us with partial info! (Sorry, don't mean to be ranting, but some details on what the problem was and what you did to fix it up would be really cool to know! .... unless you wish to let Brian post the details himself . . . :) :) :) )

Independent of that, I am really glad to hear you were able to fix the problem!

[customfabvw]

ill let brian tell the story!

[CuseTownGti]

yep she runs strong once again. Took over 3 hours just for it to be soo simple. Started off by taking a ride and matt trys to adjust the base fuel pressure. take another ride. rides better. trys again no improvement. He gets his old fuel pressure gauge hooks it to my car, i had some insanely high fuel pressure when engaging into boost. make a couple more passes. nothing. installs boost gauge, get to hit consistant 14-16psi but fueling is still choppy after a good two hours of trial and error. Also earlier had a dead end call to EIP as the tech line ends earlier than the sales and the tech had left. So pretty much decide to call it a day he sets the base and rising rate fuel pressure back to where it was when i pulled in and asked about this piece of tubing with a smaller metal reducer type thing coming of the vent of the FPR. said i dunno its been there since the install. he takes it off to see if maybe its clogged. its not, but the reducer makes airflow super restrictive, says "thats ass backwards" and figures that will make a difference lets take one more ride.....wait till 3rd gear floored and it hauled ass smoothly. un****enbelievable. Big thanks to matt for his time and fuel gauge and other various knick nacks. :cool: def. appreaciated. BUT not to have my cake and eat it too, literally minutes from house, dont ya know, the CEL comes on:p

im hoping she was just pissed from gettin beat on little and having the FPR messed with. possible fouled a o2 sensor?? we'll see im just happy it runs in boost smoothly now

[gump1119]

Good to hear man. I hope my fix is as easy.

[customfabvw]

we have to space the rear o2 sensor and make it shallow in the exhaust!

[CuseTownGti]

im gonna see how it plays it out over the next day or so and if not ill get a hold of ya