Overboost/stalling after decellaration

[MacDizzle]

So I just got my first DSM three days ago. I have been an avid SRT 4 guy for years now but i stumbled upon a 97 tsi in absolutely awesome condition. Runs great, no leaks, inside and out is clean as can be. White with the tan leather. Im loving the car but i seem to be having an issue. If i push the gas past half to three quarter throttle, i spit, pop and nose dive hard. According to the boost gauge i run upwards of 20 plus psi. Also upon decel after a hard pull like this, she doesnt like to stay running very well. keeps idoling down to almost a stall. and sometimes actually does. Have gone all through it so far, new plugs, wires, fuel filter, vacuum checks, every thing i can think of. As long as i stay half throttle she runs great though. Any kind of help on this would be great guys. thanks.....

 

[richard33]

turn the boost down. You may be hitting fuel cut cause of too much boost/not enough fuel

 

[TSi Kid]

What's your fuel setup? If its stock you can hit 17-18 absolute max without hitting fuelcut on stock injectors.

I know you said there's no leaks but have you done the BLT yourself?

 

[BLINKY619]

^ and what upgrades does the car have...

 

[Tanro]

Things that would be helpful:

Upgrade List
Logs if you have them

But it sounds like your hitting Fuel cut, or more likely you have a boost leak. Turn your boost down if your running stock fuel. Something around 14-15 would be safe.

 

[kenuwine4g63]

And also check your compression too!! Car shouldnt cut off or get close to it even if you hit fuel cut. Make sure the BOV is recirculated and if it isnt make sure that you have a gm maft to properly vent to the atmosphere. I wouldnt go full boost anymore till everything is fixed and you know it has been...Disect the car yourself 1st, so you know whats on it.

 

[TSi Kid]

Something around 14-15 would be safe.

Safe is overrated

Sounds like fuel cute though 20lbs is impossible on a stock setup.

 

[MacDizzle]

Sorry guys, upgrade list would definately be helpfull. Injen CAI, Apexi exhaust, stock side mount intercooler and as far as i can tell its the stock turbo. Got the car from a tow yard with little known in the way of upgrades or what not. As far as turning the boost down...i am pretty sure there is no boost controller and am not exactly sure how to install one on this car. any recomendations on an easy install and relativly cheap one? and god help me locating a vacuum diagram for this thing is proving to be a royal pain in the ass. even with the chiltons.... but is it me or does twenty pounds seem a like way to much for a stock snail to be putting out? any one know of a way to verify exactly what turbo this thing actually is?

My bad, left two things out. Not sure how to do a BLT on this car specifically and it does have an aftermarket, hks type blow off valve with some kind of adjustment screw at the top. Not positive as I have never used one of these but i dont think thats any thing other than a sound adjustment right?-----oh and yes the compresion check was good.thanks again guys...

 

[MacDizzle]

So re-routed some vacuum lines today according to a diagram i found online. Some things were definately out of place but didnt change a damn thing. Got a suggestion that the stalling issue could be a fuel pump problem considering it accelerates fine but wont hold an idol for shit....seems to me thats a lil backwards. any ideas?

 

[MacDizzle]

So i guess i've stumped the forum then huh? well heres an update, maybe this info can help somebody having similar issues. Stoped by a local tuner shop today and they found basically a rigged wire running to my mass air flow sensor. a red wire was just kinda stuck in to it with out having the normal pin conector. they said that of that was getting a bad connection that could cause my idoling issue and possibly why its stumbles at cruising speed sometimes. Therer primarily an evo shop so im assuming they have at least some understanding of talons. again. im new to the dsm world but new boost controller should be in by tuesday so we'll hook it up and see what happens when im not hitting fuel cut by half throttle any more. gonna try and run the idol up a bit as well. when she does idol steady she sits around 600 rpms or so. seems a bit low to me.

 

[97gstman]

the stalling can be caused by venting ## bov, make sure its recirculated.

 

[dmentdgst]

My car also does this, and after searching and searching I'm pretty sure that its because of the 8 pound fidanza, so I have to feather the throttle during deceleration to keep it on.

 

[1GRedRocket]

this happened to me when i installed my boost controller wrong once, boost gauge went 20+ and i most likely hit fuel cut, luckily i wasn't WOT and was being careful, maybe was at 3/4 throttle. i think your problem will be fixed once you get a boost controller installed correctly.
if you dont want to wait till your boost controller gets there, run a vacuum line from the nipple on the j-pipe to the vacuum port on the wastegate, that will give you stock boost levels.

 

[shadow001dsm]

im with gstman. when my 92 was next to stock like yours and i vented my bov it did the same exact thing.

 

[h2rsturbo]

sounds like fuel cut, cut the boos down to around 15psi and you should be ok.....till the mods come or get the ecru chipped..

 

[MacDizzle]

As far as venting the BOV. the only vaccum line on it is running straight to the intake manifold. Managed to fix the wire that was all jacked up to the mass air flow sensor. Doesnt seem like it did a damn bit of good though. Just curiious. any one think that solenoid that my wastegate line runs to could be shot? Im assuming thats the stock control solenoid?

 

[jimbob_843]

A bad hose on your wastegate actuator would cause infinite boost until feul cut. Run a straight vaccum hose from your j-pipe nipple to the wastegate nipple. You should only be getting around 10psi. That should solve the nose dive when accelerating. The vac hose from the bov is supposed to run to the intake. Also search for how to boost leak test on here and DO WORK.

 

[eligst21]

if hes a 2g then he's got a t25 and the nipple is on the compressor housing not the j pipe as we dont have one. but like jimbob said, hook a straight line from the compressor housing nipple to the wastegate and it should run about 10 psi. 20 pounds is a lot on a stock fuel system. even on some cars, 15 is pushing it. so it depends. hook that vacuum line up and see what happens. and glad you got a dsm instead of ano0ther srt. ha. even though there alright cars to me. ha

 

[MacDizzle]

Ok so who wants to kick me ion the nuts first? Idol issue and can't figure our whats up? wow lets try adjusting the idol screw that happens to be almost completely run out!!!! ok ok i get it. rookie friggin mistake and didnt even think to check it ### i mean come on. who messes with those any way? on a stock set up, seriously? regardless. im idoling hella better now. as far as the boost. took the advice and ran a line from the wastegate to the lower intercooler pipe. I am assuming thats what you all have been calling the j pipe. Sorry guys like i said im new to the dsm's. any way, there doesnt seem to be any nipple on the compressor housing top bottom or otherwise. Found this a little odd personally but from what i have gathered certain turbo generations of these cars didnt have one. Not sure if this one is supposed to but theres definately not one there. Ran the new line and test drove it. Thanks for the advice guys. Hits ten pounds quick as F*&#, then creeps to around 16 but the fuel cut is all but gone!!! I now understand the the passion you all have for these things. It feels great going down the road. She runs smooth as shit now. Which is great considering im drivng about 1800 miles this weekend. At this point i doubt i'll go back to my pissed off neons any time soon...if ever. im lovin this girl now!!! thanks again guys.




wow that sounded 12 years old huh....sorry, just a little excited to be cruisin again.

 

[eligst21]

is it the stock turbo on there? becasue stock ones should have a nipple on the compressor housing it the back. thats where the factory vacuum hose goes and then t's off to the wastegate and makes its was to the stock BCS. so if its the stock t25. it should have the nipple.

 

[MacDizzle]

well if the stock one has a nipple then im deffinately not rockin a stoock snail. problem is that means i don't have a clue as to what the hell this thing is. I am assuming its bigger however considering the boost it put out when uncontrolled. From what i have been told the stock snail is almost incapable of producing the 20 to 25 psi i was registering. then again i havent trailed the line from the boost gauge yet either to find out if this aftermarket gauge is even trying to be acurate....but she runs good so wish me luck gents, i am embarking on my 1800 mile journey in t minus 3 hours....if i blow this bi*** up im a be pissed!!!!

 

[eligst21]

the t25 are capable of the 20 pounds of boost just not on the stock fuel system or being efficient. what does the turbo say on the side compressor housing? and if youre running stock boost you shouldnt blow up.

 

[MacDizzle]

ok so were 933 miles into this epicly shity journey and were doin alright.... keep your fingers crossed for me.

 

[cookmeup272]

Try and see if you can find some sort of serial or Part number on the turbo. Also the shift key would be a nice thing to use in your posts. I wish you good luck on your trip though.

 

[MacDizzle]

So 2,218 miles total round trip. No t=stat therefor no heater when traveling through Oregon. SHITTY!!! Flasher relay went out so no blinkers or hazards fir the last 850 miles. And a loose oil cap that made me billow white smoke out from under the car every time i went up a steep hill....But approx 330 miles per tank, on a car with 160k plus. And no major issues to speak of other than possible frostbite when opening the window to get a cigarette. Again, no heater.....SHITTTTTTYYYYY! but yeah were all good. I love this little bastard....oh and pics coming soon.