My car runs terrible under boost!

[TurboTerror99]

Okay, so I've searched and read and searched and read until I'm blue in the face. Nobody seems to have most/all the same symptoms as my TSi. I recently bought this car from a guy whom had the engine rebuilt because he had plans for a FMIC, a larger turbo, and a Apexi Neo piggy back. During the build the machine shop bored the cyls .020 and ported the head runners. Now onto the problem! As long as you keep it as near to 0lbs of boost as possible it's cherry. If you stomp it... once it hits 7lbs of boost, almost like clock-work, it rolls black smoke out of the pipe and falls flat on it's face! I know black means it's running rich. (extremely in this case) I've checked the plugs and wires and they seem to be fine. (They're new according to the previous owner) I checked the turbo impeller, no slack and the wheel looks perfect. I pulled the intercooler and all the piping, cleaned it out good and checked for leaks... there are none. This is my first turbocharged car and I'm lost. Please help! Any tips are appreciated. "DSM for life!"

 

[1SickAuto]

what all is done to the car.

 

[TurboTerror99]

Do you mean like mods? If so, it has a Fidanze flywheel, machine work that I listed in the original post, and..... a K&N air filter. It's had the balance shaft removal and I think that's pretty much it.

 

[paultheninja]

is your bov recirculated?

 

[TurboTerror99]

Forgive my ignorance but if you mean stock and recirc'n back into the main air cleaner tube, yes.

 

[GofaST4life]

After market boost gauge right?

What fuel mods are there?

 

[gsx7707]

do a boost leak test
check your fuel pessure
find out what size injectors

 

[TurboTerror99]

Yeah, Autometer Cobalt gauge.
Already passed leak test.
Haven't done fuel PSI test though. I'll put that on my next to do. Any clue where it should be?
According to prior owner it has the stock injectors in it. Keep it up guys!

 

[TurboTerror99]

Okay, I went back to the drawing board with the ideas that I got from you guys so thanks for the comments. I haven't put a gauge on to check the fuel PSI still because my dad and I discussed it and we're confident that it's not the fuel PSI. (My dad owns his own repair facility... diesels though! ) It runs too good as long as you stay out of the boost and when you shower down on it it rolls black smoke out of the pipe and falls on it's face. (this you know) 100% of the time it will run perfect as long as you don't boost it up. You can slowly get up to whatever speed you want as long as it's gradual. I looked around the manifold for leaks and sprayed with a water/soap bottle and didn't see any. I checked the turbo shaft for play and it has little to none. Does anyone know what symptoms the wastegate would cause if it wasn't engaging like it should? I'm patient and welcome all information no matter how brief or insignificant. Thanks for reading! I love this site by the way!!

 

[#40Fan]

You know that you are getting too much fuel. A fuel pressure test will show whether it is getting too much fuel pressure.

 

[forcefed86]

First off download the factory manual. Then check your TPS. If that's good I'd Check your MAF. Swap it out with a known good unit if you can.

You just don't have enough information to really diagnose the problem. A massive leak in the charge piping could cause this also. Could be capacitors in the ECU.. etc. If you plan on keeping the car and are serious about fixing it buy a scan master from fullthrottlespeed.com. It will give you a ton of information and help diagnose the problem.

Good luck

 

[TurboTerror99]

I understand about not having enough information to diagnose but thanks for y'alls suggestions anyways. I'm going to go ahead and do the infamous BLT and then check the fuel PSI for the sake of elimination. I'm also going to find a good MAF to try. Maybe one of these things will tell me which way to go or at least give me some more info to post for you guys. Thanks...

 

[GSXSixteenG]

I had the same symptoms when one of my charge pipes blew off. So if you haven't done a boost leak test then I'm willing to put my money on that. Then next I would check your MAF.

 

[BIRDCLAWTSi]

do you have a vacuum gauge?, i mean a handheld vacuum pump..if not you can get one from an auto parts store for cheap. i would check you fuel pressure regulator, even just pull the line off and see if there is fuel in it. do you have a logger? what are your plugs gapped to? pull a couple and see what they look like, unplug your maf and check the harness and connector for corrosion. is your re circ tube hooked up? i would also suggest checking yopur fuel pressure. you could be over running your fpr, do you know what fuel pump you have or injectors? 1or 2g maf? let me know how you make out...good luck!!!!

 

[bastarddsm]

For saome reason I remember hearing that an apex afc neo won't work with our cars for some reason.

 

[TurboTerror99]

That's interesting about the NEO because the guy that I bought the car from is convinced that the problem with the car is that it's not "tuned." I find that hard to believe though because it doesn't run like it needs to be fine tuned... it runs like sh#t! He has mentioned several times that the NEO system is what he was looking into. So, in turn I too have done some reading on the NEO. It seems like a really good system. I'll gap the plugs and make note. Also, I'm hoping to pick up a MAF tomorrow off of another 91 TSi that I sold to a guy that was running like a champ before he blew the motor. I'm still running a stock 1g MAF and injectors. (according to the previous owner)

 

[Jason B]

That's interesting about the NEO because the guy that I bought the car from is convinced that the problem with the car is that it's not "tuned." I find that hard to believe though because it doesn't run like it needs to be fine tuned... it runs like sh#t! He has mentioned several times that the NEO system is what he was looking into. So, in turn I too have done some reading on the NEO. It seems like a really good system. I'll gap the plugs and make note. Also, I'm hoping to pick up a MAF tomorrow off of another 91 TSi that I sold to a guy that was running like a champ before he blew the motor. I'm still running a stock 1g MAF and injectors. (according to the previous owner)

hey man, i had the same problem with mine and it was the fuel pressure regulator solenoid which is placed above the brake booster on mine, on a turbo vehicle it uses this to not allow the boost to get to the fuel pressure regulator, if you can find it, it will have 2 wires and 2 vacuum lines going to it, and if it is bad it will have no continuity (bad coil in solenoid) i think it should have about 40-100 ohms. i actually disconnected it and hooked it to 12 volts off and on, off and on, it made it work for a couple days. i also tried a toyota solenoid in place and the solenoid wasn't strong enough for the boost

 

[TurboTerror99]

Thanks, Jason B. I'll definitely look into that. Unfortunately, I found a massive water leak coming into the car from behind the dash so I'll be spending my free time for a while pulling the dash and resealing that before I can get back on trying to get it running right. I'll post more as it unfolds, thanks...

 

[blade970]

Boost leak test. Fuel pressure test. Have you cleaned the MAF? It may be dirty. Try that.

 

[TurboTerror99]

After extensive reading of BLT threads I haven't seen mention of my specific issue. I tried yesterday to perform a BLT and with only a couple of pounds of PSI it starts pouring air from the BOV into the main intake. You can hear it through the open air filter. Is this normal? How do I dummy it off to get the system up to normal operating boost PSI to check for leaks? As always, THANKS!

 

[cummins990]

You pretty much have a diesel blowing all that black smoke hahah . I would see what injectors u actually have.

 

[godfather75]

Does it have the factory fuel pump? If you have a bigger fuel pump like a walbro 255 you would run pig rich with out a afr.

 

[juanpac0]

Too much fuel, possible culprits:

Pretty huge boost leak
Non-stock injectors
Too big of a fuel pump
Malfunctioning FPR
o2 sensor out
MAD malfunctioning

Are you running copper plugs?

 

[rEclipserGST]

After extensive reading of BLT threads I haven't seen mention of my specific issue. I tried yesterday to perform a BLT and with only a couple of pounds of PSI it starts pouring air from the BOV into the main intake. You can hear it through the open air filter. Is this normal? How do I dummy it off to get the system up to normal operating boost PSI to check for leaks? As always, THANKS!

If you can take pics of your boost leak test that would be awesome. My guess is your doing the boost leak test wrong. You attach the BLT to the turbo inlet, use a air compressor to pressurize the anywhere from 15-20 lbs. If everything is sealed up correctly, it should start to slowly leak out after 30 secs. But if your throwing out black smoke under load, that means one of these things:

You have a Boost leak
MAF is bad
TOO big of injectors or your fuel pump is overrunning your fuel pressure regulator
ECU is damaged or bad
o2 sensor is gone
Spark plugs could be fouled out. NGK all the way.

 

[snakeyes711]

After extensive reading of BLT threads I haven't seen mention of my specific issue. I tried yesterday to perform a BLT and with only a couple of pounds of PSI it starts pouring air from the BOV into the main intake. You can hear it through the open air filter. Is this normal? How do I dummy it off to get the system up to normal operating boost PSI to check for leaks? As always, THANKS!

No, when I did mine it didn't start leaking untill more like 19-20 psi on the BOV. Make sure all the hose, and all the connections to the BOV are good. Check the line coming from te intake man too. This is probably your problem right here. Also if I were you go back with a good 1g BOV for sure.

Whats happening is the air is being metered by the MAFS but its not making it into the engine however the engine is dumping fuel as if that air IS going into the engine, I'd almost bet on that.

One more thing, check out getting a palm pilot, and start logging its the best 40 bucks I've invested in my Talon. As it'll tell you loads of information about how the car runs from intake temp. to battery voltage. Plus it can pull, and clear trouble codes with the MMCd program. I got a inexpensive palm IIIc, and downloaded the MMCD program for free, then followed the diagrams to build a cable.

G/L