Thread: Lets guess whats wrong this time... Turbo maybe?

Well I've been babying the living sh*t out of my car since I got it back, trying to get things dialed in. Got the damn Throttle body plug pushed back in so now my idling issues are done and I hardwired my A/C fan to a switch so now my cooling issues are no longer issues.

So on to last night:

I'm driving down Power Inn across Elsie and the light is turning yellow so I get on it a bit to make the light (Its about 1am or so and those lights hold all day long unless you are coming from Mack/Elsie) As Im doing so I hear the weirdest cringe kind of whining noise (hard as hell to describe) The car falls flat on its face. (as far as boost goes) So I baby it even more all the way home and let it sit there praying its just another crimped vacuum line or something ruining my weekend.

I hop in this moring after looking under the hood and not seeing anything that could source as an obvious issue I drive to work. As usual the car runs good and its building small amounts of boost. (its set at 10psi and I rarely take it past 5K so it never really sees too much boost) Its driving smooth and I don't really notice any issues UNTIL I come to a stoplight. *here's the weird part* My idle is quite low with the Cams I have and it always scares the shit out of me when I stop because at 850 rpms the car rumbles like it wants to shut off but its obviously the cam/prothane mounts settling at low rpms (not use to it yet) But as I slow down (finally getting use to it) my hart begins to sink as the rpms continue to drop PAST 850 *car has never done this before* usually it will hit no lower than 800ish if I don't let off right away. It drops to like 600 or so then rises back to 850. Its a quiet drop and a quiet rise. The car doesnt sputter like its going to shut off either, it just drops past 650 (you can hear the car quiet way down) then settles back at 850 (not quickly either but not dreadfully slow)

So that is where my issue lies. WTF is it doing? I refuse to drive it anymore until I can confirm what it is. No way in hell I'm risking it on "maybe" being a vacuum leak until someone tells me so. One guy told me it sounded like my turbo was going out when I described it to him but then again this turbo has very low mileage on it and I have never ran it past 10psi. Anyone will tell you I let the car sit for at least 2 minutes before I turn it off and even after that I leave my fan on for another 30seconds-1min. Just for measure. Under regular conditions it sounds/drives pefectly fine. The only time I head that sound was once, last night when I went through the intersection and this morning driving through the LOWE'S parking lot. It seemed fine when it was off before and Jon checked over everything good and other than that there were no visuals on the turbo being bad. I'd like some other opinions on this before I hop back in this thing to take it anywhere.

Thanks guys.

Cliffs: After car made some awkward cringe/whining noise, rpms drop past 850rpm set idle when coming to a stop. Idle eventually returns to static. Car doesnt sputter when the rpms drop either. It drops, car quiets (basically it drops as low as it can go with out stopping) then it gradually goes back to regular rpms. Driving feels normal but I havent dare tried to see how it would react under decent boost. Wastegate set at only 9/10psi. Help.

Time to get yourself a nice set of useful tools: compression testor, boostleak testor, leak down (if you have an air comp). Take the intake hose off the turbo and check for shaft play. That will tell you if your turbo is getting sufficient oil since that turbo is oil cooled only. (Side note: the car should ALWAYS be turbo timed no matter what since there is NO coolant running through it, but I'm sure you knew that one already. Just in case.) If this checks out, do a compression check. Your number-set will be lower then average because of the cam profiles in the head. Since you just had it redone, the numbers should be all within close range of each other. If this checks out, no need for a leak down to see where you're loosing the compression.

I personally think the idle issue has alot to do with the ECU trying to learn your LO trim and stay at the rpm it's telling your car to. Since you have a large cam profile with a stock ECU chip, it may be having a hard time getting to 100% lo fueltrim since it constantly has to adjust.

As far as the whining goes, did the whining follow boost onset? IE did it get louder as boost increased? If you were unable to build boost, you probably blew an intercooler hose. Since you have the MAF installed right before the TB, you car will idle and drive under partial throttle fine. But once you hit atmospheric pressure, it won't be able to build any boost (obviously) and you will here the whine of air being sucked in from the leak-point. Of course, a boost leak tester would find all this :)

I'm thinking it is the turbo after running it around today. For the first 10 minutes or so of driving it boosted fine (I still didnt go past 5psi..) But when I was crusing around in traffic in first gear I got to do an rpm pull in 1st gear since I Was only at like 2k rpm and no need to switch gears, I begin applying gas and with my window down I hear/feel that damn whine/grind noise. I'm almost positive it was coming from the turbo as if it didn't want to spool. Ill definitely have to get in there and check some things out but with my luck I wouldnt be surprised if Ill be buying another turbo in the near future... :roll:

Did you buy that turbo from Bullseye? If so you have a 1yr on that thing but if you bought it from ie extreme slowboy ect you dont unless you paid an extra fee.

Jon will be back tomorrow and I have a visit with him anyways about the humongous oil leaks. I'm gunna try some of these test if time permits and see if I find anything, I just don't wnna touch or undo anything that Jon has done that will void my warranty.

As far as piping goes, I have blown off my pipes twice. All on the Ex side of course. Different areas as well, I have everything tweaked down hard and havn't had many issues but I'm 100% sure Ill have to have these things beaded as spydirt said.

Oh and I believe Manny did purchase his turbo from bullseye. I know he was thier big spokesman for a while after he put up those numbers so I'm thinkin he got it from there, maybe not... This is pretty much the last link. The last main stay from its original era. Car has changed from top to bottom, and the interior/exterior is next. the turbo was the heart that linked it to its once greatness but if that thing has to go, it has ta go.. lol BUt I rather be spending my money on a new exhuast mani than another damn turbo.

Thanks for the help guys.

+1 on it being a boost leak. then again, it was easier for me to figure that out since my gsx is auto. i was able to hold the brake pedal down and let it build boost while my dad listened/looked for the source of the noise. it sounded loud as hell when i hit 10psi. ended up being a loose j-pipe coming off the 16g.

My thing is the sound I hear when I try to get boost and the fact it only kicks in after the car has warmed up.. Its an odd ass sound and doesnt sound anything like wind. More like a whine/growl... As I could only describe it as a "cringe"