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Old 10-12-2009, 02:17 AM   #1
projektapex
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Question I'm sure this has been asked before...

If it has, then please forgive me. I was reading the information that was already available at the beginning of this forum about turbos and still had some questions about a turbo replacement. I was wondering if it is absolutely essential to use some form of aftermarket engine management with a replacement turbo? The only mods to my car are an up-pipe and a 3 in turbo back exhaust.
The reason I ask is that I've got an issue with a big boost spike at WOT (spike to about 20psi then drop back to about 12psi, then up to 20 again and back down...over and over). I would just take the stock turbo and have it fixed but I can't really afford to have the car down for a few days while that gets done as it is my daily driver.

I've been trying to look for turbos that are as close to the stock one as possible to minimize any issues with a non stock replacement. The ones I've seen so far are:
IHI VF24
IHI VF30
APS SS45
Forced performance 20g
forced performance td05 68hta
Are these to much or are there any other recommendations that anyone else would have?
Thanks in advance for any advice.
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Old 10-12-2009, 02:36 AM   #2
rjburner
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Loosen your wastegate arm. That should do the trick.
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Old 10-12-2009, 03:21 AM   #3
Rextion
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Do you have the stock BPV or do you have a aftermarket one?
If you have a aftermarket BOV, put your stock BPV back on!
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Old 10-12-2009, 03:27 AM   #4
pDubs
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^.......





It could be compressor surge you are experiencing, although I doubt it, but when I had compressor surge it would bounce around in psi like you said. You will defintely want to have engine management done if you swap out the turbo with anything other than a td-04.
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Old 10-12-2009, 04:09 PM   #5
projektapex
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I forgot to mention the aftermarket BOV. I bought the car used so I don't have the stock bypass. I also found the AVO boost control actuator last night. I was wondering about that because I was originally thinking that it might be just the wastegate actuator that was messed up.

pDubs - would you have any recommendations on websites where I might be able to find a replacement turbo like the td04 you mentioned...I looked around for about 2 hours last night and all I was finding were td05 and larger.

Last edited by projektapex; 10-12-2009 at 04:14 PM. Reason: forgot to add a questions
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Old 10-12-2009, 04:36 PM   #6
Agkelos
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Look in the private for sale here on the forums, you can get a td04 (the stock turbo) for 50-150 bucks easy.

More likely than not your problem is not the turbo, its the boost controller or some other aftermarket change that you are unaware of. I'd try and fix that first and see if it helps.
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Old 10-13-2009, 03:48 PM   #7
projektapex
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I thought about that, too...I don't have an aftermarket boost controller on the car, but was leaning towards the wastegate control actuator being the source of the problem. Oh and on top of this I now have a CEL popping up...going to get the codes pulled today.
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Old 10-13-2009, 04:21 PM   #8
twizzstyle
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Yes you need to be tuned with a different turbo, and really SHOULD be tuned having an uppipe and downpipe.

Have you touched any of the boost control hoses ever? Replaced them at all? The factory tuning is very sensitive to the boost control system and its duty cycle. If you put on hoses that aren't the exact same length and diameter as stock, it can overboost then correct by pulling boost, then correct again and over boost. I had the same problem, oscillation from 18psi to 13psi, about 2-3 seconds per cycle or so. Real annoying. I never fixed it, I ended up putting a VF39 on and did a GM boost solenoid and got it re-tuned, problem solved.

CEL code will probably tell more of the story though. But my bet is boost control hoses, look for leaks or cracked hoses. Those hoses are right over the turbo and get really brittle over time from the heat, so they are EASILY cracked. have you taken out the intercooler recently? You can bump the hoses doing that and break them right off
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Old 10-14-2009, 05:02 PM   #9
projektapex
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Haven't taken out the intercooler in a while. I am familiar with the problems relating to the vacuum lines as the guy who had the car before me changed some of them out because he had an aftermarket boost controller on the car, and it was causing really low boost when i first got the car because they were never changed back when he took it off.

I'm probably going to be going over all of the vacuum lines this weekend, and I'm still thinking of replacing the turbo (found a rebuilt stock turbo for sale for a pretty good price with a couple of options like ceramic coating on the turbine side) because I don't know if the one on the car was ever serviced and I have over 120000 miles on the car. It'll just give me peace of mind to do that.
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Old 10-14-2009, 06:28 PM   #10
soobaviator
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To answer your first question; YES YOU MUST tune EM if you put on a turbo other than the one the car's ECU is tuned for. The turbos you listed are much larger than stock requiring minimum, new fuel injectors, catless uppipe, high flow downpipe and EM tuning. This is not optional or a matter of opinion this is a simple fact.

Number two: why would you assume from a boost spike that there is something wrong with the turbo? Boost spikes to that magnitude could be caused by a number of things, not least of which a collapsed or deteriorating vacuum hose or clog therein. Have you taken data logs or done basic diagnostics? You are throwing codes so there could be many other problems besides major mechanical. Once you find what codes you are throwing that will only tell you half the story as you need to follow the diagnostic procedure given for the code. Basic diagnostics first, do them yourself or get the car to someone who knows how.

Also don't look for any turbo, determine what the boost spike problem and the code problems are first then fix the problems. This will save you both time and money. If it turns out to be a turbo then so be it. More likely than not the turbo is fine and something else needs to be repaired or replaced.

-soobaviator
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Old 10-14-2009, 06:33 PM   #11
IIdiceII
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find a tuner who tunes with rom raider. free EM
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Old 10-14-2009, 06:53 PM   #12
quazimoto
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Don't ever buy a modded car unless you either know how to work on them or have deep pockets. I have no idea why kids these days don't understand this...........
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Old 10-16-2009, 04:35 AM   #13
projektapex
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Normally I wouldn't have. Guy who had the car before me had taken all his aftermarket stuff off. Didn't know if anything had been done before until some minor things started to go wrong and I had to get the car up on jack-stands. The only aftermarket items on the car when I bought it were wheels.

As far as the CEL and its associated code go, it's p1443 - loosened up and then tightened the gas cap again, disconnected/reconnected battery. Code gone, it was the only one.

There are a few other things I am going to be checking before jumping into getting a new turbo. I still have to go over the vacuum lines, although when I'm going to get the time is beyond me. Like I said,The reason I am still thinking about buying a replacement (same kind as stock), even taking into account the fact that my spike issue is most likely being caused by something else, is for my own peice of mind. I'm not doing this right now. I am going to wait until I go over some of the other peices of advice I've gotten from this thread.

Thanks everyone for the advice. This car is my first turbocharged car, and even though I've had it for a few years now, I don't know as much about it or deciphering issues relating to the turbo as I'd like to.
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Old 10-18-2009, 03:50 PM   #14
twizzstyle
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There is no "servicing" of the turbo, so 120k miles on a stock turbo is fine. If the turbo were to be going bad, you'd be getting less boost, or no boost. The fact that you're overboosting would tell me that the turbo is spinning and compressing just fine, you shouldn't have to touch it.

That only leaves the boost control system. Either the hoses, or maybe even a gummed up and slow boost solenoid. You could try cleaning that.
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Old 10-19-2009, 04:39 PM   #15
projektapex
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As more time goes by and I get more advice that's what I am thinking the issue is.

Strange thing is that as of yesterday the problem seems to have corrected itself. As I was going to work I did a full throttle run in third gear up the highway on-ramp to see if it was still happening. The car went to about 15 PSI and stayed there with no over-boosting. There was a little flutter in the needle of my boost gauge, but no spike like I described before (I don't think I had the pedal all the way to the floor as I've seen that little flutter at near full throttle but not wide open).

Still going to check the boost control side of things and the vacuum lines for obvious damage on my next day off.
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