dbtk2 Posted July 7, 2003 Report Share Posted July 7, 2003 OK, so maybe some of you have been following my thread about the problem I am having with my TGP. Well, the mechanic that worked on the car and screwed it up in the first place said that the Turbo is bad. So my dad wants to buy a new turbo for it now, and I don't think it needs one. It would be nice to have a brand new turbo, but I think he will be very pissed when it gets installed and doesn't work. The reason I don't think the turbo is bad is because of these reasons: 1) When we took the car into the shop it was overboosting,(It would hit 10psi then drop to -8psi) when we got it back from the shop it was getting about 3.5psi according to the guage. 2) After the new boost controller we installed it makes ~2psi according to the guage. Well, my dad is thinking the guage is probably off and the turbo is making no boost, but the guage still goes into negative boost and everything. I wouldn't think the maximum boost would change on the guage if the turbo was bad. Basically I don't think it would just quit just like that and then run very low boost, but different amounts of very low boost. So, someone was telling me if you turn the turbine you could feel if it is bad or not, so I want to check it. So how do you tell. Thanks. Shawn Quote Link to comment Share on other sites More sharing options...
90TGPGirl Posted July 7, 2003 Report Share Posted July 7, 2003 Well, my TGP is spitting oil out of the exhaust. So, I was told that is an indication of a bad turbo. Since my car needs a turbo, is there any kind of upgrade for the T-25, or should I just stay with stock? Quote Link to comment Share on other sites More sharing options...
brian89gp Posted July 7, 2003 Report Share Posted July 7, 2003 Try to wiggle the compressor shaft up and down, no play is best but a little is normal. Push the shaft in and out, same as above. Spin the wheel by hand, it should spin freely and not catch on anything. Any oil on either compressor or exhaust side is a bad thing. Its possible that you have an old/blown turbo but to my knowledge they just don't go out like that (unless you drive with the oil unhooked..). It sounds like a wastegate or the vacuum system to the wastegate problem to me. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted July 7, 2003 Author Report Share Posted July 7, 2003 It sounds like a wastegate or the vacuum system to the wastegate problem to me. That is what I think it is, but my dad is sure it is the Turbo, and I really just want to make sure before he spends money on a new Turbo for it. I will check it out, and see what the turbine is like and everything, but I think it is good. Quote Link to comment Share on other sites More sharing options...
Jeff M Posted July 7, 2003 Report Share Posted July 7, 2003 Have a brief moment. First off a lot of these seasoned guys know the TGP pretty well, I would stay close to their recommendations on troubleshooting, thought we would like another who has traveled the road alone and learned even more tips. The POINT about spinning the compressor wheel must be done!! This is the easiest way to tell you if its hanging up and not allowing enough spin to make boost but, no guarantee if it can spool at 90K+, but if it does not spin freely then I would look for something that has gotten into the turbo to hang it up, maybe something from the mechanic who messed with it, I don’t know all he did and don’t care, it’s the possibilities that one must not ignore! So to test your ability to hit higher boost numbers, do this, unplug the vacuum hose at the top wastegate port (round can with actuator rod, this can may still be goldish in color still). Now go for a drive, it should boost to the sky but within .5 second, cut fuel and trigger the SES light, no big deal if testing this once, you can keep bouncing off this fuel cut but I would not recommend it! IF you do not get high boost then you must take off the black rubber inlet hose to the intake side of the turbo/compressor, drive again. One last intake issue is any hose clamp being loose, but the most common and hardest to get right is the short rubber intake hose between the throttle body and metal intake pipe. Too many times when these are connected back together after servicing the hose underneath is not all the way on and is smashed maybe even cut open from being misaligned, check this out or any intake line hose/clamp location! RESULTS: If when you unhooked the wastegate vacuum hose your boost levels came back up/hit fuel cut then the routing is incorrect for these boost hoses. If not but after you took off the inlet hose the boost came back up then that rubber inlet hose is collapsing under the vacuum of trying to suck through the stock restrictive air filter! If you found a loose hose clamp of misaligned hose well, fix it anyways. If none of these tests get you high boost levels then though it may seem odd/so soon for it to happen, I would still have the cat checked, muffler shops are setup to test this easy. A mention, when oil is found in the intake hose lines, intercooler, compressor outlet etc, this is NOT an immediate indication of a bad turbo/blow oil seal, this is common and is a result of the oil fumes being taking from the engine by the crankcase breather tube being routed from the front valve cover into the intake stream prior to the turbo, its partly an emissions thing but also a way to evac blowby. Last if blowing smoke out the back, even dripping oil out the muffler tips, then the MOST common cause is the turbo oil drain line being restricted internally, the stock hose is more than known to fail so this is the first to check, replace. Also its simple to test if it’s the engine blowing oil and not the turbo, just to take out the o2 sensor, its before the turbo/turbine side and after the engine, if its oily then it’s the engine, if its sooty it’s the cracked OEM pipe, though after the sensor has been fouled long enough its reading will degrade further and will clean back up as the computer trims the fuel with the bad sensor reading. Last least common is the wastegate rod is unhooked, or the wastegate flapper has come off. Good luck, and follow these instructions as close as possible, I have worked on several dozen TGPs here in my garage and after talking to over 2,500 TGP and TSTE owners since 1996 helping and learning with them, these are well proven tips and fixes! Add that to the guys on here that have put a lot of wrench time into these as well, to their own and on message boards troubleshooting other TGPs since 1996 and success for your TGP is right around the corner if you work with us 8) . Jeff M Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted July 7, 2003 Author Report Share Posted July 7, 2003 The compressor shaft has absolutely no play at all. It spins freely and easily. This backs up my thought that the turbo is not the problem. The vacuum line that goes to the turbo (not the wastegate) is dirty in the turbo. The line itself is not dirty it is the tip that the line goes into and it looks to be filled with some sort of dirt. It looks like it still flows vacuum easily, but it just has all this dirt on the sides and that doesn't seem normal. Also, the line that goes across the front of the boost controller and runs to the turbo and it rubber at 1 point, and metal for the rest of it is an oil line I am going to assume??? It goes across the top of the engine, and is on the front of it (technically the right side of the engine, cyl. 1,3, & 5.). I was looking at this when I looked at the turbo, and the part with the hose looks like there is a possibility that it could be leaking, but if it is an oil line, it is not leaking because there isn't any oil there. So to test your ability to hit higher boost numbers, do this, unplug the vacuum hose at the top wastegate port (round can with actuator rod, this can may still be goldish in color still). Now go for a drive, it should boost to the sky but within .5 second, cut fuel and trigger the SES light, no big deal if testing this once, you can keep bouncing off this fuel cut but I would not recommend it! IF you do not get high boost then you must take off the black rubber inlet hose to the intake side of the turbo/compressor, drive again. One last intake issue is any hose clamp being loose, but the most common and hardest to get right is the short rubber intake hose between the throttle body and metal intake pipe. Too many times when these are connected back together after servicing the hose underneath is not all the way on and is smashed maybe even cut open from being misaligned, check this out or any intake line hose/clamp location! RESULTS: If when you unhooked the wastegate vacuum hose your boost levels came back up/hit fuel cut then the routing is incorrect for these boost hoses. If not but after you took off the inlet hose the boost came back up then that rubber inlet hose is collapsing under the vacuum of trying to suck through the stock restrictive air filter! If you found a loose hose clamp of misaligned hose well, fix it anyways. OK, so I am confused at when it should get boost. I have not tried this, but the boost should go high when I remove the vacuum from the wastegate or not? If I remove it from both the wastegate and the other line, it should go high or what? It was a little confusing, and I am not 100% sure at what it should do. Quote Link to comment Share on other sites More sharing options...
brian89gp Posted July 7, 2003 Report Share Posted July 7, 2003 Unhook the vacuum line from the wastegate, this will keep the wastegate clamped shut technically overboosting. Quote Link to comment Share on other sites More sharing options...
OldsmoBeast Posted July 21, 2003 Report Share Posted July 21, 2003 I'm not a TGP owner or expert but usually hoses that clamp into metal pipes are coolant lines. Might be oil in your case but most likely coolant. Quote Link to comment Share on other sites More sharing options...
Guest fatguy Posted July 21, 2003 Report Share Posted July 21, 2003 Sounds like the hose/tube that you are talking about that runs along the valve cover is the coolant feed line. It runs from a port just above the waterpump up over the valve cover and then into the turbo. The oil feed line is the small braided steel line under the head and behind the DIS module. The oil return line is a hydraulic looking hose tucked up against the block in the same location. I would still check the cat! Quote Link to comment Share on other sites More sharing options...
90ratss Posted July 21, 2003 Report Share Posted July 21, 2003 i was having the same problems after changing the x pipe. i just ran the tests and sure enough after rerouting the vacuum lines it corrected the problem. the dealer had no clue. so the moralof the story is listen to the guys with most experience. mike Quote Link to comment Share on other sites More sharing options...
SleeperRed90TGp Posted July 21, 2003 Report Share Posted July 21, 2003 You never tied the wast gate closed did you? Unless you do some testing nobody can fix it, not even the man. The lines are easy if the turbo works. I have a picture of how the lines are routed ready to send you but didn't want to confuse you. You have to find out if the turbo works so go tie the friging wg closed just don't floor it. Your beating this to death try something anything. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted August 17, 2003 Author Report Share Posted August 17, 2003 You never tied the wast gate closed did you? Unless you do some testing nobody can fix it, not even the man. The lines are easy if the turbo works. I have a picture of how the lines are routed ready to send you but didn't want to confuse you. You have to find out if the turbo works so go tie the friging wg closed just don't floor it. Your beating this to death try something anything. I have tried everything you guys have suggested (besides exhaust stuff) with no luck, so I thought maybe I wasn't doing things properly. Today while I was installing a new air filter in it (I change it every 5-10k) I decided to pull the hose off the turbo and sure enough there was oil all in the intake of the turbo and the first 3 inches of the air intake hose that runs to the turbo were coated with oil (and none of the rest of it had any oil on it, just the 3" by the turbo, this makes me think it is coming from the turbo not the intake air), I know for a fact it was not that way a month ago when I did all this testing, for some reason it waited before spitting out oil after it failed. Because of this, and the results of all of the testing I did, I have come to the conclusion that the turbo actually is bad and needs to be replaced/rebuilt like the mechanic originally said. By the looks of the exhaust oil is coming out of the exhaust also...it is not shooting out or anything, but the tips appear to have oil on them, or the car is running very rich. Thank you all for all the help, if getting the turbo rebuilt or replaced doesn't help I will be posting again. Shawn Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted August 17, 2003 Report Share Posted August 17, 2003 Are you sure you did everything recomended to test it.: Check intercooler hoses ,TB hose(make sure that the intake pipe to the TB is bolted on right and tight,,feel underneath the tb hose to check if its poped out like Jeff said), and turbo hoses for any sighns of tears or leaking form poping out. If ok then next.... Check to see if your waste gate controler vacume lines are connected like they should. THe one from the turbo outlet should go on back of the selinoid where it has two vacume ports. It should be on the one without the clip and sponge(if it still has a sponge). THe other vacume line should go to the accumulator(round cyclinder on top of turbo) to the side of the selinoid with one port. I would replace the selinoid if I were you since you stated that there was dirt inside the vacume lines...that dirt prob cloged the port on the selinoid that lets the air out to control boost. If everythings ok then next... Unplug vacume hoses from turbo....Drive car and it should overboost. If over boosting then its fine(turbo) . If the car boosts and then it goes into vacume at WOT(without the feel of engine shutting down)..then remove the hose that goes to the turbo from the air box...try again..if you over boost then you found the culprit. If it doen't boost at all then check your acumulator(AKA wastegate,,round thing on top of turbo). Pump air into it and it should extend the rod on it to open the waste gate...then when you let the presure out it should return...if it doen't do anything...then its bad. Also ...have a boost guage on board to see real life boost...don't go by stock guage. I know you have one...borrow from your 3800. If ok...then next. Check your map...or replace it. Check the vacume lines from the map sensor to the TB..You may want to look under the upper intake to see if the vacume lines poped out of each other. Check to see if your vacume hoses poped out of your TB...a metal clip that retains them might be missing. If you were smoking like a barbecue at a stop light then you might have a bad oil return hose (goes into oil pan) or your turbos turbine seal (ring) might be bad. (rebuild)...but it shouln't loose performance...have you seen Desel truck pulls (Sterling, Kenworth, Mack)...their turbos smoke (oil) like Uncle Bert but still boost like a mother. A bad seal isn't the problem. YOu did state that your turbo didn't wable and hit anthing ...it span freely ..then its bearing are good. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted August 17, 2003 Author Report Share Posted August 17, 2003 Are you sure you did everything recomended to test it.: Check intercooler hoses ,TB hose(make sure that the intake pipe to the TB is bolted on right and tight,,feel underneath the tb hose to check if its poped out like Jeff said), and turbo hoses for any sighns of tears or leaking form poping out. If ok then next.... Did that. Check to see if your waste gate controler vacume lines are connected like they should. THe one from the turbo outlet should go on back of the selinoid where it has two vacume ports. It should be on the one without the clip and sponge(if it still has a sponge). THe other vacume line should go to the accumulator(round cyclinder on top of turbo) to the side of the selinoid with one port. I would replace the selinoid if I were you since you stated that there was dirt inside the vacume lines...that dirt prob cloged the port on the selinoid that lets the air out to control boost. If everythings ok then next... I already replaced the selinoid, that was the first thing I did. Eveything is just like you say it should be here. Unplug vacume hoses from turbo....Drive car and it should overboost. If over boosting then its fine(turbo) . If the car boosts and then it goes into vacume at WOT(without the feel of engine shutting down)..then remove the hose that goes to the turbo from the air box...try again..if you over boost then you found the culprit. If it doen't boost at all then check your acumulator(AKA wastegate,,round thing on top of turbo). Pump air into it and it should extend the rod on it to open the waste gate...then when you let the presure out it should return...if it doen't do anything...then its bad. Also ...have a boost guage on board to see real life boost...don't go by stock guage. I know you have one...borrow from your 3800. If ok...then next. The car does not boost no matter what I do to any of the vacuum lines. When I tie the wastegate closed it doesn't boost. I would put a boost guage in it, but I don't have one, as much as you would like to think I have one in the GTP, I DON'T. The point of that car is to look completely stock except under the hood, and the boost guage would defeat that purpose. We hook up the autotap if we want to see boost, and since the TGP is OBD1 and not OBDII we can't do that. Check your map...or replace it. Check the vacume lines from the map sensor to the TB..You may want to look under the upper intake to see if the vacume lines poped out of each other. Check to see if your vacume hoses poped out of your TB...a metal clip that retains them might be missing. All of that is exactly how it should be. Like I said I have already checked all that stuff. If you were smoking like a barbecue at a stop light then you might have a bad oil return hose (goes into oil pan) or your turbos turbine seal (ring) might be bad. (rebuild)...but it shouln't loose performance...have you seen Desel truck pulls (Sterling, Kenworth, Mack)...their turbos smoke (oil) like Uncle Bert but still boost like a mother. A bad seal isn't the problem. YOu did state that your turbo didn't wable and hit anthing ...it span freely ..then its bearing are good. It doesn't smoke, there is just some oil in the exhaust pipes, its not like a lot comes out. As I stated, there is also oil in the intake of the turbo. The mechanic that originally worked on the car said the turbo was bad, and he used to race and fix 944 Turbo's, so I would think he would know what he is talking about, I was just skeptical at first that it was the problem. Quote Link to comment Share on other sites More sharing options...
Chris A Posted August 17, 2003 Report Share Posted August 17, 2003 pull the hose off the turbo and sure enough there was oil all in the intake of the turbo and the first 3 inches of the air intake hose that runs to the turbo were coated with oil Shawn You have the stock airbox and flexible inlet hose? The oil seal is behind the compressor wheel, its very unlikely that the oil will come back out the inlet from the turbo. Most likely oil in the inlet is from the breather hose in the airbox. Unless the turbo is seized up, it won't affect boost. It can blow all the oil it wants to, but if it spins freely will still make boost. The black on the tips is from running rich, if you were leaking oil you would have blue/white smoke coming from the car. I don't know what you mean by "there is oil in the exhaust". Is there actually oil residue in the exhaust? Cut the darn cat off! If you have been running rich, and you have checked the turbo shaft and tied the wastegate shut, get out a sawzall and cut the cat off!!! There is no reason to replace the turbo if the shaft is ok and it spins freely and doesn't hit the housing. Running rich could have damaged the cat, or if the drain tube was ever bad that coudl have damaged the cat by forcing oil into the exhaust. You can also try banging on the Cat with your hand and seeing if it makes a clunking noise, also a good indictaion its bad. IF it is bad, punch it out and buy some stainless steel band clamps and put it back on. Chris Quote Link to comment Share on other sites More sharing options...
90TGP Posted August 17, 2003 Report Share Posted August 17, 2003 This is a little confusing to me. But, could someone PLEASE make me a detailed step-by-step procedure that I could use to check my turbo? I have a similar problem, I have the topgun 180 chip, but my car is only making 7psi [5psi without the bov, 7psi with]. I had one loose intake coupler, but I fixed that, and it didn't help my boosting problem. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted August 17, 2003 Author Report Share Posted August 17, 2003 You have the stock airbox and flexible inlet hose? As the signature says, BONE STOCK. That means the car is completely stock (plugs, filters, things like that are an exception). The oil seal is behind the compressor wheel, its very unlikely that the oil will come back out the inlet from the turbo. Most likely oil in the inlet is from the breather hose in the airbox. It is thick (1/32 of an inch) on the inlet of the turbo and the 3" before it, none of the rest of the intake hose has any oil on it at all. The black on the tips is from running rich, if you were leaking oil you would have blue/white smoke coming from the car. I don't know what you mean by "there is oil in the exhaust". Is there actually oil residue in the exhaust? I am not an idiot, I know black exhaust is rich. There is oil residue in the exhaust. The car doesn't leak oil, but is 1 quart low every 1000 miles or so, so it obviously uses it somewhere, but I have never seen it smoke before so it is weird. Cut the darn cat off! If you have been running rich, and you have checked the turbo shaft and tied the wastegate shut, get out a sawzall and cut the cat off!!! There is no reason to replace the turbo if the shaft is ok and it spins freely and doesn't hit the housing. Running rich could have damaged the cat, or if the drain tube was ever bad that coudl have damaged the cat by forcing oil into the exhaust. You can also try banging on the Cat with your hand and seeing if it makes a clunking noise, also a good indictaion its bad. IF it is bad, punch it out and buy some stainless steel band clamps and put it back on. I will see what I can do. My dad is going to pay to get the turbo completely rebuilt, so why not do it? After that gets done, if the boost problem is not fixed I will replace the cat with one of the high-flow ones and see if it fixes the problem. Quote Link to comment Share on other sites More sharing options...
Chris A Posted August 17, 2003 Report Share Posted August 17, 2003 There are many things that can cause a "LOW BOOST" Condition. To physically check a turbo for operation, you can: A: Take the air inlet to the turbo off and look and see if its spinning while the engine is idling. Be careful not to let anything enter this area as even small soft things like bugs could cause a problem. B: If its spinning, then it is at least working. Now you can check to see how much wear it has. Turn the engine off and let the turbo stop spinning. Grasp the nut on the end of the wheel and try to move it in and out of the turbo. If there is any more than a slight (.002 in IMO) of movement the thrust bearing in the turbo is wearing and will soon allow the compressor to suck itself into the housing. There is probably .010 or less of clearance between the wheel and the housing. C: Pushing the wheel up and down, try to spin the wheel slightly. If you hear any noise (metal on metal) the wheel may hit the housing during operation. D: Oil leaks will normally be really bad on the turbine (exhaust) side of the turbo since the heat is harder on the seal, and often the seal gets coked up and wears away. A mild oil leak will eventually cause smoke out the exhaust in the back. A severe leak will actually drip out between exhaust joints or cause smoke under the hood. Compressor oil leaks can happen, and usually are because of a bad oil drain. However, since the engine is sucking air through the compressor most of the time, oil leaks here will be visible in the compressor outlet. Checking Boost. For a turbo to make boost, there must be a differntial across the turbine wheel. The more boost a turbo can make with a smaller differential the more efficient the turbine wheel is. Things that can affect boost. A: Restriction. Either before the compressor inlet or after the turbine out let. The harder the turbo has to work to suck air in, the less work it can do pushing air out and will make less boost. Likewise, the harder the turbo has to work pushing exhaust out, the less work it can transfer to the compressor wheel to make boost. Possible intake restrictions include: Airfilter, air tubing, collapsed tubing Possible exhaust restricitons include: BAD CAT, Bad Cat, bad cat. also: collapsed exhaust, clogged muffler with BAD CAT chunks. B: Exhaust Bypass. In order for the turbine to do any work, the exhaust must pass over it, not around it. The same thing that keeps your boost in safe levels, can keep it from reaching FUN levels. The wastegate operates by opening a hole before the turbine that allows exhaust into the downpipe without going over the turbine. There is a valve that blocks the hole. This valve is connected to the wastegate actuator externally (gold can on turbo). The WG actuator has a diaphram with a spring pushing the rod into the actuator. On the other side of the diaphram, boost pressure pushes against the spring, moving the rod and opening the valve. B1: Solenoid. In the simplest setup, boost pressure from the turbo outlet is directed to the WG Actuator. However, this can create inconsistent boost levels, and there is no control over boost other than tightening the spring on the actuator. So on many cars including the TGP, an electronic solenoid is placed inline with the boost signal. By keeping the boost signal from reachjing the actuator, it will not get pushed open and therefore not allow exhaust to bypass the turbine. The solenoid vents the boost signal to the atmoshphere to keep it from reaching the actuator. So if the solenoid isn't working, you will see very little boost as all the boost signal will get to the actuator. Similarly, if a line is broken or missing, you will get ALOT of boost since no boost signal will reach the actuator. In this situation, exhaust backpressure will actually push against the wastegate valve causing it to open and limit the boost. B2: Actuator. As mentioned the actuator has a spring and a diaphram. If the diaphram is ripped, you will get high boost since the boost signal will not be able to push against the spring. However, if the spring is broken (typcially from rust), the boost signal will easily push open the wastegate. Similarly, exhaust backpressure can blow the WG valve open with a broken spring. B3: Exhaust leak in the crossover. A serious leak before the turbo will keep the exhaust from reaching the turbine and reducing boost levels. However, it has to be a BAD leak and will be quite obvious. C: Boost Bypass. This is pretty simple. Allowing boost to escape before it reaches the motor. Usually intercooler hose connections are loose or blown off either because of loose fittings or oily fittings. D: Engine Problems. Typcial N/A engine performance issues can really affect boost such as cam timing, valve sealing, crankcase sealing etc. But there are usually indicators to point in the right direction. Hope this helps Chris Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.