dbtk2 Posted June 23, 2003 Report Share Posted June 23, 2003 We purchased our Red 1990 TGP in December of last year as a Winter Beater off of ebay because it was a great deal, since we bought the car online we didn't know what was wrong with it etc... until we got there to get it, it was a 5 hour drive from where we lived. We picked up the car and as soon as my dad got a block down the road (he drove the TGP back, while I drove the GTP back) he noticed the transmission was shifting very hard, so we figured the transmission was bad, we found out a few months later the car had no motor mounts except for the 2 dog bones on top, which is obviously why it shifted so hard. We had to drive for about 1 hour on a 2 lane road on the way back, and the first time my dad went to pass somebody he nailed the gas, as soon as he got up to about 40 the engine just pretty much quit, it was still running, but it wouldn't gain rpms. After owning the car for a month, we figured out it had something to do with the turbo, the wastegate or something would make it loose all of its boost, and it would go to like -8psi and have no power, but the engine would still try to go up to redline on its own N/A power. After the car sat in the driveway for 2 weeks we also found out it had a major oil leak, about a quart every 2 weeks. So, we drove the car all winter with these problems and planned on gettting them fixed as soon as we got good weather so we could drive the GTP. So good weather came along and we brought the TGP into a local shop (not a dealer unfortunately). The local shop informed us that the lower motor mounts were completely gone, and needed to be replaced. We were glad it wasn't the tranny and we told them to replace them. The replaced 1 lower motor mount, but didn't want to do the work of putting in the other one because we weren't paying them labor, we were only paying for parts because the shop is owned by a friend of ours. So they replaced the 1 motor mount. The transmission still shifts hard because the other motor mount needs to be replaced. The also fixed the oil leak, and it is actually fixed so that problem is resolved. The transmission is not an issue to me and I am more worried about the turbo. Because this shop had never worked on a turbo 3.1 before they didn't want to figure out what was wrong with the turbo they just left it alone. We brought it into another shop that has a very good mechanic that we know well and he diagnosed the car and said that the turbo is bad, and it obviously isn't because it will get boost fine until it looses it all. But while he was diagnosing the car he must've messed with it or something because now the problem is really bad. I will try to explain in detail what the car did before and what it does now. When we bought the car, if you got on the gas normal it would be fine and get up to speed. If we put the gas to the floor the guage would go up to like 10psi and it would shut off, but if we just hit the gas hard enough for the boost to not go over 9 it would accelerate fine except at speeds above 60 it was very hard to make the boost not go that high. I am assuming this was the computer kicking in the overboost protection because it was getting too much boost, although it is bone stock I don't know why it would be getting that much boost. Now that the mechanic messed it up this is what it does. You can hit the gas as hard as you want and the boost guage will reach a whopping 3.5psi at WOT. When the car gets to about 5300rpms it will just sit there and never shift, if you just let off the gas a little it will shift and then you can nail it again. It will do the same thing at the top of 2nd gear, it will reach 5300rpms and just sit there, then if you let off the gas it will shift into 3rd, but then when you get into the gas it will downshift back into 2nd and be running 5300rpms again, so you have to let off then hit the gas halfway until it gets up to enough speed that it won't downshift then you can get back in the gas. Now there are 2 main problems with this. 1, it won't shift on its own and it is a PITA to just drive around and have to let off the gas every time it has to shift, if we wanted that we would have a 5 speed. The other problem is the car has no power when it is only running 3.5psi. We raced a Sunfire GT Auto from 15mph and they pulled 6 carlenths by 60, when a 150 horsepower 4 cylinder can pull 6 cars on a 205hp TGP from 15-60 the TGP has a problem. The car is very slow and it is barely fast enough to be able to pull into traffic and get out of the way. If it were much slower it wouldn't be safe. It would be nice to get this problem fixed so we can know what it feels like to drive a TGP, because the whole time we have owned the car we have never had the joy of being able to see what a TGP will do. If anyone has any clue what is wrong with the car, or will be kind enough to come to Michigan and try to figure out what is wrong with the car it would be greatly appreciated. We really would like it fixed, because it is a nice car and it would be nice to be able to use it as more than a winter beater. I think it may have something to do with the vacume lines but I know nothing about these cars so I don't know. ANy help would be greatly apreciated. Thanks. Shawn Quote Link to comment Share on other sites More sharing options...
Slade901 Posted June 23, 2003 Report Share Posted June 23, 2003 I'm no expert in turbo and I'm sure some folks here knows about turbo. What I can suggest at this time is just to make sure your cat is not partially clogged up. Partially clogged cat will manifest itself as a problem within the engine. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 23, 2003 Author Report Share Posted June 23, 2003 I am pretty sure the cat is fine, although I haven't removed it and checked, but I don't know how it could effect the turbo like that. BTW, the car has no check engine lights or anything on, so I don't think it is anything major. Quote Link to comment Share on other sites More sharing options...
Slade901 Posted June 24, 2003 Report Share Posted June 24, 2003 Well, I mentioned cat because you stated that your car don't seem to have power and your car is even beaten by a 4 cylinder car. Clogged cat or failing cat will rob your engine of power because it restricts the exhaust gases and the engine will work harder just to get the exhaust past the blockade in the cat and gaining less distance. Quote Link to comment Share on other sites More sharing options...
kheider Posted June 24, 2003 Report Share Posted June 24, 2003 the car has no check engine lights or anything on, so I don't think it is anything major. When you turn on the ignition (without turning on the car), does the check engine light (and other idiot lights) come? (If the check engine light doesn't come on, someone pulled the bulb.) Quote Link to comment Share on other sites More sharing options...
manualturbo Posted June 24, 2003 Report Share Posted June 24, 2003 your low boost is probly because the mechanic switched the vacuum lines on the wastegate solenoid(on the front of the engine--the little black thing that has an electrical connection and two vacuum lines) if you switch them back (the one with the 90 degree elbow should be on the left back nipple(i think) and connect to the wastegate while the straight one should be on the right nipple and go to the barb at the bottom front of the turbo--someone please correct me if im wrong. this should fix that problem. mitch 90 tgp 5 speed Quote Link to comment Share on other sites More sharing options...
idbeast Posted June 24, 2003 Report Share Posted June 24, 2003 You have a problem with your vacuum lines and a possiable plugged cat converter, I'll post you some links to the lines I feel are the problem tommarow, ( a couple two many mudslides tonight to look for them) Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 24, 2003 Author Report Share Posted June 24, 2003 Well, I mentioned cat because you stated that your car don't seem to have power and your car is even beaten by a 4 cylinder car. Clogged cat or failing cat will rob your engine of power because it restricts the exhaust gases and the engine will work harder just to get the exhaust past the blockade in the cat and gaining less distance. I do not think the problem is a plugged cat. The lost power is because of the low boost. The car had a lot of power before when we had the overboosting problem, with only 3.5psi boost, it just has no power, that and the fact that it doesn't shift on its own so you lose a lot of time letting off, waiting for it to shift, then getting back in the gas again. I understand why a cat would make the engine lose power, because it would make a big restriction in the exhaust, but I don't see how it would make the car do exactly what it is doing. Thank you for the suggestion though, and if it isn't a vacume problem I will remove the cat and take a look at it. When you turn on the ignition (without turning on the car), does the check engine light (and other idiot lights) come? (If the check engine light doesn't come on, someone pulled the bulb.) Yes, all of the lights come on, besides the fact that I don't think someone could remove the light from the HUD, because if I am not mistaken there is a check guages or check engine light or something in the HUD. I am not mechanically challenged, I actually know quite a bit about engines, I am just not very familiar with turbo's so this problem just has me stumped. your low boost is probly because the mechanic switched the vacuum lines on the wastegate solenoid(on the front of the engine--the little black thing that has an electrical connection and two vacuum lines) if you switch them back (the one with the 90 degree elbow should be on the left back nipple(i think) and connect to the wastegate while the straight one should be on the right nipple and go to the barb at the bottom front of the turbo--someone please correct me if im wrong. this should fix that problem. I have been suspecting it is a vacume problem, but if the vacume lines were switched, then when they are put back how they were, I will have the overboosting problem again, but the vacume lines could've been wrong before. If there is any way that anybody here could get vacume line routing for me that would be awesome. If I remove both of the vacume lines from the top of the turbo it runs exactly the same as it does with them connected if that gives you any hints, if anything it actually gets a little more boost. Quote Link to comment Share on other sites More sharing options...
TurboGTU Posted June 24, 2003 Report Share Posted June 24, 2003 Well hope my link or web site works... http://img.villagephotos.com/p/2003-3/71609/YEZMCRQFTEZZNDRLUPRO-wastegatelayout.jpg that was the waste gate hose layout. Verry simple to sort out. You might want to check to see if your selinoid is working properly. Get another if you want. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 24, 2003 Author Report Share Posted June 24, 2003 I looked at the vacume lines and the two on the top of the Turbo and they are correct, but there is a 3rd opening in the place that the lines run to that goes nowhere. This is what the mechanic must've changed, because I know before it had a screw in it to block it off, but now it is just open, so there is where the leak is, but where is it supposed to run to becuase if I just put a screw in it then it is going to get too much boost again. Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 24, 2003 Report Share Posted June 24, 2003 I looked at the vacume lines and the two on the top of the Turbo and they are correct, but there is a 3rd opening in the place that the lines run to that goes nowhere. This is what the mechanic must've changed, because I know before it had a screw in it to block it off, but now it is just open, so there is where the leak is, but where is it supposed to run to becuase if I just put a screw in it then it is going to get too much boost again. You mean a 3rd opening on the boost controller? That's for a small foam air filter. There should not be any screws plugging it. Maybe you should try replacing the boost controller. They run around $30 from GMpartsdirect.com Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 24, 2003 Author Report Share Posted June 24, 2003 So you think maybe the previous owner had a problem with it and plugged it off to get more boost or something? Or they wanted more boost so they plugged it off? I can get a picture so you know what I am talking about for sure, but I think you do. So you think if I replace that it will fix the problem. I will try that and report back. Quote Link to comment Share on other sites More sharing options...
92turboLE Posted June 24, 2003 Report Share Posted June 24, 2003 is the wastegate rod adjustable??? there is a chance that someone could have fucked with it and tried to turn it up. the 10lbs thing sounds normal as the tgp computer is designed to shut the engine off at 10lbs.... i think someone may have tried to fuck with it and turn the boost up and not realize that it pissed off the computer... then your mechanic may have turned it down.... just a thaught... as for the tranny, fucked if i know - Justin Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 24, 2003 Author Report Share Posted June 24, 2003 The boost controller is not available through gmpartsdirect anymore. They said they have discontinued the item. If anyone knows anywhere else I can get one that would be cool. is the wastegate rod adjustable??? there is a chance that someone could have fucked with it and tried to turn it up. the 10lbs thing sounds normal as the tgp computer is designed to shut the engine off at 10lbs.... i think someone may have tried to fuck with it and turn the boost up and not realize that it pissed off the computer... then your mechanic may have turned it down.... just a thaught... as for the tranny, fucked if i know I know that the computer is supposed to cut out at 10lbs to prevent overboosting, I understood why it was doing that, but I don't understand why it was running that much boost. I do not know if the wastegate rod is adjustable and I am going to go look after I get done posting. If that is what happened I am going to be really pissed. I don't know why the tranny won't shift, but it would shift fine before when we had the overboosting problem, I think it sees that it is at WOT and the rpms aren't at redline yet so it can't shift, the engine just doesn't have the power to reach 5500 under load. I think all that was changed is the screw in the boost controller. A previous owner wanted more boost so they plugged the hole with a screw to get more but it screwed it up to have it plugged like that or something. I am going to find a screw and put it back in there to see if it goes back to how it was before, if it does, I am going to get a new boost controller, and if anyone knows where I can get one that would be helpful. Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 24, 2003 Report Share Posted June 24, 2003 So you think maybe the previous owner had a problem with it and plugged it off to get more boost or something? Or they wanted more boost so they plugged it off? I can get a picture so you know what I am talking about for sure, but I think you do. So you think if I replace that it will fix the problem. I will try that and report back. http://www.neonix.org/nero/vacuum1.jpg Check that picture out. I apologize if it does not load. I've been going through some domain troubles lately..they should be resolved by the end of the day...I hope Anyway, the picture is of the boost controller. The vacuum hose at the top of the picture (towards the back of the engine) should really be on the vacuum port on the front (towards the front of the engine). On that back vacuum port, there usually is a foam filter. The filter however has rotted off of this controller. I have a brand new controller with a filter waiting to go on my car....once my turbo rebuild is complete. Hopefully I explained that clearly enough Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 24, 2003 Author Report Share Posted June 24, 2003 is the wastegate rod adjustable??? The wastegate rod is not adjustable, I didn't think I remembered it being adjustable. Check that picture out. I apologize if it does not load. I've been going through some domain troubles lately..they should be resolved by the end of the day...I hope Anyway, the picture is of the boost controller. The vacuum hose at the top of the picture (towards the back of the engine) should really be on the vacuum port on the front (towards the front of the engine). On that back vacuum port, there usually is a foam filter. The filter however has rotted off of this controller. I have a brand new controller with a filter waiting to go on my car....once my turbo rebuild is complete. Hopefully I explained that clearly enough Yup, that is what I am talking about. The 2 vacume lines are in the correct spot, but where there is supposed to be this filter there is a 90 degree bend with a piece of vacume tubing, and it is just open (it used to have a screw in it). I am assuming the boost control is bad. I tried to order one from gmpartsdirect but they said they didn't carry them anymore (they are supposedly discontinued). If you know where I can get one that would be awesome, or maybe they didn't know what they were talking about and you can give me their part number so I can order it. I would buy a working one off of you if you have one you want to sell. I really want to get it fixed. Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 25, 2003 Report Share Posted June 25, 2003 They still sell it The part # is 1997152 And after I've given it more thought, there may have been a problem with underboosting before..and that's why they restricted the vacuum line with that screw If the boost controller doesn't fix the problem, then it may be a problem with your Map Sensor...or Wastegate Solenoid. The other stray thought I had was about your transmission problem. The 4T60 is a vacuum operated transmission..so if you're having problems with boosting..and that, then you may just have a vacuum problem, or a leak somewhere that's causing all the problems. That's worse case scenario though. Quote Link to comment Share on other sites More sharing options...
idbeast Posted June 25, 2003 Report Share Posted June 25, 2003 Most people who don't know about TGP's plug that line thinking it is a vacuum leak, as they also do on the transmission vacuum modulator. If you have either of these plugged- unplug them so your car will run like it is supposed to. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 25, 2003 Author Report Share Posted June 25, 2003 Most people who don't know about TGP's plug that line thinking it is a vacuum leak, as they also do on the transmission vacuum modulator. If you have either of these plugged- unplug them so your car will run like it is supposed to. I don't know where the transmission vacuum modulator is, but I know the one for the turbo isn't blocked anymore and that is when the low boost started occuring. If you could tell me where the tranny vacuum modulator is that would be awesome so I can make sure it isn't blocked, although I don't think it is. They still sell it The part # is 1997152 That part is only $9.11. Are you sure it is the right one? Under description it just says "Solenoid," and I know that is what it is but it doesn't give me any more description telling me exactly what it is. I just want to get the right part, I don't want to order the part and get the wrong one and have to go through the trouble of finding the right one. And after I've given it more thought, there may have been a problem with underboosting before..and that's why they restricted the vacuum line with that screw That is what I am thinking. The other stray thought I had was about your transmission problem. The 4T60 is a vacuum operated transmission..so if you're having problems with boosting..and that, then you may just have a vacuum problem, or a leak somewhere that's causing all the problems. That's worse case scenario though. Yeah, I know the transmission problem is because of the vacuum problem that is causing my boost problem. I am not worried about the transmission because it was fine before I had the low boost problem. If there is any way someone could get me the vacuum routing for the whole engine that would be awesome. I am almost positive it is a vacuum problem and if the boost controller is not the problem then I am just going to have to go over all of the vacuum lines until I find the leak, or lines switched or something. Any help is appreciated. Thanks. As soon as I figure out the problem the modding begins so I wanna figure out the problem! Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 25, 2003 Report Share Posted June 25, 2003 Yup...that's the correct part. It's described as a solenoid. I was off on the price though. Although it may be $30 by the time they add shipping It's still cheaper than the dealer price though.... :shock: Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 25, 2003 Author Report Share Posted June 25, 2003 Its $17.04 including shipping. I am going to order it and see if it fixes the problem. Hopefully it does. If not, it was only $17, and I guess I will be redoing all the vacuum lines for the whole car to find the leak. I have a friend that was telling me about a valve that you can buy for like $2 that will restrict vacuum lines and it is made so you can up the boost. If the new boost controller doesn't fix the problem, I may try picking one of these up temporarily for the line that the screw was in to maybe see if I can temporarily get the correct boost out of it until I redo the vacuum lines. If anyone has heard of these before, do they work, and where I can I get one? I am just thinking of temporary fixes until I get time to redo vacume lines, because I just have a feeling the problem isn't the boost controller, because nothing is that easy for me. Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 25, 2003 Report Share Posted June 25, 2003 In theory..there is one way you can test the controller. Turn the car off, and remove the controller from the engine. Blow air through the metal vacuum port. If it ONLY comes out the vacuum port on the other side that is normally towards the FRONT of the engine, then it is good. If it comes out the one that is normally towards the back as well, then the valve is bad...and you are leaking vacuum (boost) whenever the car is running. In theory, this should be an easy way to tell if the controller works. If you had a vacuum pump, you probably wouldn't have to remove the controller from the car. Either way, replacing the controller is probably a good idea, since it had a screw shoved in it. :shock: I've never heard of this valve your friend is talking about. Could he have been talking about a Blow-Off Valve (BOV)? That's the only sort of valve I've ever seen added to a TGP. :? Quote Link to comment Share on other sites More sharing options...
Guest fatguy Posted June 26, 2003 Report Share Posted June 26, 2003 My car ran great also, but still didn't boost. CHECK THE CAT!!!!! I know Midas can check them. When I replaced it....HOLY CRAP. Other options not mentioned: 1) Air filter restrictions. Try unhooking the hose at the nose of the turbo and go for a SHORT drive. Does this help? 2)What condition is the vacuum block on the throttlebody? Is there 4 lines running into it? If not then that could be a problem. 3)Is the air coming out of the vents correctly at all times? Especially at WOT? Also does the cruise work? 4)Is the crossover pipe leaking? Mine did and it affected turbo spooling. 5)is there correct fuel pressure, and the FPR is good? The vacuum modulator for the trans is just to the right of the coil packs (as looking from the front of the car). The steel line running from the plenum neck down runs to it. At the end of the steel line is a check valve T. The 3 legs of the T are: 1)open, 2)steel line from plenum, 3) vacuum modulator. The open leg is there to bleed pressure off (under boost). If you unplug the T from the modulator and trans fluid runs out then the modulator is bad. Hope this helps Quote Link to comment Share on other sites More sharing options...
The Burning Rom Posted June 26, 2003 Report Share Posted June 26, 2003 My car ran great also, but still didn't boost. CHECK THE CAT!!!!! I know Midas can check them. When I replaced it....HOLY CRAP. Other options not mentioned: 1) Air filter restrictions. Try unhooking the hose at the nose of the turbo and go for a SHORT drive. Does this help? 2)What condition is the vacuum block on the throttlebody? Is there 4 lines running into it? If not then that could be a problem. 3)Is the air coming out of the vents correctly at all times? Especially at WOT? Also does the cruise work? 4)Is the crossover pipe leaking? Mine did and it affected turbo spooling. 5)is there correct fuel pressure, and the FPR is good? If the lines were out of the block on the TB, you'd probably hear the leak. I know I can hear it when the block blows out of my TB Sounds like a BOV. I don't doubt that the crossover is bad on this car, but I'd bet good money it's not the cause of the problem. And on the cat issue, if he was overboosting..and took it in, and now he's only getting around 3psi, I doubt it's the cat. It wouldn't plug that fast. Hopefully the new boost controller fixes everything Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 26, 2003 Author Report Share Posted June 26, 2003 I've never heard of this valve your friend is talking about. Could he have been talking about a Blow-Off Valve (BOV)? That's the only sort of valve I've ever seen added to a TGP. It is not a BOV. It is a valve, like one that you would use to turn the water on or off in your house. The further it is open the more vacuum it allows through. You put it in the vacuum line and it allows you to restrict the amount of vacuum going through so you can turn up your boost, or at least that is how I understood it when he explained it to me. He used it on his Neon or something and suggested it to me. 1) Air filter restrictions. Try unhooking the hose at the nose of the turbo and go for a SHORT drive. Does this help? Its not the air filter, I do regular maintenance to all my cars and check those things when I have a problem such as this, it is definately not the air filter. 3)Is the air coming out of the vents correctly at all times? Especially at WOT? Also does the cruise work? The cruise control works fine. There is not air coming out of the vents at WOT because there is a clutch on the A/C and it turns off at WOT, the blower is still blowing air, but it isn't cold air anymore, then the air kicks back in a few seconds after I let off the gas. 4)Is the crossover pipe leaking? Mine did and it affected turbo spooling. The crossover pipe is leaking because it is the stock one and with 110,000 miles the stock one is going to leak, but it is not what is causing the problem because it was leaking when I was having the overboosting. I am going to replace it as one of my first mods once I get the boost problem fixed. 5)is there correct fuel pressure, and the FPR is good? That thought came to my mind, but I was having an overboosting problem, and I took the car into the shop, and when I got it back it wasn't getting enough boost, so I don't think it is the fuel pressure. The vacuum modulator for the trans is just to the right of the coil packs (as looking from the front of the car). The steel line running from the plenum neck down runs to it. At the end of the steel line is a check valve T. The 3 legs of the T are: 1)open, 2)steel line from plenum, 3) vacuum modulator. The open leg is there to bleed pressure off (under boost). If you unplug the T from the modulator and trans fluid runs out then the modulator is bad. I will check this, but I won't be able to until tommarow evening because it is supposed to rain tommarow so my dad will be driving the TGP so the GTP doesn't get wet (he babies the GTP and his truck which leaves only the TGP to drive in the rain). Hopefully next schoolyear the car becomes completely mine and my dad won't be driving it in bad weather...that would be sweet. Hopefully the new boost controller fixes everything I am hoping so too, it would be a nice easy fix, and although I enjoy working on cars, I have had enough of this and just want it fixed. It would be nice if $17.04 would fix all the overboosting and underboosting crap I've had to deal with in the past 6 months. I may be replacing the 2 vacuum lines that run to the turbo also, they look kinda worn out and old, although I don't think they are leaking. Quote Link to comment Share on other sites More sharing options...
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