98t5M Posted January 23, 2011 Author Report Share Posted January 23, 2011 unbolt your dp a little, you'll get a boost leak, but if you can boost more it means you need a new cat. (if you're still running a cat) I have a hard time seeing your WG being wired shut and you only make 12psi. I would look at the wastegate sealing properly on the turbine housing, because you should be making engine-breaking boost levels with it wired shut and WOT I don't have a cat on the car. With the WG wired shut it'll make tons of boost very quickly in the midrange but it just plain sucks in the top end. I was just fiddling with it some more and noticed that the WG arm has some side to side wiggle in it, so maybe it's not seating properly in the turbine housing, but even then I'm talking like 1mm of slop. When the turbo was off the car I verified that the WG flap did shut flush inside the housing at that time (a month or so ago), however you're probably right as this is really all that's left to check out. Also I'm going to seafoam it tomorrow so if there's any kind of an exhaust leak I should see the smoke pouring out. Thanks for your input, Jaxx ! Link to comment Share on other sites More sharing options...
Jaxx Posted January 23, 2011 Report Share Posted January 23, 2011 I don't have a cat on the car. With the WG wired shut it'll make tons of boost very quickly in the midrange but it just plain sucks in the top end. I was just fiddling with it some more and noticed that the WG arm has some side to side wiggle in it, so maybe it's not seating properly in the turbine housing, but even then I'm talking like 1mm of slop. When the turbo was off the car I verified that the WG flap did shut flush inside the housing at that time (a month or so ago), however you're probably right as this is really all that's left to check out. Also I'm going to seafoam it tomorrow so if there's any kind of an exhaust leak I should see the smoke pouring out. Thanks for your input, Jaxx ! good luck, I hate problems like this. If you can't figure it out... you'll end up fixing something unrelated in a few months and it will run better than ever. watch. haha Link to comment Share on other sites More sharing options...
Keep Calm Chive On Posted January 23, 2011 Report Share Posted January 23, 2011 check your intercooler itself. I even made a post (possibly with pictures) that showed what happened to my intercooler. It had a crack in it and would read perfect vacuum because while your idling or not on the throttle there was no excessive pressure to force the crack open (inward). Once I developed 5 psi there was enough pressure in the system to push the crack open. Bye Bye boost but it was just your every day normal car. Im sure if my mother still had been driving it she wouldnt have known until a least a month after it actually was a noticeable issue because it wasnt a problem until above 5 PSI (my mom drives like the old lady she is). Over time this manifested into a large crack similar to a windshield. Im not saying your identical issues as to what happened to me but you could possibly have a minor intercooler issue thats turning into a larger issue Link to comment Share on other sites More sharing options...
Jaxx Posted January 23, 2011 Report Share Posted January 23, 2011 I've replaced all the intercooler hoses and all of the relevant vac lines.Had the whole engine ripped apart to replace some valve stem seals and every other rubber seal on the top end as well as the exhaust manifold gaskets.Carefully inspected the turbo and exhaust manifold for cracks.Replaced the CBV with an IPD HD unit, It holds as much vacuum as I can throw at it, So i know it's not leaking.Replaced entire PCV system.Added OBX exhaust.I've tested the system for leaks, only thing I found was a small leak from the vac tree o-ring, and a small leak from the IAC hose, I replaced both those items with OEM parts.Stage Zero+++And finally tonight I took it for a spin with the wastegate wired shut, and the vac line disconnected, still no boost on the top end. Link to comment Share on other sites More sharing options...
TRACStar Posted January 23, 2011 Report Share Posted January 23, 2011 I've tested the system for leaks, only thing I found was a small leak from the vac tree o-ring, and a small leak from the IAC hose, I replaced both those items with OEM parts What pressure did you test it at? This one is confusing. :blink: Link to comment Share on other sites More sharing options...
mdlimy Posted January 23, 2011 Report Share Posted January 23, 2011 Sounds like every waste of time td04 turbo....spools fast, overboosts, then fades... Link to comment Share on other sites More sharing options...
98t5M Posted January 24, 2011 Author Report Share Posted January 24, 2011 What pressure did you test it at? This one is confusing. I really don't know what pressure the system was actually pressurizing to. I was using a tire inflator thing that wouldn't read any pressure when it was held upside down, which was how I had to do it to connect to my boost leak tester thing. (Sorry, kinda hard to explain what I mean there.) However the regulator was set to 20PSI and I never achieved equalization because of the leak on the vac tree and my tape coming off the intercooler weep hole. I need to find a better plug for that and try the test again with a real gauge. Better yet I might see if I can find someone to smoke test it. Link to comment Share on other sites More sharing options...
TRACStar Posted January 25, 2011 Report Share Posted January 25, 2011 That may be why you did not find anything else, if its something that isn't opening until a higher psi it will stay sealed until you hit that psi. To really do an effective pressure test you should test it at a higher psi than what you run. Link to comment Share on other sites More sharing options...
98t5M Posted January 26, 2011 Author Report Share Posted January 26, 2011 Well i Tested all the intercooler piping (capped off at the throttle body end) and it held 20+ psi no problem. I Did however find that my boost leak tester will pop off the pipe pretty easily at that pressure. (That was a scary noise:lol:) I'm gonna make a new tool to test the throttle body/intake manifold because I really don't feel like wrestling my PTC or intake pipe off again. Link to comment Share on other sites More sharing options...
98t5M Posted February 2, 2011 Author Report Share Posted February 2, 2011 So i tested the rest of the system for leaks last night. (From the throttle body into the manifold.) Everything was A-OK here, the only tiny "leak" is some pressure comes out the little plastic vac. line from the FPR that connects to the fresh air pipe. Is this normal or am I missing some kind of check valve? I Also sucked some seafoam into the intake manifold and saw a little bit of smoke coming from the back end of the motor but I could not tell where it was coming from. I'll have to have someone else climb under the car and repeat this test. Looks like i might have an exhaust manifold leak :-/ Link to comment Share on other sites More sharing options...
98t5M Posted March 6, 2011 Author Report Share Posted March 6, 2011 So it turns out the exhaust leak was post-turbo. :-/ So I'm truly stumped at this point. Only thing left I can possibly think of is that little vacuum line from the FPR to the intake pipe. Is it normal for this line to bleed boost back into the fresh air pipe? If anyone can think of a solution to this problem PLEASE PLEASE PLEASE let me know, I'll give you $20! Link to comment Share on other sites More sharing options...
flaco Posted March 6, 2011 Report Share Posted March 6, 2011 So it turns out the exhaust leak was post-turbo. :-/ So I'm truly stumped at this point. Only thing left I can possibly think of is that little vacuum line from the FPR to the intake pipe. Is it normal for this line to bleed boost back into the fresh air pipe? If anyone can think of a solution to this problem PLEASE PLEASE PLEASE let me know, I'll give you $20! The 98 FPR setup has two lines going to the FPR. One goes to the manifold, the other one goes to the intake pipe right after the MAF. There WILL be a small leak, as that is how the system was designed. I think VADIS quotes as a 'moisture' removal design. For what it's worth, I've removed and capped that return line and just run the line to the manifold. Then again, I live in FL so icing/moisture if any is minimal. You can paypal me the $20! :lol: Link to comment Share on other sites More sharing options...
flaco Posted March 6, 2011 Report Share Posted March 6, 2011 aaaahhhh just noticed your sig says 93 GLT cams. That is the issue here. If you retard both cams by 6 deg (I have this on mine for fuel efficiency) it will behave exactly like you described yours. It will also increase knocking / lower timing due to the higher exhaust gases reversal during overlap under boost. As you advance both cams boost buildup will be more 'controlled' (less spiking) and you will have higher top-end boost pressure. It will also pull better at low-rpms and be less fuel efficient. Link to comment Share on other sites More sharing options...
98t5M Posted March 6, 2011 Author Report Share Posted March 6, 2011 aaaahhhh just noticed your sig says 93 GLT cams. That is the issue here. If you retard both cams by 6 deg (I have this on mine for fuel efficiency) it will behave exactly like you described yours. It will also increase knocking / lower timing due to the higher exhaust gases reversal during overlap under boost. As you advance both cams boost buildup will be more 'controlled' (less spiking) and you will have higher top-end boost pressure. It will also pull better at low-rpms and be less fuel efficient. Had the same problem with stock cams. I'll try looping that FPR line back to the vac. tree and if it fixes my problem you get $20 Link to comment Share on other sites More sharing options...
dimka18 Posted March 6, 2011 Report Share Posted March 6, 2011 I have same problem, let me know if u find something out. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.