Boost problem like bad BPC, but not [Archive] - SaabCentral Forums

: Boost problem like bad BPC, but not


BZach9-3
21st February 2009, 01:36 PM
Sorry this is going to be a book, but I really have no idea what's wrong.

Ok so here is how my whole situation started. I put an SMBC on my 2001 185hp 9-3, along with an intake and forge diverter valve. I had the smbc on for a while longer than the other two. Eventually I noticed that I was having a weird boost issue. I would step on the gas, get base boost for maybe half a second then it felt like the wastegate would close and I would get full boost. When it started it was no big deal, but over time it got worse, until eventually I only got base boost which was a little bit ago. Recently I swapped to a td04 and had the same issue. I undid the W hose coming out of the BPC and it spooled to full boost, but slower than I would have expected. I attributed this to having the td04 on the stock gt17 tune, so I figured a new BPC was what I needed. Put in a new BPC and only got boost to halfway through the yellow. I have the ecu from an SE HOT that I have been meaning to put in but haven't had a chance yet/don't know where the ecu actually is in my car.

So with that said, anyone have any ideas? I was thinking about putting in the new ecu this weekend if I have time, but I feel like the problem is mechanical.

Thanks,
Brandon

lms
21st February 2009, 02:10 PM
Have you taken the smbc out of the equation?
ECU is behind the glove box and you don't have to take GB out to get to it.
How is everything else in the car like plugs, dic, maf, etc??
What is your BB set at?

BZach9-3
21st February 2009, 02:46 PM
Yeah sorry the SMBC is out. Base boost is same as stock. As for plugs and such as far as I know it's all in good shape. So it's not too bad to get to the ecu then?

mr rx-7 tt
21st February 2009, 08:18 PM
http://www.saabcentral.com/forums/showthread.php?t=136753&highlight=muffler

LJ[MaVErICK]
22nd February 2009, 12:18 AM
Im pretty sure you're just hitting fuel cut, try backing down your smbc. I have that same issue, but I think your t7 is just adapting to the increase in boost. Oh and try applying the gas at a more even distribution or pace rather than stepping straight to the floor.

BZach9-3
22nd February 2009, 01:46 AM
The smbc isn't on the car anymore. I tried to apply the throttle slower and it has the same effect. It's like the wastegate is open all the time. Doesn't sound like the clogged exhaust, like I said, I got full boost with the line to the wastegate unplugged.

LJ[MaVErICK]
22nd February 2009, 08:03 PM
Maybe try turning your wastegate back to oem. Then see how the car performs and reapply turns from there.

BZach9-3
23rd February 2009, 01:00 AM
The wastegate hasn't been adjusted as far as I know. I'm thinking now my diverter valve might have something to do with it. I don't know though. Today I tried unplugging the wastegate again and it felt like something was leaking for a second, then all of a sudden it would spool really quickly and the car would take off.

byastremski
23rd February 2009, 10:45 AM
check all of your vacuum lines, you could have a tiny crack somewhere in one... are you running a boost gauge? i had a small crack in the plastic plumbing that you could only find when the car was running at idle... because you could hear the air pumping out of it.

so if you haven't replaced your lines, i would suggest looking all of them over and maybe replacing them with silicone.

Yeah sorry the SMBC is out. Base boost is same as stock. As for plugs and such as far as I know it's all in good shape. So it's not too bad to get to the ecu then?

maybe you should check your plugs because it sounds like to me you haven't touched them in a while. as far as i know you have to have a tech 2 to change out an ecu in a t-7 car, please correct me if i'm wrong?

Crothers
15th March 2009, 11:00 PM
Sorry this is going to be a book, but I really have no idea what's wrong.

Ok so here is how my whole situation started. I put an SMBC on my 2001 185hp 9-3, along with an intake and forge diverter valve. I had the smbc on for a while longer than the other two. Eventually I noticed that I was having a weird boost issue. I would step on the gas, get base boost for maybe half a second then it felt like the wastegate would close and I would get full boost. When it started it was no big deal, but over time it got worse, until eventually I only got base boost which was a little bit ago. Recently I swapped to a td04 and had the same issue. I undid the W hose coming out of the BPC and it spooled to full boost, but slower than I would have expected. I attributed this to having the td04 on the stock gt17 tune, so I figured a new BPC was what I needed. Put in a new BPC and only got boost to halfway through the yellow. I have the ecu from an SE HOT that I have been meaning to put in but haven't had a chance yet/don't know where the ecu actually is in my car.

So with that said, anyone have any ideas? I was thinking about putting in the new ecu this weekend if I have time, but I feel like the problem is mechanical.

Thanks,
Brandon

I have been having the same problem, last week when I steped on it it seemed like base boost then spooled up to full boost. Today when I drove the car boost was very low and got lower every time I steped on It and it now seems to only be getting base boost. 2001 9-3 Hot

Tomorrow I'm going to go out and check everything, but have you found out what is causing the problem?

AZR Racing
16th March 2009, 06:28 AM
']Im pretty sure you're just hitting fuel cut, try backing down your smbc. I have that same issue, but I think your t7 is just adapting to the increase in boost. Oh and try applying the gas at a more even distribution or pace rather than stepping straight to the floor.

if he was hitting fuel cut he would have a sudden lurch as if the car shut down, caused my too much pressure for the system to register so the ecu shuts down the fuel system till the pressure drops to a readable level. aka fuel cut.


i had the same issue with the td04 my stock 900 turbo boosted soo much better than the td04 for some reason. but now i have a gt30 so thats no issue. check all your hoses. what do you mean by base boost? do you mean where the needle is right at the yellow aka no manifold vac.. try running wastegate pressure by connecting your pressure line from the compressor housing right to the wastegate accuator. your wasgate could be sticking open also due to a faulty wastegate / bad accuator spring. try pulling on the acctuator arm and see if it snaps back closed. also check the vac line to your diverter valve / bov they like to dry rot or if running increased boost, they like to blow off if not secured.... let me know if this helped... if not ive got like 10 other things u can check

AZR Racing
16th March 2009, 06:32 AM
The wastegate hasn't been adjusted as far as I know. I'm thinking now my diverter valve might have something to do with it. I don't know though. Today I tried unplugging the wastegate again and it felt like something was leaking for a second, then all of a sudden it would spool really quickly and the car would take off.

that sounds like a defective boost controller. or a incorrectly set one srry for the double post

Crothers
16th March 2009, 08:48 AM
if he was hitting fuel cut he would have a sudden lurch as if the car shut down, caused my too much pressure for the system to register so the ecu shuts down the fuel system till the pressure drops to a readable level. aka fuel cut.


i had the same issue with the td04 my stock 900 turbo boosted soo much better than the td04 for some reason. but now i have a gt30 so thats no issue. check all your hoses. what do you mean by base boost? do you mean where the needle is right at the yellow aka no manifold vac.. try running wastegate pressure by connecting your pressure line from the compressor housing right to the wastegate accuator. your wasgate could be sticking open also due to a faulty wastegate / bad accuator spring. try pulling on the acctuator arm and see if it snaps back closed. also check the vac line to your diverter valve / bov they like to dry rot or if running increased boost, they like to blow off if not secured.... let me know if this helped... if not ive got like 10 other things u can check

Thanks for the reply, and yes by base boost I mean it's just barely going in to yellow. I'll try the things you said and let you know if I find anything.

Crothers
16th March 2009, 10:44 AM
I drove the car to class today and it was getting boost but still not the full amount. So Im thinking it's somthing mechanicle like the wastegate. When I get out i'm going to check it.

Crothers
16th March 2009, 12:57 PM
I conected the line from the compressor to the wastegate and it gave me the same boost presure as I had thismoring going to class, which was about 3/4s into yellow doese this mean it is my wastegate? I checked all vacume lines and I checked the wastegate rod and it snaped back like it should. Boost in that car is usually just into the red. It also seems slow to build boost.

Crothers
16th March 2009, 01:17 PM
Took it for another drive and hit the fuel cut so I don't think it's the wastegate so if anyone has any more ideas let me know.
Thanks

BZach9-3
16th March 2009, 02:56 PM
I still haven't figured out what the problem is for me. I'm at school now so I've been working on the car only a small amount of time when I've been home on some weekends. I reset the ecu and that helped a little. I'm going to check my diverter valve the next time I'm home. I just sent an ecu out to be tuned my JZW, and I'm hoping if it's not the diverter valve, the tune will solve the problem.

AZR Racing
16th March 2009, 06:00 PM
I conected the line from the compressor to the wastegate and it gave me the same boost presure as I had thismoring going to class, which was about 3/4s into yellow doese this mean it is my wastegate? I checked all vacume lines and I checked the wastegate rod and it snaped back like it should. Boost in that car is usually just into the red. It also seems slow to build boost.
when u hook it directly to the compressor it will give u 5psi of boost. thats factory wastegate setting

try a diff boost controller... it really sounds like the problem

Crothers
16th March 2009, 06:12 PM
when u hook it directly to the compressor it will give u 5psi of boost. thats factory wastegate setting

try a diff boost controller... it really sounds like the problem

The first time I had the vac line conected to the wastegate I had the same boost pressure as this morning when I got back I realized I didn't re connect the vac line going to the bypass valve, I re connected it and took it for another ride and when I steped on it in second gear I boosted very good and hit the fuel cut. Came back re connected the vacume lines the way they go, then later that day I drove it and it was fine. I don't get it.
Oh and I don't have a boost controller, bzach does.

Crothers
24th March 2009, 12:41 PM
I still haven't figured out what the problem is for me. I'm at school now so I've been working on the car only a small amount of time when I've been home on some weekends. I reset the ecu and that helped a little. I'm going to check my diverter valve the next time I'm home. I just se nt an ecu out to be tuned my JZW, and I'm hoping if it's not the diverter valve, the tune will solve the problem.

Any update for the problem? I still have no idea. I bought a smbc and it pulled great and now it's doing it again. But when tuning it I am able to turn the smbc all the way up with no CEL. I'm going to go take the smbc out and see how it feels. Any idea why I'm not getting a CEL with the smbc all the way up?

kavkazia
24th March 2009, 01:40 PM
I think what the problem is that, your T7 is detecting more boost than it should be getting and throws t/b kind of in a limp mode where ECM doesnt let it wide open. Thats the conclusion I came up with because I installed MBC on my 00'93 and raised boost to about 10PSI, right after I started pushing it, ECM detected it and threw my boost down to base 3-5 PSI, I disconnected my wastegate to see if it was turbo acting up and it was still base boost. Shut the car off, put everything back to factory specs. restarted the car and I got my 7-8PSI back so..I really think throttle body just doesnt let all the air in and is blocking it to keep it safe from overboosting and damaging engine.

AZR Racing
24th March 2009, 02:42 PM
i dont think thats the issue, with a MBC the ecu doesnt really have any control of the boost range pressure wise. your mbc should have a vac/pressure line run right from the compressor to the MBC to the wastegate accuator. now with the stock boost controller the computer messures the manifold pressure and opens the wastegate judgeing by the amount of pressure that the MAP sensor reads, and when the pressure exceeds the amount that it can read it shuts the fuel system down aka fuel cut. its really starting to sound like a bad wastegate accuator... if its boosting one min and not the next.... is your wastegate sticking?

AZR Racing
24th March 2009, 02:50 PM
I think what the problem is that, your T7 is detecting more boost than it should be getting and throws t/b kind of in a limp mode where ECM doesnt let it wide open. Thats the conclusion I came up with because I installed MBC on my 00'93 and raised boost to about 10PSI, right after I started pushing it, ECM detected it and threw my boost down to base 3-5 PSI, I disconnected my wastegate to see if it was turbo acting up and it was still base boost. Shut the car off, put everything back to factory specs. restarted the car and I got my 7-8PSI back so..I really think throttle body just doesnt let all the air in and is blocking it to keep it safe from overboosting and damaging engine.

in your case with the boost jumping all over you could just be pushing the turbo out of its efficiency my factory garrett i had set at 15 psi it would boost and hold 15 till about 4-5k then bleed off down to about 8-9psi. now running without a line to the wastegate actuator will boost you till the pressure in the exhaust manifold pushed the wastegate open. which i found to be about 19psi running a stock map sensor and stock ecu you would hit fuel cut like crazy

Crothers
24th March 2009, 03:31 PM
i dont think thats the issue, with a MBC the ecu doesnt really have any control of the boost range pressure wise. your mbc should have a vac/pressure line run right from the compressor to the MBC to the wastegate accuator. now with the stock boost controller the computer messures the manifold pressure and opens the wastegate judgeing by the amount of pressure that the MAP sensor reads, and when the pressure exceeds the amount that it can read it shuts the fuel system down aka fuel cut. its really starting to sound like a bad wastegate accuator... if its boosting one min and not the next.... is your wastegate sticking?

I was thinking it was the wastegate too, but it snaps back when I pull on it. I also connected the compressor line straight to the wastegate and it boosted like crazy and hit the fuel cut

IanT54
24th March 2009, 04:30 PM
I thought that SMBC's didn't work with T7 motors because the ECU will try to work around the extra boost pressure. I'm no expert but I've read other threads on this forum that talk about the ECU requesting specific torque output from the engine and adjusting whatever needs to be adjusted to achieve it - manually increasing boost pressure will just cause the ECU to reduce the torque output some other way.

This limitation is why most people prefer T5 engines. Unfortunately, for T7 engines, you have to remap the ECU to get significantly more torque. Of course, once you've done this you can resell the SMBC!

Crothers
24th March 2009, 06:19 PM
I thought that SMBC's didn't work with T7 motors because the ECU will try to work around the extra boost pressure. I'm no expert but I've read other threads on this forum that talk about the ECU requesting specific torque output from the engine and adjusting whatever needs to be adjusted to achieve it - manually increasing boost pressure will just cause the ECU to reduce the torque output some other way.

This limitation is why most people prefer T5 engines. Unfortunately, for T7 engines, you have to remap the ECU to get significantly more torque. Of course, once you've done this you can resell the SMBC!

An SMBC will allow quicker spool up as well as alittle more boost in the lower gears.

kavkazia
24th March 2009, 06:55 PM
in your case with the boost jumping all over you could just be pushing the turbo out of its efficiency my factory garrett i had set at 15 psi it would boost and hold 15 till about 4-5k then bleed off down to about 8-9psi. now running without a line to the wastegate actuator will boost you till the pressure in the exhaust manifold pushed the wastegate open. which i found to be about 19psi running a stock map sensor and stock ecu you would hit fuel cut like crazy

You can NOT run 10PSI on T7. You have T5 so you can fool your managment but you can NOT fool T7 without tuning for more boost. It only opens T/B certain level where it keeps turbo pushing more air into intake chambers. I got T/B activated in safe mode when I boost it up with out hitting fuel cut, opened the hood, while it was in safe mode, took MBC off, hooked everything back up with OUT shutting car off and it was still barely boosting in yellow, stopped again, took wastegate line off, drove it again with OUT shutting the car off, same thing, so I hooked my waste gate line back on, shut the car off for minute, started back up and everything was back to normal.

Just get it tuned if you have T7 and be done with it. ;) . Stock T7 ECM can only compensate for so much air/fuel that it was programmed for so just stop wasting time with that MBC like I did and get it tuned.

Crothers
24th March 2009, 07:11 PM
You can NOT run 10PSI on T7. You have T5 so you can fool your managment but you can NOT fool T7 without tuning for more boost. It only opens T/B certain level where it keeps turbo pushing more air into intake chambers. I got T/B activated in safe mode when I boost it up with out hitting fuel cut, opened the hood, while it was in safe mode, took MBC off, hooked everything back up with OUT shutting car off and it was still barely boosting in yellow, stopped again, took wastegate line off, drove it again with OUT shutting the car off, same thing, so I hooked my waste gate line back on, shut the car off for minute, started back up and everything was back to normal.

Just get it tuned if you have T7 and be done with it. ;) . Stock T7 ECM can only compensate for so much air/fuel that it was programmed for so just stop wasting time with that MBC like I did and get it tuned.

The problem started befor the smbc. But I will be doing a tune at some point. The smbc is just for alittle more kick untill then.