SaabCentral Forums banner

1 - 20 of 22 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
I have heard that the ecu will cut fuel supply if the turbo generates too much boost. I decided to try it out and disconnected the vacuum hose from the turbo to the wastegate (i put it back...duh). But does anyone happen to know at what psi the fuel cutoff kicks in?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
21 psi?? ok, i have hit the fuel cutoff, so youre telling me that my piddly little STOCK turbo can put out 21 psi? no way... seriously??
 

·
Registered
Joined
·
227 Posts
Not only can it push 21psig, but it can do it at an elevation of 7500ft+. However I think there is a question of how long it can do this.

I had the WG hose come off while I was driving in the mountains. Thought it was accelerating quite well until the cut-off kicked in and I realized what happened. The turbo died a few weeks later. Coincidence or not, I don't know that its a very good idea to push it that hard.
 

·
Registered
Joined
·
3,721 Posts
the amount of pressure a turbo can produce really ha nothing to do with how much power it can make.

it could make 30 psi, but it may be outside the efficiency range.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #6
yea... so, I just put on a manual boost controller, and in the process of tuning it, i ran into the fuel cutoff again. 21 psi still seemed ridiculously high, so I swung by o'reilly's and bought a boost gauge. the fuel cutoff kicked in at 11 psi, which makes a lot more sense that 21 psi. are we thinking of different cars or something? 1995 9000 cs, with the T25.
 

·
Registered
Joined
·
987 Posts
CS is a low pressure turbo, I would think they have been talking about the CSE or Aero which are much higher pressure turbo systems. The CSE uses the same garret turbo as the CS but pushing much more boost. It would stand to reason that a CS would have a lower fuel cut-off. I think the CS and CSE have the same turbo, just the ECU tells it the where and when of boosting. The Garret t25 on the CS/CSE does surprisingly well. A different animal than the Mitsubishi td04 on the Aero, if only slightly more smoothed off. The Aero turbo has slightly more delay but kicks like a mule, hard, fast, and borderline violent. The Garret turbo is smaller, less potent, but a bit smoother. It doesn't have that sudden "bury you in your seat" feel as the Aero, but rather a light pressing that doesn't let up. A well tuned CSE is nearly as fast as an Aero, but doesn't feel so violently so.
 

·
Registered
Joined
·
803 Posts
Thirsty9000 said:
CS is a low pressure turbo, I would think they have been talking about the CSE or Aero which are much higher pressure turbo systems. The CSE uses the same garret turbo as the CS but pushing much more boost. It would stand to reason that a CS would have a lower fuel cut-off. I think the CS and CSE have the same turbo, just the ECU tells it the where and when of boosting. The Garret t25 on the CS/CSE does surprisingly well. A different animal than the Mitsubishi td04 on the Aero, if only slightly more smoothed off. The Aero turbo has slightly more delay but kicks like a mule, hard, fast, and borderline violent. The Garret turbo is smaller, less potent, but a bit smoother. It doesn't have that sudden "bury you in your seat" feel as the Aero, but rather a light pressing that doesn't let up. A well tuned CSE is nearly as fast as an Aero, but doesn't feel so violently so.
I've seen quite a few full pressure CS's and owned two N/A CSE's.
More often than not, though, the engines generally follow the trim levels, but it's not a golden rule.

And a FPT may be smoother on delivery, but that punch in the chest an Aero gives at 3K makes almost everyone giigle like a school girl.:cheesy:
 

·
Registered
Joined
·
7,137 Posts
Cliche` said:
I've seen quite a few full pressure CS's and owned two N/A CSE's.
More often than not, though, the engines generally follow the trim levels, but it's not a golden rule.
Pre 1994? I thought after 1994 they all followed their Badges (usa models), but before that it was a lot more flexible.
 

·
Registered
Joined
·
803 Posts
Uh, well my N/A's were both '93's, but most of the FPT CS's I've seen have been '95's and '96's. I've run across one '97 LPT CSE, too.
 

·
Registered
Joined
·
181 Posts
what about the CD models??? were they all FPTs or were someof them LPTs??? i have an APC and everything that may show that it is a FPT, but the more i dig into the history of my 9k, i am wondering more if there was some foul play with my car. the PO owned a repair shop, and the car was reported stolen recently before i purchased it, and then recovered... it was then traded in at a dealership, and then i purchased it... the miles dont match exactly, but i figured out that the insurance company replaced the dash, attempting to repair the damage caused from the theft, but i am thinking that the car was originally an LPT. I cannot get more than base boost, which is almost to the red from what i have been reading, and am awaiting delivery of a proper boost gauge to start diagnosing that problem.
 

·
Registered
Joined
·
803 Posts
Base boost would have you at roughly dead center of the yellow portion of your boost gauge.

Can you hear the wastegate open once it gets to that spot on the gauge?
Also, does your cruise control work?
 

·
Registered
Joined
·
181 Posts
i can hear the turbo spool up, and my cruise control works, hardly ever use it... dont leave it on either, heard it can leave you in base boost...
 

·
Registered
Joined
·
3,721 Posts
cruise control wont leave you in base boost, but if you are stuck in limp mode your cruise will not work is what he was getting at.
 

·
Registered
Joined
·
803 Posts
Cruise control can most definitely leave your car stuck in base boost. Your car is always in base boost when the cruise system is on, and a non-functioning cruise control system can trick your car into thinking it shouldn't be making boost.
 

·
Registered
Joined
·
3,721 Posts
the car is certainly NOT in base boost when cruise is on. go get on the highway set cruise and the accel using the button, i have no issue getting full boost.
 

·
Registered
Joined
·
803 Posts
Is your car an auto or stick? That could be a difference in the cruise system right there.
I'm going off of not only personal experience, but the word of three different Saab master techs, plus the Saab factory manuals.
 
1 - 20 of 22 Posts
Top