[SuperEvo4]

Hi Everyone

I had this cutoff now and again for over 6 months now, but I would like to know now whats doing this.
Basically sometimes when I put load on the engine it seems to boost up and suddenly a nasty thing happens, it's like if the car has hit the limiter or something. it doesn't seem to hit full boost on the gauge when it does it, although I'm not looking at it most of the time. the car jerks back quite mechanically

but when I let off and boost again, the problem seems to have disappeared. What is it?
There seems to be no smoke when the car does this back-off jerk!
Is this bad and detromonial
Hope to get some answers from you Saabtec guy's and girls.
Thanks in advance


Tony

 

[mark e]

Tony,

It sounds like the overpressure fuel cutoff limit- it is very brutal.

Have you had any mods done or tweaked the wastegate? On a standard ECU ISTR the cutoff comes in at about 1.2 bar, which is enough "Headroom" for theenormal max of about 0.9 bar.

 

[SuperEvo4]

Hiya Mark E

No, not to the best of my knowledge?
When I bought the car 10 mths ago it had full Saab service history and the car was owned by a Company Director for 9 years. Although I have to admit the car does fly, I've actually out accelerated a P reg Aero in mine, and was able to give an audi s3 a run for it's money.
it certainly boosts all the way till the end of the red line on the turbo gauge.

Anyway Mark, how can you tell if it is the overpressure cutoff limit?

Oh by the way you actually live quite close to me.
I'm near Milton Keynes! Should meet up!

Tony

 

[SuperEvo4]

Oh sorry

If I forgot to write in my original post that my cars a '93 cs Aero.

 

[mark e]

The symptoms you describe uniquely indicate fuel cutoff- the fact that it is occurring at the end of the gauge suggests to me that you have a standard ECU and there is possibly a problem with the APC solenoid or the actuator.

Try disconnecting the pipe on the "C" port of the APC solenoid (the black thing mounted on the passenger side of the rad) and putting it directly on to the actuator (remove the pipe that goes to the W port on the solenoid) Alternatively, disconnect the W and C pipes and join them together.

If you then take it for a drive, you should see the boost going no higher than about midway into the orange.

If this is the case, you know it's a control problem, probably a failed APC valve

If you still get overboost, then it's a wastegate/actuator problem.

 

[SuperEvo4]

Thanks Mark E, I'll try that after work, tonight.

Tony

 

[philcrombie]

- I got this effect on 95 Ron fuel whilst flooring it in 5th . Won't do it on Optimax though - even without an Adaptation run
What fuel are you using?

PS - I have other possibly related issues to resolve on my car - so cant offer a foolproof solution (yet)

 

[SuperEvo4]

Hiya Faero

I'm using Tesco 95 ron at the moment, usually I do use optimax. I must admit I have found this problem occurs more on 95 than on 98, but this should not be the case, as it would be the 98 ron fuel that would more likely give stronger boost, therefore therefore in effect, give me my cutoff more regularly? I could be wrong, just makes more sense.

Anyway, hopefully I'll find out this evening.

chee

Tonyrs for now

 

[laurent]

I've had the same troubles with my 88 9000T16. in fact, when the sabb dealer operates a big job on my car, I took it bac and after a while I noticed the same troubles as you described. As they have putted back the hoses of the solenoid too close to the exhaust, one of them broke and the other one has a hole in it. So, first, carefully have a look at your hoses to detect any leak, even a little one whom can became bigger with the pressure.
For me you'd better do as I will : change all the hoses concerned with boost control, all the vacuum ones. It's easy to find, make, and quite inexpensive. If nothing changes, you may change the solenoid wich is more expensive. Hope this helps !