[LoTTo]

Hi!

I think I have a problem with my APC.

Putting "pedal to metal",
The turbo starts to load at 2000-2500 rpm.
When reaching 3500+, I have to release the throttle. If I fail to do so, some electronics shuts down(?) engine for about ,2 s - hense giving me a rather impleassant "shock".

Anybody have any ideas about what's faulty?

Regards
LoTTo

 

[Jezzadee]

I had this happen last week. The car drove normally, but at 3000 rpm it jolted a few times, the dash warning lights came on and it stalled. When I backed off it ran OK again. What was happening was that as soon as my boost came in with some force it blew open a hole in the intercooler pipe (don't ask ) and messed up the fuelling. So it could be a vacuum leak that is opening under boost.

 

[LoTTo]

Jezzadee: Did you're APC/Power meter also go to the top of the red area bit?

Thanks. I'll try that.

 

[Jezzadee]

Ah yes, forgot to mention that I don't have an APC. If your boost gauge went up to the red while this happened then it sounds unlikely to be vacuum related, so your original idea is probably right.

 

[Orca]

Sounds like you're hitting the boost overpressure fuel cut-off switch. It should be set to 0.95 bar on a T16S or erm, dunno, on a T8. It lives in the RHS footwell, behind the heater flue.

Have a look on http://www.900aero.com/ for a full breakdown of the APC system. Most people bypass the switch, but often have a boost gauge so they know their boost limits. It's function is to cut the fuel in the event of the APC system allowing the car to boost "too much". By too much, I mean in excess of the factory APC setting. Any slightly modified C900 turbo will need the boost overpressure fuel cut-off switch turning in more, or bypassing. Certain fuel and air temperature conditions will allow you to boost more than "normal" ... hence, hitting the overpressure guard.

 

[Alex]

If the shut down makes you try and headbutt the steering wheel then it does sound like the over pressure switch is being activated.

 

[LoTTo]

I have a over pressure problem. I think the fuel cut-off setting is right. Very nice boost indeed until it cut-off point.

Why is not my boost regulated so it wont become to big? Why must I regulate it myself by thottle?

-----------------------------------------------------------

Great site Orca!

I'll try this:

Verify the hoses to the APC-valve.
Verify the Wastegate
Check the APC-valve
Verify the base boost

Thanks everybody.

 

[Alex]

If you unplug the power to the APC valve and check the base boost, what sort of level is it running at then? If the base boost is too hight this will also affect the max boost.

 

[Ken]

I had the same issue with my T8, the pivot of the actuator arm was badly worn.
Tandino kindly passed me a replacement(guess he doesn't have to worry about turbos now with vw golfs)

 

[LoTTo]

With the cord to the APC-valve removed:
The car reacts like before:

The boost rise with the rpm until the fucel cut-off.

I hope that it's only the base boost setting that is to much

/LoTTo

 

[LoTTo]

Apc walve should be ok? Blowing true C to W or W to C.
not R.

Trying to move the arm of the wastegate, can only move it <1 mm (engine half warm / shut off)

I should remove and buy a new one, is this right?
Should I try to remove it and clean/oil it first?

/LoTTo

 

[tonyalbers]

my wastegate arm can be moved about 5mm's when the engine is cold. It's a T16

 

[LoTTo]

Removing the arm from the turbo, I can move the wastegate arm 5 mm.

Thanks - With your help I found the problem!!!
Gotta change turbo, because the arm from the turbo to to the wastegate is stuck.

Will try to use a little hammer to try to make it move first though...

 

[Orca]

Yay :! Looks like you've found it - if you're wastegate is stuck, you'll definately hit the boost over-pressure fuel cut-off switch. Good luck with the repairs/replacement.

 

[LoTTo]

I drove for 2 years with this fault. And next week it's gonna be fixed - thanks to all you.

Best regards
LoTTo

 

[Orca]

LoTTo - Where are for from, by the way? It's good to know where people live :wink:

 

[LoTTo]

I'm from Sweden...

I also have a saab 9000 turbo 16 valve 88 that I bought 1 year ago for 1500 sek/$198.

It's a bit rusty, needs atleast 1 new door badly. I just bought it because it was so cheap... My friend borrowed it from me while he changed his automatic transmision. Took him 4 months

Goes like ****. You get realy scared when you floor it. My friend drove it in 190 kmh/h, only the rear-view mirror vibrating - It had even a little more than that to give.

It also has ABS, missing that on my 900...

(When I picked up the saab 9000 and for the first time opened the hood, I was scared. The engine maked a realy loud tick, tick, tick. But when I changed the oil+filter (most of) that noise disipeared. =) )

 

[Orca]

Cool. Well, incase you didn't get a formal welcome ... "welcome" ... great to have another 8 valver amongst us 8)

 

[LoTTo]

Thanks!

Good to find this greate place where I can get help for my problems.

I used to ask my buddys that is hobby-mecanics. They use to say that then don't know much about saabs, only Volvos and such...

/LoTTo

 

[itranoudis]

CPS is your problem