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Discussion Starter #1
Ok guys and gals the car was runnin great today... finally... anyways i was only boosting 8psi just towards the end of the yellow. so i did the apc mod exactly as said on the writeup. ok great i took it for a ride after putting it back in and my boost guage hit 13 psi... wow!!! time for new tires... anyways i came back home and adjusted the actuator arm it was 2 complete turns then i took it for another ride i hit about 15 psi and it just bogged down and backfired... i dont have any exhaust only downpipe. so i turn the actuator back down and try again at normal settings. did it again. so i turned it one full turn down below stock settings and it did it again... this is only at wide open throttle if i feather the peddle up its fine until about 13 then when i hit about 15 it happens. now i have bosch platinum plugs the single ones gapped at 60 i have new wires also. i dont think i'm hittin fuel cut off cuz i'm not kissin my windshield. it bogs right down tho and makes loud bang noises from the exhaust. any ideas would be helpfull like were to start troubleshooting, i dont have a manual so telling to look in it or get it isnt going to help....... thanks in advance :D :D :D

oh and i have an 88 900T 16 valve
 

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When I've hit fuel cut off in mine it wasn't a windscreen experience either - just a jerk and loss of power until I backed off the throttle; 'bogging down' describes it pretty well. I'm a bit confused about exactly what you did here and what write up you used. There's a guide to adjusting base boost here . As a rule base boost should be half your peak boost. Once you've set base boost correctly leave the actuator alone - if you want more peak boost adjust the APC pots. 15 psi is about 1 bar, bit over, which is where the fuel cut off kicks in IIRC. Sounds like you turned up the APC too high. Have a look at www.900aero.com for details on APC tuning.

And I shall now move this into the Performance and Mods forum :cool:
 

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I'm with Jezza on this, should be the fuel-cutoff... At 1.05 bar (afair) the cut-off will hit you, so if you haven't modded the fuel-cutoff, you most probably hit that...

You can adjust the cut-off, the canister that controls it sits on the left side of the car (when in it) under the lower facis. You can follow the vacuum-lines, they will split up, one goes to the boost-gauge, one to the pressure sensor, and one goes to, yes, you got it, the cut-off... There is two wires coming of the fuel-cutoff...
Daniel.
 

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Saab-Daniel said:
I'm with Jezza on this, should be the fuel-cutoff... At 1.05 bar (afair) the cut-off will hit you, so if you haven't modded the fuel-cutoff, you most probably hit that...

You can adjust the cut-off, the canister that controls it sits on the left side of the car (when in it) under the lower facis. You can follow the vacuum-lines, they will split up, one goes to the boost-gauge, one to the pressure sensor, and one goes to, yes, you got it, the cut-off... There is two wires coming of the fuel-cutoff...
Daniel.
cut those two wires, splice them together..there ya go. You have just by-passed fuel pump cut out.:cool:
 

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Discussion Starter #5
well thanks alot guys i'm doin that mod tommorow... my actuator is back to normal i adjust the two pods that i was supposed to, one 1/4 turn the other 1/8 turn i dont remember what letter they were but i know they were right as far as following the write up i got off of here it was the one that had the resistor mods too for the apc... i've read so much on this site in the past week my brain is scrambled saabs... thanks again i'll post tommorow and let ya know if that cures it
 

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Hmm, I wouldn't cut the wires, you will eliminate the security-feature... you can just tweak the center-pot on the fuel-cutoff to allow a larger amount of boost..

Daniel.
 

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Discussion Starter #7 (Edited)
ok well i got under the dash and found the vacuum hoses. 2 of em went to some black things that seemed to be attached to the peddles both had black wires and one of them went to a metal looking cylinder type thing... i took that out and inspected it for an adjustor bolt with no luck there was a black wire and a colored wire on it i removed those and twisted them together. it doesnt seem to bog down as much was i correct in assuming that was the fuel cutoff????


ok after doin some more searchin i found that this my not be it so i put it back right someone said it was white and right by this thing that i messed with before i see something white on the same bracket but theres a bunch of wires on it... i really wanna find it and just adjust it, oh and i really really wish i had a manual any info GREATLY appreciated thanks
 

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If you have the later Bosch FI LH2.4 (plastic AMM) there is no seperate fuel cutoff valve - it's done via the ECU and you have to put a resistor in the AMM signal path.
 

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We just need more info, mate :)
But hell, I did the speedparts-search, and here you go: http://www.speedparts.se/arkiv/anvisningar/anv_tryckvakt.pdf
Yeah, it's in swedish, but it says, that you have to adjust the A-pot clockwise, about 1 to 1½ , to get the max-boost higher. DON'T touch B... There is two vacuum-lines and two wires going into the cut-off...
Daniel.
 

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Discussion Starter #10 (Edited)
ok i looked all over under the dash and through the speaker hole with no luck.. then i had to go to work.. too bad cuz it was a beautiful day, but my job is great.. ok so now i'm goin to do some searchin about the amm and see if i have one i'm not sure yet what year this car is cuz i dont have a title yet but i have a black box apc and i see bosch on alot of stuff as for the resistor that would be no sweat cuz i'll find the one i need and go get it tomorow. ok thanks alot you guys... especially for not flamin me on these noobie questions... i've been searching like crazy through the threads, forums like these is what makes the internet great..;) ;) ;)


ok just did some research and if its the case that i have a Bosch FI LH2.4 is this a good mod to fix the fuel cut problem http://www.saabworks.com/projects/overboost.html
i would almost like it to be adjustible just for safety as i dont have an air/fuel gauge and even with that its hard to watch at full boost.... I LOVE BOOST:cheesy:
 

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Your spark gap is also to big! It should be around 24-28 thousands.
 

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Discussion Starter #12
.60 mm thats what the standerd size was i thought for our cars?????
 

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24 thousands = 0,6 mm

The newer Lucas Cu14 and Bosch LH2.4 cars have the fuel cut integrated into the ECU but there still is the fuel cut switch under the fascia panel. How is this wired then? Are both circuits working and is this just wired in serial?

Joey_ZaZa, the metal looking cylinder type thing, as you called it, probably is the pressure transducer. Two wires and one vacuum/boost hose should have been attached to it. When you splice those cables together, APC will not know how much boost you actually have. The fuel cut off switch should be mounted to the same bracket as the pressure transducer (just above or underneath, cannot remember) so you were really close! There are two vacuum/boost hoses and two wires connected to the fuel cut off switch.

Best regards,

Tadek
 

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Discussion Starter #14
well i've put about an hour into finding the cutoff with no luck i'm sick too but that wont stop me lol, anyways i cant get to really anything from the speaker hole and i've only taken the very bottom of the dash off i think its part of the heater, i really cant get a good look at whats up in there and havent had much luck taking off the underdash or knee rest what ever its called, so i'm turning down the boost on the apc :cry: gonna do some test runs.... no plate or insurance :cool: then i'll update if i dont go to jail thanks again all
 

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trackside said:
If you have the later Bosch FI LH2.4 (plastic AMM) there is no seperate fuel cutoff valve - it's done via the ECU and you have to put a resistor in the AMM signal path.
Some varients of the Bosch LH2.2 also use a plastic AMM.
 

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To get the lower facia out, remove the center consol, and the large nut behind where the ashtray used to be. Locate the two bolts in the enigne-bay, one on each side, indside the fender, towards the cabin. These two, along with the ashtray, holds the lower facia in place...

Daniel.
 

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Discussion Starter #17
thanks daniel i havent turned the apc down yet so i'm goin to tackle the dash i sure hope there is a fuel cutoff under there
 

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Discussion Starter #18 (Edited)
ok got it all out i have 2 vacuum hoses coming in from the firewall one goes to what looks to be sensors on the break and clutch peddle and then to a roundish black thing that only has one hose in it and no wires the other goes to the silverish device we delt with earlier and then way up into the dash assuming the boost gauge. i dont think i have a fuel cutoff guys so whats next besides putting my car back together now :cheesy:

i just decoded the vin my car is an 89
 

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Lol, you are fidling with the cruise-control... You are looking at the left side of the car, when in it, right?
Daniel.
 

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Discussion Starter #20
ya under the seering wheel that area i have searched completely ohhh and by the way my car is an 89 does that make a difference
 
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