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Discussion Starter #1
About my SAAB; 1991 9000 Turbo with 170,000 miles. Autobox; stock ECU, BOV, Wastegate; no MBC.

In my attempts to fix the jolting experience known as fuel cutoff I have performed the following work.
  1. Replaced vacuum hoses with silicon hoses and zip ties just to be safe.
  2. "Cleaned" the APC valve.
  3. Put in new NGK spark plugs (BCPR7ES-11) gapped at .9mm
Each of these things have improved the performance noticably, I did find a small vacuum leak in the hose going to the BOV. While under the car, now I know why many have moved their BOV, I pressure tested the BOV to verify it opened when pressure was sent.

After the hose replacements failed to fix the shutoff i found direction/advise in the archives about cleaning the APC valve to try and eliminate overboost.

Read somewhere to check the plugs, as that is sometimes a culpret. WOW :cheesy: I forgot what new plugs felt like, started right up and felt like the problem was gone, found some open road and once again the cutoff was reached.

My next move is new APC valve, I have been avoiding this, but I am coming up empty on other causes. Anyone else know of other posssible culprets?

If the car had done it from day 1 I would not know what i am missing, but I am well aware that a stock 9000 can embarrass a Honda with fart can exhaust and a body kit.:cheesy:
 

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damouse1928 said:
My next move is new APC valve, I have been avoiding this, but I am coming up empty on other causes. Anyone else know of other posssible culprets?
I was hitting FuelCutt just the other week after a heap of mods, the mod which was the cuprit for me was the new FORGE Wastegate Actuator. So I lenghtened/unscrewed the turnbuckle a few milimetres to lower base boost and that fixed my probs. Even with the Stock Wastegate Actuator, it might be a good idea unwind it and see how you go.
 

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Discussion Starter #5
sticker under bonnet/hood said 1.0 +or- .1, so .9mm is at one extreme and will stay in spec for longer while 1.1mm will run out of spec sooner. I would guess (feeler gauge only goes to 1.1) the plugs I pulled had worn to 1.2mm so replacement was neccesary regardless.
 

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Plug gaps are very vague for these engines.


My 97 Aero owner's manual says plug gap should be 1.0 mm with a plus tolerance of 0.1 mm and no minus tolerance.

My dealer supplies pre-gapped plugs at 0.89 mm.

I find 0.89 mm works best for my engine.

I recommend against going above 1.0 mm maximum. I have not had good results with that wide a gap for street use, unmodified.
 
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