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Discussion Starter · #1 ·
Could this be a boost problem (I don't think so)

THE CAR: 9000 2.0lpt with SP Stage2

THE SYMPTOMS: Full throttle - cough, splutter, surge
of power cough, spl.....etc.

THE HISTORY: A few weeks after fitting my upgrade I noticed a lack of power when the accelerator was floored, easing off and she would pick up as normal, also had the occasional brief jolt when changing down and accelerating.
Checked plugs DI etc. pulled ecu fuse, heypresto everything fine but only for a day or two.

Having asked a friend who is a Saab dealer to comment on this his reply was....overboost! my reply was I have since checked through this board under topic's boost, and have come to the conclusion that I am not nuts as the fitting of the 3" cat back would reduce the pressure slightly.
I have now fitted a boost gauge which has confused me even more

Base boost is .40 bar after having shortened the rod by 1.5 turns, peak boost is 1.1 bar and goes down to .9 bar at higher revs, which would seem to be normal.
What makes me think it is not the turbo or wastegate is the fact that whilst all this coughing + surging is going on, the gauge is not
showing any signs of spiking or uneven boost.

Any ideas on what could be happening here?

It is now time to start thinking about my stage 4
upgrade, but I must sort this problem first as it's taking the pleasure out of driving such a wonderfull car.
Saabs don't you just luv em


Steve
 

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I agree with sgould. It may be possible that the DI is getting weak. When boost is upped, the spark plug gap needs to be tightened a bit otherwise it will make the DI work harder to produce the desired spark. This is turn, wears out the coil in the DI causing misfires and such. Try swapping in a known good DI and see what happens. Also, make sure your spark plugs are gapped to the tighter end of the tolerance given in the manual, but if the DI is bad the gapping won't fix the problem.
 

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DI cartridge is definitely at the top of the list of suspects, especially as your boost levels sound normal. Accepted diagnosis is to try a known good unit. You could try the DI service procedure here to see if that helps.
 

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Steve,

I'm not averse, in principle, to you swapping my DI unit for yours to test it. Obviously, the compatibility of my 97 Aero unit would have to be checked and you'd have to be confident that you could do the work without damaging anything. (I am useless at anything technical).
 

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Discussion Starter · #7 ·
Thanks for the replies and offers, I will check that spark plug gap for future reference.

Off to check with a known good DI unit


Steve
 

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Discussion Starter · #9 ·
Tried a known working one, thanks Heyes, it was the DI unit plenty of
with the new one.

Thanks again chaps.

Scotty Mc, mine was obviously on the way out when I upgraded apart from this I have had no problems at all


Steve
 
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