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Old 31st January 2010
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Join Date: May 2009                                                
Location: Australia
My Saabs: 9000cs
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Question '91 B234L -What I've found, What I've done & Whaddya think??

1991 FPT non TCS auto.
LH2.4 Jetronic, T5 Turbo, no end play, clean inside, spins freely
Bosch 028000908 ecu (Bosch catlge states for TCS equipped cars)
No ETS on thrott body,no wiring,no modules under seat.
Most posts read indicate xxxxxx910 for TCS cars
Got SAAB EPC & Mitchell repair on H/drive

What I've Done -
Checked the ecu is correct for this config - yep
Checked APC ecu same - yep
Checked fuel pump for output (1100cc/30sec)
had local SAAB speclist connect diagnostic computer
fitted calibrated boost gauge(B/B calibration)
cleaned AIC, MAF, APC sol,Contact cleaner on ALL connectors and plugs
Fitted NGK BPR's, no diff to Bosch plats fitted.
Tried 2 other DI cassettes(o2,04 & o5 manuf)
Matched all bulbs and checked
ABS light always on
Cruise cont inoperable
WG actuator no leaks
WG free operation

What I found

Whilst fuel pump is acceptable in volume, have not been able to check pressure in fuel rail. removed banjo after sitting and no fuel squirting out. gave Reg a tap in dimple and now has plenty pressure after switch off, yet no improvement in performance.

Symptoms.(with orig ECU connected) -
CEL always on.

BAD starting, stumbles and staggers to idle.

Under load, stumbles all the way through (1800 - 4300rpm)more like
hesitation from starvation than misfire.Feathering throttle is the
only way to stop it bogging
Actuator set for B/B (6.5)
whistle from turbo most of the time

Had local SAAB speclist connect diagnostic computer - He found

* unrecognizable code ???

*only other fault code was ABS input valve sticking( brake pedal takes
5secs from application to return and picto to go out)

* MAF swapped with a known good one, ran the same.

* very little power, hardly any boost but goes into overboost/fuel shut when B/B set to 6.5
(I had progressively wound out the B/B adjust so it was a no stress d/dr for my wife)

He was good enough to lend me a couple of other J/T ECU's to see if it made a diff.

He said the W/G was 'loose' should be wound nearly in and force it over WG pivot lever.

Went back to basics: checked hoses C,W & R and connections on both ends.. W&R on wrong ports on APC sol!

refitted and recalibrated B/B and read thread on performance specs. (boost being 10-15PSI)concern over the boost now being 10psi(still bucking)

Changed to borrowed ECU Bosch xxxxxxx944 (91-93 B212i)

Started car, idled smooth and a tad lower revs. CEL off. drove and found when under boost, the staggering had gone 90%
Only time CEL came on was when ACC adjusted, and went out within a minute or so. Boosting to 10psi and peaking at 12.
Because of sticking ABS valve, brought pedal back with foot when pedal released( no lights on when accelerating)

Wife drove car for a month like this, giving feedback daily (as wives do)

Changed to other ECU Bosch xxxxxxx570(88-93B202L) - wouldn't start at all.

Put original ECU back in
After reading on Mitchell Diagnosis if ECU disconnected, upon replacing; it needs to be reprogrammed
"1991 9000 series: accel at full throttle from 2000-4500rpm. Programming occurs at 2750-4500RPM and requires 3 secs to complete
perform procedure in a gear that permits operation between those speeds

Did that 3 times and no difference to running, performance or starting at all. Car would idle like its doing the Tarantella on this ECU yet switching back to the borrowed unit..like Fred Astaire and Ginger!

OK fire at me any suggestions that may persuade me from concluding the original ECU is on the Fritz.

And if you feel the odds favor my conclusion, what is the best route to take for a non-Trionic car to run as it is supposed to.

part No 8857187 is not easy to find and the chance of finding the same in a used/wreck unit is pretty high.
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