Date: 29 Apr 2003 16:53:12 -0700 From: alancemornopsamo.com (Lance Morgan) Subject: Re: ECU - Bosch 0 280 000 901
KeithG <noonenopsamspring.com> wrote in message news:<3EAE6A89.4020903nopsamspring.com>... > Brian, > > your test is missing the most important part, the voltage at idle of the > output pin. Burnoff and supply are important. I do not know which one > that is on your car, but my '92 900T (lh2.4) is orange (pin 3?). This > voltage must be in range to give a good idle. ALso check how solid the > ground is. See if there is any voltage difference between the battery > (-) and the ground to the AMM. If there is, clean them and retest until > it is the same (important ground points are the one near the AIC and the > tranny front). I do agree with the poster that suggested that a bad ECU > is generally 'no start'. > > KeithG > > Brian Dean wrote: > > As far as the AMM ... I observed the one second "glow" burn-off cycle after > > shut down... no problems... tested the back side of the connector to the AMM > > with the boot rolled back and a digital volt meter... ground at pin four and > > +12VDC battery voltage at pin five when the ignition is on... > > > > Also tested the O2 sensor .. fluctuating voltage per the Bentley test > > procedure...etc... no problems... cleaned the AIC valve and throttle body... > > removed and cleaned the fuel injectors... tested the TPS... etc... no vacuum > > leaks... no fault codes through any of the bad performance... just > > continues to run very rich with stuttering poor performance under > > acceleration/load ...etc... > > > > Suspect the ECU... but I guess I will take it past the local 25 year Saab > > mechanics and spend some money for their opinions... > > > > Brian > > > > "Grunff" <grunffnopsam.com> wrote in message > > news:b8jhud$95bmv$1nopsam52899.news.dfncis.de... > > > >>Brian Dean wrote: > >> > >>>'91 Saab 900 2.1 liter non-turbo > >>> > >>>Pretty sure I have a bad ECU. > >>> > >>>All components test correctly, but performance continues very poor with > >> > > very > > > >>>rich fuel/air mixture. > >>> > >>>Anyone have any history on repairing a Bosch ECU? I noticed a UK > >> > > company > > > >>>in South Hampton advertises on the web. Anyone ever use these folks? > >> > > ... > > > >>>http://www.carelect.demon.co.uk/frame.html > >> > >>IME bad ECUs generally mean no-start, no-run. If it's running, > >>it's unlikely to be the ECU (not impossible, just very unlikely). > >> > >>If it's running rich, my money's on the AMM. This is a much more > >>common failure than the ECU. Have you tested it? If so, how? > >> > >>-- > >>Grunff > >> > > Brian, You might have already done this in the "etc"..? Checked Engine Coolant Sensor aka NTC sensor resistance values? Checked fuel pressure / FPR? Checked O2 sensor support wiring? O2 sensor perhaps best tested with an oscilloscope. If using DMM, try here for more info http://216.78.172.244/tuneup_folder/amm.htm Check major grounds/earths for security and cleanliness? Corroded wiring or worn insulation? Running NGK "5" temp plugs (or equivalent) and not 6 or 7s? -- Question for all Re: AMM It appears the Bentley tests are not definitive? i.e., an AMM can pass the prescribed tests but still be bad... From "Bosch Fuel Injection & Engine Management" by Charles O. Probst With engine running at nomal temp, the voltage should typically read 2.12 V at 760 RPM, and increase to 2.83V at 3520 RPM. Changes are more important than the actual numbers. [sic - measured at the appropriate pin] Above is LH but not Saab specific, and I'm not sure if even this is conclusive - if the AMM has to be swapped out for a "known good one...!?" -- Rgds, LM
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