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Re: Cold start & Air Mass Meter Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 13 Feb 2004 10:17:42
In Reply to: Cold start & Air Mass Meter, Greg T, Thu, 12 Feb 2004 19:56:15 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The AMM controls all the fuel flow until the O2 sensor warms up. This usually takes a couple of minutes. When you take the AMM out of the air flow loop, the ECU sees zero airflow from the AMM. Since the ECU KNOWS the engine is running, it assumes a bad AMM, and supplies a default fuel amount - usually a bit rich.
Since the car quits right after start, and I assume it's a cold start, I'm ruling out the O2 sensor. Two -reasons - the 02 sensor doesn't have much authority over fuel (only about 25% - AMM is 100%), and in the O2 sensor is pretty much ignored for the first couple of minutes after cold start.
The two possibilities are the AMM sensor or the temperature sensor (NTC). If the NTC is bad, the engine may think it's warm when it's not. Cold engines get more fuel than warm ones, so the engine may be running too lean when cold - the fuel condenses on the intake manifold, and doesn't get to the cylinders. It could also be a AMM that isnt' right.
Check out http://www.saabnet.com/tsn/bb/9000/index.html?bID=94751
for a rought AMM test.
posted by 192.249....
, Fri, 13 Feb 2004 10:17:42 <-- Viewing This Message
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