1979-1993 & 94 Conv [Subscribe to Daily Digest] |
 | [Main C900 Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Fuel System Glitch, problem. Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 6 Sep 2001 11:44:50
In Reply to: Fuel System Glitch, problem., Carlie Bentley, Thu, 6 Sep 2001 11:30:23 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'm going to guess AMM (Air Mass Meter).
The engine control uses airflow and oxygen content of the exhaust gas to schedule fuel flow. Airflow is measured by the AMM, and the O2 sensor measures the oxygen (mixture) in the exhaust. Now, the O2 sensor doesn't start to work until it gets to 200 degrees C. It's in the hot exhaust flow, AND is electrically heated, but it takes about 2 minutes to get to operating temperature. Until then, fuel flow is completely controlled by the Air Mass Meter.
When your foot is off the accelerator pedal, a switch on the throttle body is closed and the engine schedules fuel for idle. If the AMM is bad, when you hit the 'gas' pedal, you open the throttle and air flows in. But if the AMM isn't working right, it will measure that air wrong, and the engine control won't add the right amount of gas. Most likely, the AMM doesn't see the extra air, so you run a lean mixture and the engine dies.
The other sign of a bad AMM is hesistation on acceleration. You'll be sitting at a light, and give the gas pedal a moderate push to accelerate away, but the engine will feel like it's ignoring you, then will bog. If you press the pedal way down, the car will surge forward. That is a major indication of a bad AMM.
Unfortunately, the best way to diagnose a bad AMM is to replace it with a known good one. There are two different models of AMM, and outwardly they look the same, and the connectors will fit. But they are NOT INTERCHANGEABLE. Always go by the part number, and only swap in one with the same part number.
Quality rebuilt AMMs can be bought for about $140 (after core) from some of the mail order places on this BB.
Good luck!
posted by 140.157....
, Thu, 6 Sep 2001 11:44:50 <-- Viewing This Message
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
