Question about 1991 Oldsmobile Cutlass Ciera
Car runs very rough on idle but with a wide open throttle it run fairly well.
alternator is ok and charging fine. Is my problem a bad ecm? sometimes its very hard to start, after its been running a while. I have replaced everything, crank sensor, icm, coils? Can anybody help?
Two month ago i started with the similar problem in a olds 90 2.3 tested all the sensors and... I realizad it´sa bad ECM or probably the Prom only I reasearched about and usually doen´t last more than 8 or ten years . they say are the component on it ..sympthoms: hard idle , start and sudenly stop except if you go to the HW ....and finally goes to LIMP function and finally blocks the inyection or the ignition control module ... I suggest try to test ur ECM or the Prom on it...
Posted on Jul 04, 2008
Have you taken an actual voltage measurement at the battery?
If the voltage is in fact over 15 volts, it can cause all sorts of problems. If that is the case, the alternator will need to be replaced.
Posted on May 22, 2008
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Posted on Jan 02, 2017
Tips for a great answer:
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
• The engine speed is between 450-4,000 RPM.
• The manifold absolute pressure (MAP) is greater than 5 kPa.
• The mass air flow (MAF) is greater than 2 g/s.
• The ignition 1 voltage is greater than 10 volts.
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code
(DTC) List - Vehicle.
1. Start and idle the engine in PARK for 3 minutes.
2. With a scan tool, monitor desired and actual RPM.
3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
4. Ignition OFF for 60 seconds.
5. Start and idle the engine in PARK for 3 minutes.
6. After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
* If the engine idle speed has not been learned the vehicle will need to be driven at
speeds above 70 km/h (44 mph) with several decelerations and extended idles.
7. After the drive cycle, the engine should be idling normally.
* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds
and repeat step 6.
8. Once the engine speed has returned to normal, clear DTCs.
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