Post-gridlock, f Nighting the stall... Any ideas?
MookaMobile
05-18-2005, 06:02 PM
Hi. I have a new issue with my 99 3.5L Intrigue, has almost 97,000 miles.
My tac seems to dip down a bit low (500-700) when I slow/stop my vehicle. This only happens after the car has warmed up, after first starting, it idles about 900-1000. When it gets to 500, it jumps up and down till it settles at 700 when stopping. Last time I had the "dancing tachometer" was when my cam and crank sensors went out at 60,000 miles. However, the tac didn't really jump, it was more like kept slowing down and just went to 0 for a stall. Also, with the bad sensors, I was having problems maintaining higher speed and engine revolutions. This time the tac only runs low when I stop.
We had an engine stall on the highway a month ago, which signified the start of this problem. Slowing down to an exit/interchange. We coasted in neutral and started it with no prob, but the service light never came on. We pulled into a restaurant, and let the car cool off awhile. We had been sitting in gridlock for about an hr before getting back up to highway speed prior to this stall. Car fired right up, no problems with stalling until this afternoon. I sat in a traffic jam for about 20 min, and immediately following that, when I slowed down to stop, my tac started dipping way down, to almost 200-500 before rocketing back up. I guess my engine was fighting a stall, but it didn't make any sluggish noises, or feel sluggish starting again from the stop. Any ideas why after sitting in stop and go traffic, my engine seems to be fighting off a stall? Still have no engine light, and car drives/feels fine except that I need to balance my tires. Not ready to take to mechanic yet since it only does this occassionally and I have no codes. Need ideas of things to check first. Thanks!
My tac seems to dip down a bit low (500-700) when I slow/stop my vehicle. This only happens after the car has warmed up, after first starting, it idles about 900-1000. When it gets to 500, it jumps up and down till it settles at 700 when stopping. Last time I had the "dancing tachometer" was when my cam and crank sensors went out at 60,000 miles. However, the tac didn't really jump, it was more like kept slowing down and just went to 0 for a stall. Also, with the bad sensors, I was having problems maintaining higher speed and engine revolutions. This time the tac only runs low when I stop.
We had an engine stall on the highway a month ago, which signified the start of this problem. Slowing down to an exit/interchange. We coasted in neutral and started it with no prob, but the service light never came on. We pulled into a restaurant, and let the car cool off awhile. We had been sitting in gridlock for about an hr before getting back up to highway speed prior to this stall. Car fired right up, no problems with stalling until this afternoon. I sat in a traffic jam for about 20 min, and immediately following that, when I slowed down to stop, my tac started dipping way down, to almost 200-500 before rocketing back up. I guess my engine was fighting a stall, but it didn't make any sluggish noises, or feel sluggish starting again from the stop. Any ideas why after sitting in stop and go traffic, my engine seems to be fighting off a stall? Still have no engine light, and car drives/feels fine except that I need to balance my tires. Not ready to take to mechanic yet since it only does this occassionally and I have no codes. Need ideas of things to check first. Thanks!
panzer dragoon
05-22-2005, 04:32 PM
this is from alldatadiy.com:
PCM - MIL ON/DTCs P0101 & P1441/Driveability Problems
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 00-06-04-022
Date: May, 2000
TECHNICAL
Subject:
Idle Stumble, Low Oil Pressure Cold Concerns, DTCs P0101, P1441 (Reprogram PCM with Calibration Enhancement)
Models:
2000 Oldsmobile Intrigue
2001 Oldsmobile Aurora
with 3.5 L Engine (VIN H - RPO LX5)
Condition
Some customers may comment on a check engine light, indicated low engine oil pressure, or engine idle stumble concern. Upon investigation, the technician may find either of the codes listed below:
DTC DTC DescriptionP0101 Mass Air Flow (MAF) Sensor PerformanceP1441 Evaporative Emission (EVAP) System Flow During Non-Purge
Correction
If a vehicle is encountered with any of the conditions described above and all of the diagnostic procedures listed in the applicable Service Manual have been performed with no resulting correction, then use a Tech II scan tool to verify what software calibration is programmed into the vehicle's PCM. A PCM calibration enhancement has been released to correct false indication of low engine oil pressure after cold starts and resolve Park/Neutral idle stumble concerns. In addition, this enhancement will correct the false setting of the above PCM DTC codes. If the improved calibration has not been installed, reprogram the PCM with the updated calibration listed in this bulletin.
Important : All DTCs, calibration numbers, technician observations and customer comments are to be recorded on the repair order in accordance with article 1.6.2 of the General Motors Service Policies and Procedures Manual.
Description and Operation
The purpose of the idle air control (IAC) valve is to control the engine idle speed (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/58800534), while preventing stalls due to changes in the engine load. The IAC valve, mounted in the throttle body (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/34859505), controls the bypass air around the throttle plate. By moving a conical valve, known as a pintle, in to decrease the air flow or out to increase the air flow, a controlled amount of air can move around the throttle plate. If the RPM is too low, the PCM (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34857030/101367125) will retract the IAC pintle, resulting in more air being bypassed around the throttle plate and an increased RPM. If RPM is too high, the PCM will extend the IAC pintle, allowing less air to be bypassed around the throttle plate and a decreased the RPM.
The IAC pintle moves in small steps called counts.
During idle, the proper position of the IAC pintle is calculated by the PCM (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34857030/101367125) based on the battery voltage, the engine coolant temperature, the engine load, and the engine RPM. If the RPM drops below a specified value and the throttle plate is closed, the PCM senses a near-stall condition. The PCM will then calculate a new IAC pintle position to prevent a stall.
If the IAC valve is disconnected and reconnected with the engine running, the idle RPM will be wrong. In this case, the IAC must be reset.
The IAC resets when the key is cycled ON, then OFF.
The IAC should only be disconnected or connected with the ignition OFF in order to keep from having to reset the IAC.
The position of the IAC pintle affects the engine start up and the idle characteristics of the vehicle. If the IAC pintle is open fully, too much air will be allowed into the manifold. This results in a high idle speed (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/58800534), along with possible hard starting and a lean air/fuel ratio. A DTC P0507 may set. If the IAC pintle is stuck closed, too little air will be allowed into the manifold. This results in a low idle speed, along with possible hard starting and a rich air/fuel ratio. A DTC P0506 may set. If the IAC pintle is stuck part way open, the idle may be high or low and will not respond to changes in the engine load.
PCM - MIL ON/DTCs P0101 & P1441/Driveability Problems
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 00-06-04-022
Date: May, 2000
TECHNICAL
Subject:
Idle Stumble, Low Oil Pressure Cold Concerns, DTCs P0101, P1441 (Reprogram PCM with Calibration Enhancement)
Models:
2000 Oldsmobile Intrigue
2001 Oldsmobile Aurora
with 3.5 L Engine (VIN H - RPO LX5)
Condition
Some customers may comment on a check engine light, indicated low engine oil pressure, or engine idle stumble concern. Upon investigation, the technician may find either of the codes listed below:
DTC DTC DescriptionP0101 Mass Air Flow (MAF) Sensor PerformanceP1441 Evaporative Emission (EVAP) System Flow During Non-Purge
Correction
If a vehicle is encountered with any of the conditions described above and all of the diagnostic procedures listed in the applicable Service Manual have been performed with no resulting correction, then use a Tech II scan tool to verify what software calibration is programmed into the vehicle's PCM. A PCM calibration enhancement has been released to correct false indication of low engine oil pressure after cold starts and resolve Park/Neutral idle stumble concerns. In addition, this enhancement will correct the false setting of the above PCM DTC codes. If the improved calibration has not been installed, reprogram the PCM with the updated calibration listed in this bulletin.
Important : All DTCs, calibration numbers, technician observations and customer comments are to be recorded on the repair order in accordance with article 1.6.2 of the General Motors Service Policies and Procedures Manual.
Description and Operation
The purpose of the idle air control (IAC) valve is to control the engine idle speed (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/58800534), while preventing stalls due to changes in the engine load. The IAC valve, mounted in the throttle body (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/34859505), controls the bypass air around the throttle plate. By moving a conical valve, known as a pintle, in to decrease the air flow or out to increase the air flow, a controlled amount of air can move around the throttle plate. If the RPM is too low, the PCM (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34857030/101367125) will retract the IAC pintle, resulting in more air being bypassed around the throttle plate and an increased RPM. If RPM is too high, the PCM will extend the IAC pintle, allowing less air to be bypassed around the throttle plate and a decreased the RPM.
The IAC pintle moves in small steps called counts.
During idle, the proper position of the IAC pintle is calculated by the PCM (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34857030/101367125) based on the battery voltage, the engine coolant temperature, the engine load, and the engine RPM. If the RPM drops below a specified value and the throttle plate is closed, the PCM senses a near-stall condition. The PCM will then calculate a new IAC pintle position to prevent a stall.
If the IAC valve is disconnected and reconnected with the engine running, the idle RPM will be wrong. In this case, the IAC must be reset.
The IAC resets when the key is cycled ON, then OFF.
The IAC should only be disconnected or connected with the ignition OFF in order to keep from having to reset the IAC.
The position of the IAC pintle affects the engine start up and the idle characteristics of the vehicle. If the IAC pintle is open fully, too much air will be allowed into the manifold. This results in a high idle speed (http://www.alldatadiy.com/alldata/AFI~V4824942~C33946~R0~OD~N/0/77993956/78154819/78154882/78154884/34853741/34857029/34858641/58800534), along with possible hard starting and a lean air/fuel ratio. A DTC P0507 may set. If the IAC pintle is stuck closed, too little air will be allowed into the manifold. This results in a low idle speed, along with possible hard starting and a rich air/fuel ratio. A DTC P0506 may set. If the IAC pintle is stuck part way open, the idle may be high or low and will not respond to changes in the engine load.
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