Idle fluctuation
September 10th, 2008, 1:01 PM
#11
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RE: Idle fluctuation
ORIGINAL: hquick
Yeah....need to get it on a scanner. CMP retard needs to be set at +/- 2 deg. But I don't think that's your issue.
Did you replace the dizzy...or atleast check the gear? They wear BADLY and cause all sorts of issues.
Have you had a crank relearn done since installing the new motor?
Yeah....need to get it on a scanner. CMP retard needs to be set at +/- 2 deg. But I don't think that's your issue.
Did you replace the dizzy...or atleast check the gear? They wear BADLY and cause all sorts of issues.
Have you had a crank relearn done since installing the new motor?
September 10th, 2008, 2:19 PM
#13
RE: Idle fluctuation
Dizzy = Distributor so the gear on the bottom of the distributor.
When you replace the motor or PCM (computer) in one of these vehicles you 'usually' need to perform a 'crank relearn'.
Found this description on another site:
When you replace the motor or PCM (computer) in one of these vehicles you 'usually' need to perform a 'crank relearn'.
Found this description on another site:
The Crankshaft Position (CKP) sensor sends pulses to the PCM as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more than an expected amount, the PCM interprets this as a misfire. The interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult:
Crankshaft
Reluctor wheel
CKP sensor
The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position System Variation Learning Procedure again.
Perform the learning procedure after the following actions:
A PCM replacement
Any operation or repair involving the crankshaft, the CKP sensor, or the CKP sensor to reluctor wheel gap relationship.
An engine replacement.
The ignition switch is in the ON position until the battery is drained.
FWIW, this is lifted directly from the GM service manual.
Crankshaft
Reluctor wheel
CKP sensor
The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position System Variation Learning Procedure again.
Perform the learning procedure after the following actions:
A PCM replacement
Any operation or repair involving the crankshaft, the CKP sensor, or the CKP sensor to reluctor wheel gap relationship.
An engine replacement.
The ignition switch is in the ON position until the battery is drained.
FWIW, this is lifted directly from the GM service manual.
September 10th, 2008, 10:22 PM
#14
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RE: Idle fluctuation
ORIGINAL: hquick
Dizzy = Distributor so the gear on the bottom of the distributor.
When you replace the motor or PCM (computer) in one of these vehicles you 'usually' need to perform a 'crank relearn'.
Found this description on another site:
Dizzy = Distributor so the gear on the bottom of the distributor.
When you replace the motor or PCM (computer) in one of these vehicles you 'usually' need to perform a 'crank relearn'.
Found this description on another site:
The Crankshaft Position (CKP) sensor sends pulses to the PCM as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more than an expected amount, the PCM interprets this as a misfire. The interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult:
Crankshaft
Reluctor wheel
CKP sensor
The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position System Variation Learning Procedure again.
Perform the learning procedure after the following actions:
A PCM replacement
Any operation or repair involving the crankshaft, the CKP sensor, or the CKP sensor to reluctor wheel gap relationship.
An engine replacement.
The ignition switch is in the ON position until the battery is drained.
FWIW, this is lifted directly from the GM service manual.
Crankshaft
Reluctor wheel
CKP sensor
The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position System Variation Learning Procedure again.
Perform the learning procedure after the following actions:
A PCM replacement
Any operation or repair involving the crankshaft, the CKP sensor, or the CKP sensor to reluctor wheel gap relationship.
An engine replacement.
The ignition switch is in the ON position until the battery is drained.
FWIW, this is lifted directly from the GM service manual.
I did inspect the "dizzy" and replaced the top parts, but not the teeth on the bottom. They looked fine though.
I guess I should find someone else but Rosenthal, since they messed up when it was in last. Then to have then hook it up and set the "dizzy" right and then also start a learning procedure.
On another note, the car died on me the first time today. I started it and moved it almost directly in to drive. I did this a few times since I was hooking up and moving my trailer. It would start fluctuating very bad, and at one time it went so low that it died. It started right back up though. Now I'm thinking fuelpump or pressure regulator. I got a pressure gauge that I should hook up to it while it's doing it. In [P] the pressure is fine, and it stays fine after shut off too. At least according to the test in the Haynes manual.
September 11th, 2008, 3:10 AM
#15
RE: Idle fluctuation
FYI...this is what happens to the dizzy gear in these trucks (very common).
One side...looks not too bad huh?
http://img.photobucket.com/albums/v3...r/P9100307.jpg
But have a look at the rest!
http://img.photobucket.com/albums/v3...r/P9100309.jpg
http://img.photobucket.com/albums/v3...r/P9100304.jpg
One side...looks not too bad huh?
http://img.photobucket.com/albums/v3...r/P9100307.jpg
But have a look at the rest!
http://img.photobucket.com/albums/v3...r/P9100309.jpg
http://img.photobucket.com/albums/v3...r/P9100304.jpg
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