Surging idle on cold start

Sabinoerc

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here's readings from scanner, Frame 0 there are 11 frames.
i suspect issue occurs when going from OPEN to CLOSE loop.
I don’t have experience or skills to be able to find a problem like you are describing from point in time snapshots of the engine data. I think you need to look at the data over time in a plot like this.
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I think this was after fixing my last problem. Idle steady, going from open loop to closed, the A/F being adjusted to drive O2 up/down as it should. You take a snapshot and any point in time and you could be rich, lean, whatever. You need to be able to see what's going on when the RPM drops.
Here's a more complicated trace that PlaywTBI posted in another thread which shows adding sensor data to trace. This one looks like idle to drive cycles to idle. (hope you don't mind me posting one of yours PlaywTBI - easier, quicker than opening my other laptop to find an example).
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These were made using TunerPro. It's the only tool I have any experience. I would guess most diagnostic tools have some capability like this to varying degrees but I don't know - or know anything about the tool you are using and it's capability. Maybe someone can make sense of the data you have but I'm sorry I can't help with that! Good luck.
 

PlayingWithTBI

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(hope you don't mind me posting one of yours PlaywTBI - easier, quicker than opening my other laptop to find an example).
That's cool. IIRC this was warming up to cruising with a few runs, shifting ~5000 RPM, to see if I was getting any KCs or other anomalies.
 

1997

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It’s interesting to see that your trim cell at idle is No 18. I’m showing a lean condition and code 44. I’m showing an 18 too which I thought might be a problem as the factory service manual showed it to be zero as normal? Maybe that’s an error in the manual since we are both 18. 1995 K1500 350 engine here. This forum is helpful
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are you getting a constant code 44?
no codes were present on my posted live data display, and issue is intermittent, but getting more frequent. we have the same 95 TBI 5.7, mines a 6 lug K2500.
i'll post up some open loop info when i get it and read the manual for both truck and scanner some more :)
 

1997

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I don’t have experience or skills to be able to find a problem like you are describing from point in time snapshots of the engine data. I think you need to look at the data over time in a plot like this.
You must be registered for see images attach

I think this was after fixing my last problem. Idle steady, going from open loop to closed, the A/F being adjusted to drive O2 up/down as it should. You take a snapshot and any point in time and you could be rich, lean, whatever. You need to be able to see what's going on when the RPM drops.
Here's a more complicated trace that PlaywTBI posted in another thread which shows adding sensor data to trace. This one looks like idle to drive cycles to idle. (hope you don't mind me posting one of yours PlaywTBI - easier, quicker than opening my other laptop to find an example).
You must be registered for see images attach


These were made using TunerPro. It's the only tool I have any experience. I would guess most diagnostic tools have some capability like this to varying degrees but I don't know - or know anything about the tool you are using and it's capability. Maybe someone can make sense of the data you have but I'm sorry I can't help with that! Good luck.
sounds like a good plan, hopefully scanner graphs, don't think so thou for OBD1, investigating .....
 
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Sabinoerc

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i was referring to my scanner, checked and manual says it don't do graphing on GM OBD1 and some others.

– Graphing is not available on GM, Ford, Chrysler, or Toyota ODB I vehicles.

Rats
Ah, I see. Can you freeze frame? That is, hit a button to capture the data at a particular point in time? If so, maybe comparing the data captured during the idle surge vs non-surge may show something? Eg. A burst of knock counts, some sensor data changing, etc?
 
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