16197427 PCM...how to disable DFCO
04-26-2010, 08:56 AM
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16197427 PCM...how to disable DFCO
I've used the SEARCH feature and tried all the tricks listed, adjusted all the sliders and parameters I could find, but the truck still surges badly during deceleration, with the WB02 gauge showing the AFR cycling between 13 and 20ish the whole time.
Once I get under 10mph, it stops. I raised the threshold for it to stop to 70 mph, 65 mph, etc, nothing changed. It still surges til I get the speed down under 10mph.
Worse, as I've driven the truck more and put miles on it, I've begun to notice a noise that sounds like pinion bearings or something similiar as the fuel shuts off and the truck decelerates via engine braking. It goes away when the engine picks back up, comes back as the PCM shuts the fuel off again.
Anyone have a sure fire method of disabling DFCO, or lessening the surge effect?
Once I get under 10mph, it stops. I raised the threshold for it to stop to 70 mph, 65 mph, etc, nothing changed. It still surges til I get the speed down under 10mph.
Worse, as I've driven the truck more and put miles on it, I've begun to notice a noise that sounds like pinion bearings or something similiar as the fuel shuts off and the truck decelerates via engine braking. It goes away when the engine picks back up, comes back as the PCM shuts the fuel off again.
Anyone have a sure fire method of disabling DFCO, or lessening the surge effect?
05-04-2010, 08:49 PM
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Re: 16197427 PCM...how to disable DFCO
I was thinking the same thing whitelightnin VE is off . I never heard of disabling the DFCO before .
05-15-2010, 03:52 AM
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Re: 16197427 PCM...how to disable DFCO
a datalog woudl help verify if you are even in DFCO or if the problem is something else.
it's possible you have funky VE entries at the high-vacuum end of the table.
or some funky timing values again in the high vacuum (low kpa) range.
10mph is probably around hwere it kicks over to the idle tables instead of the normal run tables.
it's possible you have funky VE entries at the high-vacuum end of the table.
or some funky timing values again in the high vacuum (low kpa) range.
10mph is probably around hwere it kicks over to the idle tables instead of the normal run tables.
05-15-2010, 11:25 AM
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Re: 16197427 PCM...how to disable DFCO
Usually the easiest way to disable DFCO is to set the CTS enable threshold high.
However, DFCO being active can't cause surging. There is no fuel, the engine is just freewheeling.
The surging during decel can be caused by the closed loop proportional gains. Setting the calibration/code for open loop during decel will eliminate the surging caused by the prop gains. Usually during this time the PW is so small that it becomes difficult to get precise PW control from the proportional gains.
Surging during open loop decel can be caused by having the AFR too lean. The density of the mix is so low that it is difficult to light off consistently. A little more fuel makes a big difference.
Spark advance also plays a role in controlling the surging.
RBob.
However, DFCO being active can't cause surging. There is no fuel, the engine is just freewheeling.
The surging during decel can be caused by the closed loop proportional gains. Setting the calibration/code for open loop during decel will eliminate the surging caused by the prop gains. Usually during this time the PW is so small that it becomes difficult to get precise PW control from the proportional gains.
Surging during open loop decel can be caused by having the AFR too lean. The density of the mix is so low that it is difficult to light off consistently. A little more fuel makes a big difference.
Spark advance also plays a role in controlling the surging.
RBob.
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