What is causing my car to stall when pushing in clutch after coasting?
11-22-2015, 09:49 PM
#1
What is causing my car to stall when pushing in clutch after coasting? ok, still fighting some issues with the car stalling when coming to a stop. I have been able to pinpoint how it happens and I'm hoping someone can tell me which parameter is related to that condition. I have verified that I don't have any vacuum leaks, etc.
If I'm cruising along with TPS at about 5%, and need to slow down for a red light, sometimes I will depress the clutch and put the car in neutral. Revs drop, come down to about 900-1000ish, and generally stay solid until the vehicle comes to a stop. No problem.
However, same scenario, cruising along with minor throttle input, and I take my foot off the gas to coast (0% TPS for at least 5 seconds or more, roughly); after the car has been decel'ing in gear for a few seconds, if I then push in the clutch and put it in neutral, the revs will controllably drop to 0 and the car stalls completely. I can recreate this time after time. Is this a function of running idle airflow? Why does it only do this after I've been coasting for a few seconds? Perhaps the throttle follower has already decayed away and there is no airflow left?
I am posting up my log and tune - I also noticed that the timing is doing some crazy things while the car is in the process of stalling. Could be something else to look at. Pretty frustrating stuff since the car drives around town pretty nicely otherwise.
Here is my tune and a log of the stall events
The stall event starts at frame 2400
I push in the clutch at frame 2403
Timing goes beserk immediately after (full advance).
Another stall condition starts to occur around frame 2779 when I push in the clutch again after a long decel (5 seconds) in gear (coasting down). However this time I blip the throttle to save it. Timing again goes beserk leading up to it.
I am wondering if it is being caused by a lack of airflow or incorrect timing.
Any help is greatly appreciated!
If I'm cruising along with TPS at about 5%, and need to slow down for a red light, sometimes I will depress the clutch and put the car in neutral. Revs drop, come down to about 900-1000ish, and generally stay solid until the vehicle comes to a stop. No problem.
However, same scenario, cruising along with minor throttle input, and I take my foot off the gas to coast (0% TPS for at least 5 seconds or more, roughly); after the car has been decel'ing in gear for a few seconds, if I then push in the clutch and put it in neutral, the revs will controllably drop to 0 and the car stalls completely. I can recreate this time after time. Is this a function of running idle airflow? Why does it only do this after I've been coasting for a few seconds? Perhaps the throttle follower has already decayed away and there is no airflow left?
I am posting up my log and tune - I also noticed that the timing is doing some crazy things while the car is in the process of stalling. Could be something else to look at. Pretty frustrating stuff since the car drives around town pretty nicely otherwise.
Here is my tune and a log of the stall events
The stall event starts at frame 2400
I push in the clutch at frame 2403
Timing goes beserk immediately after (full advance).
Another stall condition starts to occur around frame 2779 when I push in the clutch again after a long decel (5 seconds) in gear (coasting down). However this time I blip the throttle to save it. Timing again goes beserk leading up to it.
I am wondering if it is being caused by a lack of airflow or incorrect timing.
Any help is greatly appreciated!
11-23-2015, 09:58 AM
#3
The throttle cracker table is only used with the clutch pedal out. For the clutch in issue, you need to enable the rolling idle tables. Start with 1 g/sec in the 2 mph & up cells. And set the enable & disable speeds the same as your throttle cracker.
32 degrees idle timing is too high for the underspeed spark table to be effective. I would lower it to 26.
Russ Kemp
32 degrees idle timing is too high for the underspeed spark table to be effective. I would lower it to 26.
Russ Kemp
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11-24-2015, 07:11 AM
#9
Last night I made the changes - turned on rolling idle to enable above 2mph and shut off below 1mph. The table was zero'd out so I started with 1 g/s which actually ended up being pretty damn close to what I needed. It seemed like it needed a bit more so I doubled it and that ended up being too much, so I backed it down to 1.5 and it works well. I may end up taking just a hair more out. I have only put about 20 miles on it since the fix but it's much happier now. I also took out that timing in the idle tables (both P/N and in gear) down to 26* and it seemed to help. I will continue to drive it and see if I can find anything else that needs work.
Thanks all very much for your help!
Subeone: feel free to make any suggestions based on what you see
Thanks all very much for your help!
Subeone: feel free to make any suggestions based on what you see
06-27-2020, 10:32 AM
#10
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The throttle cracker table is only used with the clutch pedal out. For the clutch in issue, you need to enable the rolling idle tables. Start with 1 g/sec in the 2 mph & up cells. And set the enable & disable speeds the same as your throttle cracker.
32 degrees idle timing is too high for the underspeed spark table to be effective. I would lower it to 26.
Russ Kemp
32 degrees idle timing is too high for the underspeed spark table to be effective. I would lower it to 26.
Russ Kemp