Dieseling (run-on)
03-01-2013, 08:56 PM
#1
Dieseling (run-on) Hi All,
Got bud with a similar combo in his Mav, but his is a 5.3L with dual-plane and 650 carb. He's always had a run-on problem after shutting down the engine. So far, he's had a tuner rework his ignition curve to pull all advance below 500 RPM, re-jet the carb, and add a kick-up solenoid so he could completely close the throttle blades. Still does this... Any advice on what to try next?
Got bud with a similar combo in his Mav, but his is a 5.3L with dual-plane and 650 carb. He's always had a run-on problem after shutting down the engine. So far, he's had a tuner rework his ignition curve to pull all advance below 500 RPM, re-jet the carb, and add a kick-up solenoid so he could completely close the throttle blades. Still does this... Any advice on what to try next?
03-01-2013, 09:35 PM
#4
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Someone said once they had good luck running higher timing at idle. Like really high. I'm gunna try it this summer since I have a hard start/diesel issue too
03-01-2013, 10:49 PM
#6
03-02-2013, 09:23 AM
#7
The carb jets won't have much effect on dieseling. That would be things like float level, idle screws and idle feed restrictors.
Most dieseling is caused by low octane gas with high compression. The problem can be made worse if the combustion chambers are all sooted up.
Typical solution is better gas, then take it out and "blow out the carbon" (i.e. beat on it). An idle mixture that is too rich will make the problem worse. Sometimes hotter plugs also helps. Make sure the float levels are correct and the choke properly adjusted.
I remember the thread with guy who went to outrageous idle timing to stop run on. That was a weird solution. One thing for sure, too little timing at idle will make the motor run hotter making the problem worse. Less timing also slows the idle RPM causing you to open up the idle screws more. That might make the car draw more gas when shutting off, especially if the the transition circuits aren't tuned just right.
For a temporary fix leave the car in gear when you shut it off. Also flooring it will usually stop the run on.
Most dieseling is caused by low octane gas with high compression. The problem can be made worse if the combustion chambers are all sooted up.
Typical solution is better gas, then take it out and "blow out the carbon" (i.e. beat on it). An idle mixture that is too rich will make the problem worse. Sometimes hotter plugs also helps. Make sure the float levels are correct and the choke properly adjusted.
I remember the thread with guy who went to outrageous idle timing to stop run on. That was a weird solution. One thing for sure, too little timing at idle will make the motor run hotter making the problem worse. Less timing also slows the idle RPM causing you to open up the idle screws more. That might make the car draw more gas when shutting off, especially if the the transition circuits aren't tuned just right.
For a temporary fix leave the car in gear when you shut it off. Also flooring it will usually stop the run on.
