another problemo
Thread Starter
Race Director
Joined: Apr 2004
Posts: 17,066
Likes: 3
From: Milpitas ca
another problemo
Got car started. turn off key and pull it out. The motor keeps running for another 5 secs (scares the hell outta me) , car shakes badly then stops. Take a chance and try to duplicate and can't. Now starts everytime and turns off everytime correctly.
What happened? Alternator warning sign?
What happened? Alternator warning sign?
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
Sounds like the ignition is staying on and the residual pressure in the fuel system is burning off which may cause the stumbling you're experiencing til it dies. Seems strange that the park/neutral safety switch and the ignition switch (not the ignition key tumbler) are both acting up.
Art
Art
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by jabez
Got car started. turn off key and pull it out. The motor keeps running for another 5 secs (scares the hell outta me) , car shakes badly then stops. Take a chance and try to duplicate and can't. Now starts everytime and turns off everytime correctly.
What happened? Alternator warning sign?
What happened? Alternator warning sign?
Jake
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Preignition cannot happen with the ign switch off because the ECM does not pulse the injectors. No fuel, no run. What you experienced was the ignition switch not being turned off all the way when you pulled your key out.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
There's a condition we use to refer to as "Run-On"; the squad cars were notorious for it. The engine would continue to run, knock like crazy, shake and give off an awful smell.
Some would continue to run until the engine was again started, trans put in gear and the key turned "Off".
Bad or low octane gas coupled with glowing combustion chamber parts or carbon was how it was explained to me.
What you're explaining doesn't sound like that though.
If it recurs you might want to try a higher octane gas unless you're running the max already.
You can also allow the engine to idle for 30 seconds or so before shutting it down.
Jake
Some would continue to run until the engine was again started, trans put in gear and the key turned "Off".
Bad or low octane gas coupled with glowing combustion chamber parts or carbon was how it was explained to me.
What you're explaining doesn't sound like that though.
If it recurs you might want to try a higher octane gas unless you're running the max already.
You can also allow the engine to idle for 30 seconds or so before shutting it down.
Jake
Racer
Joined: May 2004
Posts: 476
Likes: 0
From: DFW TX
Originally Posted by jfb
Preignition cannot happen with the ign switch off because the ECM does not pulse the injectors. No fuel, no run. What you experienced was the ignition switch not being turned off all the way when you pulled your key out.
Its a condition in which hots spots in the combustion chamber (carbon deposits/ unburned fuel) cause the engine to run on after the key is turned off.
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Racer
Joined: Feb 2005
Posts: 398
Likes: 1
From: Kelowna BC
Originally Posted by vetster86
Dieseling/pre-ignition/engine run-on, has nothing to do with the ecm.
Its a condition in which hots spots in the combustion chamber (carbon deposits/ unburned fuel) cause the engine to run on after the key is turned off.
Its a condition in which hots spots in the combustion chamber (carbon deposits/ unburned fuel) cause the engine to run on after the key is turned off.
but, dont you also need fuel? I thought run-on occured with mechanical fuel pumps because as long as the engine ran, it kept fuel coming. With the Vette system, can that happen?
Racer
Joined: May 2004
Posts: 476
Likes: 0
From: DFW TX
Originally Posted by 86C4EVER
but, dont you also need fuel? I thought run-on occured with mechanical fuel pumps because as long as the engine ran, it kept fuel coming. With the Vette system, can that happen?
Racer
Joined: Feb 2005
Posts: 398
Likes: 1
From: Kelowna BC
Originally Posted by vetster86
Excess FUEL (or build up of carbon deposits) that was not burned during the combustion stroke, hot spots in the combustion chamber can fire the excess FUEL or carbon deposits and cause the engine to run-on when the key is turned off.
:o
Racer
Joined: May 2004
Posts: 476
Likes: 0
From: DFW TX
Originally Posted by 86C4EVER
OK, this time, I got it. Dont you just love it when you have to say the same thing over and over again?
:o
:o
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
Could also be leaking injectors. They would cause the carbon deposits from an overly rich mixture during normal running and also supply some fuel after the ignition has been shut off.
Just a thought
Just a thought