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Car runs after you shut it ...

4K views 18 replies 5 participants last post by  Clutch 
#1 ·
Every so often, my Mustang will run for an extra second or two once I've shut off the ignition. I was told it's because I need to let it "sit" for a few seconds after putting it into park, before removing the key.

True?

Why does it run that tiny bit?
 
#2 ·
Its called running on.
its normally caused by a high idle/poor ignition timing.

This is a SERIOUS issue that any decent mechanic will be able to fix quite easily. Running on has the potential to take the top off a piston and force a rebuild.

GET IT LOOKED AT!!!

in the interim, when you shut it off, do it in drive, that way there is a load on the engine, that will force it to stop rotating, then grab park.
Same for any manual that runs on, switch off, and release the clutch a little.

this method should only be used until the car can be looked at.

its a simple tune issue and nothing terminal, unless you ignore it.

Cheers
Jas
 
#4 ·
Long time no see Pammie! :driver: Yeah, you should have it checked out by your resto guy. Like jas said, turn the car off in drive until than. When the motor diesels thru like that after being shut off, it would cause damage, just a matter of time when the damage adds up.
 
#5 ·
Hey, toots! Thanks for recommending this place :)

The resto guy will never, ever touch my car after all the "mistakes" he made on it. I now have a rock-solid mechanic, a Ford guy, who knows his stuff. He's the type that was taught by his father to diagnose a car by the sound it makes, not hook it up to a computer -- an old time car guy. Sorta like most of you, I suspect!

It hasn't kept running like that for several weeks, ever since he adjusted the carb (and rebuilt it a second time, don't ask). It uses more gas now as he told me it would, but it makes vacuum correctly and isn't open all the time, so everything else works properly, like the brakes that wouldn't make vacuum correctly for the first minute or so of driving it.

She purrs now and has a ton of get-up-and go. I took the highway yesterday (I don't do that often, preferring the long country roads) and had to pass someone and floored it and like the good little pony she is, smoothly went fast past the guy as if she was a brand new car.
 
#7 ·
200 inline 6, not sure about the carb -- it seems the company who rebuilt it did a swapout and I'm currently trying to get back my original carb.

Not only that, they drilled the outtake hole (I think that's it) a half an inch off so porting it was difficult, hence the rebuilt and fix.
 
#8 ·
Alright, You have the same set up as me. Try and find out exactly what they did to your carb. Just the fact that they drilled into the carb makes me uneasy.

The replacement for that carb is the Autolite 1100 1v carb. There is a site that can get you one for $189. It's actually off the 170ci I6, but works fine for the 200. If you want a little extra torque 13~ bux can get you a splitter for the intake just under the carb that splits the #1, #2 and #3 clyinders from the #4, #5, and #6 clyinders and you can run the exhaust manifold off of a 250ci I6 for another increase in power.

Don't listen to the guys over on MF talking about fordsix.com or whatever. I have been waiting for 2 years for them to finish the intake and everything else and get some numbers up and personally, anyone who runs a business without updating regularly is someone I don't like. For months there would be the same update saying the same thing and we were just left in the balance to wait and get tired of waiting. :noNO:
 
#9 ·
Check your PM elsewhere for more info on the carb. They had no choice but to drill since the hole was in the wrong place (I typed that with a straight face, too).

He gave me a very intense explanation as to what was done on the carb, but honestly, after waiting 3 weeks for them to diagnose and fix it, I was just anxious to get her back and drive and didn't fully understand all he told me. I'm going to ask again this week and write it all down, as it got quite technical. I've been meaning to do that but haven't been there that much other than to talk about restoring my other car.

I'm almost positive my car had the original carb when it went in for restoration, but the guys they sent it to sent back a swapout that was done incorrectly. The problem is this was about 10 months ago so even if I were to call them and demand my carb back, they'd have no clue who I was or where it went, since they do tons of these every day.

I'm not searching for an original carb since almost everything else on the car is either original or rebuilt.
 
#10 ·
Running on (also called diesling) is often caused by carbon build up creating hot spots in the head that ignite the gas even when there is no spark. This can be fixed on cars without catalytic converters by either using a upper cylinder head lubricant/cleaner like Red-X (takes longer) or spraying a fine mist of water down the carburettor throat for a few minutes while the engine is running (flick the throttle every now and then so a pool doesn't build up on the butterflies valves). Try this water spray trick on a car with catalytic and you risk blocking the cat converters.

Some carbs have a anti runon solonoid valve that cuts off the fuel when you switch off the ignition. Check you carb hasn't got one and if it has that it is connected and working (ie wiring going to the carb). Also seeGM-GMC: "dieseling"
 
#11 ·
Thank you!

Carbon buildup, huh? I was told to take it on the highway every so often and floor it to blow out the carbon .... which I haven't done in a while. I guess it's time to do it again.

(Funny thing is I can remember my father doing this in the late 60's/early 70's with his cars and thinking he just wanted to go fast)
 
#12 ·
..and Dieseling - Wikipedia, the free encyclopedia
Potential causes
This condition can occur for a multitude of reasons:

Built-up carbon in the ignition chamber can glow red after the engine is off, providing a mechanism for sparking unburnt fuel. Such a thing can happen when the engine runs very rich, depositing unspent fuel and particles on the pistons and valves. Similarly, non-smooth metal regions within the piston chamber can cause this same problem, for they can glow red. It has also been suggested that an improperly rated sparkplug can retain heat and cause the same problem.
A carburetor that does not close entirely can contribute to running once the engine is off, for the extra fuel and oxygen mixture can combust easily in the warm piston chamber. Similarly, hot vaporized oil gases from the engine crankcase can provide ample fuel for dieseling.
Incorrect timing.
An engine that runs too hot or too lean may produce an environment conducive to allowing unspent fuel to combust.
An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running.
[edit]
Potential fixes
Items similar to carburetor cleaners and carbon cleaners have been suggested as partial remedies for attempting to clean the piston chambers and valves of engines that run too rich.

For those engines that have sharp metallic edges, it has been noted that poorly milled heads and blocks can contribute to this problem, so having the rough spots smoothed may help.

For those engines that run too hot or too lean, verify that all mechanisms in place to cool the engine properly function as they should. Replace the thermostat if necessary. Clean the radiator. Verify that all auxiliary fans engage at their proper temperatures, and ensure that the thermostatic sensors on belt driven fans engage as necessary.

In the case that there is too much angular momentum, lower the idle speed if possible.
 
#13 ·
#15 ·
That fast idle worrie me too note the Wikapedia comment: "An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running. " Try turning that idle screw down a mite.
 
#16 ·
You know what, I totally forgot about that! Yeah, see if maybe they had to adjust the idle screw or maybe knocked it up a bit when installing it. you really shouldn't idle above 800-1000 rpm. I had a problem with one of my other car where I had to advance the idle to about 1300-1500 rpm cause it would bog at a dead stop and come very close to cutting out. After a while I took off the intake and sprayed a whole bottle of carb/intake cleaner in (WHILE RUNNING) to clean out some of the crap in there and it ran a bit better after that.
 
#18 ·
"Italian tune up" so called as road testers and service garages both found that the performance of V12 Ferraries, Lamborghini's and similar exotic Italian multi-cylinder, multi carburettored cars of the 1960's and 70's could often be restored with a quick high rev fang to clean the carbon of the fouled spark plugs (often fouled from idling around in suburbia).
 
#19 ·
Aussiblue said:
"Italian tune up" so called as road testers and service garages both found that the performance of V12 Ferraries, Lamborghini's and similar exotic Italian multi-cylinder, multi carburettored cars of the 1960's and 70's could often be restored with a quick high rev fang to clean the carbon of the fouled spark plugs (often fouled from idling around in suburbia).
That makes sense seeing how a lot of these cars are stuck in the traffic of Cali and really aren't able to be opened up the way they were built.
 
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