My car just started doing this, what could it be?

[Brandon T.]

It started this last week, when I turn the ignition switch off the car wants to run for 1-3 secs before finally cutting off.

Sometimes it will do it most time not but it will say 1 out of 5 times after running it and turning it off.

it did it the other day when I got my tires put on! was embarrassing.

I would guess the timing has got off somehow and is a bit high maybe? would that be something that may cause it? Only thing I've done lately since it's been rebuilt was put new r45xls plugs in it and shielding plug wires..that wouldn't have anything to do with it just saying nothing has been messed with. So, if it is the timing not sure how it just got out like that unless the dizzy set bolt got loose.

thoughts?

[Keith B.]

Re: My car just started doing this, what could it be?

can you tell us what we are working with

[Jean C.]

Re: My car just started doing this, what could it be?

When you turn the ignition off, is the engine dieseling or contuing to run normally?

[Brandon T.]

Re: My car just started doing this, what could it be?

1. It's a 68 l36

2. The engine is what you're referring to as dieseling, it's still running but struggling and knocking kinda like you say (diesel sound) then it will die.

haven't had any issues since I rebuilt it and got it back on the road until now, just all the sudden started this but no other symptoms are present, it still runs fine.

[Jean C.]

Re: My car just started doing this, what could it be?

Google "dieseling" or "engine run-on".

[Dick W.]

Re: My car just started doing this, what could it be?

What's your idle speed?

[Brandon T.]

Re: My car just started doing this, what could it be?

What's your idle speed?

I seem to think it's around 650 or so.

[Dick W.]

Re: My car just started doing this, what could it be?

Check the manual and see what it is supposed to be. 50 rpm too much could cause your problem

[Brandon T.]

Re: My car just started doing this, what could it be?

thanks, because I did just idle it up the other day justa hair! bet thats it.

[John D.]

Re: My car just started doing this, what could it be?

Brandon, It could be the crappy gas.
Typically I almost agree with old DW but I don't think 50 RPM would do squat. You have other issues.
Maybe you have an LT1 cam causing the problem. JD

[Brandon T.]

Re: My car just started doing this, what could it be?

Under google it mentions plugs COULDA cause it by being too hot of a heat range.

would r45xls's be a possible issue here? I haven't been long put them in, maybe a month ago?

[Roy B.]

Re: My car just started doing this, what could it be?

Well back in the OLD days 60's 70's it was quite common. Poor gas causing carbon to build up on top of the pistons .
Which stayed lit . We ran water or trans fluid down the Carb to clean off the carbon , some times the carbon build up was so bad you got a engine knock and people thought their rods were going. Anyone that don't remember this and using water will think I'm crazy but it worked

[Timothy B.]

Re: My car just started doing this, what could it be?

Brandon,

A hot spark plug has the porcelin more exposed and extended down lower to conduct heat out to the metal outer spark plug housing then to the head. They run hot and therefore keep cleaner and are less prone to foul. This heat can cause run on like you describe.

Take a look at a few plugs and compare the color to a chart like in your service book to see if that's a possible cause. Other problems can be caused from carbon, plug threads sticking down into the combustion chamber etc., anything that will retain heat.

I think that's where these idle solenoids came into play because when the ignition is turned off the throttle blades shut closed to prevent run on..

[Stuart F.]

Re: My car just started doing this, what could it be?

Plugs being too hot can act like glow plugs.

Stu Fox

[Ed D.]

Re: My car just started doing this, what could it be?

distributor timing