Jump to content
Sign in to follow this  
Timwell

Car runs on when ignition is off

Recommended Posts

Hey guys, been keeping an eye on this forum for months but only till now have had the need to speak out.

 

Everytime I turn the car off the car runs on for about 10 seconds.

 

It has SUs, electronic ignition and the timing is correct.

 

Could it be the coil that is shorted?

 

I initially thought it could be the timing but that isn't the case.

 

Any help apreciated.

 

Thanks,

 

Tim

Share this post


Link to post
Share on other sites

Sounds more a case of pre-ignition, caused by excessive carbon on the heads. Might be time for a de-coke. You could try running some ATF (auto transmission fluid) through the fuel for a few weeks - about 1lt per tank full, and that may clear it after a few weeks. You will need to have some new fuel filters on hand though as it will clean out the entire fuel system.

 

Another option is to pout water SLOWLY down the carbie while it is running abd try and burn it off.

Share this post


Link to post
Share on other sites

Sounds more a case of pre-ignition, caused by excessive carbon on the heads. Might be time for a de-coke. You could try running some ATF (auto transmission fluid) through the fuel for a few weeks - about 1lt per tank full, and that may clear it after a few weeks. You will need to have some new fuel filters on hand though as it will clean out the entire fuel system.

 

 

 

Aegean

 

Out of curiosity..where did you pick up this trick....

Share this post


Link to post
Share on other sites

Wow, they are some novel ideas.... had a slight feeling that it may be preignition however there is no knocking (as far as I know).

 

We'll I'll give it a go and see how it goes.

 

Ill try the ATF method first.

 

Any other ideas??

Does it sound like an ignition problem?

 

Thanks for the help so far

Share this post


Link to post
Share on other sites

Have you noticed if the engine runs backwards when it happens? Way to check is, when it does it, stall it in gear and see which way the car jumps. If it lurches forward in first, or backwards still in first. I had a 910 Bluebird that ran backwards, when stalled in first, it would jump backwards. Problem solved when I backed the timing off a couple of degrees.

Share this post


Link to post
Share on other sites

Actually,

 

now you mentioned it.....yes it does run backwards when shut down!!

 

Ok so Ill change it a few Degrees tomorrow.

 

So what should I set it to at Idle?

It is currently set to 10 degrees, however this is the "factory" correct setting. Doesn't chaning the timing jjst mask an issue that requires rectification?

 

Will this then stop the run on??

 

Every solution produces more questions...sorry.

 

Tim

 

 

 

Share this post


Link to post
Share on other sites

Back when we had good fuel with a nice octane rating, 10' was fine. But with today's $hitty fuels, you have to back off timing a tad. Or if you can score some avgas from an local airport like we used to, that could help also.

Share this post


Link to post
Share on other sites

Well it still runs on with the timing backed to 8 Degrees,

 

Will now pull the plugs to see if there is any evidence there.

 

Tim

Share this post


Link to post
Share on other sites

Whats the idle set to

if the idle is to high this will cause this as well

You could try a heat range colder in the plugs as well

Share this post


Link to post
Share on other sites

 

Aegean

 

Out of curiosity..where did you pick up this trick....

 

This has been something used for many years by Mercedes owners with high compression/output engines - such as the 6.3, 6.9, etc. I have a few of them, and believe me, it works. You also don't need to use new oil - any old ATF that has been filtered is fine. It is especially good in fuel injected engines as it cleans the injectors as it goes. Also good for cars that don't get a lot of use as it cleans out the varnish that forms on the fuel lines - and that is why I said you need to have new filters on hand.

Share this post


Link to post
Share on other sites

With regards to the timing - I know you have said you have checked the time and set to the factory settings but did you check the balancer is not gone ie the bonding of the outer rings had failed and the ring has moved and thus your timing marks are not correct so even though you have knocked it back 2 degrees it could still be off if the rings has moved.

Share this post


Link to post
Share on other sites

Ok all good advice, Ill TDC physicaly. The plugs are carboned too.

 

The secondry winding in the coil isnt reading the correct ohmage either.

 

The primary seems fine.

 

Ill change the coil. Check TDC and then........repost.

 

Regards,

 

Tim

Share this post


Link to post
Share on other sites

All done,

 

Coil changed, TDC checked physically, its now at 5 degrees. incidently the vacume advance isnt working so ill get a new one.

 

Am currently running the equivilent of ATF through the system, just a little scared about what ATF will do to the carbies.

 

I spoke with Stewart Wilkins and he reckons I should just wind the idle right back...so Ill do that today.

 

If this doesn't work ill try the ATF.

 

thanks,

 

Tim

Share this post


Link to post
Share on other sites

ATF won't hurt your carbies - or anything else, but it will clean the varnish out, so that's why I said to have filters on hand. Vacuum advance only affects the idle speed and at low revs so that isn't going to change too much, but still better to replace it. Look for vacuum leaks at the same time. All will effect the timing and tuning.

Share this post


Link to post
Share on other sites

is it electronic dizzy? this happens a lot with electronic dizzy been amped up the alt is feeding the ignition system causing run on ..... let me know ive fixed this alot with customers

Share this post


Link to post
Share on other sites

OK,

 

long time since posts, I have been away a bit.

 

I have replaced all elec parts, rotor, plugs, leads dizzy cap and plugs.

In addition I have run decoke through the car. The timing is set and the idle is wound back.

 

It has made a big difference but still does it occasionaly. I think the "carbon in the cylinder hypothisys is correct".

 

Great advise from all, I am very appreciative but it looks like I will pull the head off and give it a clean up......gives me something to do at least.

 

 

And yes it is an elec dizzy.

 

 

Share this post


Link to post
Share on other sites

Does the car have Thermo Fans?

The reason i asked about the Thermo Fans is i changed back to a single and took out the relay. Where i had tapped into the fuse block was ignition on. When i switched the ignition off the fan kept spinning as it slowed and it produces eletricity when diong so. It was pumping it back into the ignition keeping the car running after the ignition was off for a few seconds until the fan slowed enough to stop producing power.

Share this post


Link to post
Share on other sites

I think the "carbon in the cylinder hypothisys is correct".

 

Great advise from all, I am very appreciative but it looks like I will pull the head off and give it a clean up......gives me something to do at least.

Just be aware that if you pull the head and clean everything up, you will likely have more compression. If the rest of the motor is not in top condition, the increased compression may cause some further problems, such as blowing smoke because the oil rings are worn. I'm not saying it will happen, but it is something to be aware of if all of a sudden it starts blowing smoke when it never used to. If you can find another way to decoke the head without removing it, it might be better - it won't be as good, but then, it might be enough to get rid of the run on problem. Have a look at water injection for cleaning the head.

 

http://www.hotrodder.com/kwkride/tech.html

 

 

 

 

 

Share this post


Link to post
Share on other sites

agean....your not trying to use my engine as a gunie pig are you? I read this can cause severe engine damage....ha ha

 

Ill give it a go in the lab and get back to you all:-)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×