The car won't stop...

CAR ALARM??

Wow, I had that happen with my first car, it was a 1967 Old's Cutless, and it didn't even have a car alarm. Do you think the mechanic is looking for her to turn the alarm off so he can steal the car?

I don't remember what I did to fix my old car, but I could walk across the street and it would still be running. And there I was with the keys in my hand. I think I just gave it a tune up, you know, new plugs, wires, cap, and oh yea, and adjusted the timing.

I know what you're saying but I really don't know what the guy would want with an old Grand Prix. If I remember right, they had the first generation (series I) V6 and were plagued with "pinging" problems among other things...

I also think it is a timing issue.

Thanks for the response...

Ditto! Plus...

She would have to remove it? This inquiry boils down to:

Get a new mechanic.

It happened quite a lot with older cars ±1960.

It was mostly caused by a valve in the carburetor that do not close and the petrol fumes gets ignited by the heat and pressure. (a sort of diesel effect)

Check your weiring and connectors to the carburetor.

Hi Hendrik,

The 1993 Grand Prix is fuel injected; surely the same principal wouldn't apply, right?

I don't know but injector problems can do the same.

I had a 197? VW (412 or 212?) with air cooled fuel injection that did it.

A mechanical fuel pump is a must.

The little bit of fuel coming through is barely enough to keep it running and usually cannot power the wheels. What I did was to attempt to pull away - that usually stopped it)

Unless I'm mistaken, it has also an electric in-tank fuel pump (but I will check to make sure). I remember seeing that on an old VW beetle. Those older cars were a lot easier to deal with, though...they were missing a lot of the sensors and electronic gadgets...purely functional...

The gadgets thy tried out were usually the big cause of problems, but I suppose the industry had to go through a learning curve.

I don't what type of pump it had, It just seemed logical that the fuel is needed to keep going. maybe the fuel in the line were enough.

The little bit of fuel coming through is barely enough to keep it running and usually cannot power the wheels. What I did was to attempt to pull away - that usually stopped it)

Putting the car in gear and letting out the clutch, or putting it into ANY gear (Neutral & Park aren't actually gears!) and attempting to move will usually stall out a Dieseling engine; this is considered the simple & safe way to handle the problem. Not all automatics will let you shift with ignition off, though. Listen to "Car Talk" radio show; last week's show included "Got carbon? Kate sure does-- her Chevy Nova is filled to the gills with the stuff. Find out why her repair might require a search for a toothless, bald mechanic." (Because she needs a mechanic old enough to be familiar with carburetors). Available at http://cartalk.com/menus/show.html for your listening pleasure.

Sometimes, just hitting the gas pedal is enough to stall a Dieseling engine, regardless of type of transmission or whether it's in gear.

The use of fuel injectors eliminated most of the dieseling in cars. The dieseling is due to improper timing. I suspect you have bad injectors that are leaking. The engine is dieseling until fuel line pressure bleed down. Pressure to the injectors is regulated. Fuel pump pressure greater that regulated pressure. So there is a check valve holding the pressure.

Possibly...but remember that dieseling is a result of spontaneous combustion as opposed to sparked combustion. Whether the injectors are leaky or not (that is, if residual fuel circuit pressure is being bled to the rail), we must ask, why ignition after ignition primary cut-off. And we must suspect (in addition to surplus fuel in chamber--possibly from over-rich mixture) either overheating of combustion chamber components (the chamber itself or the valves) or overcompression inside the chamber (as a result of deposits), or an ignition source in the chamber (possibly metalic particle from plugs or elsewhere. On a car this age, all are not unlikely.

If overcompression, engine vacuuming might be in order.

Timing could also be a factor.

Best recommendation would be a new "mechanic" (not one who doesn't know how to disable the alarm for diagnostics), preferably at a shop skilled in emission systems.

This problem almost certainly requires a full engine diagnostic due to the age of the vehicle.

Continuing to run after the ignition is turned off is usually caused by carbon deposits on the valves or the top of the piston. The deposits are heated up by the burning fuel and stay hot long enough to ignite the fuel without a spark the next time fuel enters the cylinder. This is commonly called dieseling. Each time the fuel ignites it heats the carbon up again. It can also be caused by the engine running too lean and hot, or incorrect timing. http://en.wikipedia.org/wiki/Dieseling

I feel the problem is , the car being some 15 years old and must have clocked some miles and this probaly has resulted in carbon accumulation in the cylinders, causing sustained after-burning in the chambers .

The solution is to have the de-carbonisation done( removal/cleaning of accumalated carbon in the cylinders and may be have it machined too for new set of Pistons ) . All this, if she still wants to keep the same car, since the process might cost as much as a used car which is rather better maintained. Hope this helps !

Radirs, Bangalore, India.

Give the engine and injection system a good service, use a good quality injector cleaner, then take the car for a looooooooong run. with a bit of luck, and this particular engine being fairly low tec, you should clear a lot of the carbon deposits. In my experience, it's 'high' points on the deposits, creating a hot spot, that cause the problem.

The VW -(station wagon) were bought second hand for a specific requirement at that time. (I think it was sold because of the problem).

It only showed up after traveling for a longer period.

carbon - I forgot about that. 30 years is a long time for an old brain.

About vintage cars - I wish I had enough space and money available at that time. I would have had a nice collection by now. Most of the cars I had is collectors items by now.

I agree about the problem being carbon build-up, but it may be worth trying to "clear" it out before doing an engine strip. Find a long ( private obviously) straight piece of road, uphill even better, and thrash it within an inch if it's life. In the past this has worked with varying degrees of sucess, but sustained high revs usually produce a nice firework effect out of the exhaust a night.

replace the fuel pump relay. its sticking. chances are the fuel pump is about to quit working. amp overload or a bad ground to fuel pump or relay. if you have a 130k on the car, its time for a fuel pump and relay.

Hey guys,try this troubleshooting procedure..alarm system has a ignition cut off relay,try to replace it or locate the ignition wire from the relay and directly connect it,bypass the relay, and then try to start and stop the engine,if it works then replace the relay. I hope this may help.

I have found stuck EGR valve will cause detonation, as well as several stated explanations above.

It has been my experience the alarm will not allow the car to start, when the relay goes, not the other way around.

Here is what some folks recommend, (please pardon the terminology):

2.5 to 3 cups distilled waterYou can use tap or bottled water if that is not available, if you are working alone the ideal container will easily stand up on it's own, not a plastic soda/water bottle. Suggest: 1 qt mayo jar / Mason jar / spaghetti sauce jar.1 can of SeaFoam (16 oz) *click for pic*2 to 2.5 feet of small vacuum line, 4mm (5/32")Procedure:Preheat the oven: Always start with a fully warmed up engine that has been running, preferably driven, for at least 20 minutes. Then park where you will be up wind of the car's exhaust, leave it running, or turn it off, but don't leave it off for long.Locate a suitable vacuum port and connect your vacuum line, this will be a small nipple, around 4mm in size with good vacuum at idle, where possible down stream of the throttle body. Do not use any large ports such as for the brake booster *click for pics*(Assuming your are working by yourself) Place the jar of water where it will stand on it's own, hold the throttle around 3000 RPM, best guess, and with the other dip the vacuum hose into the water. Use a rhythm where the hose is submerged for 1/2 second, and lifted out of the fluid for 1/2 second, repeated until all of the water is used up, while at the same time regulate the throttle to keep the engine speed around 3000 RPM as it will run rough.Repeat using the SeaFoam. I recommend using an entire can for this, others have reported good results using between 1/3 to 3/4 of a can, then putting the remainder in the gas tank. During this process, Turbo cars seem to like to leak at the manifold, either between the head and manifold or between the manifold/turbo junctions...don't worry...it will seal back up after you run the car for a while.It is recommended, but not required, that toward the end of the process you allow the engine to stall. This is done by dropping the throttle, leaving the vacuum line submerged in the SeaFoam, and allowing the engine to stall. An alternative and possibly better method may be to drop the throttle and immediately pull the hot wire off the (+) #15 terminal of the ignition coil, or if you have a helper, switch off the ignition. Then let it sit for 5 to 10 minutes. Then crank it up, and finish feeding in the remaining SeaFoam.Then right away take the car out for a rev fest, here you want the tachometer to reach red-line several times, stay in low gears. You should immediately notice the improvement in power.Optionally you could run another can of SeaFoam in the tank, and then if you are planning to change the oil, wait until after the tank is run down, reason being most fuel injection cleaners run through the tank will tend to darken otherwise clean looking motor oil.As for SeaFoam substitutes:You want to use a product specifically designed to be fed through the intake manifold, they are commonly known as top engine cleaners, it must be oxygen sensor safe, which SeaFoam is. GM makes a top engine cleaner, Mazda does too, these are designed to be fed into the intake manifold just as this procedure describes and should produce similar results. Another alternative that I know of would be Lubro Moly "Ventil Sauber Valve Clean". I do not recommend using Barymans Chemtool (B12) or any other carburettor cleaner. I recommend using SeaFoam wherever possible.

Additional information can be found here: http://www.seafoamsales.com/

Use this data at your own risk. It worked for me, I just passed emissions with a known oil burner.

I would be certain there is no sludging under the valve cover, if you can take a peek under there, first. You cannot clean the EGR if it is going to just suck more sludge from the valve train, all over again. Bad fan relay, or not changing the oil is a known cause of sludging.

May be time for a new Catalytic converter, as well. Post detonation can occur through reverse engine stroke when the cat is bad or molten hot. Especially if the EGR has caused carbon to keep the exhaust valves open. Possibly back to a bad cat...

Wow. I remember doing something similar with an old Mustang I used to have... Dropping a glass of water in the carburetor while revving the engine would clean up all the gunk from the engine and make it run like new . I just didn't think (never had too, I guess) that it could be done on a fuel injected.

Thanks. I'll do some research on that...sounds promising.

Rick - You are absolutely right! One of the best ways to clean out the carbon deposits was to rev up the engine to about 3000 rpm and add water to the intake. You had to be careful not to add too much at one time and stall the engine then watch the white steam billow out the exhaust. I think a water spray bottle would work as well. I can't remember for sure why this works so well, may be the thermal shock of the water to steam transition, but It sure worked well on my 57 Chev's 283 CID.

Working with older cars would attract older mechanics with all their tricks to get around problems. I've learned a lot from mechanics that were initially just attracted to the memories the car would bring them. Then you start talking about this and that and before you know it, they're under the hood showing you how to properly adjust the four-barrel carburetor...hit the fridge to grab a beer or two and you have a neighborhood party in no time....

Sadly, I went away from all that and now I just want to drive something reliable and not worry about the performance tune-ups and all. My time is more dedicated to home-projects and machine building (homemade CNC in the works).

Cheers,

Man, you are certainly correct about not adding too much! I wouldn't worry about stalling the engine as I would be about blowing it up. Water does not compress too well and it sure ain't gonna combust.

Kyoto- the trick is not to add too much and ahve a high enough flow rate to keep the liquid drops very very small. They vaporize in the cylynder. A slug of water would not be a good thing I agree.

Will anyone who has bent a rod buy going through a ford too fast please raise a paw!

Meooooow .

I took the plugs out, turned it over...a nice jet of water shot out of one plug hole. Put the plugs back...it fired up fine...just sounded like a diesel!

I sold it shortly after.

If you weren't so far, I would have thought I bought that car !!! I owned a few Fords (relatively cheap for a student) and one of them sounded like that...hmmm

bad kitty.......baaaad kitty...

Were you in the USA, you could just shoot it through the cylinder block with your Magnum...that should stop it.

In England we have the opposite problem with old cars...they don't START !

(I think the guys have covered the real answers already...I couldn't resist the image of stepping out and shooting the poor thing!)

Thank you all for your responses; I knew I could count on you. The carbon deposit will probably be the one I would investigate first since she does a lot of city driving and barely ever takes the car on the "open road".

You guys are great.

Oh, and Del: the car is in Canada but I could always find a hunter friend to lend me his riffle if all else fails...

I 'll let you know how it goes....

Hi, I had a similar problem in the 50's and it turned out to be the timing.

If I remember right it was firing after tdc (or something like that) and

you could actually pull out the ignition key and the car would still keep going!

Doing the easiest things first is recommended; i.e. not stripping the engine,
but getting the timing spot on first. (bet that cures it)

Strangly, if the alarm was "wired" incorrectly, eg to by-pass the ignition,????
(but then you'd never stop it!) Not so in my case with no alarms in the 50's!

jt.

http://www.fastfreeads.com

I rewired an old truck with burned wiring. Not having done this before, I ran a hot lead from the battery to a switch, then T-d off the switch to the electric cooling fan and also to the distributor power terminal. Turning the switch off would kill power to both the distributor and the electric fan, thus killing the engine. Or so I thought. I killed the switch and the engine kept running for a while before it would quit. The reason was that the fan motor turned into a generator when the power was removed. The fan free-wheeled for a short while which produced a current which back-fed to the distributor causing the engine to keep running. Since the electric fan had no power to it, it would eventually stop turning, and the engine with it.

Likewise, if your wiring from your alternator is messed up, the engine can run off the alternator continuously with the battery power disconnected. It might be that when they installed the burglar alarm, they somehow inadvertantly caused the distributor or ignition system to remain energized even with the key switch off. Not sure about 93, my old truck is an 84 with all the old stuff, conventional ignition, no computer, no smog, no problems. You can have anything made after 84 or so. Good luck.

Main reason for detonation (car running after it is turned off) is the fuel quality being used.

Here in Canada, you can get all the way down to 89 octane. My suggestion is follow PLbMak's suggestions and also completely fill the tank with a high grade octane fuel. 94 octane is the highest commerically available in Canada. This along with the fuel injection cleaner will "burn" out all the junk left behind from the lower grade gas you have probably been using.

Good Luck

Thanks unclefastguy,

I read all the posts this am and kinda went through them fast so "missed" (sorry PLbMak) a couple of points. Everything seems to be pointing towards carbon build up (bad fuel would contribute to this) so I will print the whole thread and bring it to her. She will also take the advise on "find a new mechanic".

I'll let you guys know....

I have read the different replies to the problem. First of all - I take it you have a gasoline engine. No one has mentioned the fuel as a possible cause to the problem. If the octane number is too low - a warm gasoline engine might run as a Diesel engine. Combustion chambers with sharp edges combined with low octane number are known as cause for gasoline engine running after the ignition is turned off.

PS. You will have to excause if the language is incorrect. The English lanuage is not my native tounge.

lean-burn technology ended by the catalytic converter produced a similar problem of running-on. the lean mixture burned hotter causing the engine to diesel or self ignite after the spark plugs had stopped sparking. it was solved by an in-line solenoid valve in the fuel line. Using this analogy it could be mixture - or it's probably just carbon build up.

If it's pre-ignition (dieseling) It needs fuel to happen. Being fuel injection, this may have leaking injectors.

If the engine is actually running, there has been some known inferior ignition switches for this era of GM cars.

It sounds like desieling, but without a carb. If the gas miliage is poor, you may have leaky injectors. To keep running there needs to be a fuel source.

There are companies that clean carbon out of cylinders with a nozzle that shoots finely ground cashew or walnut nut shells into the plug hole. There is enough space left so the used shells and carbon come out the annular space.

Drill this:-

http://www.google.com/search?hl=en&q=%22engine+cleaning%22+%2Bshells&btnG=Search

At last a use for all those damned nut shells after Xmas !

Thanks Aurizon,

I'll pass the info along...

regards,

R.

Hello,

Since there are common causes, i.e. improper timing, air/fuel ratio, et cetera, I would have thought someone out there who has troubleshooting sense would just create a flow chart to identify the problem the most efficient way possible to minimize the repair costs for this woman. Jeez, by the time you guys get done "fixing" her car, should should have bought a new one, all because of a minor issue that wasn't managed properly !

My quote: The dumber you are, the dumber you get.

Redex engine cleaner http://www.honeywell.com.au/business/holts/redex/ref.html does a gradual decoke if you add it to your fuel. Should improve things slowly.

Thanks,

I'll give that a try in my own car (190000 Km)...and counting

Had similar problem with older Firebird(Not fuel injected)- Higher octane fuel (88-90+) solved the issue, of course back at the time I could not afford to always buy the higher octane, so I learned to live with it, releasing the clutch, in gear - stalling the engine.

Mevel 123.

To use lower octane than recommended in the engine manual is a risky business. The fuel ignition dosn't start at correct time, and the resulting engine knoking is known to be a common cause for destroying the crankshaft bearings.