Engine continues when turned off!!

i have an 88 corolla. whenever the car has been driven for a while, when i turn it off the engine keeps going and starts to knock for like 10 seconds. i tried to losen the idle control screw where the accelerator cable is, and the less tense it is, the problem almost dissappears or is minimal. however, if the idle is set too slow, when the engine is cold, the car shakes and rattles a lot especially when put in reverse, or drive and if the AC is turned on..

any suggestions would be greatly appreciated


thnxx..

-frank

I had this problem a couple of years ago, with my '82 corolla. I didn't
take it to the mechanic until it got so bad that the engine would fire
for up to a minute after turning off the ignition. The mechanic said it
was just that the carburator needed cleaning, which he did for <$30.

Sounds like you're also due for a tune-up, i.e. adjust belts, carburator.

Hope that helps.

-Joe


i have an 88 corolla. whenever the car has been driven for a while, when i turn it off the engine keeps going and starts to knock for like 10 seconds. i tried to losen the idle control screw where the accelerator cable is, and the less tense it is, the problem almost dissappears or is minimal. however, if the idle is set too slow, when the engine is cold, the car shakes and rattles a lot especially when put in reverse, or drive and if the AC is turned on..

any suggestions would be greatly appreciated


thnxx..

-frank

This sounds like diezeling, its when there is left over combustion in the cylinders. Either that or detonation. either way you need to get it fixed- probably need to check your cooling systems. usually what happens is the o2 censors get screwed up. check those and your timing and youll have your problem fixed im sure.

My 86 will do the same thing if i accidently touch the gas after or while i shut the car off. Mine has a 2 barrel carb where is the 02 censor? if it has one.

Dieseling is caused by too high and idle speed or if the fuel mixture is ignitied by hot spots in the combustion chamber after the car has shut down.

I'm guessing you may have a vacuum leak which is causing you to have poor idle. I also agree with cleaning the carb as mentioned above.

A way to test for vacuum leaks is with small direct sprays of carb cleaners. Aim the cleaner away from the intake or filter to avoid the carb from sucking in the spray since this will mess up the test. When testing for leaks spray a little carb cleaner around the vacuum line connections and at the gasket between the intake manifold and cylinder head... also spray at the base of the carb. If there is a leak present the car cleaner will be sucked in and the ile will raise slightly and breifly, then fall bak down.

As fore mentioned, spraying into the carburetor will also have a simmilar effect so please avoid doing this.

If you have a PCV valve chek it to make sure it is working properly.

The reason most dieseling occurs in neglected carbed cars is that as the seals degrade and the carb gets dirty... the idle drops. So whoever works on the car does the Quick Fix and simply turns up the idle.

I've seen carbed cars with such a high idle setting that they are completely off the idle circuit and are basicly running off throttle... and becuase the carb is in such bad shape it still manages to idle low but very sporaticly and tends to stall.
anyways enough of my rant.

I'm thinking of ditching my 4A-FE for a 4A-F, just cause I miss carbs. :)

This sounds like diezeling, its when there is left over combustion in the cylinders. Either that or detonation. either way you need to get it fixed- probably need to check your cooling systems. usually what happens is the o2 censors get screwed up. check those and your timing and youll have your problem fixed im sure.


I agree too much ignition advance can cause dieseling.

I also agree if the coolant system isn't working or the fluid is low or oil is low then the engine may get hot enough to cause detonation, run-on, dieseling...

I'm not positive that the O2 sensor would cause the car to diesel all on it's own. Carbs should behave properly without one.

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Toyota like to use a device on their carburators called a Fuel Cut Off Solenoid. If it is stuck open it can cause dieseling which is what you described. You can replace them yourself in about 20 minutes to 1 hour depending on the quality of the work you wish to do. They are about $23.00 from any parts store. I recommend a little carb cleaner be shot in all the vacuum ports on the carburator and into the Fuel Cut Off Solenoid opening once you have removed the defective unit.