Car Diesels
- Thread starter TK_05
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bmorrisj
Member
sounds like fuel is somehow getting into the cylinders and detonating, you might want to check compression ratio on the heads ... what gas are you using?
thegabrielles
Member
Bad gas, timing to far advanced/retarded, since you have a fuel injected car I would not think it can be to much fuel.
Has it been doing it long? Or did it just start? Hopefully you just got some bad gas.
Has it been doing it long? Or did it just start? Hopefully you just got some bad gas.
IndyBlk5.0
New Member
do you have an electric fan? bad wiring could be the problem if so.. sounds like an ignition problem. correct me if im wrong, but what should happen when you turn off your key, it kills the injectors and coil... therefore you would get no spark, and no fuel. only way i can think of it running after key off is an ignition problem
makarov
New Member
What's the heat range on your spark plugs? Stock or hotter have a longer insulator and dissipate more slowly than a colder plug and shorter insulator. The hot plugs can stay hot enough to burn anything within reach in the combustion chamber, carbon, unburned fuel, etc. after the engine is shut off. The trick is to get the coldest plug you can without fouling. Most engine guys recommend a colder heat range for every step up in timing or boost. You don't mention an aftermarket ignition in your sig, but with an msd, crane, etc., you can run a colder plug because of the spark energy produced by the aftermarket boxes keeps the colder plug from fouling. Hope that helps, good luck.
makarov said:
i run some copper autolite plugs same heat range as stock... i dont see how that could cause it to diesel tho? the ignition is stock.. i got 24# injectors and converted to MAF...
sometimes ill turn it off and the car will shut off then spike back up then off again... i can even turn the key off then back to the on position and keep it running... i hate this car...
IndyBlk5.0
New Member
where is your fan pulling its juice from? if its tied to your coil any way at all it will keep the car running for a while by the fan turning and creating energy like an altenator, my car did this...
makarov
New Member
TK, you almost answered your own question. Stock ignition and stock plugs and running 12 to 14* of timing on a pretty well modded motor. Stick with the autolites, but go one range colder than stock as a start. If that doesn't work, try two ranges colder. It's a cheap fix, and I can just about guarantee that's your problem. And with your mod's, invest in an aftermarket ignition, if possible, and a fuel pressure gauge.
You might start by pulling some plugs. Look for damage on the ground strap and specks on the insulator (aluminum balls from the pistons), and if it's bright white, it's lean and hot. If you don't have one already, invest in a fuel pressure gauge, and adjust accordingly to get rid of the problem. I'd start with the plugs and then go to fuel pressure. You have to remember that you've done alot of performance mod's to the motor, so try to think beyond the stock plugs, fuel pressure and ignition. These are important upgrade items also. By the way, I'm not trying to rag on you, I'm just speaking from experience over the years.
You might start by pulling some plugs. Look for damage on the ground strap and specks on the insulator (aluminum balls from the pistons), and if it's bright white, it's lean and hot. If you don't have one already, invest in a fuel pressure gauge, and adjust accordingly to get rid of the problem. I'd start with the plugs and then go to fuel pressure. You have to remember that you've done alot of performance mod's to the motor, so try to think beyond the stock plugs, fuel pressure and ignition. These are important upgrade items also. By the way, I'm not trying to rag on you, I'm just speaking from experience over the years.
makarov said:
ok ill try that.. plugs are cheap... what should i set my fuel pressure at? i used to have a guage but i gave it away.. guess ill have to invest in a new one... the ignition will have to stay stock because im close to selling the car and dont want to put any big money parts into it... hope it something cheap thx for the info
IndyBlk5.0
New Member
If it diesels after you turn off the ignition switch, it is still getting fuel.
The computer shuts off the injectors, so one way for it to continue to get gas is if an injector is leaking.
The other path for fuel to get back into the intake is a leaking fuel pressure regulator. If the diaphram leaks, it will vent fuel back into the intake by the vacuum line
The computer shuts off the injectors, so one way for it to continue to get gas is if an injector is leaking.
The other path for fuel to get back into the intake is a leaking fuel pressure regulator. If the diaphram leaks, it will vent fuel back into the intake by the vacuum line
TK_05 said:
The fuel pressure regulator is easy - remove the vacuum hose from the regulator prior to shutting off the engine. If it is leaking past the diaphram, fuel will come out the vacuum port where you removed the line.
The injectors are harder, pull all the spark plugs and look for a plug that shows evidence of carbon fouling. The bad injector will usually make the spark plug insulator much darker than the other spark plugs. Replacing the defective injector with one from the junkyard is the fix. Cost is about $10 per injector where I live.
jrichker said:
i heard this for the injectors.. drive the car fairly hard... rev it up a little bit then shut it off before ruturning to idle... coast to a stop and check the plugs.. if any if them are wet then thats your problem.. could that work?
Icepick
Founding Member
as per Haynes, take it for what it's worth.
1. Idle speed to high
2. Electrical solenoid at side of carb (if equipped) not working properly
3. Ignition timing incorrectly adjusted
4. Thermo controlled air cleaner heat valve not operating properly
5. Excessive engine operating temperature. Probably causes of this are malfunctioning thermostat, clogged radiator, faulter water pump.
1. Idle speed to high
2. Electrical solenoid at side of carb (if equipped) not working properly
3. Ignition timing incorrectly adjusted
4. Thermo controlled air cleaner heat valve not operating properly
5. Excessive engine operating temperature. Probably causes of this are malfunctioning thermostat, clogged radiator, faulter water pump.
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