Dieseling?

[gohan69]

I have the 85 with the 2.2 2bl and the car is is dieseling and running really rich and getting bad mileage i have already done a basic tune up what else could i do to fix these problems

[dodgeariesguy]

Well with some experience here I can tell you a few things that cause dieseling (same stuff i posted to Wikipedia):
-Built-up carbon in the ignition chamber can glow red after the engine is off, providing a mechanism for sparking unburnt fuel. Such a thing can happen when the engine runs very rich, depositing unspent fuel and particles on the pistons and valves. Similarly, non-smooth metal regions within the piston chamber can cause this same problem, since they can glow red. It has also been suggested that an improperly rated spark plug can retain heat and cause the same problem.
-A carburetor that does not close entirely can contribute to running once the engine is off, since the extra fuel and oxygen mixture can combust easily in the warm piston chamber. Similarly, hot vaporized oil gases from the engine crankcase can provide ample fuel for dieseling.
Incorrect timing.
-An engine that runs too hot or too lean may produce an environment conducive to allowing unspent fuel to combust.
-An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running
If you need more from me ask! Love helping!

[dodgeariesguy]

Some remedies would be these:
Items similar to carburetor cleaners and carbon cleaners have been suggested as partial remedies for attempting to clean the piston chambers and valves of engines that run too rich.

For those engines that have sharp metallic edges, it has been noted that poorly milled heads and blocks can contribute to this problem, so having the rough spots smoothed may help.

For those engines that run too hot or too lean, verify that all mechanisms in place to cool the engine properly function as they should. Replace the thermostat if necessary. Clean the radiator. Verify that all auxiliary fans engage at their proper temperatures, and ensure that the thermostatic sensors on belt driven fans engage as necessary.

In the case that there is too much angular momentum, lower the idle speed if possible.

[turbokcar]

Try 1 tank of good gas 91 octane, I once had a 2.2 carb engine that dieseled, and I was told to run good gas and the problem went away for a while. and make sure the idle is not set up to high.

[kent_vollans]

I have the 2.2 in my lil reliant, and I just put a head gasket in to solve a cold start problem. . . Where it got fun was timing the lil bugger, but trust me it makes a whole world of a diference. If im not mistaken you should be running 12degrees advance, check that though, im not posative on it (Check on the underside of the hood, it should say). I had the same problem and now she runs like a champ. Oh ya and if you happened to replace the timing belt, or pulled it off for some reason and you skipped a tooth, there should be enough give in the distributer to corect for that, though I do recomend setting the camshaft timing if it turns out that you skipped a tooth (just makes life easier). Also check your sensors, notably your O2 sensor, if your running rich, its either dead, or its going to be poisened pretty good.
Let me know if this helps you at all.
Cheers,
Kent

[kent_vollans]

Oh ya, and make sure, if you do time it, to unplug the electric fan, it should plug in by the thermostat housing (where the rad hose meets the engine) and plug it back in to reset the loop.
Cheers,
Kent