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Q: rough idle . excessve fuel at cyl 4 (2.0 eng).tons of smoke from tailpipe on 1993 Ford Probe

already replaced fuel injector and fuel pressure regulator , timing belt new, plugs ,wires and cap new .compression good approx 170-180 at all 4 cyls
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Maybe it aint fuel in #4,, possible coolant! Excessive fuel should produce BLACK smoke. Is that the color you get? Yeah, i see the compression readings! Check for injector 'pulse' signal with a noid light.
It is mixed with gas! Been loosing coolant? It is possible it's gas. But the white smoke usually indicates coolant burning in the chamber. Hold a piece of cardboard in front of the cyl with plug out, see what comes out. Coolant should bead, gas wont!
no coolant loss. are you thinking blown headgasket? I have never overheated it . lots of miles though .wouldnt the compression be low in cyl 4.thank-you for all the help
Not necessarily. Coolant/water doesn't compress and will hold the compression, unless the system is empty or radiator cap is removed. Then the compression will show up. Do the cardboard test i suggested. Can be checked with chemical, it's called a combustion leak test.
I will recheck the smoke color to be sure. Is sure is stinky.I will also test the connector with a noid light .
thank-you so much.
You bet, read suggestions again, i type slow! Plus i come up with more ideas after posting. Let us know what you find.
I sure will reply with more results and once again i thank you , Merry chrismas!!!
Hello again .Well i checked injectors with a noid light as you suggested. Clys 1,2,3 flash = normal oper.
At cly 4 the noid light stay on with no flash. checked connector and wire to connector = ok .
Is it possibly the pcm ? Any other checks i can do . Thanks again
That's the problem! It is most likely the #4 injector driver circuit in the pcm. Check the wires going to that injector to be sure they are not damaged. If not replace pcm. I was trying to think of a way to piggyback off of another injector circuit but haven't decided yet. Oh, that is the reason for all the gas in that cyl, injector is stuck open and shooting gas into it. Enough gas will cause white smoke from exhaust!! I will let you know if i can come up with a bypass. I have done it before on the V/8 engines and it works great, but i have not tried a 4 cyl. Not as many choices on the 4. Wait until tomorrow.
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