Fuel In the Exhaust

[hclowey]

I have a 2000 Explorer XLT with a 4.0 SOHC and it just started running really rough with no power at low speed and had blueish/white smoke coming out of the tailpipe. My check engine light was on, so I took it and found out 1&2 cylenders are misfiring and banks 1&2 were running lean. I was told the first issue was due to spark plugs, so I changed them and it was still doing the same thing, so we reset the computer to see if the check engine light would come back on and it didn't (trying to see if any new codes come up). You can hear rattling around the injectors and I had fuel coming out every joint of my exahaust. I have looked thru the other tips, but since I don't know what would actually be causeing it, I don't know where to look. Have checked the oil, it is good, not milky or runny or low. Any ideas would be greatly appreciated!!

 

[CPUNeck]

It would really help you if you could find an older shop that still had a scope to test your ignition. Could be a couple wires have broken or burned through... maybe the ignition coil. The old fashion scope would tell you in a second if that spark (if it even exists) is making it down the wire and into the cylinder. In a pinch you could use a timing light to look for spark intensity. Sounds like you have one perhaps more plugs that should be SOAKED with fuel. Could start there.

 

[hclowey]

I looked at all my spark plugs and they all looked worn but good except for the top one on the passenger side closest to the radiator, it was not worn and had fuel on it. Did the old trick where you disconnect the spark plug wire and take the spark plug out, put it back in the boot (but I used one of the other spark plugs that looked worn since I KNEW they were working) , ground it out and bump the motor. Spark is getting to that plug, so not sure what the deal is.

 

[Dilbert5]

I looked at all my spark plugs and they all looked worn but good except for the top one on the passenger side closest to the radiator, it was not worn and had fuel on it. Did the old trick where you disconnect the spark plug wire and take the spark plug out, put it back in the boot (but I used one of the other spark plugs that looked worn since I KNEW they were working) , ground it out and bump the motor. Spark is getting to that plug, so not sure what the deal is.

Since you have spark, you need to check the injector, and compression. Which you check first is up to you. If you have a compression gauge available, that would be a good one to start with.

To check the injector, first use a mechanics stethoscope to listen to the injector while it is running. Compare the sound to another injector. If it is making similar sounds, the next step would be to swap injectors with a working cylinder. Just make sure that you check compression before trying to swap injectors. (you can substitute a screwdriver handle for a stethoscope).

 

[hclowey]

Thanks, I was just thinking about checking the compression. We did listen to the injectors and there is a ticking (best way I can describe it I guess) coming from around them, not sure what that means... you have to forgive me, I am used to dealing with 70's and 80's model vehicles, so this truck is teaching me alot! But, I love it. (even though I want to kick it every once in awhile)

 

[Dilbert5]

Injectors should make a ticking noise, that is the internal parts switching. Compare the sound to another injector that is running. What this means is that the ECU is switching the injector, and eliminates the electrical part of the injector (it is still possible that the injector is clogged).

So you need to check compression, if it is good, I would then swap the injector with another cylinder.

 

[CPUNeck]

I'm pretty sure that unless you have a broken valve or piston, SOME of the gas going into the affected cylinder would still burn. I wouldn't think you'd be getting liquid gas out of the exhaust unless there was no spark, or not at the right time. I'd think at this point, the plugs would be pretty fouled in that cylinder anyway. Just thinking out loud.

 

[Dilbert5]

If you had very low compression, the plug for that cylinder would be fouled. This could be a piston/ring problem, or valve problem. If the compression test showed low, you would add a teaspoon of oil to the cylinder, and re-check. If it goes up, the rings are the problem. if compression does not go up the next step would be to check valve clearance (at which point you would also inspect the valve train.