Cyl 1 misfire up to 2000RPM

[dasfinc]

the title pretty much describes it,

I have a 2000 4.0 OHV 4X4 with 152K on it, and it is throwing a CEL for Cyl1 misfire.

I replaced the plugs and wires, cleaned the MAF, MAF Plug, Coil pack, Coil pack plug, and it still hasn't gone away.

2 other things I've noticed, that I am unsure if they are related or not,

1) The truck smells a bit 'sulfury' but I just replaced brake pads and bearing and haven't gotten around to replacing the warped rotor yet, but the smell seems to come from the opposite side of the truck *pass side is the smell, driver side front is the new pads*

2) Also, the Both cats make ALOT of crackling/pinging sounds after I turn the truck off (pass side of truck also), I know it will ping a bit, but its sizzling inside of both of them, which seems unusual.

Suggestions? Can a single cyl be impacted with a failing coil? Can clogged cats cause a miss JUST below 2000RPM?

 

[srteach]

1) When a cat is plugged, you will get a sulfur smell from the exhaust (most of the time), and may create back pressure that can cause misfires in any or all cylinders at any RPM. The back pressure can push the sulfur smell through previously unknown gaps in the exhaust system.

2) The catalytic converter uses heat (in excess o 500F) and chemical reactions to clean the exhaust. When you allow some metals to cool, they can ping as they cool. The noise is normal.

I believe there is a coil on each plug / cylinder pair. Yes, one cylinder COULD be affected. Not will be, but COULD be.
PS - There is only one cat on the ranger with a stock exhaust. The other cat looking thing is a resonator chamber.

 

[dasfinc]

1) When a cat is plugged, you will get a sulfur smell from the exhaust (most of the time), and may create back pressure that can cause misfires in any or all cylinders at any RPM. The back pressure can push the sulfur smell through previously unknown gaps in the exhaust system.

2) The catalytic converter uses heat (in excess o 500F) and chemical reactions to clean the exhaust. When you allow some metals to cool, they can ping as they cool. The noise is normal.

I believe there is a coil on each plug / cylinder pair. Yes, one cylinder COULD be affected. Not will be, but COULD be.
PS - There is only one cat on the ranger with a stock exhaust. The other cat looking thing is a resonator chamber.

I know what the 'pinging' sound is, but this it sounds like I poored a package of pop-rocks into a cup of water, not just an occasional 'Pop/Ping' sound

I found out that there are 3 coils, *3 pairs of 2*, but it all tested good regardless

Thank you for the input I'm like 99% sure its the cat/cats *I could have sworn I saw one on either side of the Y-pipe for my 4.0....?

 

[dasfinc]

With the cat cut-off, it idles smooth *Albeit crazy loud* and feels a bit stronger, no more sulfur, but still has a mis... Last step will be replacing that injector and praying it didn't suck a valve.

 

[Big Jim M]

Yep!

With the cat cut-off, it idles smooth *Albeit crazy loud* and feels a bit stronger, no more sulfur, but still has a mis... Last step will be replacing that injector and praying it didn't suck a valve.

The only "stuck" valves I ever saw were BENT from the piston hitting them. Sounds to me like a burnt valve or bad injector. In either case it misses all the time but high revs cover the miss so you can't tell it is missing.
Big JIm

 

[dasfinc]

The only "stuck" valves I ever saw were BENT from the piston hitting them. Sounds to me like a burnt valve or bad injector. In either case it misses all the time but high revs cover the miss so you can't tell it is missing.
Big JIm

I replaced the injector with no love, and what other side-effects are there from a burnt valve? Wouldn't it be burning some oil? That spark plug is CLEAAAAAAN

I'm almost thinking the coil is still bad, and that even though it tested good that something else is wrong with it

I'll compression test it as soon as I have a moment too.

 

[Big Jim M]

Yeah

I replaced the injector with no love, and what other side-effects are there from a burnt valve? Wouldn't it be burning some oil? That spark plug is CLEAAAAAAN

I'm almost thinking the coil is still bad, and that even though it tested good that something else is wrong with it

I'll compression test it as soon as I have a moment too.

I'd start with swapping coils just to make sure. If that don't do it then a compression check will tell you if a burnt valve or a cam lobe worn or what ever..
Doncha just hate to have a missing engine?
Big JIm

 

[dasfinc]

I'd start with swapping coils just to make sure. If that don't do it then a compression check will tell you if a burnt valve or a cam lobe worn or what ever..
Doncha just hate to have a missing engine?
Big JIm

I'd rather not drop $75 on a new coil if its not going to forsure fix my problem since I've already dropped $150 in new gaskets/seals/plugs/wires/oilchange and the new injector...

 

[Big Jim M]

IF!!

I'd rather not drop $75 on a new coil if its not going to forsure fix my problem since I've already dropped $150 in new gaskets/seals/plugs/wires/oilchange and the new injector...

If that engine has more than ONE COIL... swap positions to see if the new position causes a miss THERE!
Big JIm

 

[dasfinc]

If that engine has more than ONE COIL... swap positions to see if the new position causes a miss THERE!
Big JIm

The coil 'pack' is unfortunately one unit with 3 separate coils internally.

There are 2 tests, one test for the 'primary coil', and then another for the 'secondary coils', of which there are 3. Everything was within spec as far as ohm's were concerned.

 

[dasfinc]

Any more ideas/love guys?

 

[Big Jim M]

Next!

Any more ideas/love guys?

Nope a burnt valve don't add to oil loss. So if you have a good wire from the coil to the plug and the plug is good and you have swapped in a new injector..
NOW your miss comes down to a worn cam lobe, a bad lifter or most likely a burnt valve.
SO now it is time to do a compression check to verify a loss of compression on that cylinder.
Big JIm

 

[dasfinc]

Nope a burnt valve don't add to oil loss. So if you have a good wire from the coil to the plug and the plug is good and you have swapped in a new injector..
NOW your miss comes down to a worn cam lobe, a bad lifter or most likely a burnt valve.
SO now it is time to do a compression check to verify a loss of compression on that cylinder.
Big JIm

I still find it hard to believe any of those things because the problem came on 'suddenly' after it had sat for a period of about 3 months...

I'm almost thinking I should check the harness wires for mouse bite marks....

 

[dasfinc]

Thank christ....

Vac test passed, Compression is good, Replaced the coil pack out of futility, and that fixed it.