Please Help me with my Ranger!!!!

[bgass1421]

Ok, so no one has responded to my previous post because they think I have one of the old similar misfire problems, but I don't. I know a lot about cars and I have talked to several different mechanics and no one knows, please read below and I REALLY need advise!!!!!!!


Ok, so I have been chasing a misfire problem for about 4 months. Here's the deal. I have an intermittent misfire on cylinder #6 only. I have tried 3 different spark plugs, 3 sets of wires, a new coil pack, swapped injectors to see if the problem moved(nope), compression test (dry) read good. New fuel filter and oil changed regularly. Cleaned IACV and MAF. Can't find a vacuum leak. The misfire comes and goes. It hardly ever acts up on very cold days. On warmer days, after the engine is very warmed up, it acts up but ONLY at idle, when I drive the misfire stops, but as soon as I pull up to a stop light, VERY rough idle and misfire. The RPMs hold steady at 700. I have no idea what to do next!!!!!!!!!!!!!!!!!!! please someone help me. PS I have a 2002 Ford Ranger XLT 3.0L V6 145,000 miles

 

[corrond56]

probably not even close to what yours might be but check your TPS. my buddies jeep was throwing several different codes that had nothing to do with the TPS (his also said something about the cylinders) but on the forums he found people saying that it was actually a common code for the TPS going bad. He hooked up his OBDII software to it and he could see the throttle being off when at idle and WOT. Hope this helps some

 

[bgass1421]

Thanks for the advice. I will do this tomorrow evening and post an update.

 

[dbp]

Only two things I can think of that you haven't already done would be the wiring to #6 injector...and the PCM that obviously tells that injector to fire...a noid light could verify that it is getting the signal to fire at idle, not sure why it wouldn't be. Also not sure how *sensitive* that light is to see if it's getting full or partial voltage...sounds like if that were the case you'd have a dead miss...but I've seen weirder.

Your CEL doesn't flash when it misfires right, just turns on steady?

 

[snomaker321]

Ok, so no one has responded to my previous post because they think I have one of the old similar misfire problems, but I don't. I know a lot about cars and I have talked to several different mechanics and no one knows, please read below and I REALLY need advise!!!!!!!

nobody replied because we are all just as stumped as you are

 

[Big Jim M]

Could it be a small air leak into that cylinder? When cold the rich fuel and retarded timing covers it up... then when warm, lean and advanced shows up the extra air?
Big JIm

 

[bgass1421]

Hey guys thinks for trying to help! dbp- actually when at idle after sitting at a stop light for a while the CEL light will blink, then I will take off and it will go away. But sometimes it blinks when I stop, but when I go it turns solid, stop again it blinks, go=solid. Ok I found a new problem, my engine is using a LOT of coolant and there are no visible leaks.

 

[Big Jim M]

If there isn't coolant in the oil and there isn't excessive pressure puking the coolant out the overflow.. Then keep looking the leak is EXTERNAL!
Big JIm

 

[bgass1421]

Thanks for all the help big Jim. I did find the leak. It was actually my cap! I found this when I squeezed the upper radiator hose I heard air coming from the cap. I got a new one and no more coolant is leaking. The next think I thought the misfire could be is a possible head gasket leak. I did not see coolant in the oil, but I flushed out my coolant system and the coolant seemed to have a little oil in it. I decided that I might need to pull the heads but I was given advice from a mechanic that before I did that to try a head gasket repair chemical to see if it helps at all (not a permanent solution) just to see if I need to pull the head. Well I did that. It did not help at all. Problem is still the same but my coolant is not leaking anymore. OH and I changed out the spark plug. Still misfire same cylinder. But one thing I notice is that #6 misfires, #4 and #5 don't but the spark of those seems to be weaker than #'s 1-3

 

[Big Jim M]

Just for the hell of it why not call Ford and find the EXACT Motorcraft spark plug for your engine and then get a set of them...EVEN if you have to order them form a particular parts house.. We know those will work as designed.
As for a spark SEEMS to be more here and less there.. Just forget you ever thought that! Sparks build up till enough voltage is there to jump the gap provided.. You have no way of visually inspecting the difference between sparks. ANY spark will lite up the fire..
Big JIm

 

[bgass1421]

Yes, I have gotten a set of the motorcraft spark plugs for my vehicle from advance and no change.

 

[bgass1421]

okay, now when i pull to a stop, the check engine light is blinking, goes solid when i pull away.

 

[TomB1269]

Have you run a full anylizer on it? Any engine codes? You are getting CELs................

 

[bgass1421]

my only CEL is a po306 cylinder 6 misfire. compression checked ok. went through 4 plugs, 3 wires.

 

[Big Jim M]

Tells it's own story!

my only CEL is a po306 cylinder 6 misfire. compression checked ok. went through 4 plugs, 3 wires.

Can't think of anything else it could be.. ONLY an air leak. AND it is very near that one cylinder.. Could be exhaust manifold or intake manifold.. OR even a crack in either of them.
Spark plugs only melt from too much heat! Too much heat can only be too much air!
Big JIm