Cylinder 1 misfire when accelerating, 06 Ranger 2.3L

Phatty · #1 12-09-2012, 08:22 PM

Hello,

I would like some suggestions on what to do about my misfiring 2006 ranger 4x2 2.3L reg cab with 109000 miles.

I noticed 2 months ago that while accelerating in any gear, my truck would sometimes buck and jerk, most noticeably happening from a dead stop to first gear or while accelerating in overdrive. I assumed it was an engine misfire and about 3 days after I noticed the misfiring, the computer threw a P0301 code (misfire cylinder 1).

I have the factory workshop books including the PCM book, which outlines what steps to go through when diagnosing a P0301 code. So here is what I have done so far:

1. Checked that I had spark to all cylinders using a spark plug/wire pen tester. I held the tester next to each plug wire and saw that the spark was constant and bright on all wires.

2. Changed all four spark plugs and spark plug wires. The plugs were only about six months old and not in bad condition at all when I inspected them upon removal, but because these parts are cheap I replaced them anyway. I gapped new NGK's and installed them. This had a slight improvement in my idle but the misfire was still there when accelerating.

3. I checked the resistance of the coil pack, and found it to be within spec. The 06 ranger 2.3L has cylinders 1 & 4 on the same coil and 2 & 3 on the other. The resistances were the same when measuring the ohm's between the 1 & 4 tower and the 2 & 3 tower.

It looked like the ignition system was working so the book told me to go on to fuel delivery. I could not check the injector PID's cause the scanner I was using couldn't read them, but no other error codes, KOEO, or KOER codes were present.

First I put a bottle of STP injector cleaner in the gas tank and saw no improvement, then tried a bottle of rislone engine treatment to no avail.

I thought it may be the No. 1 injector so I replaced it with a new one, and also installed a new intake manifold gasket set and new O-rings on all 4 injectors. While the intake manifold was off, I didn't see any buildup on the intake valves except some minor buildup on the No. 3 cylinder valve. When the engine was back together it seemed to run smoother but the misfire quickly returned.

Keep in mind I had disconnected the battery to change out the injector so the code was erased and hadn't come back on after I had begun driving on the new injector.The car then threw the P0301 and a P0316 code. The scanner was able to run a Test $53 which counts the misfire on every cylinder even before the computer will throw a P03xx code and it had only registered misfires on cylinder 1.

I ran a compression test today and found that cylinder 1 has a dry compression of about 185 psi, while the other 3 have a dry compression of 200 psi. When I tried a wet compression on cylinder 1, it was about 210 psi, and when I did a wet compression on the other 3 cylinders they went up to about 210 psi as well. Since the lowest cylinder compression reading is within 75% of the other cylinders, the book says that it is in spec but obviously something is wrong with cylinder 1.

This would seem to indicate worn piston rings on cylinder 1 but I just didn't think that rings would go bad on just one cylinder, or that a compression difference of 15 psi would cause a misfire. I was hoping for the psi to remain the same on the wet compression test so that I could consider the valves as a possible culprit. The truck doesn't burn oil, has had regular oil changes every 4,000 miles since I bought the truck in 2007, and has never overheated. I have also used a bottle of sea foam in thirds (some in vacuum line, crankcase, and gas tank) in the hopes it would free a stuck ring but so far nothing.

I have read about valve recession happening on 04-07 rangers with the 3.0 Vulcan engine, but is it possible that this problem is also shared with 2006 2.3L rangers?

Should I tear the engine apart and replace all the rings on every cylinder? Are the valves possibly to blame? I am going to perform a cylinder leak down test when I have time this week, but if anyone has had any experience with this problem, help would be greatly appreciated.

Thanks

Phatty · #2 01-08-2013, 03:15 PM

Well I was hoping for at least one reply out of 120 views...

I completed an engine leak down test today, and the results are not what I had expected. This problem is very strange.

The problem cylinder (#1) had about a 12-15% leak, and the only escaping air I could detect was out of the oil filler cap. I did the test twice and got the same reading. I had expected a much larger leakage of about 40% to confirm my suspicion of a broken or stuck piston ring being the culprit, but only 15%!! That's almost expected because there is usually always a small leak past the piston rings, evident out of the oil filler cap.

I ran a leak down test on the #2 cylinder just to see what it was, and I got a reading of 15-18%! Keep in mind there is only a misfire on cylinder #1.

My misfire still appears when accelerating from a stop or if I accelerate quickly from a constant speed. I need ideas for other tests I can perform to pinpoint something that may be wrong.

On a side note, I was calling around to Ford dealerships to get an idea of how much the a piston ring set would cost when I ran into something weird- You can't order the piston rings, connecting rods, or piston heads from Ford dealerships for a 06 ford ranger with a 2.3L engine. Their service department instructions tell them to recommend a new short block, even if you only want rings. There are not even instructions to perform a piston ring change in my ford factory workshop manual for the 2.3L engine, but there ARE instructions for doing this on the 3.0L and 4.0L in the same book. I do have instructions on how to take basically everything else off, so this wont be a problem but I find it weird.

PorKChoP13 · #3 01-08-2013, 04:27 PM

I do not know how to help you fix your problem but i would just like to say if you are using a workshop manual similar to mine, i feel your pain my book says the same thing. Ford does not sell any of those parts you are correct there. Im in the sidle of rebuilding my 2005 i found all the parts to rebuild it rods pistons rings oversize bearing ect. but when i went to put the bottom end back together i couldnt find the torq specs for the main and rods i called the dealership, ford themselves, looked in my hanes book, and my Ford workshop manual. I found nothing, Ford told me that it was a NON-Rebuildable engine. So right now parts alone im in the hole 1100 for a NON-Rebuildable engine. I did manage to find the specs today though i was able to get them from a engine shop today. Im hoping they are correct Main-63ftlbs thrust last, Con Rods-26 ftlbs+ 90 degrees. So i feel your pain right now, and i hope you are able to fix your problem without having to replace it all.
Dustin

Ranger_EDGE · #4 01-08-2013, 04:38 PM

you could still have a bad plug. just because you replaced it dosent mean its fixed. i had a miss in my lightning for over a month under load and i did plugs also once i got a miss. so i thought it was my 8 coils since thats a sign of a bad coil so i replaced them all. still missed so i put in new plugs again and it fixed the miss. my ranger had a miss under load only and i thought it was plugs. turned out to be a coil pack. did you test your coil pack at idle then gave it some r's? if so thats not a true reading of the coil pack. you would need to put a load on it.

Phatty · #5 01-09-2013, 03:20 PM

Porkchop13, yeah the factory service manual is awesome in the depth it goes into for almost all components of the truck but leaving out information about critical engine parts is a little ridiculous. I find it laughable that the dealerships categorize these engines as 'non-repairable' when it comes to major engine repairs, but there are always ways to do these things and online parts suppliers are great.

I started looking back at the ignition system, and I used one of those pen style spark testers that you hold next to the spark plug wire and you can see a spark jump inside the pen. I found that when held to the No.1 wire and with the engine at idle temp and running, the spark was a little erratic. The spark would be brighter at certain times than others and it would coincide with a bit of a rough idle and you could feel it missing. This didn't happen when I held it to all other wires.

I re-checked the tower resistance on the coil pack between 1&4 and 2&3, they were the same at about 11.4 ohms on the 20k setting. The resistance on the connector side between the middle pin and each of the side pins were exactly the same, each being 2.0 ohms. Could the coil pack still be to blame? It seems functional and I don't think its the culprit, but I don't know how else to test it. How do you test the coil pack while putting a load on it? Everything has to be disconnected from the coil pack in order to use the multimeter so I am confused on how else to test it.

Despite my reservations about the coil pack not being the culprit, I think I am going to go buy one today as they're only like $80 at Autozone with limited lifetime warranty. The only other thing in line to replace is the PCM, and I'm not about to do that.

Any ideas?

Phatty · #6 01-09-2013, 10:36 PM

Ok, I bought and installed a new coil pack today and the misfire disappeared!

I checked the resistances after driving around on the new pack and they are IDENTICAL to the readings I was getting on the old one. Makes no sense.

Glad that it is fixed though.

Scott586 · #7 01-23-2013, 08:07 AM

If your old coil had a crack/defect, it could have been arcing under load but wouldn't measure any different with a ohm meter. Good post, glad to hear you got it sorted.

Phatty · #8 02-10-2013, 10:59 AM

Scott586 you are correct, after I cleaned off the ignition coil pack I noticed a small hairline crack across the front, by the towers for 1 & 4. I can't believe this was most likely the problem