I'm in the process of stripping down the ignition system and returning it totally back to Motorcraft except the coils which were replaced a week ago. I don't see anymore arcing on them at night. Nor did we see any coming from the wires leading to the plugs. I still have not figured out why it has a variable idle and sometimes shuts off when slowing or turning. I've sprayed all over the various places there could be vacuum leaks and there was no change in idle at all. So I'm not suspecting a vacuum leak externally. I've still got good fuel pressure but every 100 miles or so I get that P0171 back. We checked #1 and #2 injector with a noid light and they are both working fine according to the noid light. However, I don't know how good the pattern is. We couldn't get to the #3 and #4 plugs for the fuel injectors. But I was able to listen to the injectors with a scope and they are all clicking even when you hear the miss through the tailpipe. I dowsed the PCV area as well as the hose and there was no change in idle at all. You can hear it working too with the scope. I scoped the block and the valve cover and everything sounds like it's running smooth internally. The plugs are Autolite Platinum and they've got store brand wires, definitely the worst you can get. I tried swapping back the MAF with the original one I had and it made no difference at all. I'm planning on taking the upper intake off, replacing the plugs, wires, and injectors. I've got Motorcraft wires, plugs, and Motorcraft Bosch injectors 9F593's. The PCV hose I thought was available NOS is no longer available but I actually see not even any stress cracks in my original one. I will inspect it internally when we've got the intake off. I will also attempt to replace the PCV grommet if I can get to it without removing the lower intake. But what about this fuel pulse damper? Can it have any impact on vehicle performance? I know I've never replaced it? I don't plan on removing the whole fuel rail. I can lift up the rail and replace the injectors without even disconnecting the line, I've done it before without too much trouble. But I'm wondering should I hold out and buy this fuel pulse damper too? I'm trying to do it all while the upper intake is off.

 

Probably a good idea to put everything back to stock set up.
It sounds like you may have more than one problem that's confusing things some.

What did the Tech say his scan tool was measuring when doing the power balance test & #2 cyl was bouncing around all over the place?
Did you ever perform a compression test on #2 cyl?

Did you ever perform a end to end resistance check on the low end plugs wires & if so how did they measure up to the values in post #25?
Perform this test on the new wires before installing them.

Good idea to have had a listen with the stethoscope, too bad it didn't turn up any suspects so far.

Wanting to, or stalling when slowing, or making a turn is a good clue, so what does the ELM snap shot PID readings look like when that's happening?

When it acts like it's going to stall, what happens if you quickly shift to "N", will that prevent the stall?
Are you having any erratic speed-o readings when this happens?

With the fuel trim being so High/+, it says there is too much air & the computer is having to add that % more fuel to try & get fuel trim in balance, so a vacuum leak, or dirty fuel injectors with a wimpy squirt, belong on the suspect list. Seeing as how you've done a vacuum leak test of sorts, put the fuel injectors on the suspect list, especially with this many miles if they haven't been cleaned.
Maybe consider a 1.0 oz/gal mix of Techron Concentrate Plus in the tank, at the pump before filling, so to get good mixing & if you'll fill up with Chevron, Texaco, Caltex, or now Shell, which already have some PEA in their fuel ad pack, it'll bring the treat rate 10X above pump gas, so may be able to tidy up the injectors, intake valves & combustion chambers in one treatment.

Run most of the treated tank out with some daily rpm run up's to 3500 for a mile or so, to blow out loosened valve & combustion chamber deposits & see how it goes in case dirty injectors with a runny nose are the cause of the rough restarts & wimpy squirts are the cause of the high + fuel trims, or CCDF is causing #2 cyl to randomly act out.

More thoughts for consideration, keep the feedback coming & sooner or later you'll likely begin to get some positive results if you have more than one problem confusing things.

 

I'm going to try and stop by and talk to the mechanic about the test results on the scan tool. Hopefully he can rescan after I replaced the coil packs and #2 plugs. You can definitely hear the miss at idle in park slightly. I could check the wires but they're going to be replaced once I gather everything together. I didn't notice anything different in the PIDS when it almost stalls just the fuel trim short and long go high. Even when the P0171 came on the freeze frame didn't give me any data that could help. At that time the fuel trim was within specs, but I was using the HF scantool because I don't like driving around with my laptop in the truck. I know there's not much else to consider except a valvetrain problem but I would be surprised if a fuel injector is fouled up. I replaced them about 4 years ago with the same original Denso injectors that I took out. The originals weren't really clogged either. I still have the original injectors in my garage. I was told by the company I was going to buy the new injectors from that the Bosch injectors are a newer upgrade and provide a better spray pattern. I looked on the Ford parts catalog and it's got the Bosch injectors as the new part#. I know I may have to break down and do a compression test on this truck but I'm trying to wait until I have all the parts in case a wire snaps or plug is cracked and I won't be able to put it back together. What is the procedure on this Ranger to do the compression test? I will likely use the exhaust side plugs to do the test. If using the exhaust side do I remove all plugs at once? Do I disconnect each coil pack? I doubt I will be able to drive it around and warm it up to operating temp and then go out and pull the plugs. It will be too hot. I maybe able to warm it up a few mins before doing it. Also I don't have a compression tester so I need to go get one.

 

I went by the mechanic shop today to ask about the cylinder balance scan we did. He said the value being showed was the number of misfires per minute. It was in the 20s while we were scanning and on #2 cylinder. We also did the scan today too after I've already changed the arcing coil packs as well as replacing the #2 spark plugs on both sides. When we did the cylinder balance test today it still showed #2 cylinder misfiring. I saved the plugs I pulled out and they didn't look bad to me and he verified it too by looking at them. He said it's running too lean because of the misfire and having to add more fuel to keep it running so thats why the fuel trim #s were off. He didn't suspect a valve sealing problem or ring problem because of how it's running most of the time. It doesn't smoke and doesn't use any oil. He said it was likely the ignition wires. I asked could it still be a lousy #2 fuel injector. He said it's possible but with it making the same clicking noises all four injectors it's doubtful it's a clogged injector. He said it still could be a vacuum leak. But I know I shouldn't have especially knowing I could have arcing but I dowsed everywhere on the engine with brake cleaner to try and find vacuum leaks and nothing changed. I've got a new set of wires but it's for a 93 2.3 since we've got a 93 as well. I thought about pirating the #2 wires out of it and swapping them over to see if it changes. I believe the wires are still all the same lengths except it doesn't have the plastic wire pullers for the 3 intake ones. But right now I don't have time to pull the intake, change the plugs, and all the wires and injectors because I'm back to work tomorrow. I've got to get it going. It's still driveable without any problems, just aggravating that I can tell it's missing. How do you check the resistance of the ignition wires? Don't you just set the multimeter to ohms and probe each end of the wire while it's disconnected?

 

Yup, multi-meter on ohms, end to end resistance on the plug wires should be in the range mentioned in post 25.
If the #2 spark plug wire resistance is out of spec enough, it could cause a wimpy spark that randomly blows out.

 

I just took off the #2 wires and cleaned them. I didn't see any burns,corrosion, or cuts in either one. The intake side was 2.5 feet long and with the meter on 20k ohms it read 4.5 no matter straight or bending it. The exhaust side was 1 foot long and it read 3.5 set on the 20k setting. I looked in my FSM and it said wires should have 7000 ohms of resistance per foot. So these don't pass do they?

 

Ok, good feedback on the #2 spark plug wire end to end resistance reading.
With those resistance readings they probably don't meet Fords EMI/RFI specifications but if the readings were steady as you flexed both ends while measuring, they wouldn't likely cause a plug misfire imo.

 

If you can borrow a scan tool like the Actron CP9145 or the like, that can perform a cyl balance test, by disabling each cyl fuel injector & measuring RPM drop, you could quickly & easily get an idea how well the valves & rings are doing.

 

The mechanic told me when I replace the #2 ignition wires with new ones to come back and he will redo the cylinder balance test on his scanner. He has other options of testing. He's got a fancy Snap On scanner. He showed me on the graph the scope where the cylinder was missing and then leveling out and then missing again. I wouldn't be surprised if this wire wasn't up to the task of firing the #2 cylinder right. These are the absolute worst lowest quality wires you can get for any vehicle. I just had them on the shelf when I was doing a tune up and I was in a hurry because I was going out of town the next day. Eventhough they are not the cheapest priced wires out there I bet these would be the lowest quality on whatever test you could try on them. I've had problems with these wires before under warranty years ago arcing before and it was all the way on the #4 cylinder under the intake. I've tried many brands of ignition wires. Bosch, Accel, NGK, Motorcraft, Wells. Eventhough everyone says Motorcraft is the best for this Ford, the best wires I've had on here were the NGK. It was total quality wires. They lasted 100,000 miles with no issues. I find the Motorcraft burn out fairly quickly too. I still wouldn't be surprised either if there is a valve sealing problem knowing how many videos I've seen on youtube with similar problems. I don't know what I'll do then. It wouldn't be worth opening up the head to fix it.

 

Lots more for you to try & give us feed back on that you haven't done yet.

Having a scan tool sequentially disable a cyl fuel injector & measuring rpm drop each gives is a relative measure of how well a cylinders valves & rings are sealing compared to each other.

Seeing as how the problem seems to be random, if #2 cyl has been missing for some time, it could have deposits that are flaking off = CCDF = Combustion Chamber Deposit Flaking, getting stuck under a valve seat, or fouling out a spark plug & causing a miss, before the particle moves on. A reason for suggesting the Techron treatment, along with Fords high rpm de-carbon blow it out routine during the Techron treatment. As mentioned previously, it can tidy up the fuel injector spray pattern, as well as remove carbon from intake valves, piston crowns & combustion chamber heads.

The miss, or rough idle, or stall when coming to a stop may be a different problem, like the torque converter randomly not unlocking when stopping, which is like not pushing the clutch in on a straight drive when stopping. SO again, does shifting to "N" stop the problem when slowing to make a turn, or coming to a stop & it wants to stall, or run rough?

Again, have you been having any problems with the speed-o being erratic, cruise control acting out, like not wanting to take a set, or randomly dropping out for no reason?
Random tranny up, or down shifting problems?
Any random ABS warning lights?
Any of those could point to a rear differential ABS speed sensor problem.
More thoughts for consideration.

 

I'll have to check with the mechanic on that type of cylinder test to see if it's something he can do. I usually use Shell. When I had the Superchip in it required 91 Octane so I always used Shell 93 Octane. Since I've removed it I've gone back to the Shell 87 octane and it has some spark knock under load, even with 89 octane. If I used 93 Octane there is none. So I imagine the valves are pretty nasty. When I ran some seafoam through the intake per directions only 1/3 of a pint there was no smoke as usual on a very neglected system. I tend to run some kind of fuel injector treatment every 3,000 when I change the oil. Even the original engine had same spark knock problems using 87 octane. I usually use Redline fuel system cleaner. I've never tried Techron. I did try to shift to Neutral once when it was running worse but nothing changed. I have no problem with the speedometer or the ABS. The vss pid matches what the speedometer is putting out. And I don't have cruise control and it only has RABS. It's been acting a bit more normal lately since I switched back to my original MAF. I had the mechanic scan the MAF pid and he said there was nothing wrong with it. The new Walker MAF I had in was throwing the fuel trim all out of whack. But when I put in the old MAF the fuel trim is within specs. The transmission in this truck has been the very best transmission I've had over the whole life of the truck. I bought the truck brand new in 1998 and the original transmission lasted 87,000 miles with regular maintenance and no towing. It had the valve body replaced and lasted 1,000 miles. I had a Motorcraft transmission put in that lasted almost the same amount of mileage about 88,000 miles. I finally had a transmission shop custom build one with HD bands, shift kit, and some other odds and ends plus the 4WD pan. I also added a external cooler. This transmission has outlasted both the original transmission and the second one combined mileage and it still shift fine. The fluid is still as clear as it was when the transmission was put in. I still have the Motorcraft replacement transmission that bombed out at 88,000 miles in my garage because the custom transmission I had built didn't require a core.

 

I changed out the #2 cylinder plug wires with new ones. There was no stopping the miss. I'm getting closer to thinking its in the valvetrain. If I have enough time I'm going to pull the exhaust side plugs and do a compression test. Can I do one cylinder at a time or do I need to remove all 4 plugs at once? The mechanic told me to unplug the coil pack connectors and pull the fuel pump relay. I probably will replace the remaining 3 plug wires on this side as the #2 came apart today when I pulled it even using the special plug wire pliers. Also since switching back to my old maf no P0171 code but still noticeable miss.

 

Update. I went ahead and did a compression test while I had the time off. Good idea that I had an extra set of wires on hand because everyone one of except the #2 I already replaced came apart. #1 plug was slightly hard to come out because I remember the last time I replaced the plugs it was going in different. When I took the plug out today it had some very fine hairlike filings on it. I blew everything out around the plugs with my compressor before I removed any. Luckily the #1 plug went back in ok. I always use antiseize. I had just driven back from lunch and the parts store so the engine was warm but not too hot. I disconnected the coils and took out the fuel pump relay. I cranked each cylinder over about 4 times. All 4 cylinders were between 125PSI-130. #1 was 125, #2 130, #3 125, #130. I didn't have any kind of oil to put in the cylinders but I didn't see any problem either. I did the test twice with the same results. When I got done I replaced the #1, #3, #4 exhaust side plugs and wires. As well as the #1 plug and wire. So except for the #3 and #4 intake side plug and wire they are all new. It did a weird thing when I got done and started it up. It started up no problem and when it fired up it was ticking like a dry lifter. So I scoped around the head and valve cover and it was totally quiet. It appears that the clicking was an injector. After a few minutes of running it quieted down and stopped. It still misses while idling. So I again scoped the injectors and you can hear the miss in the #2 injector when the miss occurs. I believe there is a problem with this injector. Still not a 100% sure but I did hear the delay in the injector click when it missed. But I don't know if that's what it was or if I was just hearing the miss of the engine through the scope. So if I throw a set of injectors on there should I replace the #3 and #4 plugs and use the API wires I got for a 93 Ranger 2.3 since I've already done every other cylinder? I know it's not Motorcraft but I haven't been able to get all the Motorcraft parts I want. The only difference in these 93 2.3 wires and the 98 that I can see is the absence of the boot pullers on 3 of the wires. They were the same length on all the cylinders I replaced already.

 

Another Update. Since finding out #2 cylinder is the one misfiring. I've done the compression test after a short drive to warm it up. I did the test 2 times and all cylinders were 125-130 PSI. I heard a miss through the #2 injector when the miss occurs idling. I've changed out coil packs, plugs, wires. We took off the upper intake manifold, cleaned it, the egr passage, throttle body has recently been cleaned at the beginning of this problem, we swapped out all 4 injectors with new injectors not used. We also checked the PCV hose for blockage and there was none. i replaced the spongy PCV grommet and check the valve. It's nice and tight in the new grommet. Idle air valve, EGR valve, DPFE, EPR, TPS, MAF, catalytic converter, muffler, tail pipe, O2 sensors have all been replaced with 100% new parts as I started to try and figure out this problem. Timing belt has about 30,000 miles on it. Timing checked out ok with a timing light. About the only sensor I've yet to replace are the CAM and CRANK. After doing the injectors and PCV grommet it still has a noticeable miss. I haven't had any codes or CEL in thousands of miles since when first trying to diagnose this miss. I haven't been back to the shop to have the cylinder balance test redone because we just did the injectors last night. It does drive good and doesn't cut off. But if you've done a compression test that checks out, gone through the ignition system, and fuel injectors. Also the fuel pressure is right on with 65PSI. What else is going to cause a miss at the specific #2 cylinder at idle in Park, Neutral, Reverse, or Drive? Right now I think it's running the best it's going to. There also is no smoke or oil usage.

 

Ok good feedback summary.

Since you've performed the cyl compression test & all look balanced, replaced the fuel injectors with new ones, have heard the miss be in time with the #2 injector, in my mind that sorta leaves you looking at the #2 injector wiring all the way back to the computer #2 injector ground switching driver.
I'd begin by monitoring the B+ under load to the injector, to see if you can detect a sudden under load voltage drop that's in time with the miss. Then test it's ground switched wiring run & connection to the computer firewall connector & if ok there, the computer circuit board ground switching driver connections, looking for cracks in the solder, cold solder, or signs the driver has been running hot.
This would require you to remove the computer & open it up for inspection.

When I opened my 94 Taurus OEM computer about 5 years ago, I was stunned at the sheer Number of Poor quality solder connections. I reflowed the worst ones but no joy, so a Ford reman computer finally put the fix on the Taurus sudden appearing random stall woes.