The vacuum gauge tutorial has a scenario check for a clogged exhaust.

The shudder you described sorta sounds like the torque converter acting out, maybe not unlocking all the way. Is the tranny fluid level & condition ok???? Any motor or tranny mount problems, or untoward driveline noises?????

 

When I did the vacuum test in park, it passed the clogged exhaust scenario. I imagine if the exhaust was clogged it would give me problems in Park as well, am I right?

The tranny fluid and level is good. Doesn't smell burnt. I replaced the filter and the fluid about 3,000 miles ago. No clutch material in the pan, very little metal shavings on the magnet. The motor and transmission mounts look to be solid. As for driveline noises, there's none that I can recall. If it was the torque converter going out, wouldn't it give me fits even when the truck is cold? I just really find it hard to believe that the TC would be at fault when the truck only has about 50,000 miles on it. Also, if it helps, I used to get a condition where the O/D Off light would suddenly start flashing around 45 MPH on long highway trips with no noticeable symptoms. That seemed to happen only when the truck would shake due to the original tires still being on the truck. I replaced all the tires and the O/D Off light hasn't come back on since. I had the code read at a transmission shop, and unfortunately I neglected to write it down, so I forget exactly which code it was, but it had to do with the Torque Convert Control Circuit, or Stuck Off if I recall correctly.

 

The torque converter doesn't need to be bad, for you to have problems with it. If it's lock up control system is acting out for some reason, the computer can cause the torque converter to act out.

Maybe run this puppy by the tranny shop & have the tranny computer scanned again & post any code Numbers that turn up.

Are you having any shifting problems, or the speed-o, cruise control, or ABS system acting out???? If so, maybe look to the rear differential mounted speed sensor, as all of those things use it's PID output to the computer to do their thing, so if it's PID output is corrupt, a number of things can be affected.

More rambling thoughts for pondering.

 

I'll probably run by the trans shop tomorrow to put it on the scanner, as I have a day off. We'll see what that shows.

As for any shifting problems, the only problem I ever noticed is it shifts kinda crisp. It's doesn't shift smoothly, but it doesn't miss a gear either. It's just a little rough. But other than that, the speedometer, ABS are all okay. I never use cruise control, so I'm not sure about that.

 

Subscribing

 

Just got back from the trans shop. He couldn't find any codes on the TCU or for the engine's computer either. I described my symptoms, and he said that he doubts a TC issue would be causing the fluctuating idle and the bog down at acceleration, simply due to the fact that the truck works fine at speed, shifts into each gear, etc. He did mention to me that at 50,000 miles, I could need a plug/wire change. When he tried to pull one of the wire boots to check a plug, he couldn't get it off, which according to him is a good indicator that they should be replaced anyway. So i'm gonna go out and look for breaks in the wiring first, but will probably go out later and pick up some new plugs and plug wires and give it it's 50,000 mile tune-up.

Edit* Went out and managed to pull the plug wires myself.lol. I pulled the #1 plug out, and the plug is wearing normal. But as soon as I slid the gap gauge in, woah. It's gapped at .70, when factory recommends .40 or so. I looked at the plug and it's the factory Motorcraft platinum. So, maybe the plug gap is my entire problem. Gonna go out and pull them all out, check them, and then re-gap them.

 

OK, good feedback on the torque converter & good to hear no problems with it or the tranny & no codes stored, but that makes your trouble shoot a little more difficult!!!!!

My 99 OEM/Factory single platinum plugs were 008 over Max gap at only 36K miles & that was After I had pulled & gapped them to the Min side of spec when it was new, so your finding on gap growth doesn't surprise me at all!!!!!

If a spark is weak, it can blow out, or not ignite all of the fuel when undrer load, so power can be affected.

I recently replaced my OEM plugs & wires with the newer design fine wire iridium enhanced center electrode, with platinum sidewire Motorcraft product, set to the Min side of spark gap spec.
The fine wire design plugs spark gap should remain in spec longer in our waste spark ignition system.

Be sure to add some antisieze to the plug threads & some dielectric compound onto the plug external insulator & inside the plug wire boot, on both ends. This will help reduce flash over on wet humid days & the spark plug wire boot from sticking to the plug.

 

This trouble shoot has been hard since day one.lol.

I went out and pulled the other 5 plugs. They were all in the same normal condition as plug #1. The rest ranged from .065 to .070. I set them back to .044. But upon the test drive there isn't much of a difference that I can tell. It's still doing the hesitation. So now just about the only thing I can think of would be the fuel issues. But it's just so confusing because the truck runs fine when it's cold, this only starts to happen when the truck warms up. A clogged fuel filter should give me problems no matter what the temp of the engine is, unless the computer somehow compensates when the engine is cold.

 

Okay, so upon the test drive it appears changing the gap made no noticeable difference. The hesitation is still there. However, one important thing I noticed is that when I apply light "normal" throttle, the truck does not hesitate. It only hesitates under mid or full throttle, almost as if i'm starving it for fuel unless I go easy. So it definitely seems like it could be a fuel delivery issue. Possibly a clogged fuel filter. Gonna remove it and try to see how much resistance it gives back, and if it's a significant amount, then i'll know it's the filter. It hasn't been replaced to my knowledge since 2005, or 25,000 miles. However if it's not the filter, i'll have to test fuel pressure, but i'm not sure where to do that at. Any suggestions on where to check that at? Hopefully not the tank.

 

Check fuel pressure at the on engine fuel rail schrader valve fitting, using a proper fuel pressure gauge & pressure hose. Do a KOEO, KOER & leakdown test.

I'd not remove the MAF, or Throttle Position Sensor from your suspect list either.

 

When you pulled the spark plugs, did you see a 'bristle' in the middle of the center electrode? I believe that platinum plugs used a very fine piece of wire as the electrode. I didn't know better back when, and gapped the plugs ignoring the bristle, which broke off.
I would take the MAF apart again, and closely inspect the two wires for any bit of dirt or mud at all. I would also check fuel pressure as PawPaw suggested, and check its volume, and the regulator function.
Hesitation on acceleration is often caused by a dirty MAF. You have been through the TPS thoroughly, so it's likely not the guilty party.
The malfunction almost makes me think the MLPS doesn't tell the computer that the engine is in D or R and it should bump the idle appropriately. If you have a tachometer, you could get it at operating temperature, read the idle in P, then shift to R and D pausing a bit in N, you should see the idle pick up and then hold steady in every gear position. If it drops in D and R, you should check the MLPS further.
tom

 

When I pulled the plugs they did not have the bristles you speak of. Just a normal center and ground electrode and the electrode gap. I will try cleaning the MAF again tomorrow. I will also check the fuel pressure since I see it is easily checked at the schrader valve. I do have a factory tachometer in the truck. When ever the truck is in park, it tends to idle around 800. But as soon as I put the truck in drive or reverse, it drops down to 600, sometimes 500. That is a very good point you made about the MLPS, because this all started when I had to drive the truck through about 2-3 feet of water to get to an adjoining barn after a storm. I'm sure that the MLPS got at least a gallon of water splashed at it. Thanks to the both of you for all this help, it really means alot. I'll update with my findings tomorrow.

 

Update. Tom suggested that I check the Manual Lever Position Switch (aka Transmission Range Sensor). Well I had previous experience adjusting the Neutral Safety Switch on my F100, so I decided to check the alignment of the MLPS on the Ranger. I pulled the shift cable off the ball mount, and removed the shift selector lever from the transmission. I took a look at the Neutral notch on the body of the MLPS, and looked for the corresponding notch on the inner white ring that allows the shift selector shaft to pivot. Sure enough, the notches were off by at least an inch. So I pulled the MLPS, and manually adjusted the inner ring and lined both notches up. I put everything back together, made sure the truck still started, and took it on a test drive. I drove around for about 10 minutes to warm the truck up, and then put the truck through it's paces going into reverse, and then into drive, and then accelerating in reverse and accelerating in drive from a stop. It performed flawlessly with absolutely no shuttering in either drive nor reverse. It seems to only drop around 100-150 rpms, which I feel is normal due to the load produced by the Automatic transmission. I have an hour long drive coming up tomorrow afternoon, so I will update with how it performed then.

 

Well, i'm still fighting this problem. A few days ago after quite a bit of driving, I was waiting at a stop light when all of a sudden it just shut down. It started right back up, but it was the first time in awhile it had shut down on me. It just seems to get worse the longer I drive. I decided to change the fuel filter, and of course that made no difference, as it's still doing it. I unplugged the MAF and drove around a little to see if that may be bad, but it still hesitated/bogged down when I accelerated, and it pretty much put the transmission into fail safe mode, so I pulled back off and plugged it back in. I'm guessing that means that it's working correctly. I have still yet to check the fuel pressure, but that will be coming as i'm running out of ideas. I think this week I'm going to check the fuel pressure, check for any coil cracks, check the plug wires for breaks in the insulation, and one night try to get it to warm up and see if anything is arcing. Also gonna test the vacuum with the engine put under load. After that, I'll have to baby it as I'm not in the position to replace the plug wires yet, although I can probably fit a new pair of plugs in. And I do still have the transmission in my mind. I've had wiring problems with it before, so in September when I have my next pan drop planned, I'll check out the solenoid brackets, check the wiring connections, and ohm out the solenoids to see if maybe they're at fault. It's just so confusing how it runs fine when cold, but then gets worse as it warms up.

Also, I do have an occasional smell of fuel in the cab, however it goes away pretty quickly. I'm trying to feel if the truck is misfiring, but I have very little experience with light misfires, so I really can't tell. The truck does run a bit rough, however it's a truck, and I've never heard of a smooth running 3.0 in the first place, so I'm not sure. Can anybody enlighten me on what a light misfire may feel/sound like?

 

Instantaneous shutdowns generally point to an electrical or electronic failure. Bad grounds or wires that have been flexed too many times and start to break causing intermittent connection. A bad ignition switch will make the engine stop just the same as if you turned the key to OFF. I don't think a transmission problem would kill the engine without the engine putting up a little bit of a struggle, such as surging or shaking back and forth.
tom