I have a 2000 Ranger XLT Supercab with 122,800 miles. It has a 4.0L Six Cylinder and generally runs excellent. As of about a month ago, the engine started to miss and of course within the week the OBDII indicated the Check Engine light. I had the code read and it informed me that No 6 cylinder had a misfire. I replaced all of the spark plugs with Bosch Platinum 2 Plugs and Bosch 8mm Lifetime Plug Wires. The truck ODBII still indicates a problem and I beleive it still will indicate the same issue when I check it. The truck lugs down and shudders at the speeds of 35 MPH and also at 40 MPH, once I lift off the accelerator and then depress the motor is fine for a few seconds then still lugs at the speed mentioned. Has anyone experienced this and if I have to replace the O2 sensors. Where in the world are they located?

Thanks

Tery

 

Welcome to FTE!

I had a very similar problem recently and I 'm pretty sure I narrowed it down to a problem with one of my fuel injectors. So you might try listening closely to see if you can hear the #6 fuel injector clicking (you can also test the circuit by hooking up a test lamp up to the harness connector... it should blink).

But injector problems are not as common as some other causes, so you should try pulling the new plug in #6 to see what kind of story it might tell. If it's wet with fuel, you'll know that there is something wrong with the spark. Also, you might consider changing your fuel filter, just to rule it out as much as anything.

 

hi tery, i'm a new user here . i also have a 2000 ranger xlt and am having the same problem except with cylinder #2. i've read a lot in here and got some great tips but still can't seem to find the problem, i'm writing because i haven' seen the lug down and shutter problem which is exactly what i'm experencing too. heres what i've done so far..new plugs & wires, ran a couple cans of sea foam through the intake, swapped out the coil, checked the injector to see if it was gettiing voltage, did a compression check on all cylenders, all were 122-125lbs, changed the # 2 injector, changed fuel filter and checked fuel pressure, 62psi.....i'm starting to think it might be the eec. the truck has 322,000 on it but up until this misfire started it was running great! keep me informed if you find out what the problem is or maybe someone else has some suggestions, thanks, perry

 

p.s, i forgot to tell you, before i changed the injector, i checked resistance on all the injectors and they were all between 15.3 and 15.4 but i thought maybe it was plugged. but nope, still missfiring, p0302 is the code.......

 

Perrydean, welcome to FTE!

Your feedback is interesting. Sounds like you've done pretty much everything to try and isolate the cause of the problem. Yours is a 4.0L too?

This is just me thinking out loud here, but I'm wondering if these isolated, hard-to-pin-down misfires might have something to do with the "newer" type of fuel delivery system used on 98+ Rangers (or maybe the circuit?).

Now I realize that usually a fuel pump issue will affect fuel pressure in such a way as to have a negative impact on all the cylinders, not just a single one.

But the '98+ 4.0L fuel delivery system does not use a typical fuel pressure regulator (the one that is normally mounted on the fuel rail), and there is no return line to the tank. Instead, the regulator is in the tank along with the pump. There is also a vacuum line that connects to the fuel damper (not regulator) which is mounted on the fuel rail. By virtue of this arrangement, somehow the PCM knows when to tell the pump to run (and how much fuel to pump) in order to keep the fuel pressure @ 64 psi +/- 8 psi. Note that this type of returnless fuel system involves much higher fuel pressure specs than the usual 39 psi +/-or so found on most Fords up until '98.

I think that's roughly how it the returnless fuel system works. Unfortunately, the Ford Manual is a little weak on the specifics, so I can't say for sure. In any case, as I said, I'm wondering if this newer type of fuel delivery system is capable of what I will call "hiccups" that could possibly cause misfires in isolated cylinders?

Just something to chew on.

 

thanks rockledge for the comeback and the info on the fuel delivery system. by the way it is a 4.0. the fuel damper thats inbetween cylinder(injector) 1&2 is the reason i checked pump pressure but wasn't sure if too much of too little pressure could effect just one injector. the truck runs ok going down the road, but misses at idle and does the exact thing that terys is doing. i thought the trans was going really, but now that i see the same problem with his i think it has to do with the misfire. i have a 99 explorer that i swapped out the coil to test. it worked ok so i figured i'd do the same with the ecc, not good, lol....the theft light flashed real fast and the truck wouldnt start , so i scratched that idea. so my question is if i get a eec from the junkyard will it work? it was almost like the eec didn't like the fact that the key chip wasn't programmed for that eec. the eec on the explorer was an aftermarket i think so no numbers to try and cross reference. also do you think it's possiable for a cam position sencer to give a false code? can ya tell i'm starting to grasp at straws yet?lol......thanks for your help

 

Rockledge and Perrydean,

Thanks to both of you. It's great to have kindred spirits when dealing with this. As an update I replaced the Bosch Platimnun II spark plugs with Autolite Platinum Plugs this morning with limited success. Rockledge, I did take a look at the old plugs and it looked like two were bad. I checked out the resistance with a Fluke DVM and the two suspect plugs measured an open at the electrode tip, to the top of the plug. The other four measured about 1.84Megohms of resistance. The New Autolites measured about 5Kohms of resistance on 5 and 8 K ohms on the 6th plug. Big Difference, I will never use and would not recommend using the Platinum II or IV Bosch spark plugs for the resistance reason alone. Trust me, I've learned. But back to the problem at hand. The truck seems to idle better, but I am still experiencing the same lugging problems at speeds of 30-45 MPH now. I am having a difficult time locating a fuel filter, so if any one has any suggestions, please feel free to let me know. Thanks for all of the input. Hopefully, we will find something out

Thanks Again

Tery

 

Tery, do you have the 5spd auto tranny, or the 5spd manual???

I can't determine if the auto isn't down shifting properly, or if your lugging the engine in 5th gear, if it's a staight drive.

If the fuel filter hasn't been changed in the last 40K, or not at all, in the last 122K, it needs it no matter what.

It's located on the drivers side frame rail, fore & aft, about where your foot hits the ground, when you get out.

If you change it yourself, be shure to depressurize the fuel system, by pulling the fuel pump cutoff switch electrical connector, located in the passenger side foot well, on the firewall just above the carpet.

Then crank the engine about 10-15 seconds, it'll sputter & try to start, as the fuel line pressure bleeds off.

Also I like to loosen the fuel cap, to relieve tank pressure.

I leave the cap off while I'm working on it so it won't build up presure while I'm tinkering. Just remember to replace it when finished.

Then your good to go, to loosen the filters pressure connections. If you've never done this before, get a good repair manual like Haynes, Chiltons, Clymer, ect at your favorite autoparts store. You'll also likely need a special tool to relieve the banjo spring in the fuel line fittings, also available at the autoparts store.

Also check the forum's technical sticky thread/s at the top of this forums main page, for some additional tips.

When you replaced the plugs & wires, did you butter the plug boots on both ends & the plug insulators, with dielectric grease????

This will help prevent spark flashover on humid/wet conditions & will also aid in plug wire removal later on.

 

Pawpaw,

Thanks for the advice. I changed out the fuel filter this morning, and you were right in did need it. Unfortunately, I wiped out the banjo connection for the main fuel feed line. The great news is that NAPA is only two blocks away and I purchased the plastic connectors for the recirc, and fuel line to the injectors.
Once I got this I installed the filter with no problem at all. I also added a can of BG 444 Fuel system restore and enhancer, this is pretty spendy about 25 bucks for an 8 oz. can. The truck is running a little better than it did before I swapped the filter out, but is still rough, once I get a tankful of gas through the Ranger, I'll see if this helps out. Hopefully, I wont have to replace the fuel injector, but if it still runs bad, that's next. Here's the list of what's been replaced and the OBD II code.

Code: Misfire Cylinder 6

1. Replaced Bosch Platinum IV Plugs with Bosch Platinum II's (Big Mistake!)
2. Replaced Old Bosch 8mm Plug Wires for new
3. Replaced the Bosch Platinum II Plugs with Autolite Double Platinum Plugs
4. Changed Oil (Because I was under the truck anyway )
5. Replaced the Fuel Filter (Altough it wasn't totally clogged, it was close)
6. Filled the tank and added BG 444
As of today, the Truck's "Check Engine" light for the OBD II System is still on, but it is still running better than the last couple of weeks.

I will keep everyone posted. Thanks for all of the advice. If anyone ever needs to replace either fuel feed connectors, or recirc and feed to injectors, I would recommend going to NAPA.

Recirc and injector feed connection kits are NAPA p/n: 730-4913 5/16 Hose with 5/16 filter connector

Fuel Feed from the tank 730-4918, 5/16 hose with 3/8 Filter Connection

Thanks again

Tery

 

I have a '97 6 cyl 4L XLT 4wd that I am having the same problem. P0303 misfire in # 3 cylinder. Have tried all that u all have talked about to no avail. Also I get a strong smell of gas just before the problem clears up for a while but then returns. help. jac525

 

Jac, pull the #3 plug & check it for any internal & external damage to the ceramic insulators. This includes them being dirty, cracked, chipped, carbon tracks & make shure it's gapped corectly.

Next, inspect the spark plug wire's insulating boot, on both ends for damage, like cuts, splits, carbon tracks inside, dirt, ect.

Then measure the wires resistance & flex it a little & watch for discontinuity or big changes in resitance.

If all this checks out ok, move on to the fuel injector harness for the #3 injector. Make shure the electrical connections are clean & tight. If ok, then pull the #3 injector & check it for damage, or deposits, around the pintle area. If the deposits are heavy, carefully clean it up & reinstall it, or replace it.

Add a good fuel injector/combustion chamber cleaner, like Chevron Techon, to the fuel tank in the proportions called out on the can, then fill up with Chevron regular & run most of this tank out before refilling.

Let us know what you find.

 

Thank you very much. The tip of the plug was cracked. I must have done it when I changed them. $4.23 for an Autolite plug fixed my problem. I owe u big time. Thanks again jac.

 

Thats the kind of fix we like to hear about Jac, quick, easy & low cost!!!!

Good find, fix & feedbak!!!!

BTW welcome to FTE!!!!

 

newbie here, not so good with this newfangled efi/emissions stuff.
98 ranger 4.0 5-spd 111k miles
have similar problem-code 301 cyl 1 misfire - misses sometimes more than others
changed plugs/wires; can of bg 444; new coil pack; no change.
replace #1 injector, better for a day but now reads code 303 same symptoms.
will replace fuel filter + vacuum line coming off throttle body (evap?)
often runs better for a short while after working under the hood.
thanks for everyone's help, it's much appreciated. i've never had a mechanic work on one of my vehicles but this truck is trying me! thanks...

 

Welcome to FTE!

I'm not sure if your situation can be considered "random" misfiring, but along those lines the camshaft positon (CMP) sensor has to be on the list of things to consider. The CMP is responsible for properly sequencing the fuel injectors so that they squirt fuel at the proper time into the proper cylinder.

Also, you might want to look over this previous post of mind:

https://www.ford-trucks.com/forums/s...77&postcount=5

Let us know if you make any progress.