Help diagnose the Ranger please....

[stieny]

Copy and pasted from another site I have it posted on:

So I'm going to make this as clear and short as possible.

On a road trip to NYC I started running into a really heavy hesitation issues half way through the trip and throwing lean codes. It would hesitate in 5th gear real bad as it lost speed, downshift to 4th, it hiccups a few times and starts to accelerate smoothly. This has happened to me once before and it was a clogged fuel filter. So I stop at a parts store in New Jersey and swap it out on the side of the road. No more real bad hesitation but it is definitely still there on the ride back.

So when I get back I change cap, rotor, wires, plugs, air filter, changed the oil and flushed the coolant. Still have hesitation issues and really bad fuel milage. So I went ahead and replaced the fuel pump because I thought it was dying on me because I've been known to run the fuel down pretty low.

Still having some slight hesitation on the highway and still getting real bad fuel milage. About 10-15 all highway miles in a 3.0L 5spd Ranger.

I did a compression test on the coolant system. It held steady pressure. I did a compression test on the motor and got about 150 psi on every cylinder.

Now, I noticed this hesitation after the manifold developed some leaks a little while ago. I was trying to hold off until after winter the replace the manifolds as the leak have gotten progressively worse.

A few weeks ago I drive to work. Half way through the day I go out to move my truck. I start it up and its popping pretty good under the hood. Now the popping is coming from the leak from the manifold. I can audibly hear this but its much louder then the *tick, tick, tick* that I had before that an exhaust leak sounds like.

I give it some gas and it revs pretty easy with no hesitation but the popping is random, almost like a miss. I just figure that the leak opened up on me. I go to drive it and the truck is stumbling and missing all over the place. I can hear the leak that now sounds louder and is now popping as the motor is stumbling and missing. I pulled off the old manifolds and I can see all the leaks that were on both sides. Probably 4 cylinders were leaking. So I replace the manifolds with gaskets and now no more leaks but that popping/missing is still there just in the exhaust instead of at the leak.

Then I ordered new injectors and put those in. No dice.

So now I'm stuck at a wall. I've changed everything I can except the IAC, MAF, TPS, O2's and exhaust. It's not throwing any codes.

I did clean the MAF and IAC though and the truck holds a steady idle, it just has that hiccup in there. When you rev it, it revs fine and smooth.

When you put it under load, part and mid throttle has a bad hiccup/hesitation but when you floor it, it all but goes away. And I'm still getting terrible milage. Last tank was all highway miles and got 13 mpg. Used to get over 20.

I'm at the end of my patience with this truck. It's completely solid and only has 97K on it. I got it three years ago with 42K so I'd like to keep it but I can't justify blindly throwing money at it because no one can correctly diagnose it.

A few more weeks and I'm going to take some gas and a book of matches to it.

Give me your suggestions guys. Thanks.

[Martin0660]

Odd on the issue related to popping and the manifolds. Leaks there will burn an exhaust valve, but that should show up in some way on your compression test. I still lean to an issue related to this.

I didn;t see you mention O2 sensors. At that milage, they could be suspect and will kill milage and affect part throttle cruise. Contaminated won;t throw a code but will slow the sensor .. .expensive to throw parts at, but suspect.

With no codes, and your past issue related to the fuel filter (and a new filter "helping" this time) ... I would really try to go at it with SeaFoam, the Berryman cleaner, etc. It sounds like the fuel system in that thing has some dirt floating around and could be living in the rail / injectors / etc. Effectively it's a cheap attempt to do something when you don't know what else to do ;) The Seafoam is helpfull anyway.

Random thoughts

[badstanglx]

u check 2 set if the cat was plug up check set u have any vac leaks lines off intake leaking

[stieny]

Odd on the issue related to popping and the manifolds. Leaks there will burn an exhaust valve, but that should show up in some way on your compression test. I still lean to an issue related to this.

I didn;t see you mention O2 sensors. At that milage, they could be suspect and will kill milage and affect part throttle cruise. Contaminated won;t throw a code but will slow the sensor .. .expensive to throw parts at, but suspect.

With no codes, and your past issue related to the fuel filter (and a new filter "helping" this time) ... I would really try to go at it with SeaFoam, the Berryman cleaner, etc. It sounds like the fuel system in that thing has some dirt floating around and could be living in the rail / injectors / etc. Effectively it's a cheap attempt to do something when you don't know what else to do ;) The Seafoam is helpfull anyway.

Random thoughts

Thanks. I ran the compression test to check for a burnt valve because that's what I was leaning towards but came up with good pressure and it held too. I know that bad o2's will mess with performance but I don't know how it would cause this mid throttle hesitation.

I ran cleaning products through the fuel system and inspected the tank when I had it out. It all looked pretty clean and the sock on the old pump was pretty clean too.

I also seafoamed it as well. I did that the same day I ran the compression test a few weeks ago. It didn't help.

It's just odd that it will rev fine and at WOT run a lot better then at part/mid throttle. I heard that the TPS controls a lot of the fuel curves. It's one of the few things I haven't changed yet but I don't want to keep throwing money at this.

u check 2 set if the cat was plug up check set u have any vac leaks lines off intake leaking

I checked all vacuum lines and all are good with no leaks. I did think about the cat being plugged up though.

The original exhaust is on the truck still and my muffler used to rattle at certain RPM and I knew the baffling was loose inside but never really cared enough to change it. It has since stop rattling as much so I was thinking that my exhaust is finally getting restricted but I don't see how that would cause the engine to hesitate at certain rpm ranges. A clogged cat/muffler would hurt mpg and bog down the motor some, sure....but would it cause a miss?

[badstanglx]

well yea it not reading the 02s right not letting the motor breath

[stieny]

well yea it not reading the 02s right not letting the motor breath

Well, my truck is OBD I so there isn't an O2 after the cat. So I'm not sure that an obstruction in the exhaust would really affect O2 performance.

[badstanglx]

yes it would make it mess up

[stieny]

yes it would make it mess up

So, you're suggesting that I look into the exhaust?

The only bad thing is that there isn't really any good way to check it besides replacing it.

[2000GT]

drop the exhaust before the cats. It will be noisy though!

[stieny]

drop the exhaust before the cats. It will be noisy though!

Yea, I was thinking about that....just taking the exhaust off before the cats and seeing how it runs.

I was just hoping I could fix it without resorting to that because I'd probably have to torch the bolts off of where the cat flange bolts to the Y pipe.

But does this sound like it could be the problem? A clogged cat/exhaust?

Because I was leaning more towards the TPS.

Hell, who knows....maybe I just blew the 3.0 up. Ugh.....

[2000GT]

I can't see a TPS killing your gas mileage as bad as you are reporting. A clogged exhasut could impair you MPG though. Are you getting a Check Engine Light?

[badstanglx]

put ur hand by the tailpipe see if anything coming out are if its hott

[stieny]

I can't see a TPS killing your gas mileage as bad as you are reporting. A clogged exhasut could impair you MPG though. Are you getting a Check Engine Light?

I agree about the mpg thing because I can't see anything besides a clogged exhaust affecting it that much.

And no, no CEL's....

put ur hand by the tailpipe see if anything coming out are if its hott

I have and I do have exhaust there and it's hot but I have no clue as to how much exhaust I should be expecting at the tailpipe.

[mustang50lx]

Possible bad distributor (Pick up coil ) or ignition coil. Do you have someone who could scope it for you? That would would probably show something. Are you able to scan it?

[stieny]

Possible bad distributor (Pick up coil ) or ignition coil. Do you have someone who could scope it for you? That would would probably show something.

I have no one that can scope it for me unless I take it in to a shop.

Although, it's worth mentioning that the whole distributor was replaced about 3 years ago.

The ignition coil is newer as well. It was replaced the same time the new distributor was put in.

[How Much?]

Def sounds electrical to me,,,,,try unpluging Ur mass air sensor,,,poping will go away if its faulty, then replace it

[stieny]

Def sounds electrical to me,,,,,try unpluging Ur mass air sensor,,,poping will go away if its faulty, then replace it

I did that as well.

I unplugged it and no change except I got a CEL. So I'm assuming that the MAF is good.

[2000GT]

I still think you have a clogged cat. Although it would be a pain, I think you need to drop the exhaust. Another thing you can try is to spray the vacuum lines with parts cleaner while the engine is running. If the idle increases, you have a vaccum leak at that line.

[stieny]

I still think you have a clogged cat. Although it would be a pain, I think you need to drop the exhaust. Another thing you can try is to spray the vacuum lines with parts cleaner while the engine is running. If the idle increases, you have a vaccum leak at that line.

Yea, like you said, I can't see anything else causing my huge drop in fuel milage except for that. BUT, would that cause my hesitation? It almost feels like I'm dropping spark or something at light throttle. I just don't get it.

And I already sprayed down the motor and try to locate a vacuum leak and didn't find any.

[2000GT]

Yeah, that is weird about the hestiation. I would start with the exhaust and go from there.