Hey guys i'm new here and in a bind. My work truck a 99 2.5 ranger manual. Has been giving me problems since i changed the plugs, wires, and fuel filter. Here's the story:
1. changed plugs & wires At 63k miles (3 days ago)
2. The truck would miss underload in every gear (engine vibrates as if it'll stall) it stops when the rpms go up. It idles fine though. Gas mileage is horrible.
3. I changed the fuel filter the following day. No difference.
4. I take the upper intake man. off to get to the spark plugs, checked spark plugs, everythings fine. Replaced wire again. Put everything back together.
5. Now I get a check engine light, loping idle, and more importantly when I drive it (reverse or forward) above 1,000 rpm (estimate, don't have a tach) and disengage the clutch the engine would rev all the way to redline. But when idle it revs as normal.

 

Big-Time air leak. The free-revving is the giveaway. You are letting air into the intake manifold somewhere, and the engine is using it to rev. Check all your hoses and routings that could have been disturbed, as you probably knocked one off.
You could have a defective plug wire also. They can be bad from the factory. I'd check the ohms and if infinite, that would be an indicator.
Also check to make sure that the vacuum line to the fuel regulator is there. A 'low' vacuum will make the regulator think you have floored the gas pedal, and will flow a lot of fuel .. thus the poor gas MPG.
Is it worth 2 centavos?
tom

 

thanks alot Tom, I'll check it out and update as soon as I can.

 

Hi thi, and welcome to FTE. Sorry about the delayed welcome, I was just made moderator of this forum yesterday and have some catching up to do!

Here's a link to the guidelines, please check 'em out if you haven't done so already:

https://www.ford-trucks.com/guidelines.html

So how did it go? Did you find the problem yet? Keep us posted.

 

Hey, thanks Dan. I've been quite busy myself. Here's an update on my truck: The misfiring came out to be a bad ign coil. But my motor still surges all the time. My check engine light is also on (P0122, tps sensor).

I can't seem to figure out what the problem is. I've changed the tps, idle air control valve, & dpfe.

MY temporary fix for it is to unplug the idle air control valve, when the iacv is unplugged the surging goes away. I've changed the iacv twice one from autozone and the last one from oreilly's.

I think the surging may also be from a vacuum leak somewhere, I tried to find it by listening through a tube but cannot find a problem. Also, related to a vacuum prob. is my ac would occasionally blow from the defrost instead of the vents. This only happens for about a minute or two before it blows out the vents.

 

Well, if the code points to the TPS, I'd focus on that. Remember, just because you get a code from a certain componant doesn't mean the componant itself is actually at fault. It can be a loose/dirty connection, or something associated with that componant. Perhaps pinpoint tests are in order here. EFI isn't really my strong point, I'm more into the engine mechanicals so I'm going to refer you over to Ken00 in the Ranger and B series forum.

First, read through the Technical Information sticky at the top of the Forum page. Here's a link:

https://www.ford-trucks.com/forums/s...d.php?t=107538

If you don't come across anything in there that helps you, post a question in the forum itself, perhaps asking specifically about the Pinpoint tests. They'll help you out.

 

Two things come to mind:
1) what happens when you unplug the TPS? Does the surge go away? Is the volts about .9 when closed?
2) At some point in time, FoMoCo changed where the back-EMF diode was located in the TPS circuit... They swapped the wires... You may have one of those, unlikely, but possible.
3) (i lied) Did you adjust the TPS or is it unadjustable. The older ones needed to be adjusted with the throttle closed.
4) (another lie) Is the throttle stop screw adjusted such that you get a decent base idle? Usedta was that you could adjust the 'base' idle up with the throttle stop screw, and maybe get out of a surge situation,( and pass Calif smog, bye the bye)
Just smore thoughts.
tom

 

Hey guys, I recently aquired a 2000 Ranger XLT. It was going through cycles of surges since I got it. It was part of a package deal I'd made with a family member, so I didn't check it out before hand, to ask questions about its previous owner etc. The weird thing is that it ran very smooth the first week or so. Now that I've had it about 6 weeks it has shown that it likes to cycle through good to bad performance. At its worst it chugs and sputters at idle dying frequently, then in the lower RPM range it surges quite violently. Then without notice the next time I start it up it runs fine. The gas mileage around town has been frightening, usually around 13 or 14 mpgs. Not what I'd expect from a 4cyl.

The check engine light has been coming on and off, as you'd expect it is on when running bad. Sometimes it will begin running smooth then the light goes out. Unfortunately I was unable to find the year model manual for it, that is without the dealer style $330 one. So I closed my eyes and replaced the sensors that the readout record gave me, plus two. It read: camshaft sensor, idle speed sensor, coolant temp sensor all of which I replaced to no avail. Also replace Idle Constrol Valve and Oxygen Sensor. Now I've had the codes read to only get back Camshaft Sensor. ?

When running bad it surges at idle, when decelerating or more like when stopping at light foot off accelerator the rpms climb sometimes so high I let the clutch out to lower them. As I said before lots of various chugging at low rpm cruise speeds.

I've cursorily looked at the vaccum lines to no help. Is there any tricks or methods to more thoroughly check the vaccum lines? Like some gauge or other that I could plug in? Also there is a possibility that the fuel supply hose from the fill nozzle to the tank could have been damaged by a tool box installation, it doesn't look like it was penetrated but I haven't removed it yet to stretch it or otherwise check it, as the performance problems were occuring before the work was done on the bed.

I'd appreciate any tips, I see this thread went silent a month ago without ever any definite resolution.

Also I just remembered the last few times it has went beserk when decelerating I can hear a relay maybe under the dash or maybe through the firewall? But for a few seconds it clicks very fast maybe a dozen or more times.

Thanks.

 

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