I apologize if this was covered... I found lots of threads on replacing fuel filters but didn't see anything on symptoms if it is clogged. I tried different keyword searches but hit the 30 second per search limit.

99 Ranger 4x4 4.0L 5spd(auto trans).

My IAC appears to be bad, via another thread.

I also just started getting a severe idle problem especially cold started. Then when taking off under light throttle the car bucks and surges. I also notice this on the highway with "maintaining speeds" acceleration. When I left the house cold this morning and had to climb a light hill, I thought I heard some backfire-style pinging in the exhaust too.

Is this a symptom of the fuel filter, IAC, or ???

Any help appreciated.

 

It wasn't the IAC. I guess it's off to the dealer

Hopefully it'll be something like a vacuum line or a fuel filter and not an expensive ignition issue!!!

I sure miss having a garage!

 

Good luck and let us know what you find out.

 

Could be the Mass Air FLow Sensor. It sounds like a tame version of what happened to my Ranger. The sensor I guess measures the density of the air coming in, allowing the computer to mix the correct fuel to air ratio. If your sensor is giving bad readings, you'll get either to much air or too much fuel, sending unspent fuel through your system. I may be wrong, because I don't know too much, but I am still learning. Mostly from this forum...Thanks everyone...

 

The dealer's diagnosis was plugs, wires, fuel injection flush.

The CEL was for a misfire from the #4 cylinder. Like I posted in another thread - the cost for these is very high (going through the dealer) but they haven't been done in 78,000 miles. I should be picking it up today, so I'll update this evening what happened.

 

I was wrong, sorry

still learning, though...

 

Steve, I have a 98 Ranger XLT 4WD 3.0 manual five speed. I am reading 92k on my odometer and I just started having the exact same problems you have had. I changed my plugs two weeks ago and that seemed to help. They definitely needed to be replaced. I also ran injector cleaner. The problem seemed to go away, but a few days ago, it came back. Hesistation when taking off, low idle hesitation, sustained speed (on highway) bucking... The only thing I haven't done yet is replace my wires which I intend to do very soon. The funny thing about it is, my gas mileage is better than I have ever had. (20+) I can't complain about that, but it definitely is running very rough.
When you get yours back, let me know if changing the wires took care of it, would you?

 

OK, I got the truck back.

It pretty much got a full tuneup (it says something like tuneup kit on the receipt).

The problem appears to have gone away. I'll have to drive it for a couple of days to be completely sure. I think I noticed a bit of spark knock on the highway on the way home though.

But, it is VERY hot in WA right now and I had the AC running along with climbing a bit of a hill while I gassed it. I gave it enough that the trans dropped down a gear (out of OD). I'll have to see how things go.

I may end up at a dragstrip on Saturday. If I make some passes I'll have to see how it compares to my previous bests.

I did put some fuel injector cleaner through myself in this current tank of gas, but I'm guessing they do a bit more when the do the injectors.

 

Exact same problem I was having minus the backfire style pinging. I have 99,000 on my 99 Ranger 3.0 v6 4x4. Changed the plugs and plug wires, problem solved, runs like its new again. I had crossed some plug wires when I reinstalled them, thanks to Rockledge and the manual I figured out the firing order. I also thought it may have been the fuel filter and bought one, but haven't put it in yet.

 

My boss here at work has an '87 2.9 that was beginning to "act up". He took it to a garage that he trusts. They changed the fuel filter, and did a thorough flush of the fuel system (I don't know how they do it, but it is way more thorough than just running something through the system from the gas tank). He was amazed at the improvement. They DID CHECK CODES FIRST to determine that it was a fuel starvation problem.

 

I changed my plug wires this morning and found that to solve the problem. My truck is definitely running smoothly again. It still seems to have a bit of a rumble as it runs, but it is better than it has ever been. I will let you know how it runs a week from now.

I am wondering though what I can do with my stock engine to get more power out of it without dumping a lot of money into it. Any ideas?

 

I know this was posted a few months ago but I am having virtually the same problem. I have a '99 B4000 4.0L 4X4 auto with 107k. On acceleration and at driving speeds the truck shudders and misfires terribly. No pinging though. If you accelerate very lightly it is less of a problem. It sometimes idles okay, esp. when cold but often idles rough as well. On a cold start is less of a problem until it warms slightly then starts. The only code I am getting is an occassional "missfire cylinder 6". I clear it and it returns every 3-4 days after the problem is particularly bad. No other codes have shown. It started about three weeks ago as an occassional missfire under load or acceleration and gradually got worse to the point it is nearly constant now.

I've replaced plugs, wires, air filter, fuel filter (an ordeal described in another thread), PVC valve, cleaned the MAF, IAC and throttle body, checked for vacuum leaks, and ran injector cleaner a couple times with different brands but no help. I'm getting strong spark to all cylinders.

Any and all suggestions apprecitated.

From a suggestion in the forum here that it could be a bad #6 injector I have ordered one from the dealer which I am waiting for.

 

Boy that is a tough one. The first thing that comes to mind is maybe an ignition problem, but it seems like you've done all the right things to try and resolve the problem from that angle. A cylinder misfire can also be caused by a bad injector, and it's good that you are going to address that.

Here is a description of how a cylinder misfire is detected:

"The Misfire Detection Monitor is an on-board strategy designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause. The Misfire Detection Monitor will be enabled only when certain base engine conditions are first satisfied. Input from the ECT, MAF and CKP sensors is required to enable the monitor.

1. The PCM synchronized ignition spark is based on information received from the CKP sensor. The CKP signal generated is also the main input used in determining cylinder misfire.

2. The input signal generated by the CKP sensor is derived by sensing the passage of teeth from the crankshaft position wheel mounted on the end of the crankshaft.

3. The input signal to the PCM is then used to calculate the time between CKP edges and also crankshaft rotational velocity and acceleration. By comparing the accelerations of each cylinder event, the power loss of each cylinder is determined. When the power loss of a particular cylinder is sufficiently less than a calibrated value and other criteria is met, then the suspect cylinder is determined to have misfired...."


So, based on the above, if the injector is not the problem, then you should at least consider the crankshaft position (CKP) sensor, and then after that, maybe even the PCM itself.

Hope this helps. Good luck.

 

I have a 97 Ford Ranger with 80,000 miles on it. I have a 2.3L 5-speed manual truck. I hade the same problems; no pickup, hard time mantaining highway speed, bucking/jerking. I had a shop look at it and it was the fuel pump. Had it replaced. It was the problem. Then it started doing it again 3 months later. Had the dealership look at it, it was the fuel pump. The first shop put in a aftermarket pump and it failed. Also the ford dealership told me the first shop improperly installed the pump?! Had the dealership put the new factory pump in, it failed. The second one they installed was not faulty and has been fine ever sence. Now I have to try to get my money back from the first shop, they are driving me nuts!! They are giving me the runaround. Spent almost $1000 to get this problem fixed.

 

Thanks. I will test fuel pump pressure when I get ready to replace the injector. The thing that had me stumped though was why only the #6 cylinder would show a misfire rather than other cylinders as well but maybe due to its position it is more prone to lean fuel conditions if pressure is weak.