I have a 1994 Ford Ranger XLT 3.0L 6cyl 4x4 with 140,000 miles that's been having an idle problem. When I first start the truck in the morning, the idle is very rough. It will shake quite hard and try to die. The truck seems to do fine after it has warmed up, or the problem isn't quite as noticable, there is a slight miss with it warmed up that isn't very noticable unless I'm listening really hard for it. I've also noticed a slight dead spot or hesitation in acceleration. So far, I've changed the distributor cap and rotor, put new plugs and plug wires on it, new pcv valve, new dpfe sensor, new vacuum regulator, new egr valve, cleaned the MAF sensor, cleaned the IAC valve, new coil, nothing I've done has seemed to help much at all. I suspected the MAF was not working, so I unplugged it and my truck really ran rough with it unplugged and I got the CEL with it unplugged. My CEL hasn't came on with the MAF plugged in. I ran my codes on it and all I got was a code 111, which is an all clear code. I've also tried running a couple of cans of fuel injector cleaner through it, all to no effect. Has anyone else had this problem and solved it? I would sure appreciate some advise here, I'm about at the end of any ideas.

Thank you,
Jack

 

You may have a vacuum leak in the intake that closes up as parts expand with the heat. You can spray carb cleaner on the intake gasket area when the problem occurs to see if it clears. Follow the intake mating surfaces with the cleaner. If the engine smooths out, that is where your leak is. The other way to check for an intake leak is to remove the air cleaner and slowly chock off the intake with your hand(s). If the engine smooths out you have a vacuum leak. The card cleaner with just isolate where the leak is. Also check for cracked/broken vacuum lines.

 

I've checked all of my vacuum lines and they are all good. That's a good idea about using the Carb cleaner around the intake, I'll give that a try when I get off work today. I also bought a new fuel filter that I'll put on this evening. I thought I might have low fuel pressure at idle that could be causing the problem so I'll let you know if changing the filter had any effect also.

 

Vacuum leak could have very well been what the problem was. I checked the vacuum lines on this 2 different times and didn't find a leak, just before trying the carb cleaner trick, I decided to check the vacuum lines one more time, running my fingers down each line. I found a hole in the vacuum line that comes out of the pcv valve that I had somehow missed on the previous two inspections. This hole was in a vacuum line right next to my alternator and the "hiss" that I thought was coming from the alternator was actually the vacuum leak! I'll drive this for a couple of days now and see if this solved my problem! Thanks for your help Common Sense! Your comment really helped!

 

Hey man! Its your fuel filter. mine did the same thing. I changed the fuel filter and she runs like a champ now!

 

You are absolutely right about the fuel filter being part of the problem. I took the old fuel filter off and got brown sludge out of it, that when I got it on my hands, GOOP wouldn't wash it off! I also tried to blow through the old filter and could barely get any air to go through it. The new filter was installed, the vacuum leak was fixed and now my truck is running great!

Everyone, thanks for helping me get through this problem!

 

your welcome man! i read your post and i knew exactly what was goin on! it happened to me about a month ago! im just glad it was a simple fix. glad i could help! now you can come and help me change both my front wheel hub assembly. haha

 

aloha, i changed my plugs and fuel filter and it still shakes in park , worse in drive. reved up it only gets up to 3000rpm, andsurges up and down there. dissconected battery to reset engine lite and it comes back on.. can,t here vac leak.
whats up, john

 

Run a code reader, and tell us what you get. Also what year and what engine & Trany. Diffenent years and engines have their own little tweeks and issues. A surge/hesitation/bucking on a 98/99 or newer without a CEL can be a sign of Syncro shaft failure a know issue on the 3.0, along with belt sqeals that continue even when the belt is removed. The short is you need to give us more. and best on a thread you start. FYI, rev'd in park or neutral will cause rev limiter to engage, again depending on model year and trans.

 

aloha, sorry its a 2002 ranger, 3.0 ltr., code reader read fuel surge problem. mechanic was not helpful. my freind just happen to read it when mechanc wasn,t looking. i changed the fuel filter and plugs. still runs ruff and engine lite is still on.