90 Ranger with a rough idle

[jpz]

Hey guys. I'm new here and I'm having a problem with my truck. it's 90 Ranger 2wd with a 4.0.

Recently it started having a very rough idle. It sounds and smells rich. I've ran a code scan and it comes up that everything is fine.

I'm stuck as to what could be the problem. I just replaced the plugs and that didn't help. I'm wondering, could I have a bad injector or two? Or, could this be a sign that the timing chain is worn and needs to be replaced? The truck has 265,000 miles on.

Any help would be much appreciated.

Thanks.

jpz

 

[Bill]

Thank you, in reading the thread got to 265K miles and started laughing. Guess you like your truck? Two ideas, 1st is to check for vacuum leaks, vacuum leaks are more noticeable at idle but have little effect at higher RPM's. 2nd, would be to take a compression reading on the engine. Perhaps at this mileage its getting tired.

 

[jpz]

Yes I love my truck. She's been a good girl so far. That mileage is the original engine and tranny. And believe it or not, all of the original accessories other than A/C compressor. Any way, I have checked for vacuum leaks, but I will check again. I'm really hoping it's a simple fix. Hate to give up on the old girl because she's idling rough.

I'm also due for an oil change, maybe I'll try Restore. Never been a big fan of additives, but I'll give it a shot.