1998 2.5 engine idle issue, only when cold

[Ranger Sport Honduras]

good u fixed!!!
now enjoy the 2.5 beast

 

[cf3232]

Turned out to be low compression in the second cylinder. Changed the head and the truck runs like a champ. So happy I got down to the bottom of it. Only a year and a half after the problem.

 

[britej]

Can the temparature sending unit affect the idle? this may be what is wrong with mine. my temperature guage does not work right...

 

[Rogue_Wulff]

Can the temparature sending unit affect the idle? this may be what is wrong with mine. my temperature guage does not work right...

There are 2 seperate temp senders. 1 for the guage, and 1 for the computer.
The temp sensor for the guage should be a single wire unit on the side of the engine, while the sensor for the computer is a 2 wire unit. Not sure what year model your truck is, but on my 95 this sensor is located right by the upper radiator hose.

The gauge sensor going bad should not have any effect on how the engine runs.
The computer temp sensor going bad will effect how the engine runs, and should throw a check engine light.

 

[britej]

gotcha.. my truck is a 1996 model and i am having a hard time diagnosing a rough idle. but the temperature sending unit is bad or something, because when the truck is fully warmed up, the guage barely gets to the minimun operating temperature.. thanks for the info.

 

[fairman86]

im having the same issue, thanks for the tips! ill go try cleaning my IAC and replace my fuel filter, well see how it runs after that

 

[fairman86]

wait a sec, cf3232, you said that you changed your fuel filter and it solved the problem, now your saying it was low compression in cylender # 2? what caused the weird idle? and hesitation.

 

[Rogue_Wulff]

gotcha.. my truck is a 1996 model and i am having a hard time diagnosing a rough idle. but the temperature sending unit is bad or something, because when the truck is fully warmed up, the guage barely gets to the minimun operating temperature.. thanks for the info.

My 95 is the same way. I suspect either the temp sender is reading incorrectly, or the previous owner has installed a 160* t-stat. Given the things I've found done wrong, I'm leaning towards the T-stat being too low temp.
My rough idle issue was the timing belt installed wrong. The cam was 6 teeth advanced, and the oil pump/cam pos sensor was ~120* out of time...... The PO had lined up the wrong marks...... Amazingly, it did run, just not that well.
You can see why I would suspect the t-stat, right? Radiator is new, so I believe they was chasing down an issue with it running too warm.

I can't really complain though, I only paid $700 for it.

 

[cf3232]

wait a sec, cf3232, you said that you changed your fuel filter and it solved the problem, now your saying it was low compression in cylender # 2? what caused the weird idle? and hesitation.

I wanted to convince myself it was the fuel filter. Although it seemed like it fixed the issue initially it came back almost immediately. It was definitely the engine compression low on the 2nd cylinder.