1998 2.5 engine idle issue, only when cold

[cf3232]

I have searched through the forum and have not found an issue quite like mine. I am not sure if it is fuel, ignition, or just a bad sensor. Everything I have read states or implies that the idle problem is the same even if the car is up to temperature.

I have a 1998 Ford Ranger 2.5 liter manual 5 speed transmission vehicle. When I start the engine cold the engine run absolutely fine for the first 3 minutes or so with no issues. I have no check engine light and the engine runs smooth. After the engine runs for the first 3-5 minutes it will not stay idle. When I come to a stop I have to hold the accelerator down to keep the engine running. I just have to keep it revved up so that it does not die. After I continue this the engine will come up to temperature normally. Once the temperature reaches normal operating temps the engine will stay idle with no issues. When it first comes up to temp it may stumble a bit but it will not die and over a short amount of time it will stop stumbling all together. At this point I will not have any problems with it staying idle whatsoever. I can drive around all day with no trouble from it dying while idling. If I park the car and let it cool all the way down I will then get the dying at idle issue until it is back up to operating temperature then it will run fine again. Whenever it is at operating temperature I have no issues.

What is throwing me for a loop is that it runs fine without dying for the first minutes after it is started and only after about 3-5 minutes do I have problems with it dying until the engine is completely warm.

Any help or insight into this issue would be greatly appreciated.

 

[dhendrix]

Maybe a shot in the dark, but you could check your IAC. (idle air control) It is a common issue with Ford. Not hard at all to check or change. Maybe someone else will chime in, this seems to be a common issue. Hope this helps in some way. Also check for vaccum leaks.

 

[Ranger Sport Honduras]

mine does it while cold, but 2minutes of warming fixes it, check the IAC, mine has a lot of carbon, its being cleaned as we speak, maybe tomorow ill see if it fixed the problem

 

[cf3232]

Will try it guys and report back. I appreciate the help.

 

[Ranger Sport Honduras]

ok tested the truck today, idels smooth, runs fine, no stalling no black smoke. i deff recomend to clean the IAC first, i cleaned the MAF, throttle body and all the sensors neaby. if not the coolant temp sensors could be failing

 

[budah30]

how do u clean the IAC ?

 

[Earl43P]

Remove it (two 8mm bolts), save its gasket for reuse.

Spray it with a good solvent, I like SeaFoam and Deep Creep, throttle body cleaner will work too. Get in there with a pipe cleaner or bore brush and get the crud out of the shaft area. Let it dry, reinstall and try it.

Some like to disconnect the battery and let it relearn its idle. I usually don't bother. If you do: Idle for 5 min in Park, then 5 min in D, then 5 min in Park with AC on, then D with AC on. Don't touch the gas pedal during any of this time.

If it's a stick shift, 5 min in neutral, 5 with AC on. Done.

 

[Ranger Sport Honduras]

yeah it will improve after that i can assure

 

[budah30]

thanks for the info

 

[cf3232]

Okay I have tried a couple of things and the problem still persists.

The one thing that strikes me is that the problem does not show its head until about 5 minutes after I have started and driven the truck. This makes me think it is an electrical sensor issue. Not a mechanical issue. I am thinking a mechanical issue would show immediately, and electrical issue would show when the electronic component starts to fail. I think that it starts after the five minutes because the component that is failing is not being utilized by the computer until the engine starts to warm up.

Any opinions on this theory?

Okay things that I have done:

I have cleaned the IAC valve. It was nice and clean when I put it back on the car.

I have checked the resistance hot and cold on the Engine Temperature Sensor it shows 67K at 40 degrees Fahrenheit and shows 3000 at normal operating temperature.

I also checked the Engine Temp Sending unit and it is working properly. I know this has no bearing on the engine running, but it is working properly.

I have cleaned the MAF sensor as well. It looked really good.

I also cleaned the posts on my battery and made sure I had a good metal to metal connection on all the connections. I have known of peoples cars dying at random times when idling when the battery terminals have been gooked up.

I also pulled the electric connectors off of the coils at different times to make sure the coils were not going bad. I let the engine idle and I pull the connector off of one coil and it kept running then I put the connector back on and pulled the connector off of the other coil and it kept running so I think the coils are not the issue.

I have not taken the car to have the codes read using a computer. I will do that next. For anyone reading this post and not my previous one the CEL is not on.

 

[Ranger Sport Honduras]

maybe a throttle position sensor?

 

[modelageek]

how is your air filter

 

[cf3232]

Air filter is fine. What is the a procedure on checking the TPS. I understand that you should hear clicks or something like that when the throttle is opened and closed.

 

[Ranger Sport Honduras]

my mom's 03 had a bad tps, and it sputtered once it went to normal temp range
no clickings tho

 

[cf3232]

Okay guys got it fixed. It was the fuel filter. Changed it and the car runs fine from start to finish. I just never thought that was the issue. I just did it because it was cheap and I can change it in like 5 to 10 minutes. I thought it was electrical because the issue went away after the car warmed up, which is weird because the heat has nothing to do with the fuel filter. Oh well it is fixed so I am a happy camper. Thanks for all the input. Wanted to give a couple of days before I posted after the problem left just in case it came back and this was not the fix.

Also I changed that fuel filter for a new motocraft filter less than 50k miles ago so that was another reason I did not suspect the filter.

Thanks again to all that replied!!!