engine revs when in neutral with the heater on.

[craveman85]

2008 Ford ranger 2.3/5spd. It's only been doing it for a month. No other issues or check engine light ever. If I have the heater on and push the clutch or pop it out of gear the rpms slowly rise to 2000-2200 rpms. Eventually they will go down but it takes a while. It does it while sitting at a red light and coasting and changing gears.

 

[Lil-Pony]

Dirty iac?


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[craveman85]

Would that make it only happen with the heat on? Never did it until a week or so before Christmas. What would I use on it? Mad cleaner?

 

[RonD]

^^ IAC Valve would be worth a look.
With engine idling unplug the IAC valve's connector, idle should drop to approx. 500, then plug IAC back in, if engine is warm idle should go to 750, if cold 1,000.
If this doesn't happen remove IAC and clean it.

If heater is on Defrost and you have A/C then the A/C will be on which can kick up the RPMs a bit.
Put heater to floor or something else and see if changing RPMs go away, if so then could be an issue in the A/C circuit.

Computer for manual trans is setup to hold the RPMs high when shifting gears, also RPMs shouldn't drop below 1,000 until speedometer gets below 5mph, these are fuel saving and emissions settings.

As far as climbing RPMs I would check the throttle linkage specifically its spring return and the cruise control cable if so equipped

 

[craveman85]

Every manual ranger I've ever had didn't hold rpms when changing gears ( 2 95's , a 99 a 2004, an 06 and an 08). Whenever I pushed the clutch in they dropped right down to 1000 rpm. I checked this against my friends 04 and his doesn't do this. It does it on any heat setting.

 

[craveman85]

My rpms do jump a little when shifting but quickly drop back down. I thought you meant it holds rpms until you shift. I tried switching between defrost and floor and sometimes when I go to floor heat it drops down to my normal 980 rpm idle. I'm going to assume its something in the ac then. Any idea what to check? I cleaned maf iac tps and I the throttle body. Cable doesn't stick at all and is regularly lubricated with graphite powder.