4.0 sohc/5speed high idle sometimes - Ranger-Forums - The Ultimate Ford Ranger Resource


4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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  #1  
Old 10-30-2008
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4.0 sohc/5speed high idle sometimes

Sometimes when I'm driving after the engine is warmed up (190~ coolant temp), and step in on the clutch, wanting to coast, the engine will rev to around 2k rpm and stay there generally until I slow for a stop. Sometimes I can correct this by quickly turning the ignition off then on, and it will idle right. I'm glad it idles like this when cold, but not when it's warmed to opp. temps. Any suggestions?
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Old 10-30-2008
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Well here is an easy thing to try. Clean the IAC valve.
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Old 10-30-2008
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Mine does the same thing, has done it for 7 years, stays at a high idle if its cold out for a minute, come to a stop and a couple seconds later its comes back down
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Old 10-30-2008
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IAC valve....I clean it using MAF sensor cleaner, seems to do the trick. Clean or replace should cure that.
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Old 10-31-2008
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If it comes down to 750 at a full stop.... clean the IAC, dis-connect the battery, turn on headlights, turn off, reconnect, and put it through the idle learning process.

If it is 800+ rpms at idle... look for a vacuum leak or the throttle body not closing all the way.

Also, try quickly opening and closing the throttle when in coast down. Does that lower it? (there is a setting for this in the tune)

Rich
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Old 11-01-2008
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I cleaned the IAC and that had no effect. I checked voltage to the IAC and it's doing what it's told, not sticking. It idles around 740~770 when it comes down. I'll try snapping the throttle and let you know.
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Old 11-01-2008
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my aic has been replaced and mine does it too. ill be in the house letting it warm up and i hear it idle high then go back down and it goes back and fourth
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Old 11-01-2008
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There was a TSB that corrected mine. I had the same issue. I think its in the 500 range. I dont remember which one it is. I think I posted it here or RPS. I'll look and if I find it wi will post the thred. Basically ford reloaded the code into the computer. Now the code on the outside of the computer is diffrent than whats actually is in it.

****
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  #9  
Old 11-01-2008
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I posted about this somewhere but i cant find it. I think it was this tsb

http://www.ford-trucks.com/tsb/tsb.p...y-2004/t-05510

I went to the shop on base and got it printed out to prove to the dealer that this was a known issue. they told me 3 times that this was normal. BS any way. Take a look at that if you can get it.

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Old 11-01-2008
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found it! RPS site:
http://www.rangerpowersports.com/for...ight=high+idle

If that dont work go to:
Ranger Power Sports Forum > A/V & Electronics > Electrical Tech, idle too high . Oroginal poster: rigigoogoo

Hope this helps.
****
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  #11  
Old 11-03-2008
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Thanks. I'll have to check out Ford sometime, see what they can do.
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Old 11-05-2008
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My 5 speed 06 Mustang 4.0 did the same thing. Clutch in, coasting to a stop, RPM would remain above 1500 until I stopped, then it dropped to normal. On the Mustang forums it was said it was normal, it's an emissions thing. (so did one of those posts on RPS)
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Old 11-06-2008
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1500... IMO...too high 1200 better but still not right... 1000 still too high for me.

Common... the base idle of a manual trans car is like 700-800 rpm. If you are coasting to a stop sign and running 1500 rpm your using fuel, period. With fuel prices these days i dont want to use any when i dont need to and your running 1500 coasting while the base is 700-800. thats twice as much as you should be.

This is all set up by the computer these days. its not even set up by the screw on the TB anymore. I dont like that they have it this way but its not right if its more than say 1000 coasting warmed up. They might say its right but i dont like it. In fact idle control on my truck is slower than i like to see it but it does finally come back to 700-800 while coasting. Sometimes i can get it to come all the way to 500ish with the SCT tune but it dont always do it.

1500, Normal.... not in my book. I wouldnt have it if it did.

****
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Old 03-08-2012
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Just bought my 3rd Ranger in 22 years 2 months ago. 1st - 1990XLT 2wd with 2.9 EFI. 2nd - 2002XLT 4wd with 4.0EFI. 3rd - 2011Sport with 4.0EFI. The 2011 is the only one that continues the high rpm after depressing the clutch and coasting. Returns to normal 700rpm after stopping though. I visited the dealer yesterday to inquire and was told it's all normal. That is the way EFI works. He also said, How about this!! We are tricking the computer because the wheels are still turning. Hard to believe when the feds are requiring higher gas mileage and the big three are cheapening up and making lighter vehicles to comply, that stupid me could trick a computer into worsening my mileage.
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  #15  
Old 03-08-2012
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I am with you. If the engine is running at 1500 coasting it is using more than twice the fuel if it coasted at 750. Can you cay bad mileage, i can.

First you need to quantfy high rpm. Mine was from 1200 to 1800 and was almost never the same. Now mine is fixed, sorta. It coasts at 1000 ALWAYS then falls to base when you stop. I even had a tune built for a supercharger and tried to get the guy to fix it but he diddnt even understand what I was talking about. Some tuner, $550 for a chassis dyno tune for a supercharged 4.0 and he cant even understand that I want coasting rpm to be the same as base idle.


Prety much blew me off after i paid for it and picked it up. Any body needing to get a tune and going to memphis (or Alabama) let me know I will tell you who to stay away from

****
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Old 03-08-2012
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Whoa, old thread. I've had it in the shop to find a vacuum leak, using a smoke machine, found nothing. Everything else in the PCM was ok. Still does it. I quit caring. I drive my diesel more anyway. The truck gets good fuel mileage, usually around 20 some times up to 21 or 22
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  #17  
Old 03-09-2012
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You really should look into the TSB's. TSB 05510 is the holy grail…..

http://www.rangerpowersports.com/for...gh-180487.html

I went from 25-28 to 21-24 when we went to 10% alcohol fuel and only lost about 1 mpg after the blower install.
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Old 03-09-2012
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What year do you have?
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  #19  
Old 03-09-2012
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2004
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Old 03-09-2012
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And you were getting 25-28mpg?
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  #21  
Old 03-09-2012
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On non-alcohol fuel, with a tune for 93 torque tune. Fairly easily I might add.
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