High Idle Help
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Mountain Pass
Joined: Jul 2007
Posts: 187
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From: Watkins IA
High Idle Help
2004 E350 10ft box van with 5.4 gas and 87000 miles. Was down in Florida at the state fair. Had had no problems with unit until one night I came out and the idle at starting went to 2250-2500 rpm and would not go down. Checked throttle linkage and vacuum lines the next morning but everything appears ok. Had codes checked. Bad MAS sensor. Replaced MAS sensor with new ($155 ouch). No change. Drove that way rest of fair shutting off engine in gear to prevent higher idle speeds and dieseling. Got back into Iowa and stopped for gas and idled at regular 800-1000 rpm when I shut it down. At restart back to high idle speeds. If matters..temp in FL was low 70's...in IA is low-mid 20's. Now with the lower outside temperatures it is idling around 2000 rpm. Any help or suggestions greatly appreciated as I don't want to take it to "stealership" for diagnosis. Thanks.
Elder User
Joined: Mar 2012
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From: Outside of Memphis, TN
The 'Bad Mass Air Flow Sensor,' do you know what the actual code was? For some reason people will just replace stuff when the computer says somethings wrong, when in reality the condition could be caused by lots of things.
Lead Driver
Joined: Dec 2012
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From: Tennessee
Postmaster
Joined: Feb 2011
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if the code was "mass air flow sensor range problem" or similar, that means that the MAF sensor was reading something other than what the engine was getting, which is often a sign of a vacuum leak. there are a number of other codes that could relate to the MAF, which could relate to damaged wiring, or a bad sensor.
the idle air control valve (IAC) would be among my first guesses for any idle speed issues, including yours. they usually fail without throwing a code, causing either excessive idle speed or stalling at idle.
if you don't already have one, go to your local auto parts store and buy or borrow a code reader. find out exactly what your computer says to you, and post it here, that'll help us help you
the idle air control valve (IAC) would be among my first guesses for any idle speed issues, including yours. they usually fail without throwing a code, causing either excessive idle speed or stalling at idle.
if you don't already have one, go to your local auto parts store and buy or borrow a code reader. find out exactly what your computer says to you, and post it here, that'll help us help you
Thread Starter
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Mountain Pass
Joined: Jul 2007
Posts: 187
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From: Watkins IA
Throttle linkage and cruise linkage are all free and ok. Didn't see the actual codes but was told the indication was a bad sensor. I hate just throwing parts on also but considering I was in a parking lot 6.5 miles from our motel with no other transportation I went ahead and installed a new sensor which didn't help. After I got home yesterday, from Florida, I looked into my Chilton's and read up on the IAC. That is where I am going to test and clean-up next. I would like to get a good but inexpensive code reader as all this newer FI systems and TB's are a mystery to me. I am an old carb and distributor man myself. Any suggestions on an OCB-II reader?
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Mountain Pass
Joined: Jul 2007
Posts: 187
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From: Watkins IA
Follow-up. I replaced the IAC valve. The idle at start-up is now down where it should be 800-1000 rpm. But after running around with operating temp in the normal range the idle runs at 1300-1600 rpm when put in neutral or park. Anything?
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Lead Driver
Joined: Dec 2012
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From: Tennessee
No vac leaks ? Throttle closing all the way ? Sounds like a vac leak . Bad booster ? ck pcv hose .
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Mountain Pass
Joined: Jul 2007
Posts: 187
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From: Watkins IA
Thanks JWC, the throttle linkage is all free movement so believe is closing all the way. Will recheck all vac lines again and pvc hose. Which booster? Brake seems to be ok with good pedal and stopping action. Pumps up and holds at the pedal. Thanks again.
Fleet Owner
Joined: Aug 2010
Posts: 21,254
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From: Reynoldsburg, Ohio
Maybe needless to add but the complete PCV hose as well as the PCV itself thoroughly checked----those have been a very frequent source of thrown codes and drive-ability issues.
The check valve for the brake booster pushed into a grommet should also be checked, especially if you're also losing brake fluid.
Whatever you eventually find might be helpful to others too.
The check valve for the brake booster pushed into a grommet should also be checked, especially if you're also losing brake fluid.
Whatever you eventually find might be helpful to others too.
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Mountain Pass
Joined: Jul 2007
Posts: 187
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From: Watkins IA
Follow-up. Rechecked all hoses including PVC and booster. Everything looks ok. Started and ran to operating temp. Sprayed all hose connections with ether and carb cleaner to try and find trouble spot..nothing. Pulled battery cables to clean and let system reset itself (still don't have access to scanner/reader). Started up and everything has returned to normal..no more high idle. Can only believe holding the codes was causing the ECU to hold on to the high idle. Have driven over 40 miles of in town and highway without any more trouble or codes to be thrown. Thanks for the imput and ideas. Still looking for a reasonable priced scanner...any ideas, what are you using?
Lead Driver
Joined: Dec 2012
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From: Tennessee
I like Launch for a cheep scanner . OTC has a good one for about a grand , a couple fair ones for around 3 to 400$ . Tried ones from the parts stores , was not happy with them . My Snap On Modis has me spoiled . Full scan , US and Asian , Heavy duty , And 4 channel lab scope and component tests .
Fleet Owner
Joined: Aug 2010
Posts: 21,254
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From: Reynoldsburg, Ohio
I've owned only the Actron CP9580 and for what I do its more than enough. Found my through the 'net, eBay tends to have a few good deals on brand new units. There is an upgraded version but I'm not likely to ever outgrow mine---it's database can be updated to include later model vehicles but they tend to run about 2 years behind what's new or current vehicle model wise.
This certainly isn't the ultra sophisticated version the professional guys use---I could see getting spoiled by those in a hurry!
I like mine because it has the Code Connect feature. This gives you a few examples of what has historically fixed a code, input by peers who've made repairs or discovered what caused the malfunction.
For a full scanner and code cancelling unit figure about $160, reader only less than $50 but not advisable IMHO---why read something and not be able to cancel it after repairs? Here's but one on FleaBay: Actron CP9580A Autoscanner Plus OBD II Can ABS Scan Tool New SEALED | eBay
This certainly isn't the ultra sophisticated version the professional guys use---I could see getting spoiled by those in a hurry!
I like mine because it has the Code Connect feature. This gives you a few examples of what has historically fixed a code, input by peers who've made repairs or discovered what caused the malfunction.For a full scanner and code cancelling unit figure about $160, reader only less than $50 but not advisable IMHO---why read something and not be able to cancel it after repairs? Here's but one on FleaBay: Actron CP9580A Autoscanner Plus OBD II Can ABS Scan Tool New SEALED | eBay
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