Idle Surging
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5th Wheeling
Joined: Aug 2012
Posts: 37
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From: Mountains of Northern CO
Idle Surging
I've searched the posts in the forum and haven't found one related to what I'm experiencing (maybe just missed it)... My '03 7.3 is "surging" on idle. When warmed up, and idling, the RPMs will drop by 300 or 400 for a few seconds and then will correct and shoot back up. It cycles like this (every 5 seconds-ish) continually 
. I just put in a new IDM and checked the UVCH - is there a separate idle control mechanism that I need to have a look at? (2003, 7.3, 214K, stock) Thanks for any help you guys can provide.
. I just put in a new IDM and checked the UVCH - is there a separate idle control mechanism that I need to have a look at? (2003, 7.3, 214K, stock) Thanks for any help you guys can provide.
Senior User
Joined: May 2006
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From: Harrison Twp., Michigan
PD Jim,
Sounds very much like what I am experiencing also. With one more symptom. Drop to 300 and stall . Starts right up and on my way till the next light. I did have surges up to 700 or so but not very often. Once stalled at 30 mph and again I was able to start before stopping. I will also check the harness today , Thanks Z31. Where is the IDM mounted ?
Sounds very much like what I am experiencing also. With one more symptom. Drop to 300 and stall . Starts right up and on my way till the next light. I did have surges up to 700 or so but not very often. Once stalled at 30 mph and again I was able to start before stopping. I will also check the harness today , Thanks Z31. Where is the IDM mounted ?
Senior User
Joined: May 2006
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From: Harrison Twp., Michigan
"Inner fender well" Are you saying the rubber wheel liner ? I see a bank of connectors to the rear of my 6637 mounted to the down slope wheel house, inside the engine bay.
Assume that some of those will lead back to the IDM ?
Assume that some of those will lead back to the IDM ?
Logistics Pro
Joined: Oct 2011
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From: Mcdonough, GA
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5th Wheeling
Joined: Aug 2012
Posts: 37
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From: Mountains of Northern CO
Checked connections/moisture etc... I probably should have been more specific: Once the truck is warm, when put in park, it will idle at around 1700 rpm, then drop to 1200-ish, pop back up to 1700 in a second or so and repeat (repeatedly). Essentially the same routine as if it were warming up on a cold day, higher rpm's until the brake is depressed, only repeating the routine on its own. I'm assuming that there is a "control" for this that I need to look at?
Senior User
Joined: May 2006
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From: Harrison Twp., Michigan
Sunday I did some checking , didn't find any chaffing or worn areas . No stalling for two days then on the way home last night it stalled. Thinking that when I moved the wire bundles , I isolated the short , until it went back to it's normal position. IDM showed no signs of moisture. I'm stumped.
Posting Guru
Joined: Sep 2014
Posts: 2,404
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From: Asheville-where weird is
Do you have any way of monitoring the sensors that the PCM sees that the truck utilizes like ICP, IPR, IPRDC, etc?
If not, this is a link to software (FORScan) that may assist us in helping you. It will also allow you to see any codes that are being stored.
https://www.ford-trucks.com/forums/1...the-cheap.html
Check out FORScan. If you have a windows laptop, you can be up and running for about $15.
Also, check the tin nut on the back of the IPR just for S&G's.
If not, this is a link to software (FORScan) that may assist us in helping you. It will also allow you to see any codes that are being stored.
https://www.ford-trucks.com/forums/1...the-cheap.html
Check out FORScan. If you have a windows laptop, you can be up and running for about $15.
Also, check the tin nut on the back of the IPR just for S&G's.
Elder User
Joined: Jul 2015
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Checked connections/moisture etc... I probably should have been more specific: Once the truck is warm, when put in park, it will idle at around 1700 rpm, then drop to 1200-ish, pop back up to 1700 in a second or so and repeat (repeatedly). Essentially the same routine as if it were warming up on a cold day, higher rpm's until the brake is depressed, only repeating the routine on its own. I'm assuming that there is a "control" for this that I need to look at?
I don't have an auto, so maybe I'm wrong, but 1700rpm, or even the 1200rpm, IDLE, in PARK seems crazy high. (Cold warm up excluded). My 6spd truck idles at about 600rpm, in my 80DD tune, and slightly higher in the stock tune ( I think about 800rpm).
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5th Wheeling
Joined: Aug 2012
Posts: 37
Likes: 3
From: Mountains of Northern CO
Did anybody else catch that?
I don't have an auto, so maybe I'm wrong, but 1700rpm, or even the 1200rpm, IDLE, in PARK seems crazy high. (Cold warm up excluded). My 6spd truck idles at about 600rpm, in my 80DD tune, and slightly higher in the stock tune ( I think about 800rpm).
I don't have an auto, so maybe I'm wrong, but 1700rpm, or even the 1200rpm, IDLE, in PARK seems crazy high. (Cold warm up excluded). My 6spd truck idles at about 600rpm, in my 80DD tune, and slightly higher in the stock tune ( I think about 800rpm).
More Turbo
Joined: May 2016
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It's been my experience surge at idle suggests the HPO system is acting up. The idle is controlled by the PCM based on sensor input. Notably the ICP or IPR assuming Turbo, Boost Leaks, and CPM have been ruled out.
Many people attack the IVS. But, on ours the circuit is eiter on or off and normally only produces surge with a damaged potentiometer (AP).
You can try disconnecting the ICP and see if idle improves. The PCM will default to 700 psi which is more than enough to correct the idle if the ICP is defective.
Next is the IPR. The IPR opens and closes to allow oil pressure to increase/decrease based on the ICP reporting reference voltage.
IPR's can be easily removed and cleaned. Just a few towels to absorb oil in the valley when removed. New are about $150
A Scantool may help with diagnosis monitoring both of these sensors voltage and duty cycle and save you both money and hair loss. One that record or stores the data is preferable as you can review the data away from heat and noise or just play it back immediately. you can also retrieve code, do CCT and the like.
You may have to test the entire HPO system with air to rule out Injector O-Rings or other leak.
That's all I got! Good luck.
Many people attack the IVS. But, on ours the circuit is eiter on or off and normally only produces surge with a damaged potentiometer (AP).
You can try disconnecting the ICP and see if idle improves. The PCM will default to 700 psi which is more than enough to correct the idle if the ICP is defective.
Next is the IPR. The IPR opens and closes to allow oil pressure to increase/decrease based on the ICP reporting reference voltage.
IPR's can be easily removed and cleaned. Just a few towels to absorb oil in the valley when removed. New are about $150
A Scantool may help with diagnosis monitoring both of these sensors voltage and duty cycle and save you both money and hair loss. One that record or stores the data is preferable as you can review the data away from heat and noise or just play it back immediately. you can also retrieve code, do CCT and the like.
You may have to test the entire HPO system with air to rule out Injector O-Rings or other leak.
That's all I got! Good luck.