7.3 Missing / Hiccuping
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New User
Joined: Sep 2021
Posts: 6
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From: East TN
7.3 Missing / Hiccuping
Hoping to find some helpful advice here as I am new to the 7.3.
I have a 1997 7.3 and I am having an intermittent "miss" problem. Typically worse when the motor is cold, but the problem remains after heated up as well. (No CEL or Codes)
When its acting up it has a noticeable bad stroke that feels like completely dead cylinder, followed by a knock, and then goes back to normal. Problem is worse on acceleration, and the issue comes and goes.
So far I have done an oil change with hot shots stiction eliminator, CPS ICP, IPR, Cleaned fuel bowl, starting to suspect UVCH or IDM, but wondering if it could be Injectors or Injector O-Rings.
***SOLVED***
After a couple months of trying what seems like everything on this truck, we installed ANOTHER new CPS (Black with Purple O ring this time) and the problem was resolved.
The only thing we can figure at this point is that the CPS was sending incorrect signals and causing the random misfire.
I have a 1997 7.3 and I am having an intermittent "miss" problem. Typically worse when the motor is cold, but the problem remains after heated up as well. (No CEL or Codes)
When its acting up it has a noticeable bad stroke that feels like completely dead cylinder, followed by a knock, and then goes back to normal. Problem is worse on acceleration, and the issue comes and goes.
So far I have done an oil change with hot shots stiction eliminator, CPS ICP, IPR, Cleaned fuel bowl, starting to suspect UVCH or IDM, but wondering if it could be Injectors or Injector O-Rings.
***SOLVED***
After a couple months of trying what seems like everything on this truck, we installed ANOTHER new CPS (Black with Purple O ring this time) and the problem was resolved.
The only thing we can figure at this point is that the CPS was sending incorrect signals and causing the random misfire.
Last edited by soggyburrito; Nov 4, 2021 at 08:22 AM. Reason: Solved
Lead Driver
Joined: Mar 2006
Posts: 5,098
Likes: 1,504
From: western SD
Check the wiring harness to the valve covers for melting and/or burned pins. If one shows signs of overheating, the miss will get worse, and may even lead to one bank shutting down. Do you know how many miles on the injectors?
Where are my manners, Welcome to the best forums on the net for these old trucks.
Where are my manners, Welcome to the best forums on the net for these old trucks.
Thread Starter
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New User
Joined: Sep 2021
Posts: 6
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From: East TN
Hey, thanks for the reply and the welcome! I did check the wiring on the passenger side but could not see the harness on the driver side to check for bare spots...
As for the injectors I have no idea, I swiped the truck on the backside of a dealership trade in thanks to guy I know. The truck has 339,000 on the clock and with this strange occurrence aside runs great.
I imagine that nearing 350,000 the injectors have been replaced at least once already.
As for the injectors I have no idea, I swiped the truck on the backside of a dealership trade in thanks to guy I know. The truck has 339,000 on the clock and with this strange occurrence aside runs great.
I imagine that nearing 350,000 the injectors have been replaced at least once already.
Laughing Gas
Joined: Nov 2020
Posts: 992
Likes: 367
From: Republic of Texas
How are you checking for codes??? FORScan is pretty much the standard. Most of the readers you can purchase a the corner store do not read the truck properly.
Also just because you do not have a light does not indicate no codes.....
Also just because you do not have a light does not indicate no codes.....
Former Vendor
Joined: Sep 2020
Posts: 2,597
Likes: 695
From: Florence, MT
Could be IDM, wiring, non FoMoCo sensors or injectors. At 350K it's 50/50 if the injectors have been charged, or changed with a quality product. Even a quality product can be abused. It's not uncommon for people to dump vehicles with known issues at a dealership vs selling private party.
Logistics Pro
Joined: Mar 2007
Posts: 4,577
Likes: 837
From: knoxville, tn
You need to unplug the connectors to check for burnt pins.
You can also unplug IDM connector and use this test with a simple multi-meter:
https://www.ford-trucks.com/forums/a...6&d=1564842340
You can also unplug IDM connector and use this test with a simple multi-meter:
https://www.ford-trucks.com/forums/a...6&d=1564842340
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New User
Joined: Sep 2021
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From: East TN
Thanks for the reply, using a Snap-On SOLUS to check for codes.
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New User
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From: East TN
Could be IDM, wiring, non FoMoCo sensors or injectors. At 350K it's 50/50 if the injectors have been charged, or changed with a quality product. Even a quality product can be abused. It's not uncommon for people to dump vehicles with known issues at a dealership vs selling private party.
I knew the truck had an issue when I bought it, and for what I paid I could put a reman engine in the truck and it would still be a good deal for me.
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Thread Starter
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New User
Joined: Sep 2021
Posts: 6
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From: East TN
You need to unplug the connectors to check for burnt pins.
You can also unplug IDM connector and use this test with a simple multi-meter:
https://www.ford-trucks.com/forums/a...6&d=1564842340
You can also unplug IDM connector and use this test with a simple multi-meter:
https://www.ford-trucks.com/forums/a...6&d=1564842340
Thread Starter
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New User
Joined: Sep 2021
Posts: 6
Likes: 1
From: East TN
After a couple months of trying what seems like everything on this truck, we installed ANOTHER new CPS (Black with Purple O ring this time) and the problem was resolved.
The only thing we can figure at this point is that the CPS was sending incorrect signals and causing the random misfire.
The only thing we can figure at this point is that the CPS was sending incorrect signals and causing the random misfire.
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