Knocking at Idle
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Junior User
Joined: Sep 2006
Posts: 93
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From: Watertown, WI
Knocking at Idle
I have a 2001 F350 that has an intermittent knock at low and high idle. It will also knock at lower cruising speeds. 129,000 clicks on the odometer. No major mods. 4" MBRP turbo back exhaust with a Predator programmer, which is usually set on the 100hp setting (although this will happen on all settings). I have been thinking it could be a leaking injector after reading about a similar problem on another post. I have tried additives with no cure.<O
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Today I had the Predator programmer hooked up and it has a setting where I can check the "% of change" in each cylinder. # 3 and # 8 showed 5-6% change at idle when it would knock, 1-2% change when there was no knock. Two other cylinders would have a 1-2% change every now and then.
I have a great place to start with the #3 and #8 cylinders probably being the culprit of the knock. My question is this; would it be worth my effort to just replace them all? If so, which brand would you recommend? I am not looking for anything too crazy. This is my toy hauler, with which I tow 10,000-12,000 lbs with.<O</O
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Thanks for your input!<O</O
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</OToday I had the Predator programmer hooked up and it has a setting where I can check the "% of change" in each cylinder. # 3 and # 8 showed 5-6% change at idle when it would knock, 1-2% change when there was no knock. Two other cylinders would have a 1-2% change every now and then.
I have a great place to start with the #3 and #8 cylinders probably being the culprit of the knock. My question is this; would it be worth my effort to just replace them all? If so, which brand would you recommend? I am not looking for anything too crazy. This is my toy hauler, with which I tow 10,000-12,000 lbs with.<O
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</OThanks for your input!<O
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Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
Wait, before doing anything....... did you do the CPS recall, or install a grey CPS?
If so, that is the cause of the #3 and #8 cylinder's showing a very high change in rotational velocity. Don't swap injectors just yet. The grey CPS causes a lot of problems, and it's easier and cheaper to replace.
If so, that is the cause of the #3 and #8 cylinder's showing a very high change in rotational velocity. Don't swap injectors just yet. The grey CPS causes a lot of problems, and it's easier and cheaper to replace.
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
It's become quite common. The grey CPS causes cylinder contribution faults typically on #3 and #8 cylinders. Quite a few people have complained about idle issue, and decreasing MPG's with the grey CPS. If you are having problems like you are now, try your hardest to locate a black CPS.
Thread Starter
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Junior User
Joined: Sep 2006
Posts: 93
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From: Watertown, WI
It is located at the front of the motor. Just above the crank pulley. About half way up the motor. You cannot see it from the top.
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Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
As Curtis mentioned, the rotational velocity numbers are more than likely from the CPS. We used to recommend fixing this by telling you to get a Black CPS from International. The problem is International has now switched over to a gray CPS as well. We do not yet know if the gray IH CPS has the same issues as the gray Ford one, so you might try one of the gray ones from International and see what kind of difference you notice.
If you do this, please write down the % change for each cylinder with the current CPS, then again with the new one from International and share those numbers with us. We're all wanting to see if there's any difference between the two.
Here's the old International part number (black one) for our trucks 1825899C93. You can also check to see if they have a 1821720C99 (in black). If you can get either of those part numbers in black from International, I would recommend you buy at least 2, if all they've got are the gray ones, try the C93 part.
Welcome to guzzle's CPS R&R Web Page<
If you do this, please write down the % change for each cylinder with the current CPS, then again with the new one from International and share those numbers with us. We're all wanting to see if there's any difference between the two.
Here's the old International part number (black one) for our trucks 1825899C93. You can also check to see if they have a 1821720C99 (in black). If you can get either of those part numbers in black from International, I would recommend you buy at least 2, if all they've got are the gray ones, try the C93 part.
Welcome to guzzle's CPS R&R Web Page<
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