I was monitoring crank rotational velocities noticed cylinder number 8 was averaging four and cylinders 1 2 3 were only averaging about two. The other cylinders would just barely come off of zero every once in awhile. Would this indicate there is a problem was cylinder number eight? The cylinder contribution test failed on cylinder number 2.

I also wanted to say thank you to everybody who has contributed to this site. By far the best way to fix your truck is to look here first.

 

Are you running an OEM gray "recall" CPS? Also what transmission do you have, manual or auto? If cylinder #2 is reading 2% than you should not be failing the test. What code is it giving you?

With an automatic transmission you will see higher numbers, and the CCT will allow higher PERDELS before a code is set. The manual trucks run lower numbers but also fail sooner. If you have a gray CPS, then you are in the normal range.


Here is some information I put together on the effects from different cam position sensors.

Cam Position Sensor Information Using Autoenginuity

 

I just had the crank position sensor replaced and it is gray. It's a 2001 F350 with an automatic. I did the cylinder contribution test before I had the recalls done and I cannot remember what code. I just remember that it failed on cylinder number two. I just got this scan tool and I definitely have a lot to learn about this software. Thanks for the link that's interesting information. I finally got a laptop so I won't have to drag a desktop out to my truck just to run the scan tool. I am in the process of setting it up right now and I will definitely run the cylinder contribution test over again.

 

Don't put too much stock in those tests.

Rotational velocity is normally higher on #8 simply because of the firing order. #6 fires right before #8, and since they are close together, and #8 is a deadhead cylinder, it's going to read higher.

As for the CCT, that also can be deceptive. AE at times can pull a failure for no reason at all.

With those tests, they are a comparative test to other cylinders. If one fails, it doesn't always mean that cylinder is weak. It could also be that the combustion event on another cylinder is stronger, enough to fool the test into thinking that cylinder is weak, when it might be perfectly normal.

The big question is... are you having issues with the engine running? If not, then there's nothing to be concerned about, and you can ignore the test results.

 

After changing the exhaust pressure sensor and cleaning the tube the truck has never ran better. I am glad to hear that these are normal readings thanks for the information.