I have been chasing a slight idle fluctuation for some time now. I ran a contribution test on AE and it comes up with p0263 Cyl 1 injector circuit contribution/ balance fault. And p0281 Cyl 7 injector circuit contribution/balance fault. Where do I need to start looking? Valve cover gaskets? TIA

 

What CPS is in the truck ?
Do you have a spare CPS ?
If so change it and run your test again and see if the cylinders change.

 

I have a ford cps about a year old. Will change and try again. I have no burned pins on valve cover gasket or harness

 

How could a cps cause something like this? Also the 1 and 7 cyl would be on passenger side front and rear. Correct?

 

Changed cps but engine is to cold to run another contribution test today. I will tomorrow. Buzz test is good. No other codes stored.

 

Truck runs good just a 30 -50 rpm up and down idle.

 

Did another test this am got 1-4-7- cyl injector circuit contribution /fault . What do i check now?

 

Ran another test this afternoon with a hot engine and I am getting cyl 1-6-7. I am at a loss , any help would be appreciated.

 

Was it the newest Ford one, Dark Gray with purple o-ring?

CPS is the heartbeat of the engine. It informs the PCM where exactly the cylinders are in rotation. Yes, odd numbers are on the passenger side.

My 97 also does that, especially when warm at idle. I just ignore it as over the years got tired of trying to figuring it out. On the 99 it's much better but different injectors and PCM coding is different, go figure.

Not a big supporter on the cylinder contribution test results. Seems like almost everyone had issues with the reported result. It doesn't mean it's not a good test for overall engine efficiency though. The fact that you flashed the PCM to 60 HP would probably make the actual test invalid. But that is just a guess on my end.

 

Yes both cps were new ford. I also have another one coming from riffraff.
I have done some searching about the contribution test on here today and it seams that you are correct about test results not being very reliable. Yep just live with the up and down idle but I sure would like to put my finger on it. Thanks for the info.