For CAT Techs only

[2cycle2]

Actuation pressure on a 3126. Idle verses full load. I got one that's cuttin my butt with a performance problem. No codes with ET, everything looks fine. Checked all the mechanical stuff. Swapped all actuator valves and sensors, and even the ECM. This is a marine engine, so I got her sister sittin right next to her. Tested vehicle, and engine harness for short, open and continuity. Everything tests fine. I found the ECM power harness tied on to the starter with a .25volt drop from the battery. Rewired it strait to the battery, with no good results.
There is just a few tests I aint done yet. One is HEUI actuation pressure, and the other is exhaust back pressure.

Any clues?

[grounder]

Did you do the step up test on ET and check actual VS desired ICP.Also there are plugs INSIDE the Oil galley on certain years that go strait in to each Injector bore.They have been KNOWN to come out.This will cause a performance problem and Erratic ICP.Sometimes that particular Injector where the plug may have came out will fail sometimes it wont.There are 6 external plugs on the outside of the Oil rail.Drain the rail first then remove these plugs on the SIDE of the rail.Its tough but you can look strait in the hole and you should be able to see another allen head plug right inside the rail.Each cylinder will have one.IF you find one missing remove the large plug on the rear of the rail and usally its right there.It CANNOT go anywhere else or into the engine.I would also stick a long head allen in and check that each one is tight if you decide to do this.Also when you decide to do the ICP test and fing that there is a problem.You will also have to pull the V/cover and depending on the year of the engine it may have a Bad jumper tube that feeds a inj or blown or leaking O-rings on the Newer style heui's there is alot to look for.

[2cycle2]

grounder, sorry for so long gettin back to you. All tests with ET were within specs. Sometimes ET will BS you, so all results were verified by test gauges. The customer got impatient with me, and my services were no longer needed. I'm an independent now, that has worked with electronic CATS since they first appeared (I was working for a dealer then). I sure do miss the 300 series though.

Greg

on edit... when the cat dealer did a sea trial, the starboard engine was only 150rpm off the top. I know most every tech in this area, even trained e few of them.