Good evening. I'm working on a Cat 242D with a DZT serial number prefix. It has 616 hours on it. It has the Kubota (Caterpillar)3.3 liter in it. It came in with a rough running issue. Field tech said to replace injectors 3 and 4. Did that and calibrated the new injectors. Runs the same. Ran a cylinder cut out test. When 1 is cut out there is no change, 2 is cut out there is a little change. When 3 is cut out there is very little to no change. But when 4 is cut out the engine actually smooths out and runs beautifully. Compression was a little below spec. Our Technical Communicator said to remove cylinder head. I did that, found nothing wrong. Put all back together with new gasket of course. Has better compression but still runs rough with number 4 injector plugged in. I say it's in the ECM/electrical system. Machine runs in a very corrosive environment loading fertilizer. It's only 3 years old with 616 hours on it but looks bad. The ECM is all corroded externally. There are no codes at all on this machine. I'm thinking there is an issue within the ECM. Has anyone else ran into a similar problem? Thank you.
Common rail?
Yes it is common rail.
Given the back story, I would be checking for corrosion at the ECM plugs. Those Kubota ECMs have VERY fine automotive style pins and are, IMO, pretty unsuited to a heavy equipment environment. I can't say I've actually come across corrosion before but I have had a couple with pins damaged by careless re-connection of the plugs.
Thank you for your response. I think I found the issue. The pins look clean but when I checked for continuity between pins I found that the power wire pins for injectors 1 and 4 are right next to each other and have continuity between them. I checked the pins for cylinders 2 and 3 and they do not have continuity between them. Waiting on a response from our technical communicator for his thoughts.
Good find. Let us know how you go.