steeler

I have a feeling nobody has had this issue before but I`m working on a vmac3 LE garbage truck with dual operating positions.

The truck just got back from transmission shop for new Allison. Now when you switch the operating position switch, the trans pad will switch from left to right and back, but the throttle stays left. it wont work on the left side at all. I`m not sure how the switch is tied into the electronics and I have no diagram.

The Trans shop says its not on them, they didn't have anything to do with it.

No fault codes.

Anybody got anything?

I've had 2 of them (mp7 I assume you have?) Leaking compression from underneath the injector cups. Had to replace the head on both due to pitting. I had tested it for combustion gasses and came up negative, but it was there.

I vote harness as well, if the ecu plug is oil free. I've seen a bazillion harness issues for the same problem, especially where the harness runs over top of the air compressor. They love to rub there.

You need to install 3 .025 shims under the rocker stands of the rear head.

Common issue with a re man head. I can't think of the part number off the top of my head, but your dealer should have them in stock.

Reason for this is that your head was machined and now the valves are sitting higher. Shimming up the rocker will eliminate any engine brake clearance issues.

Could be, definitely worth a shot.

Did your clutch lock in with the shop air applied or unlock? 

Make sure the new solenoid you installed is the correct part, if not it could work backwards from what it is supposed to do.

IF it's the typical Horton (air unlocks it) the ecu will send a ground to the fan solenoid to apply air and unlock it. The solenoid would have constant 12v with the ecu using ground for control.

All Etech blocks are interchangeable. Even Asets can interchange with Etechs.

I've seen this happen more than a couple times. The pump has usually been the culprit over fueling.

Fuel pressure should be somewhere in the 60-75 lb range. Testing under load would be ideal, but often you'll see it near zero at idle when the gear is slipping on the shaft.

If it's a restriction in the fuel system pressure might be good until you get it under strain.

Ya, my first thought is fuel pressure, luckily the etech is almost as easy as it gets to diagnose. Even through the internet.

Some have asked me why I would offer help on the net. These are some of the problems some of us pulled our hair out on 15 years ago, but learned all the ins and outs through it. Why not help somebody else out? 

Sorry I'm rambling.lol

Does the electronic malfunction light work? Any smoke? Does it sounds like a single cylinder misfire, or definitely a stumble?

It runs fine at higher rpm?

Yes, if the derate is turned on in the programming then it will cut power.

Or a worn out clutch brake, worn front seal housing on transmission. Either will allow the throw out bearing to travel too far rearward causing the release fork to contact pressure plate.

I've never paid attention to the drv either, once it's starts dosing anyway.

I think that is normal. 

Never had an easy pedal that I couldn't get unstuck. I think I've only seen a couple solos make it through their full life.

^ this. If the stick is physically stuck in gear, and not because it came up over the fork, then very well could be twisted mainshaft. Once you pull the shifter up you'll get a better idea. 

Yeah if you could get those code numbers I'd be glad to look at the diagnostic tree and maybe give you an idea on what to check.

I wish these were as easy to diagnose as the AI or Etech, but those days are gone sadly.

Any vgt codes?

Sounds like synchronizer is bad.

Any grinding sounds when you go to 6th?

Does the stick return to neutral but tranny status in gear? Or is the stick physically stuck in?

Broken shift fork would be my first thought.

Low batteries? Possibly bad thermal switch?

You say various boost codes? Different fmi's? What are the code numbers?

Possibly not actually a mechanical issue but maybe electrical. High resistance in the circuit for example.

Might pull the connectors off of the ecu and check for oil wicking. I've seen that cause some really strange things.

I would check boost and fuel pressure with a manual gauge if it were me.

He's referring to the air cooler mounted in front of the radiator, check the tubes for cracks.

But 10 is way high to do those 2 things.