Another thought on this subject would be checking the intake manifold for crack at #1 cylinder. As unit get warmer the crack will open up and allow unit to surge on top end and run somewhat poor on idle. Also check LPG assist injector for proper operation. A quick removal inspection and check is simple.
This may sound rediculous, but it has worked for me. If you have abnormal readings from the oxygen sensor & can't find the reason, try changing the engine oil. For whatever the reason, changing what appears to be clean oil can make a difference. I put in the thinnest oil available at the time, run the machine for a day, then change again & put in the correct viscosity. I've had this happen a few times with newer trucks with O2 sensors. It's the first thing I do now with driveability issues.
try removing the main injector on the injector body and cleaning it and see if that improves things any?
when you remove it take note if there is any oil buildup on it
if after cleaning it performance improves then this is most likely your problem, but do keep in mind you may ultimately have to replace the main injector, cleaning it is just a step towards that if the cleaning does not hold up.
Thanks, makes sense, why it would run ok at start-up. Don't have the software to check anything, they want you to do the impossible with a box full of wrenches and that just won't happen anymore. They just don't get it.
stephen;
From the description, the engine runs fine when it is in open loop mode, but not in closed loop. Your description has something to do with the O2 sensor readings that the ECM (Engine Control Manager) sees. If you have the computer software program, the handset with the software program and the interface cable for the truck, look at the O2 readings. But, if you don't have these items find a good OBD II handset. Under the dash after the cup holder is lifted out, you will find the blue OBD II plug. This may give you an answer to what is wrong.
Does this Have the NIKKI Refulator in it??
The Regulator can be rebuilt and is much cheaper than replacing the whole regulator. Check Your pressure coming out of it,on top is a 17 mm hex put a gauge in it and see what it reads should be about 4.5 PSI idling and under a load(tilt bypass).
Cleaned MAF sensor and did not help. Noticed that when the truck is first started after sitting a while that it will run ok for about one minute. Also driver said that when he first uses it first thing in the morning that it will run ok for about 5 min. I drained the regualtor. Since there are no codes I thought I should try another regulator.
No lights on dash, or codes.
Remove the Mass Air Flow (MAF) sensor, clean lightly with a couple quick shots of carb cleaner and blow it dry with very low air pressure, reinstall and test. Also check MAF plug wire harness, I have found the black wire breaks all the time.
uplift;
This vehicle is according to model number a N. American throttle body L.P.G. fuel injected engine and not the gasoline multiport injected European model.
Try a compression test, I had a few trucks with burnt out valves, doing a very similar thing
stephen;
Are there any of the dash lights flashing? If this isn't the case do a learn on the fuel system and a pedal learn.