Help with (possibly) butchered CM870

[389driver]

Hello all...

I'm hoping one of - or some of - the more experienced members can help me out. I have an O/O that bought a truck with a CM870 that has had the EGR and VG turbo d;lted. It is exhibiting idle and driveability problems that we need to get straightened out before he can put it on the road.

The truck has a lope at idle that comes and goes. It seems to be worse when the engine is cold. It will lope and/or hunt at idle 50-75 RPM. It also has a touchy accelerator. It's difficult to drive the truck smoothly. The best that i can describe the problem is that that relation of the throttle position to engine output is non-linear. The ramp rate at which the RPM's rise and fall seems to be slow as well.

In trying to diagnose this problem, I hooked INSITE up to monitor sensor outputs. Everything appeared normal with exception to the Out Of Range flags for the sensors that were no longer present (EGR Temp, Press Dif, Turbo Speed, Etc.) I did a cylinder cutout and performance test with both coming back as PASS.

I am not getting any active trouble codes.

It got interesting when I tried to do an injector check valve test. Insite would not start the test because it said the fuel pressure sensor was out of range. I checked the output and it was reading 3.50 volts 250 psi. When I would raise/lower the RPM of the engine the voltage output of the sensor remained the same but the pressure reading would rise/fall with engine rpm. My next move was to unplug the fuel pressure sensor. The engine was loping and idling rough until I unplugged the sensor. It then immediately began to idle perfectly smooth - and the accelerator wasn't as touchy as before. Plugging the fuel pressure sensor back in brought back the idle/throttle issues.

So I replaced the fuel pressure sensor only to have the problem remain. The bad idle and touchy accelerator pedal appear with the fuel pressure sensor plugged in and disappear with the sensor unplugged.

Now here's my question: Could the issues I'm experiencing be the result of a bad d'lete? Or should I be looking at metering and/or timing actuators? I would definitely think the actuators were the cause of my problems, but only if it weren't for the fact that the fuel pressure sensor being absent makes the problems disappear. I don't want to tell this guy to buy $$$ actuators if he doesn't need to obviously.

I've pulled the cal with C@lt&rm and done a compare with a stock file. The only thing that makes me believe its a big boy butcher job is the timing tables have been messed with to the tune of about 5 degrees. Other than that there are no glaring changes that caught my eye - although I'll readily admit I only have experience with the CM871 - and that's with following Rawze's instructions.

I'd appreciate ANY input ANYONE can give me on this. I want the calibration to be right so that it doesn't cost this guy a head gasket, cracked head, or sunken liner. Should the VG turbo be put back on this engine even though it is not as accurate as the electronically actuated version on the CM871? Id like to be able to sort out the idle and driveability problems first then monitor it's performance against my @m*m^2'd CM871 to see if putting a stock VG turbo back on would be warranted.

I can upload a copy of the cal file from the engine and a compare report if anyone is interested.

Thanks in advance!