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!

[Hedley]

PM Gearhead or Unilevers.

[Old Driver]

Sounds a lot like what my motor used to do with bad actuators. Loops and feels like your in a boat at idle when cold.

[jorden486]

I just converted one of my 870's back to a VGT and will be doing a second soon. It's possible your metering valves are bad but talk to unileavers first. That guy is literally a genius. Trust him.
By the way another 870 I have that he tuned still has the VGT and is smooth as butter at idle even cold and runs amazingly strong.

[Rawze]

Dont fool yourself,.. i see engine destruction in its future,...

YOU HAVE A BIG-NAME HIGH DOLLAR VERY VERY VERY BAD DELETE ON YOUR HANDS THERE!!!!


Spend the money to PUT BACK! that VG turbo!!. WHY ANY IDIOT DELETE COMPANY would even slightly recommend the removal of THE MOST EFFICIENT, BEST POWER PROVIDING TURBO EVER DESIGNED for that engine to be taken off of it is ridiculous!.

===========

There is no telling how bad that programming is, or how many sensors they are fooling, etc. It is most likely that the computer has NO CLUE how much fuel is going into the cylinders nor what the final cylinder pressures are any more. This makes it unstable and lope because it is in a constant state of correction because it knows something is wrong,.. but it does not know WHAT!.

Most of those bad programs make engine the ECM are very unstable,.. it has NOTHING AT ALL to do with the power settings and 90+% of all programs i have looked at by those big name companies and their copy-cats out there look like some ignorant kinder-gardener did it. --- REFLECTIVE OF THAT TYPICAL SHITTY $12,000 DOLLAR ENGINE DESTROYING RIP-OFF PUKE DIESEL shi#t DELETE CRAP FOR SURE,.. OR A CLOSE COPY OF IT!.

READ THIS ARTICLE...
http://rawze.com/forums/showthread.php?t...01#pid5901

I can't stand to see an engine butchered by an idiot with a computer. Happens way too often.

[389driver]

Thanks Rawze. I really wish I would have known the VGT was deleted before he bought it. I would have steered him away. Now he's gonna be money in the hole before he ever gets on the road with it.

[Rig Wrench]

Depending on what your doing, the 870s do very well with the fixed vane turbo so long as the tune is correct. The air vgt is somewhat inferior to the 871 electronic vgt. The fixed vane does help drop back pressure for high torque load applications. I'd just have one of the aforementioned verify the cal is safe. Wore fuel system components will cause a bit of a rough idle, but soo won't increased timing and fuel in the idle areas.

[Rawze]

(10-15-2016 )Rig Wrench Wrote:  Depending on what your doing, the 870s do very well with the fixed vane turbo so long as the tune is correct. The air vgt is somewhat inferior to the 871 electronic vgt. The fixed vane does help drop back pressure for high torque load applications. I'd just have one of the aforementioned verify the cal is safe. Wore fuel system components will cause a bit of a rough idle, but soo won't increased timing and fuel in the idle areas.

That statement is only somewhat valid...

Most big-boy, bad, fixed-vaine deletes use an undersized 12-litre turbo and/or that crap of a big-boss junk. -- The only half-decent Borg Werner for the ISX is the 16-litre turbo they make,.. and it STILL is less efficient than a Holset.

Yes, the engine can be re-tuned for the fixed turbo but no matter what you do,... It will never be nearly as efficient as a VG can provide for most highway applications.

I tend to not give false hope for any kind of miracle-program fix to many of those who do already have bad del;etes.

Not everyone is bent on big power etc., and even if they are, a bigger Holset still wins. For most, doing the right thing and putting it back the way it is supposed to be is the correct solution.

Sure, there are some people who remove the VG turbo's off their engine for various legitimate reasons,... but it is mostly high-torque-only applications, trading away efficiency in lower torque bands and lower RPM ranges to get those slight gains. Even so,.. It has been proven over and over that even in the case of higher than normal power applications, that a bigger Holset still wins, and for everything else, a VG is much better by leaps and bounds towards overall engine efficiency. It is just a matter of size and/or staying within the bounds of its design, and last I checked,.. A Holset HX series turbo (holset big fixed-type turbo) only starts to give flow advantages ABOVE about 640-HP or so HP on an ISX so if your engine is BELOW this HP,... YOU ARE LOOSIONG SOMETHING BY NOT HAVING A VG TURBO ON IT!!!

Do it right -- FIX IT and solve your problems CORRECTLY AND THOROUGHLY then Don't look back! -- this means PUTTING BACK OR LEAVING INTACT THAT HOLSET VG TURBO for most highway applications! -- PERIOD!

This is ALWAYS THE ARGUMENT...

AND EVERY SINGLE ONE OF THOSE ARGUING TOWARDS THOSE FIXED TURBOS ARE ALL HELL BENT ON AND ARE PROPONENTS OF HAVING BIG POWER AND SHORTER ENGINE LIFE!. I COMPLETELY DISAGREE WITH IT!!! -- THAT IS ALL THEY WANT AND DO AND THEY GO AROUND AND PROMOTE IT AND ARGUE IT TO MAKE THEMSELVES FEEL BETTER LIKE IT IS SOMETHING GOOD --- WELL IS IS NOT when it comes to actually making a profit!!! -- AND IT IS WRONG!!! -- If you need that much weight moved,.. RE-GEAR THE TRUCK!

> I AM NOT A PROPONENT OF MORE HP IN YOUR ENGINE === I AM NOT A PROPONENT IN BUTCHERING YOUR ENGINE BY PUTTING A LESS FUEL EFFICIENT TURBO ON IT EITHER!!!

Even in cases where Holset HX fixed turbos are used, I have seen some really good tuning get them close,.... but even those really good tuners will say that a VG Holset is the correct solution above the inferior crap usually seen slapped onto someone's engine as the result of a bad delete. 99.9% of the time those bad delete companies DO NOT GO WITH A HOLSET HX SERIES but vastly inferior turbos. But even an HX knocks the truck back into the stone-age and they always end up with lower fuel mileage, higher EGT's, black smoke at the tail pipe in lower RPM ranges, black oil, higher fuel costs per year, and weaker engine brakes. -- Just because there are some short-sighted people out there hell bent on making those fixed turbos work for them does not mean it is a correct solution at all for anyone else.

[Brock]

If you haven't, I would pop that rocker cover and check for worn cam lobes. I just replaced my valve cam and 4 rockers and it was doing exactly as you describe. Even with @m*m^2, if I turn it to 625 this thing is snappy as he'll. .. response is instant and jerky taking off.