Threaded Mode | Linear Mode

Hgilp · 02-19-2021, **(Subject: Issues earlier CM870 )**

Wanted to get some opinions on what could be my issue. I have awful fuel mileage, surging, rough idle, but only when cold, motor stops pulling at 1700rpm, and my turbo always sounds like it’s building boost. I’ve done a lot of reading, and all my reading brings me back to one thing, turbo actuator. I have an older CM870, and I don’t think it will throw any codes for the actuator always being closed. I just replaced the CAC and don’t have any boost leaks. TIA.

Hgilp · 02-19-2021, **(Subject: Issues earlier CM870 )**

Anyone? Rather not throwing money at an issue to guess and check.

Nilao · 02-19-2021, **(Subject: Issues earlier CM870 )**

Well your correct in there's no monitr on the actuator of a 870...best you can do is hit it with 60 psi shop air and measure the travel and make sure it isn't binding.

Rawze · 02-19-2021, **(Subject: Issues earlier CM870 )**

maybe this helps...
http://rawze.com/forums/showthread.php?t...3#pid61613

tree98 · 02-19-2021, **(Subject: Issues earlier CM870 )**

EGR problems can do this too but you would have a CEL.

Chamberpains · 02-20-2021, **(Subject: Issues earlier CM870 )**

The surging and rough idle also point to injector, fuel issues, fuel system issues, and fuel actuators. Id have a good look at all of it.

Hgilp · 02-20-2021, **(Subject: Issues earlier CM870 )**

Truck has been demandated, but not tuned yet. Haven’t looked into who to have tune yet. I’d also like recommendations on that, if anyone could give any input. I did buy the plate to check the injectors, and a dial indicator to check the timing actuators. I don’t want to put a lot of money into this engine. It already has almost 1.2 million miles on it, and I don’t plan to inframe it. I was quoted $24,000 at the low end for an inframe, and don’t trust any smaller local shops. They won’t even diagnose the issues I’m having now. I just can’t afford to run a truck getting 4.78mpg. Thanks for all the replies. I’ll update once I do more diagnosing.

I’ve never seen the VGT actuator move. I moved it by hand and it knocked rust off the turbo, I know that isn’t a good sign. Does the actuator hold the canes normally open, or normally closed? I know if it was normally closed, I’d always be making boost, and won’t get any fuel mileage.

tree98 · 02-20-2021, **(Subject: Issues earlier CM870 )**

If it's demandated that means it's tuned. Who did it is the million dollar question. That could be your problem right there. Before you go any further you need to get a copy of that program over to Rawze for review.

Rawze · 02-21-2021, **(Subject: Issues earlier CM870 )**

(02-20-2021 )Hgilp Wrote: ...
Truck has been demandated, but not tuned yet.
...

Is there a check engine light on in the dash for the egr valve or other devices being unplugged then?