Newer stuff, GM wise, still has pvc systems, metering system built into valve/camshaft covers piped over to intake. Trucks have a belt driven vacuum pump for the brake booster now also.
Steve
Hey Steve,
Do you see intake manifold leaks with the 2007 era 6.0L engines ? I know that the buick 3.8L V-6 plastic intakes are troublesome.
4-wheeler magazine awhile back had an article on the different new process transfer-cases, and that was where it mentioned the 246 having internal clutches, and I think they are electronically controlled is my guess with solenoids maybe, and the ABS wheel sensors may control the clutches.
The 4x seems to work very well, as I backed the stock trailer down through a swale to load up fir rounds, and I was actually surprised the suburban pulled the trailer up and out without fuss. It was several months after that test that the wife was reading through the 'build-sheet' that was with the vehicle when we bought it "used" and the doggon thing has an optional Locking Differential in the rear. That is why it didn't fuss much pulling that trailer out of the swale.
Fuel-trim …………. hmmm …….. a new arena for me.
It would be cool to be smart enough to just plumb-in a manual (milliamp) rheostat controller to adjust on-the-fly the fuel-air ratio while watching the f/r gauge to fatten-up the mixture when feeling the Lean-miss. But I am not an electrician.
I wonder if relocating the O2 sensor to a hotter location would fool the ECU into fattening up the f/r ratio ?
And, too, I wonder if my mechs are looking at the individual injector data to check the pulse data of each. I doubt that I have a partially plugged injector, but I don't know who had their hands on this engine for the first 70k miles, or what the original owner put it through towing in the 112 degree summers here.
The 4L80E automatic transmission behind the 6.5 td free-wheeled in direct, and really needed an exhaust brake or something to help slow it down on descent pulling a trailer. ( I know, just burn the trailer brakes
I think TDI offered a kit to reprogram the shifting which may have incorporated the lock-up in the torque converter for descent. I don't know, because rather that buy the kit for $1200, I just cussed a lot whenever I had to go to the Pacific Coast and back to the Sacramento Valley pulling a trailer.