Join Date: Jun 2009
Location: Star, Idaho
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Black smoke, Lots of Extra power, Rough running, Wont idle, unplug icp runs good.
Like the title says.
I have an 00 diesel excursion with an afe intake, 35" tires and 4" exhaust. It also had an ebay 5 position "chip" that plugged inline with the icp sensor. I have driven the excursion the last 30,000 miles it now has 200000 miles. 10000 miles ago i replaced the valve cover gaskets and under valve cover wire harnesses as well as the glow plugs. since then It has run great- until lately.
First thing I noticed on a long drive to the mountains was intermittent loss in power at freeway speeds, then Excessive power. The first time I slowed below 25 mph the engine was running as if I was cycling the throttle. Floored 1/10th of a second and then released 3/10ths of a second. When I put it in nuetral the rpms raised to 2500 without pedal input and then cycled down to 1000. But it was still cycling as if I was flooring and releasing the throttle. And when I did push the throttle while in park or nuetral, it would violently increase in RPM's and black smoke billows out the exhaust. And all the while it is REALLY loud.
After shutting down it required 1/2 throttle travel to start. without throttle input it would make one forceful attempt to run and then die. Removing the 5 position chip made no improvement or difference. An interesting note... the mpg display on the console stated I was getting about 23 mpg. Way higher then the usual 13mpg.
I read the posts on this site and figured it was the ipc valve sticking or the icp sensor. I removed the ipc and cleaned it out, and then upon reassembly there was no improvement.
THEN i disconnected the icp, and it ran real smooth. But the power is down, and the mpg is also down. I assumed the computer is reverting to 700 psi oil pressure. When I unplug the ipc it wont start.
I replace the icp with an ebay buy (120 bucks)- but it didn't help. So either I have a bad new icp, or a shorted wire harness? I unravelled the harness tracing the wires and found a few places the insulation had chaffed, but I electrical taped them and it still runs the same.
Do I have a bad new icp? A bad icp plug? the plug was not oil soaked it has been and is dry, with no visible defects. Or is there a short somewhere else in the wiring? Or something else?
I think it is running bad because the computer thinks the oil pressure at the injectors is low even though it is way too high. Too high of pressure is what i think is causing the power, black smoke, and inability to idle smoothly.
Anyone care to give this mystery a shot?