GregH Posted June 13, 2011 Share Posted June 13, 2011 At 127K miles this vehicle came in with an intermittent misfire on cylinder #2 when pulling a hill. It's fixed up as a transit bus. Tested and found P0266 in memory, and power balance showed #2 misfire when loading it in the stall. Installed an injector in #2. Started it up, and it stuttered a few times after it had been idling a few minutes. Road test, retest power balance, and still had an intermittent drop on #2. EEC test showed nothing. Overlaid harness to #2 and FICM. Reran all test, no problems found. Released vehicle. It comes back in today, P0266 in memory, intermittent dropping of #2 cylinder on power balance, and a slight popping in the intake manifold. Relative compression shows a slight drop sometimes when testing, and sometimes there is a single crow hop during the 10 second crank. I'm thinking there is an intermittent loss of compression on #2 causing the issue - likely related to the opening of an exhaust valve because of the slight pop in the intake. I haven't torn into it yet. Kinda want to speculate as to what I should find before I start searching. Possible camshaft going flat? - should be material on the drain plug, which I haven't removed yet. Maybe a sticking valve? Why would the problem be intermittent? Any help would be appreciated... Quote Link to comment Share on other sites More sharing options...
Jeff Clyde Posted June 14, 2011 Share Posted June 14, 2011 engine harness ? common area that causes problems; way too much wiring crammed into one spot under the turbo inlet pipe. Quote Link to comment Share on other sites More sharing options...
cbriggs Posted June 14, 2011 Share Posted June 14, 2011 Possibly a broken intake valve spring? Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted June 15, 2011 Share Posted June 15, 2011 Possibly lifter just on it's way out causing intermittent misfireing. I would take a look at the oilpump to see any evidence of metal just starting to get in there. Quote Link to comment Share on other sites More sharing options...
GregH Posted June 16, 2011 Author Share Posted June 16, 2011 Another unit was brought to me today - P0272 in memory. Power balance shows #4 dropping out, and there is that characteristic pop in the intake... 128,000 miles on this one. uh oh.. Quote Link to comment Share on other sites More sharing options...
OHNO60 Posted November 14, 2011 Share Posted November 14, 2011 127K ON A TRANSIT BUS....Sounds like a lifter beginning to fail, Especially when the relative craps out from rpm inconsistencies. Quote Link to comment Share on other sites More sharing options...
blown99 Posted November 15, 2011 Share Posted November 15, 2011 I have one in my bay right now, popping out the intake. Passes the relative compression test with flying colors. No skip at all, pretty good tapping noise when decellerating. Had a code for #4 for cylinder balancing. No metal on the drain plug (where did the metal go??). Pulled the heads found the #4 exhaust lifter flat. I would pull the valve covers, if you don't see anything with the rockers/springs then it is a sure bet that the cam/lifter is failing. Quote Link to comment Share on other sites More sharing options...
Aaron Posted January 13, 2012 Share Posted January 13, 2012 How many miles do the hour meter say the truck has? Quote Link to comment Share on other sites More sharing options...
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