inconsistant counterbalance test!!

[broncobuyer]

my 01 psd developed a intermitent miss, a couple of months ago i performed a counter balnce test and a buzz test, the buzz test passed but counter balce showed cylinder 4 fault, also when i drove it when it was cold it acted like it was starving for fuel so i figure the #4 injector was bad and aerating the fuel system, i just pulled it into the shop today to replace that injector and performed another counterbalnce test and now it says cylinder #8 fault, why did it change? i was going to replace the bad injector and the o-rings on all the other injectors because my fuel milage is 8mpg right now but now i dont know what injector is bad or if it is bad, can someone help me out?

[RadarRider]

Originally Posted by broncobuyer

my 01 psd developed a intermitent miss, a couple of months ago i performed a counter balnce test and a buzz test, the buzz test passed but counter balce showed cylinder 4 fault, also when i drove it when it was cold it acted like it was starving for fuel so i figure the #4 injector was bad and aerating the fuel system, i just pulled it into the shop today to replace that injector and performed another counterbalnce test and now it says cylinder #8 fault, why did it change? i was going to replace the bad injector and the o-rings on all the other injectors because my fuel milage is 8mpg right now but now i dont know what injector is bad or if it is bad, can someone help me out?

The #8 is known for starvation because of it's location. You're best bet is to take it for a couple of good rides during the week & perform a contribution test on it after each ride to monitor the injectors. It's common for the #8 to fail & I think the only way to remedy it 100% is to get a crossover line to keep fuel circulating to both heads.

[johns4dor]

Howdy again RadarRider, How do you do the buzz test and the cylinder contribution test. I keep reading that they are easy. I must need a different scanner. I thought I bought a decent one, but other than codes, it hardly does anything on my diesel. Thank goodness I have a buddies Diablo that will at least do a few other things. Maybe it would do the buzz and contribution if I knew how. Thanks for any help, and I am sorry to bust in on Broncobuyer's post, but it was the same subject I posted on a few weeks ago. John

[RadarRider]

Originally Posted by johns4dor

How do you do the buzz test and the cylinder contribution test. I keep reading that they are easy. I must need a different scanner. I thought I bought a decent one, but other than codes, it hardly does anything on my diesel. Thank goodness I have a buddies Diablo that will at least do a few other things. Maybe it would do the buzz and contribution if I knew how. Thanks for any help, and I am sorry to bust in on Radars post, but it was the same subject I posted on a few weeks ago. John

The cheapest scan tool you can get that'll do a buzz or contribution test is a Scanner. They're a dime a dozen on ebay, but they're obsolete as hell. As far as I know, all the Snap-On software for the Scanner has diesel diagnostics with functional tests(except for the Generic OBD II cartridge for '08...that one just reads codes). You pick 'Functional Tests' out of the main menu after you enter the VIN & you can select either Buzz Test or Contribution Test. You run the buzz test with the engine off, & run a contrib test with the engine running. I don't think the Diablo can do functional tests. It just reads codes.

[broncobuyer]

i used the mac taskmaster to do mine, its a 1200 scanner. do you think my #4 injector is bad because that failed the test a couple months ago? or do you think with the o-rings being bad that it aerated the fuel and that was causing the fault?

[RadarRider]

Originally Posted by broncobuyer

i used the mac taskmaster to do mine, its a 1200 scanner. do you think my #4 injector is bad because that failed the test a couple months ago? or do you think with the o-rings being bad that it aerated the fuel and that was causing the fault?

The o-ring theory is a very good possibility, but I'm not 100% sure. I have seen injectors fail a contrib test from faulty o-rings, but I wasn't around to find out if the o-rings were the final verdict. I'd still try a contrib test after a few rides just to monitor your injectors. The #8 failing is pretty normal with injectors with a decent amount of mileage on them.

[johns4dor]

The Diablo was originally mine but I didn't need the tuner after I chipped the truck so I sold it to my buddy. It will do the codes, live data and live streaming. I spent good money on an Innova that does OBD1 and OBD2 but it doesn't seem to access any of the functional tests for the diesel, unless I just haven't found the directions to make it happen. Hate to think that after putting out a couple of hundred bucks on it after researching whether it was a decent scanner and being told YES that I will need to buy another one for my truck. I have clips coming for the UVCH connectors today (Monday). The parts guy at my local Ford Dealer ordered the wrong one last week.

[RadarRider]

Originally Posted by johns4dor

The Diablo was originally mine but I didn't need the tuner after I chipped the truck so I sold it to my buddy. It will do the codes, live data and live streaming. I spent good money on an Innova that does OBD1 and OBD2 but it doesn't seem to access any of the functional tests for the diesel, unless I just haven't found the directions to make it happen. Hate to think that after putting out a couple of hundred bucks on it after researching whether it was a decent scanner and being told YES that I will need to buy another one for my truck. I have clips coming for the UVCH connectors today (Monday). The parts guy at my local Ford Dealer ordered the wrong one last week.

There should be something right in the main menu of your scanner that allows you to perform functional tests. If you can't find it, it probably doesn't have it.