Balance rate question Broke my toy [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: Balance rate question Broke my toy


theTDIguy
02-15-2009, 11:50 AM
Balance rate Question,
I have 2 LB7’s that knock; neither is warranty due to being swapped into SUV’s. With the Predator I see #4 on the burb (134K) is @ -6.20 or more when warm and in gear, the knock is very noticeable but tolerable and the engine seems to run smooth. On my second motor I get a reading of -7.50 on # 2 and it has a definite misfire that seems to fade up around 1200 rpm or so. If I’m correct in my understanding, doesn’t this negative # mean fuel is being removed from the firing event? The second engine knocks so bad you would think a rod is about to let go. I did inadvertently unplug an injector on my LLM a while back it knocked and misfired the same way but that would be lack of fuel right? Can to much fuel case a misfire too? Seems logical, this all started yesterday after twisting the piss out of the second truck with a Diablo 85hp tune, did I trash an injector? Could the tuner have done it? I checked the rates the day before and they were all within .75 +/- and only have about 2500 miles on them after being replaced under warranty prior to the swap. I doubt there is anything mechanical wrong as the motor never turned over 3500 rpm and I drove it straight home as I realized I had just broke my toy. Any thoughts?

tysmith
02-15-2009, 12:01 PM
Sounds like just a bad coincidence. I doubt beating the bag out of it caused it to suddenly fail. It was either on its way out, or just gave out. Either way, it sounds like you will be getting new injectors.

I would say get a set, and do all of them in each bank that is bad, that way you don't have to go back in if another fails in 150 miles...

theTDIguy
02-15-2009, 01:34 PM
good advise, thanks. I was just suprised at how bad it missfires, that sucker must be dumping a bunch of fuel. how high is to high? I've got a -7.50 has anyone ever been worse?

pooch
02-15-2009, 03:10 PM
i think they can go to +/-14.00.
I just did injectors in a guys truck that had the exact same problems. and Tysmith is right, if your gona take anything apart do all of them and save your self the pain in the A$$. everytime you take the injector lines off the crap that has made its way into the cracks of the lines falls into the injector and messes it up.