i have a 98 chevy c/k 1500 4x4 w/350 & ineed to know if theres a way to test the vcm befor i spend alot of $?

Question

i keep geting a code showing a leen mixture in bank 2 with a random misfire, when actualy testing it shows an actual overly rich mixtuer so i think its the vcm but dont know for sure. this has proven to be costly because replascing differant things that dont fix the real problem just doesnt work. so if theres anyone out there that know anything about the actual actions of the vcm unit it would be helpfull ????

Answer 1

Have you looked at the o2 sensor output? If that sensor on bank 2 is showing a lean condition the pcm will automatically enrich the fuel to that side by holding the injectors open longer. If your actual test involved tailpipe testing of the exhaust gas or another o2 sensor that would confirm that the pcm is enriching bank 2. I would suggest that you have the wires to the o2 sensor ohm tested and see if there isn't something wrong there or at the o2 connector or possibly at the connector at the pcm, also check for exhaust leaks. What did you get from the vehicle for freeze frame data, did it show high short and long term fuel trims(above 140) or did it show closer to normal(128). Was a fuel injector balance test done to make sure that each injector was doing its job and not clogged or stuck open, compression and vacuum tests for the cylinders on bank 2?

Answer 2

You didn't tell the codes so we are in the dark. What is meant by "actually testing" and an "actual rich mixture" ??
A lean mixture in bank two and random misfire could be an injector problem if you have throttle body injection. could be a bad fuel pressure regulator if you have multiple injectors or tbi. The best solution is a computer scan that can graph all your sensors while the engine is running. If the vcm was bad you would be having a lot more problems than a misfire. NEVER replace ANY part till you know the problem as dodge man advised

Answer 3

i own a repair shop,and why don't you do this before you decide to try another part,,take it by any auto zone store ,and have them scan it for you its free,and see what they say about i,,they might be able to come up with another code on it,,that may give you a clearer picture of what its doing,,to be honest with you i don't think it is the vcm unit,,but they can tell you for sure,playing the guessing game gets to be pretty expensive after a while ,,i know,,been there and done it before,,on that ,another opinion cant hurt anything at all right now..good luck hope this help,s.happy new years.