86iroclamarque

i'm not much of a mechanic, i'm a paint and body guy so here it goes.

Is it possibe to change a bad mcs without pulling out the whole carb or would u want to do that? this is my first 3rd gen and never played around with carbs. (first camaro was a 97) I just got this car it's all completly stock (great all around condition just negleted). it had been sitting for a looong time with this old lady. the MCS is the only code that comes off the ecm. it's running super rich and after a while of idling it will miss and start to run on 6 cyl's.

I think after this hurdle i'm ok to finally drive this car!! (i've had it for 3 weeks)

five7kid

iTrader: (14)

Welcome aboard.

1st make sure the connector hasn't come loose from the MCS. This post https://www.thirdgen.org/techbb2/sho...hreadid=253438 has some good pics that show all that.

If the MCS is indeed bad, it's best to remove the carb from the engine and disassemble in a more controllable fashion.

RB83L69

It is extremely rare for the MCS to go bad.

The first thing one needs to understand about the ECM and its "codes", is that the code it gives you, doesn't necessarily mean "The {fill in the blank} is bad, replace it". What it means, is that the thing the code concerns, isn't responding in the way the ECM thinks it should. It may also mean that the ECM does some sort of diagnostic routine on it, and doesn't get the right results; or it may mean that some set of conditions exists that is not possible, and some one of the indications is therefore wacked. For example, the ECM may get inputs from the sensors that say that the engine RPM is 800, the throttle is wide open, and the vacuum is 18" (high vacuum)..... clearly impossible. Under those circumstances, it may set a code, which may or may not be the code for the thing that's actually malfunctioning. It's just saying "I hurt here", not "Replace this part".

Before you go tearing the carb apart and changing out a part that virtually never fails, check to make sure that it's hooked up; the choke is fully opening after the engine has been running for 4 or 5 minutes; and that there's not fuel pouring out the top of the carb somewhere and spilling into the throttles. Either of those other things will create an extremely rich condition that will not respond to the ECM's control inputs. Another thing that will cause a very rich idle, is leaking plugs under the primary metering wells, which about 80% or more of all Q-jets have this condition.

86iroclamarque

plus some of the hoses were bad too. had the whole thing rebuilt and i bought a 5.0 ho dual snorkel air cleaner off ebay to get some more air in that baby.
All most road ready! i've only driven the car once and it was anything but fun with all the engine probs i've had with it.

say a prayer for a clean emmisions test for me guys!