sugarsn10

iTrader: (2)

I've been trying to get this car running right for a couple of months now and I think I finally found some symptoms pointing to the source of the problem. Everywhere I read it says that when you jump the diagnostic terminal with the ground, you should hear the MCS cycling. I always heard a clicking and figured it was the MCS. Since I thought it was cycling and I got a solid 25 ohms at the MCS terminal, I figured that was operating correctly.

Well last night I had the EGR solenoid unplugged and for some reason decided to see if the MCS was still clicking. I found out it wasn't the MCS cycling, but it was the EGR solenoid all along. I have never read anywhere that the EGR solenoid will cycle in diagnostic mode. Also, I am getting a solid 11.91 volts from the MCS plug both when the key is in the run position normally AND with the terminals jumped. With the key on, you can hear it click once when you plug it in, but it won't cycle. The EGR solenoid doesn't give me a solid volt reading. It jumps between about 3 and 10 volts, but I'm guessing that is because of the input from the computer?

Does this sound like a computer problem or something else? The computer seems fine otherwise. It gives me code 12 and has given me other codes like it should when I unplug the terminal to set ignition timing or other things like the vacuum sensor. I would really appreciate any help anyone has. I don't know a whole lot about the ECM's functions so I'm really lost.

sugarsn10

iTrader: (2)

Does anybody have any ideas? I'm probably going to try putting in a different computer, but I'd like to somehow make sure this isn't caused by a wiring issue or something like that. I'd really appreciate it if someone who has some knowledge in this area could give me some advice.

EagleMark

What's an MCS?

Ronny

iTrader: (1)

Eagle: I believe the fuel pump and the IAC can be cycled at the ALDL but what others mechanicals can?

EagleMark

Yeah but his car says CCC so I don't think it's the IAC making noise. I don't know what a MCS is?

RBob

iTrader: (1)

Mixture Control Solenoid. It rattles a tapered rod up & down within a jet. This adjusts the AFR via feedback from the O2 sensor (primaries only).

sugarsn10: I don't know much about the CCC systems, I do know that they varied over the years and the different makes. Buick for instance, usually pulsed the MCS at key-on, engine-off.

But I don't believe that the f-body's did.

Part of the MCS set up is to measure the 'dwell' and to make a mechanical adjustment to get the dwell correct.

You may be able to find more info on the system on the carb board here.

RBob.

sugarsn10

iTrader: (2)

Thanks for the suggestion. I'll try it in the carb board. I tried it here because I've read everywhere on there that it (Mixture Control Solenoid) should cycle, but mine isn't, so I thought maybe this board would be able to tell me if it was an ECM problem. Thanks again.

sugarsn10

iTrader: (2)

Just wanted to bring this thread to a close by stating that I went and pulled a different ECM from the junkyard and that completely fixed the problem. Hope this helps anybody in the future who has these symptoms. Thanks again everyone for the help.