green.Z

If you unplug the MAP sensor and no codes are set, what could that mean? PCM not reading?

shoebox

To me, it is a bad way to test something. I would rather monitor it with a scanner.

MikeGyver

lol you could hook a hose to the MAP and suck on it to pull vacuum while watching the signal output wire with a volt meter.

Injuneer

Was the engine running when you disconnected the MAP sensor? Was the RPM less than 1,200? IF RPM was under 1,200 it will set the code at idle. If RPM was over 1,200 it won't set the code unless throttle position is above 15% for 4.5 seconds.

Are you trying to verify MAP operation, or PCM operation, or both?

green.Z

Yes, the engine was running when I disconnected the MAP sensor. I also turned it off and restarted it with the MAP disconnected. When I pulled the entire sensor off, it did die due to the massive vacuum leak. But when unplugging just the electrical connector, there was no change in anything, no codes, no change in how it idled or ran going down the road.

I am trying to verify PCM operation. I already replaced the MAP sensor and electrical connector, the connector was in pretty bad shape. The car is pretty much running like crap. It doesn't want to pull and sometimes wants to die altogether when you mash the throttle hard. I'm also trying to do this on the cheap as I only have a code reader, not a scanner.

I confirmed that 5V is getting to the connector with the key on.

When I took the MAP completely off (and taped over the hole in the intake to keep the engine from dying), I hooked up my vacuum gage to the MAP, pulled up to around 28 inches Hg, then back down to zero several times. It seemed to have no effect.

Any way to do this without going out and spending $200-300 for a scanner?

green.Z

Injuneer, also to answer your RPM question:

It is under 1200 and I let it run for several minutes. This same test on my Camaro caused the SES light to come on immediately.

Seems like the PCM isn't reading the MAP.