Help -- A/C guru needed - Page 2 - ZR-1 Net Registry Forums

bike01 · 10-28-2005

Oh yea,

I forget, yes I replaced the MAP sensor and cleaned the hose, haven't changed out the PCV valves, I'll do that next if it screws up again. Question, There is a map sensor looking thing under the ECM, is this another MAP sensor or it it something else.

tomtom72 · 10-29-2005

The look-a-like MAP under the ECM is the MAP sensor that the ECM uses as a reference signal. I don't know what the reference is referring to but it comes off of the vacuum hose assembly that is under the plenum. The line from the ECM MAP sensor is traced back to the secondary vacuum hose assembly and is "T-eed" off of one of the secondary actuator vacuum supply lines...if I remember correctly.

In any event it does originate in the secondary vacuun hose assembly and I would guess if the actuators fail it might set a code for secondary actuation malfunction. I'm just guessing, here. The only thing I know for sure is it is another MAP sensor under the ECM & it gets it's vacuum signal from the secondary vacuum hose assembly under the plenum.

Tom

tomtom72 · 10-29-2005

I'm not C4/ZR-1 literate enough to really assist in the issue you're having but when I re-did my vacuum stuff for the secondaries I learned from Jeffvette that there is a vacuum control valve under the plenum that supplies vacuum to the HVAC system. The thing I'm driving at is if that valve had a leak could the resultant vacuum leak affect the idle quality of a motor???

Sorry for not having more than this dumb theory/question to contribute.

Tom

10-28-2005	#11
bike01 Join Date: Apr 2004 Posts: 14	Re: Help -- A/C guru needed Oh yea, I forget, yes I replaced the MAP sensor and cleaned the hose, haven't changed out the PCV valves, I'll do that next if it screws up again. Question, There is a map sensor looking thing under the ECM, is this another MAP sensor or it it something else.

10-29-2005	#12
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Help -- A/C guru needed The look-a-like MAP under the ECM is the MAP sensor that the ECM uses as a reference signal. I don't know what the reference is referring to but it comes off of the vacuum hose assembly that is under the plenum. The line from the ECM MAP sensor is traced back to the secondary vacuum hose assembly and is "T-eed" off of one of the secondary actuator vacuum supply lines...if I remember correctly. In any event it does originate in the secondary vacuun hose assembly and I would guess if the actuators fail it might set a code for secondary actuation malfunction. I'm just guessing, here. The only thing I know for sure is it is another MAP sensor under the ECM & it gets it's vacuum signal from the secondary vacuum hose assembly under the plenum. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

10-29-2005	#13
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Help -- A/C guru needed I'm not C4/ZR-1 literate enough to really assist in the issue you're having but when I re-did my vacuum stuff for the secondaries I learned from Jeffvette that there is a vacuum control valve under the plenum that supplies vacuum to the HVAC system. The thing I'm driving at is if that valve had a leak could the resultant vacuum leak affect the idle quality of a motor??? Sorry for not having more than this dumb theory/question to contribute. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member