a/c questions and power loss
07-22-2012, 02:24 PM
#1
Pro
Thread Starter
a/c questions and power loss
Sometimes when driving REALLY hard for short blasts, without the a/c, like in an "autocross" type situation, I have thrown codes for camshaft position sensor, and or crankshaft position sensor.
I got the cam position sensor replaced and after driving REALLY hard for short blasts, sometimes get a crankshaft position sensor error.
This all goes away when reset, or battery disconnected, or just driving it regular.
Since I always shut the a/c and the fans when driving REALLY hard, I was thinking maybe putting just the fan on with possibly the temp all the way on hot, as opposed to the a/c on. I think it may be possible that without the fan running that when I stop and go slow or idle I get a clicking noise from the engine bay, seems like on the left side. Could clicking noise be because the engine fan wants to come on but won't ?
How much power do I lose by running with the a/c compressor button in the off position, but the fan running or running on hot to vent heat from the enigine.
Will running the fans only reduce possible heat buidup ---that might be causing my sensors to be overly sensitive.
Power loss from fans only on high----and low ?
Power loss from regular a/c running ?
Does a 10' GT3 disengage a/c compressor at full throttle ?
Partial throttle ?
Thanks
I got the cam position sensor replaced and after driving REALLY hard for short blasts, sometimes get a crankshaft position sensor error.
This all goes away when reset, or battery disconnected, or just driving it regular.
Since I always shut the a/c and the fans when driving REALLY hard, I was thinking maybe putting just the fan on with possibly the temp all the way on hot, as opposed to the a/c on. I think it may be possible that without the fan running that when I stop and go slow or idle I get a clicking noise from the engine bay, seems like on the left side. Could clicking noise be because the engine fan wants to come on but won't ?
How much power do I lose by running with the a/c compressor button in the off position, but the fan running or running on hot to vent heat from the enigine.
Will running the fans only reduce possible heat buidup ---that might be causing my sensors to be overly sensitive.
Power loss from fans only on high----and low ?
Power loss from regular a/c running ?
Does a 10' GT3 disengage a/c compressor at full throttle ?
Partial throttle ?
Thanks
07-22-2012, 09:04 PM
#2
Rennlist Member
Camshaft position codes are no joke. It shouldn't relate to your A/C compressor, on, off or whatsoever. Something' quirky with your timing chain or cam adjusters.
To your questions: the compressor is powered by the serpentine belt and engaged through a viscous coupling inside the compressor unit. AFAIK it is not sensitive to throttle conditions. This is just speaking from anecdotal experience during sustained, 150mph+ highway blasts when we're continuously on full throttle in 5th/6th.
I always track mine with max fan, min temp and A/C off. Have never driven a lap in anger with A/C on, but maybe one of these days I should, just to see if there's a quantifiable difference in laptimes...
To your questions: the compressor is powered by the serpentine belt and engaged through a viscous coupling inside the compressor unit. AFAIK it is not sensitive to throttle conditions. This is just speaking from anecdotal experience during sustained, 150mph+ highway blasts when we're continuously on full throttle in 5th/6th.
I always track mine with max fan, min temp and A/C off. Have never driven a lap in anger with A/C on, but maybe one of these days I should, just to see if there's a quantifiable difference in laptimes...
07-23-2012, 01:03 AM
#3
Pro
Thread Starter
It seems when the car gets really hot like after a hard autocross run, i.e. pro solo drag start 30-45 second run, do this 4 times with about 1 minute idling between.
Sometimes in the afternoon (4-runs).....final 2 runs of the 4 car has gone into a limp mode. Afterwords totally fine. Morning 4 runs fine.
Coolant I just noticed is 1/2" below min mark.....not sure if this amount that it's under---while not causing any coolant or temp warnings.....is possibly letting one of these senors temporarily get too hot, and then when sensor is not reading what it should.....car computer says, "WHOA".
Dealer told me that the code has to be present for them to do something. When I was out in Nebraska a few months ago, I had a dealer under warranty replace cam position sensor, and one time after that in like 400 miles I got a crank position sensor CEL.....that went away pretty quickly.
Could a slight low coolant possibly cause a crankshaft and or cam position sensor to get too hot, and thereby cause the car to say "WHOA" ?
Sometimes in the afternoon (4-runs).....final 2 runs of the 4 car has gone into a limp mode. Afterwords totally fine. Morning 4 runs fine.
Coolant I just noticed is 1/2" below min mark.....not sure if this amount that it's under---while not causing any coolant or temp warnings.....is possibly letting one of these senors temporarily get too hot, and then when sensor is not reading what it should.....car computer says, "WHOA".
Dealer told me that the code has to be present for them to do something. When I was out in Nebraska a few months ago, I had a dealer under warranty replace cam position sensor, and one time after that in like 400 miles I got a crank position sensor CEL.....that went away pretty quickly.
Could a slight low coolant possibly cause a crankshaft and or cam position sensor to get too hot, and thereby cause the car to say "WHOA" ?
07-23-2012, 02:19 AM
#4
Rennlist Member
It seems when the car gets really hot like after a hard autocross run, i.e. pro solo drag start 30-45 second run, do this 4 times with about 1 minute idling between.
Sometimes in the afternoon (4-runs).....final 2 runs of the 4 car has gone into a limp mode. Afterwords totally fine. Morning 4 runs fine.
Coolant I just noticed is 1/2" below min mark.....not sure if this amount that it's under---while not causing any coolant or temp warnings.....is possibly letting one of these senors temporarily get too hot, and then when sensor is not reading what it should.....car computer says, "WHOA".
I had a dealer under warranty replace cam position sensor, and one time after that in like 400 miles I got a crank position sensor CEL.....that went away pretty quickly.
Sometimes in the afternoon (4-runs).....final 2 runs of the 4 car has gone into a limp mode. Afterwords totally fine. Morning 4 runs fine.
Coolant I just noticed is 1/2" below min mark.....not sure if this amount that it's under---while not causing any coolant or temp warnings.....is possibly letting one of these senors temporarily get too hot, and then when sensor is not reading what it should.....car computer says, "WHOA".
I had a dealer under warranty replace cam position sensor, and one time after that in like 400 miles I got a crank position sensor CEL.....that went away pretty quickly.
I'll let others chime in, but in my own experience and what I've seen over the years, never has a GT3 thrown codes serious codes like that from hard driving alone. Overheating, yes, but not codes. A broken sensor I can relate to, but that's one-off in nature and yours appears to be an ongoing issue.
Some 3.8 GT3 engines have an inherent problem with the intake variocam actuator where the screws literally unseat themselves over time. Unfortunately there's no way to tell without dropping the engine and opening up the cam covers.
Between the missing coolant and crank/cams out-of-position I think you have a case for the dealer to warrant a serious look.
BTW have you ever tested your used motor oil? If not I recommend Blackstone. Costs less than a tank of gas but tells a good story about your engine internals. In your specific case, I'd be looking for stats on metal particulates...
