dirtbagit

Ok from what I thought I understood about the ambient air temp sensor is that it does not impact performance but I had noticed that my temp was showing 185 degrees but things were mostly working fine in terms of performance, the SC would kick in and things would accelerate as normal. So today I went to see what was up with the sensor and found that it was missing. There was a wire going to the fog light that had two wires just hanging out with nothing attached, I'm assuming those are where the sensor should be attached, I noticed they were shorted together so I decided to separate them until I could get a pigtail with a connection to a new sensor (and boy that pigtail was not easy to find). So I got in the car to take a drive and now the temp gauge shows -45 and the kicker is that it will not engage the SC.. So unless something else happened while I was underneath the car the ambient air temp sensor seems to impact performance, is this correct or am I nuts?
Thanks in advance.
tr

whoover

It makes sense that the ECU would kill the SC if it thought it was that cold. Operating one below 25 degrees will mess it up pretty quickly. The sensor plugs into a connector. It sounds like the socket was ripped off somehow. Hopefully you'll be able to get one. Unless the pigtails are the remains of the sensor and are in the connector.

Edit: I see online that it's easy to buy a sensor with a replacement socket so I guess this is a common thing.

AMGPilot

Outside Air Temp is part of the speed density calculation that the ECU does in order to properly fuel the motor. the car will NOT run correctly without a properly functioning OAT sensor

AMGPilot

LOL, the supercharger operates well below 25 degrees....

whoover

Once it's warmed up. But spinning it at 45 below will not make for happy bearings.

dirtbagit

Thanks guys just waiting for the pigtail and sensor assembly.

Pmarino

LOL then Boowho....

IMPORTANT COLD WEATHER INFORMATION

"In order to achieve the low noise level of Lysholm superchargers, Lysholm specifies manufacturing procedures that call for minimal internal clearance. These precise tolerances however are not conducive to temperatures below 25° F. Therefore, storing the vehicle in a heated garage and/or employing the use of an engine block heater/aftermarket engine blanket is required when the vehicle is subjected to a "cold startup" in ambient temperatures below 25° F. Failure to comply with this may result in immediate supercharger failure and invalidate the supercharger warranty."

dirtbagit

Ok what should I expect in terms for performance if I put it back to the shorted out configuration (temp shows 185)? This was how I found it last week, the car mostly ran fine but under WOT and at about 110+ mph it seemed to have a misfire and would go in to limp mode, haven't pulled codes when in that condition was just assuming a coil pack/plug wire issue.
thanks

whoover

The ECU really needs to know the temp. I'd fix it before I worried about anything else.

StarvingArtist

In real life, 50,000 miles seems to give it enough clearance to run in the cold. I've run hard at 27 below 0. All kinds of power it doesn't normally have. Back tires didn't work too well though. Could spin endlessly at 70mph. No heatsoak ha ha

Pmarino

If you still have a clutched pulley you're protected. When the car is started there is no super charger engagement( MB has and does extensive cold weather testing. Those schmart engineers!) . So unless you start it up cold and romp it hard right away (which is not a good idea for the motor/drive-train, let alone the SC) you should be OK. Unless you're running a fixed pulley! As I'm sure most sub freezing cold weather dwellers know.... take it easy until you get the car warmed up. For me, when living in consistent -20F temps, car's usually get block heater's and battery mat's, never had the luxury of a heated garage

And yes, these beasts are hot blooded and love running in the cool/cold weather!

trabots

Both my E55 and SL55 show OATs which appear to be much higher after parking while hot and moving again due to heat soak in the engine bay I presume. Both cars run well without issues. Where is the OAT and is it the same sensor the ECU supposedly uses? I cannot see why the ECU would use OAT except possibly at start-up when the OAT number is accurate..

tw2

Cars use the intake air temp sensor in the charge pipe to calculate air charge. Outside temp is irrelevant once it goes through a supercharger and intercooler. I thought the outside one was for your dash display and maybe to disengage supercharger clutch in cold weather as mentioned above.

dirtbagit

Thanks guys to summarize besides disengaging the SC below a certain temp the ambient temp sensor does nothing as far as performance is concerned, correct?

SICAMG

Jesus Starving.....27* below.....You don't need an inter cooler at that temp LOL !!!