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I don't normally drive my car when it gets over 100 degrees but I had no choice. A weird thing happened today and I want to know why. After driving about 30 miles I stopped at a gas station to fill up. The a/c was left in the on position and as I cranked up the car it slightly hesitated to start. It has a fairly new battery. After starting the car, the dash lights were slightly flickering as if there was a voltage issue. I quickly turned off the a/c, radio, auto lights and drove off. Then the flickering stopped. I hope the heat didn't fry anything under the hood. Is this a common thing when it gets really hot out? The car was slightly sluggish when accelerating and shifting. My worst fear is a car that breaks down due to hot weather leaving me stranded.
Why would you not drive if over 100°? In PS it is often over 100°. So all of the desert Southwest, and much of the Midwest are not suitable for Mercedes? Insane.
Record heat in Tucson and Phoenix this past Sunday and Monday. I came out to find a large crack running almost the entire length of the windshield vertically...
You mean the CPS (crankshaft position sensor)? That makes sense - those things HATE extreme temps. But I can't see that causing voltage problems unless the engine was stalling.
Electronics do weird things due to excessive heat. On the motorcycle (ZX6RR) I did some exhaust work and didn't replace one of the heat shields (I assumed it was for rider comfort). The next day we rode the mountains and about half way up I was experiencing all sorts of stuttering and misfiring, until finally it just stalled. I let it cool off and tried again but as temps increased the issues returned. I finally put it in the back of the truck and took it home. I later realized that the heat shield was not a creature feature, it was a heat shield for the ECU mounted under the seat. Long story short, I reinstalled the heat shield and never saw the problem again. In your case, it could just be heat, as temps cool down you might be ok. Heat can bring out the worst.
You mean the CPS (crankshaft position sensor)? That makes sense - those things HATE extreme temps. But I can't see that causing voltage problems unless the engine was stalling.
When cold it will start. When hot it doesn't. How does the CPS work? Does every car have one?
The CPS is a Hall Effect sensor. Basically, that's a magnet that generates a small electrical current when it becomes attracted to a metal surface. The flywheel has a ring around its outer edge with alternating holes and solid surfaces that the CPS detects. The CPS sends a signal to the ECU so that it can determine the angle of the crankshaft for timing purposes. If the crankshaft stops rotating, the CPS stop sending a signal and the ECU will shut off the fuel pump. This would also happen when the CPS fails. For some reason, the CPS units tend to be very sensitive to extreme temperatures, and more often high temperatures. One trick MB Roadside Assist techs use is to pour cold water over thhe CPS to see if that makes it work again.
The CPS is a Hall Effect sensor. Basically, that's a magnet that generates a small electrical current when it becomes attracted to a metal surface. The flywheel has a ring around its outer edge with alternating holes and solid surfaces that the CPS detects. The CPS sends a signal to the ECU so that it can determine the angle of the crankshaft for timing purposes. If the crankshaft stops rotating, the CPS stop sending a signal and the ECU will shut off the fuel pump. This would also happen when the CPS fails. For some reason, the CPS units tend to be very sensitive to extreme temperatures, and more often high temperatures. One trick MB Roadside Assist techs use is to pour cold water over thhe CPS to see if that makes it work again.
Interesting! Thanks for the info. I understand that they aren't very expensive to replace. My mechanic wants 200 for the part and labor.
2009 SL550 Roadster Diamond White, 2008 CLK550 Coupe Obsidian Black
My CPS failed on my 04 e320 after driving back from vegas to la non-stop in the heat of summer. I turned the car off when i got home, tried to turn it back on 15 minutes later, no go good thing i didn't stop on the way
One trick for temporarily fixing an overheated CPS (and determining that it is the culprit) is to pour cold water on it. MB Roadside will do this to get you going again so you don't have to pay for a tow.
So this thread is tripping me out. I'm heading out to PS for the weekend, and yes, taking the CLS55. I figured my VW bug would be a tad warm to drive in. That 2-60 AC just doesnt cut it for me.
Havent had any CPS issues to date but thinking this thread just might jinx it....
It's so strange how the cps sensor is working now. Now I'm able to start the car when hot! Maybe just a glitch? I'm still going to replace the sensor. Is it normal to be intermittent like this??
I replaced the sensor myself and I'm very pleased with the outcome. I went to mb dealer and almost spit out my coffee on the parts rep when he told me the price! Holy crap I was not expecting it to cost that much. Obviously the aftermarket ones are junk so I'm glad I went with the factory one that is guaranteed to work. I was very happy to discover that the e8 torx bolt was not actually stripped at all and my mechanic tried to rip me off big time. Thanks to these forums and YouTube I can say I successfully fixed my car. She made it back home no problem and with no starting or stalling issues. Thanks everyone for all your help!!
06-20-2016, 08:04 PM
good thing i didn't stop on the way
