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Discussion Starter #1
Okay, so last Winter I observed something weird with my car. In temperatures at or below 17 Fahrenheit my engine ran a little odd.

When accelerating the engine would feel and sound like it had the hiccups. While cruising it feels like I'm driving on a rippled road.

So now that this season that I actually have an UltraGauge, I can now also provide additional information!

During this time, here are some stats:

Outside air temp: 17 F
Engine temp: 155 F

If I stop moving, the engine will heat up to 160+ F but as soon as I begin rolling again it'll go back down to 155 F. Normal running temp is usually around 188-195 F.

Also during this time the car's fuel economy goes waaaaaaay down.

Is this an issue of the car not heating up to full running temp?
 

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You could try to block the grill (top and bottom) with some black duct tape leaving a hole about 4 inches square in one of them, it can help warm it up and as long as you can monitor the water temp you should be able to get warmer temps safely. If it gets too warm you just remove some tape. Chumly
 

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I run a 160 degree thermostat in my ford truck. In my truck, that's as low as I can go and still close the loop on it. Other wise it's in open loop and does not hand off control to the O2 sensor. Maybe your thermostat is hung open?
 

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Discussion Starter #7
Makes sense. Would this be an item covered under warranty?

As I mentioned, I first noticed it last Winter, but I never had the chance to take it to the dealer since I wasn't old enough to obtain a loaner myself.
 

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Discussion Starter #9
Eh, I have a Genius Exhaust and the stock air box has a rubber tube exiting it (rather than the huge plastic baffle box), but neither of those have nothing to do with the Thermostat...
 

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Discussion Starter #11
Good question! I haven't heard the cooling fan run since October. I never sit idle enough for the engine to reach 200 F (which is when I notice the fan kicking on).

Last night it "hiccuped" three times in a row when I set off from a gas station. It was 10 F outside and the engine was at 153 F.

It's 27 F outside right now and I just drove the car. It made it to 179 F in about ten or so minutes. No hiccups, normal fuel economy, no odd noises or feelings.

So this issue only seems to happen under twenty degrees outside temperature.
 

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Good question! I haven't heard the cooling fan run since October. I never sit idle enough for the engine to reach 200 F (which is when I notice the fan kicking on).

Last night it "hiccuped" three times in a row when I set off from a gas station. It was 10 F outside and the engine was at 153 F.

It's 27 F outside right now and I just drove the car. It made it to 179 F in about ten or so minutes. No hiccups, normal fuel economy, no odd noises or feelings.

So this issue only seems to happen under twenty degrees outside temperature.
It's probably just really really cold and needs more time to warm up. The thermostat may be sticking slightly open and as such I would consider testing it if it bothers you much.

Barney's suggestion about the cooling fan was that it may be turning on too soon and preventing warmups, but then you say you don't recall it even turning on. Maybe it's just turning on as soon as the key is turned and you don't notice. If the fan is dead your car will heat up rapidly anytime you're idling or stuck in gridlock traffic.
 

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Discussion Starter #13
Sometimes I can drive an entire hour and it'll stick at 150 F and sometimes into 160 F.

The fan definitely doesn't turn on though, it has a very distinctive sound that largely differs from my snarling exhaust.

If temperature isn't the issue, what would causes the hiccups and "rippling" that I observe in temps under twenty?
 

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Sometimes I can drive an entire hour and it'll stick at 150 F and sometimes into 160 F.

The fan definitely doesn't turn on though, it has a very distinctive sound that largely differs from my snarling exhaust.

If temperature isn't the issue, what would causes the hiccups and "rippling" that I observe in temps under twenty?
Your car is running rich because it is not heating up. That's a thermostat issue. If your fan won't turn on and the car won't overheat it's because the car is not heating up.

Does your heater work? Cool? Lukewarm, or hot?
 

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Discussion Starter #15
Hot enough, but on max, not as hot as it usually is. I'm more concerned about the engine temp, which is obviously not getting as high as it should.

Thankfully I'm now old enough to obtain a dealer loaner on my own. I shall schedule a visit this week!
 

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Daughter, today was complainting about the heat in the smart car sucked. Of course the car use to spend it time, in a heated garage. It sits out side apartment. It been really cold here. It going back to the MB dealership, for the new seatbelt sensor tomorrow. They could check it out. Really doulbt there's any thing wrong with it. It would have over heated already.
 

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Discussion Starter #17
Update:

I'm at the dealer now. The service writer says that if the thermostat needs replacing, they would need the car to throw a code first.

On top of that, it's over 30 F and snowing today so it's going to be near impossible to replicate the issue.
 
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