Performed a road test at discretion of a smart engineer.

"Mercedes Streeter" (smart) 10/05/2016 at 22:36 • Filed to: engine

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P0303...or Misfire in third cylinder.

Well, could be worse, right?

Alright, so apparently what happens now is that at any random given moment, the third cylinder nopes out and the car loses a third of its power. Restarting the car usually sets it straight until the cylinder misfires again.

Axial > Mercedes Streeter 10/05/2016 at 22:45

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Well, that’s a mostly useless error code because you still need to know what’s causing the miss.

XJDano > Mercedes Streeter 10/05/2016 at 22:49

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Does the car burn oil? Metro does and will cause one of the spark plugs to misfire, runs like crap, goes away, then back, until I swap plugs, then it’s fine again.

Denver Is Stuck In The 90s > Mercedes Streeter 10/05/2016 at 22:50

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Things that can cause a misfire:

-Lack of spark

-Lack of air

-Too much air

-Lack of fuel

-Too much fuel

-Detonation

-Oil in the combustion chamber

-Bad Ignition coil

-Bad distributor

-bad cap/rotor

-bad spark plug

-bad spark plug wire

-loss of compression

-incorrect timing

What parts have you replaced and when to eliminate possibilities?

OPPOsaurus WRX > Mercedes Streeter 10/05/2016 at 22:51

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P303 engine side 2 missing.

Sorry. I can’t help it. Would a leak down test help. I tried it and its not hard. It will tell u if ur piston ring, valves or head gasket is leaking but I dunno if any of those would cause a misfire.

Hayabusa swap time

Funktheduck > Mercedes Streeter 10/05/2016 at 22:53

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Well there’s your problem. You don’t have enough cylinders. I would recommend a V8

crowmolly > Mercedes Streeter 10/05/2016 at 22:56

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How hard is it to pull the spark plug on that cyl?

OPPOsaurus WRX > Mercedes Streeter 10/05/2016 at 22:58

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I’d start with the spark plug

RallyWrench > Mercedes Streeter 10/05/2016 at 23:01

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Very likely you have a bad coil in cylinder 3. The ECM will shut off the injector in the offending cylinder when it detects active misfires in order to protect the Cat, which is why cycling the key temporarily restores operation until the coil heats up and fails again. I can’t say I’ve seen any of the small number of Smarts we work on lose a coil, but that’s a typical symptom.

Swap the cylinder 3 coil with cylinder 2 and drive it again after clearing the code. If the miss moves to 2, that’s your culprit. Check the plugs too.

EDIT: just saw your older post. While it’s possible a lack of compression in the cylinder is causing a miss, first things first proceed with the coil test. I hope the miss moves, but if it doesn’t, it’s something cylinder specific, which is usually bad.

Mercedes Streeter > OPPOsaurus WRX 10/05/2016 at 23:01

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I think that’s a good place to start...now, just gotta find the wrench that does that...

The Lurktastic Opponaught > Funktheduck 10/05/2016 at 23:02

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That two stroke marine V8 from the FP might just fit.

Mercedes Streeter > crowmolly 10/05/2016 at 23:03

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Takes about 10 minutes...my hands aren’t flexible enough. I’d have to find my tool and attack it after work tomorrow. Sadly, misfires in smarts usually mean burned valves...which in turn, is hilariously expensive to repair even by DIY.

Satoshi "Zipang" Katsura > Mercedes Streeter 10/05/2016 at 23:03

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At least you don’t have to deal with “P0330.”

Hint: It involves a knock sensor hidden under intake plenum.

Mercedes Streeter > XJDano 10/05/2016 at 23:04

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Nope! Well, maybe now it does. I guess I’ll soon find that out...I’ll check the plugs first.

Mercedes Streeter > Funktheduck 10/05/2016 at 23:04

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So, what you’re saying is that I should steal my parents’ Expedition, then swap the engines between the two vehicles? :D

PS9 > Mercedes Streeter 10/05/2016 at 23:05

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Well that’s one problem down. Now maybe he can do something about that pesky 90%-of-the-car-being-missing problem.

Shit man, car thieves back in my day just took the wheels. Now they’re going all barbecue steakhouse on our shit and stripping the damned thing clean.

Mercedes Streeter > Denver Is Stuck In The 90s 10/05/2016 at 23:05

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I think the first thing I should do is replace the plugs. However, misfires in smarts are most commonly caused by burned valves, so I may be throwing money away trying to perform all those tests.

crowmolly > Mercedes Streeter 10/05/2016 at 23:07

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Just saw your other post. When the car was getting super hot before, did that register on the temp gauge?

Mercedes Streeter > PS9 10/05/2016 at 23:08

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Muahahahaha!

Usually when people ask me “where’s the other half?” I say “I get it when I pay off the loan!”

Daily Drives a Dragon - One Last Lap > Mercedes Streeter 10/05/2016 at 23:11

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So what you’re saying is Hayabusa swap?

Mercedes Streeter > crowmolly 10/05/2016 at 23:11

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It registered 20 degrees higher than normal...10 degrees higher than when the cooling fan should kick on...it didn’t. 210 degrees in itself is still within operating temperature (max engine temperature before damage is 230 degrees), however the car had no reason to be running that high.

Also, the sensor doesn’t pick up internal engine heat that isn’t liquid. So like, the engine could have been much hotter, but I only have the gauges to go by.

Mercedes Streeter > Daily Drives a Dragon - One Last Lap 10/05/2016 at 23:12

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Nah. W16...just like...put it on a trailer and have it push the car...like an articulated bus!

Funktheduck > Mercedes Streeter 10/05/2016 at 23:13

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That would be an amazing idea. 2 (sometimes 3) cylinder Expedition and a V8 Smart

The Lurktastic Opponaught > Mercedes Streeter 10/05/2016 at 23:13

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This sounds like the next Oppomeet.

crowmolly > Mercedes Streeter 10/05/2016 at 23:14

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Huh. I’m just guessing here and somebody can feel free to call this BS:

But I wonder if the A/F mixture is too lean/too rich which is what caused the miss and engine to run very hot. Not a head gasket failure.

For what it’s worth on carbed engines I’ve seen the A/F be off enough to make the headers glow. Timing too, but I dunno if that can even get out of whack on your car.

Mercedes Streeter > Funktheduck 10/05/2016 at 23:14

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It’s what I call, smart cylinder deactivation.

Daily Drives a Dragon - One Last Lap > Mercedes Streeter 10/05/2016 at 23:14

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I imagine some uh... Stability issues with that one.

Mercedes Streeter > crowmolly 10/05/2016 at 23:17

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It’s about as good enough of an explanation as anything right now. I don’t know what went wrong until I tear into the spark plugs..which could be a weekend project..Or just let it be and trade in the car and let the dealer deal with it.

AMGtech - now with more recalls! > Mercedes Streeter 10/06/2016 at 02:09

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If you can pull plugs you can check compression. I remember reading about your harrowing exhaust replacement adventure, so this should be easy for you. Most parts stores should carry cheap or rental compression testers.

AMGtech - now with more recalls! > Mercedes Streeter 10/06/2016 at 02:16

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This makes me think even more it’s low compression. So that would cause the cylinder to function, but not burn with its full intended force, so to speak, which would then register as a misfire but you wouldn’t really notice too much of a rough run or power loss because it is still firing. Once the computer had picked up a certain number of misfires it will cut fuel to that cylinder to prevent damage to the cylinder and particularly the catalyst, that’s when you experience the major power loss. A bad plug or coil would be far less likely to reset, because they either work or they don’t, there’s no middle ground like with low compression.

random001 > Mercedes Streeter 10/06/2016 at 06:22

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HAH!