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-   -   Misfire (https://www.saturnforum.com/forum/saturn-vue-24/misfire-11244/)

lbolton64 03-30-2018 08:24 PM

Misfire
 
I have a 2008 vue xr, 3.6L. I noticed the check engine light flashing so i know i had a misfire. I pulled codes and the misfire was coming from cylinder #6(which I believe to be at the front on the driver's side). I replaced the ignition coil and spark plug and I'm still getting a misfire on that cylinder. I greased the spark plug tip and torqued it to 13ft/lbs. Any suggestions?

lbolton64 03-30-2018 09:45 PM

The car was purchased about a year ago with 175k miles. Car has run hot before and the water pump was replaced. These are the codes that are coming up.

P0113 - Intake air temp sensor 1 circuit high input
P0117 - Engine coolant temp sensor 1 circuit low input
P0306 - Cylinder 6 misfire detected
P0430 - Catalyst system efficiency below threshold bank 2
P0700 - Transmission control system(malfunction indicator lamp request)
P1258 - Engine coolant overtemperature - Protection mode active

19bonestock88 03-31-2018 03:53 AM

Umm, you’re just supposed to use anti-seize in the threads, not the tip of the plug...

clear all the codes and watch for them to reappear...

if they do, check the coil and plug again... check the connector at the coil to make sure it’s not loose... double check to make sure you got the right plug(why not change all six?)

0700 is likely just due to misfire... has to do with “torque management” and with a misfire it’s difficult for the PCM to regulate torque...

0430 is likely gonna come up after a misfire... unburnt fuel can be burnt inside the catalytic converter, making it less efficient and throw that code

0113 and 0117 could be sensors and could be the cause of your misfire... check IAT and ECT sensors... replace as necessary with OEM brand or equivalent

1258 is due to the overheat... it should be reasonable to do a compression test on at least cyl 6 to make sure you didn’t warp the head or blow a head gasket... for sake of being sure I’d at least test all three cylinders in that bank and post the results...

lbolton64 03-31-2018 05:59 PM

Thanks for the reply, I did put dielectric grease on the tip that touches the spring in the coil, im going to wipe it off good and the spring and post results

derf 03-31-2018 09:44 PM

Bones thought you used anti-seize on the tip....you used dielec grease...you're fine

I would agree that your problem at least partially lies in the temp sensor arena.
What troubles me is the Coolant temp sensor is reading low, yet the PCM is detecting an overtemperature condition and has activated protection mode (new one for me).

The ECTS low input usually means the ECTS is reading abnormally high. You do have an overtemperature code.
The question is--is it a correct reading of the coolant temp (meaning the car is overheating) OR is the coolant temp sensor internally shorted, telling the PCM the engine coolant is at some ridiculous temperature?

Measure the resistance across the 2 pins of both the coolant temp sensor (ECTS) and the intake air sensor.on an ice cold engine.

If the ECTS is internally shorted or reads a few hundred ohms ice cold, it is defective. Replace.
If the ECTS reads infinite resistance (doubtful given other codes), replace [included for completeness]

Normally I would recommend you compare the ECTS and IAT sensor resistances. They should be quite similar and in the thousands of ohms. However, the IAT code implies there might be something wrong with it, so hold off on that till you get the ECTS straightened out.

Also, since the 5V put across these sensors comes from a shared line, so to speak, a single sensor on that line OR THE CIRCUIT WIRING that is shorted (my guess for ECTS) can affect other sensors' readings as the 5V potential is no longer being applied across them. This may be what is causing the IAT sensor code, or it may be open circuit.
As a quick check, measure its resistance on an ice cold engine,

If it reads infinite resistance, replace.
if it reads in the hundreds of ohms, replace
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But take care of the ECTS first. The A/F ratio is highly influenced by the engine (coolant) temperature. All kinds of bad things and weird things happen when this sensor goes bad.
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I agree with the compression check advice on that bank of cyls.
Remember to pull fuel injector fuse and hold the throttle wide open with all plugs out.
If your head gasket is going then you'll likely see it as reduced compression and if severe enough that can cause a misfire.

Also, head warpage is not uncommon, especially if the vehicle has been repeatedly overheated and repeatedly boiled off ALL the coolant.
You can't check until you pull the head, so that's a last-ditch check if you pull the head to iinvestigate head gasket issues. No point in putting a warped head They can be machined down if not too severe.


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