Engine Misfire and Lean Codes

[HowAboutThis]

Hello,

While commuting today my car (17 Corolla with about 85k) threw a CEL and the traction control off (which I think is normal with a CEL). It was idling like garbage too and felt sluggish. RPM's bouncing from about 500-1250, shaking, etc. Was doing great up until today. This was a sudden thing.

I believe the codes were P0171, P0300, P0301, P0302, P0303, P03004. So, multiple engine misfire and all the cylinders showing up. And the P0171 is lean engine fuel/air ratio I think. And I can never remember if it's P(letter O) or P(zero) so don't make fun of me if I got it wrong LOL

Posted is some live data screen captured too.

 

[LostInTransit]

Typically this means one should replace the sparkplugs, check fuel rail and or replace the coil packs. More commonly, if you've just topped the fuel tank with around $10.00 this can throw a code also. The owners manual should say never top off at least wait till half a tank to fill up

 

[HowAboutThis]

Typically this means one should replace the sparkplugs, check fuel rail and or replace the coil packs. More commonly, if you've just topped the fuel tank with around $10.00 this can throw a code also. The owners manual should say never top off at least wait till half a tank to fill up

Can't tell if you're being totally serious. I did just have it filled yesterday. Had a tiny bit above 1/4 left (about 150 miles till empty on the computer). The attendant didn't top it off (I live in a state where it's too hard to pump your own...). But I've filled once per week 7-8 gallons for the life of this car.

 

[carviewsonic]

Vacuum leak, possibly intake manifold gasket is an item to check. EGR valve is another.
Or, bad gas (water contamination).

 

[HowAboutThis]

Vacuum leak, possibly intake manifold gasket is an item to check. EGR valve is another.
Or, bad gas (water contamination).

I've never had bad gas (the fuel kind) in a car, but was wondering if the fill up within 24 hours and 40 miles of driving before the engine light kicked on was a coincidence or not. It's a highly used ARCO station I got the gas from.

 

[HowAboutThis]

Vacuum leak, possibly intake manifold gasket is an item to check. EGR valve is another.
Or, bad gas (water contamination).

I checked the MAF sensor and it looked clean to me. The ones online and YouTube look gooped up that they clean. Mine looked clean, from what I could see. So I kind of moved on from that. I did stab my thumb with a screwdriver getting the clip loose from the MAF. So that was proof the car hates me.

 

[atikovi]

The owners manual should say never top off at least wait till half a tank to fill up

Example please.

 

[carviewsonic]

I checked the MAF sensor and it looked clean to me. The ones online and YouTube look gooped up that they clean. Mine looked clean, from what I could see. So I kind of moved on from that. I did stab my thumb with a screwdriver getting the clip loose from the MAF. So that was proof the car hates me.

EGR would throw a specific code, not sure if one of the codes you listed is for EGR.

 

[carviewsonic]

I've never had bad gas (the fuel kind) in a car, but was wondering if the fill up within 24 hours and 40 miles of driving before the engine light kicked on was a coincidence or not. It's a highly used ARCO station I got the gas from.

The one time I recall filling the car with bad gas the check engine light and poor running happened within minutes of filling. I suspected water contamination. Problem cleared up immediately after the next refill.

 

[HowAboutThis]

Update: brought to the dealer at 3pm and they diagnosed I believe a purge valve causing vacuum issues. Should have part by tomorrow and it's covered under warranty. Not bad.

 

[LostInTransit]

Example please.

According to our owners manual, one should not top off the tank with less than $10.00 etc they suggest wating till at least half a tank to top off.. this will throw the lean code because the fuel system hasn't calibrated the amount of fuel thats in the tank, this is exactly what happen to our van. But I was running the eFuels and topped it off with approx $10.00 worth of fuel.. a few mins later we get a lean code. Had the shop clear the code then checked the owners manual.

 

[wtd]

Update: brought to the dealer at 3pm and they diagnosed I believe a purge valve causing vacuum issues. Should have part by tomorrow and it's covered under warranty. Not bad.

I would think that if it was the purge valve that you would also have an Evap trouble code of some sort, especially on a vehicle that new. I guess you will find out if it fixes it. Your fuel trims definitely show that you have quite a lean condition. plus, or minus 10% fuel trims are considered acceptable for most vehicles.

 

[HowAboutThis]

I would think that if it was the purge valve that you would also have an Evap trouble code of some sort, especially on a vehicle that new. I guess you will find out if it fixes it. Your fuel trims definitely show that you have quite a lean condition. plus, or minus 10% fuel trims are considered acceptable for most vehicles.

300 miles and no check engine light back. Car idles way better. Throttle is more responsive from coasting to back on gas. Idle while coasting stays up higher too.

 

[wtd]

300 miles and no check engine light back. Car idles way better. Throttle is more responsive from coasting to back on gas. Idle while coasting stays up higher too.

That's good. I guess you never know what components or systems will set a trouble code.

 

[HowAboutThis]

That's good. I guess you never know what components or systems will set a trouble code.

Yeah, Google says if it's stuck open or closed (can't remember) it's basically a vacuum leak and causes the lean code. The other stuck direction causes a buildup of vapor that's released to the environment. That second option might be the more likely EVAP code one. Anyway, happy with how fast they diagnosed and seem to have fixed it. Great dealership experiences for me, so far.

 

[MSCH]

put your scanner on the 02 sensor and monitor the signal, if it is all over the map... its probably the 02 sensor.

 

[Bill7]

Hello,

While commuting today my car (17 Corolla with about 85k) threw a CEL and the traction control off (which I think is normal with a CEL). It was idling like garbage too and felt sluggish. RPM's bouncing from about 500-1250, shaking, etc. Was doing great up until today. This was a sudden thing.

I believe the codes were P0171, P0300, P0301, P0302, P0303, P03004. So, multiple engine misfire and all the cylinders showing up. And the P0171 is lean engine fuel/air ratio I think. And I can never remember if it's P(letter O) or P(zero) so don't make fun of me if I got it wrong LOL

Posted is some live data screen captured too.

Just to be extra safe, check engine oil and transfmission fluid level immediately.
In the event it's low, top it off ASAP.

 

[HowAboutThis]

put your scanner on the 02 sensor and monitor the signal, if it is all over the map... its probably the 02 sensor.

Already fixed (see above). EVAP purge valve solenoid stuck and causinga vacuum leak. Thus the lean code and misfires.

 

[HowAboutThis]

Just to be extra safe, check engine oil and transfmission fluid level immediately.
In the event it's low, top it off ASAP.

I check oil weekly. You can't easily check this CVT fluid. Already fixed (see above). EVAP purge valve solenoid.

 

[wtd]

Yeah, Google says if it's stuck open or closed (can't remember) it's basically a vacuum leak and causes the lean code. The other stuck direction causes a buildup of vapor that's released to the environment. That second option might be the more likely EVAP code one. Anyway, happy with how fast they diagnosed and seem to have fixed it. Great dealership experiences for me, so far.

That is good to hear. Purge valves are normally closed so it probably was stuck open. I'm still surprised that it didn't set a purge valve evap code.