Running lean with misfire

1498 Views 26 Replies 6 Participants Last post by JakedaSnake, 9 mo ago

JakedaSnake

Discussion Starter · 9 mo ago

After driving the car home one night it was fine, the next morning it starts up the idle is bad and it's pretty much undrivable. I was finally able to get a scanner on it tonight. Codes pulled were p0102, P0113, and p0303. After being after being told about it I figured it was an air mixture issue, was running very lean and I can smell fuel from the exhaust. Cleared the codes to take it for a test drive it wasn't throwing a misfire code yet. But after that idle went back down and fuel smells gone. Doing some work on it tomorrow is anybody have any tips or things to look out for?

1 - 20 of 27 Posts

MuranoSL2003

· #2 · 9 mo ago

What year and how many miles?

I would start the troubleshooting process by having your alternator and battery load tested.

If you have a VOM, check the battery voltage (turn the headlights on for ~10 seconds first to dissipate the surface charge). The voltage should be over ~12.2-3 volts ideally, and around 12.6 or so if fully charged and new.

Also check the voltage just after a cold start. The voltage should be 14-14.8 volts or so if your alternator is healthy.

I need coffee

· #3 · 9 mo ago

JakedaSnake said:
Codes pulled were p0102, P0113, and p0303.

Those two codes get thrown when the MAF sensor is unplugged and the ignition switch is turned on. Unplug the MAF sensor and inspect the connector. If it looks o.k. (e.g. no corrosion or anything out of the ordinary) plug it back in and make sure it's secure.

JakedaSnake said:
I figured it was an air mixture issue, was running very lean and I can smell fuel from the exhaust.

This actually sounds like a rich A/F mixture.

BTW, did you do any work on the car recently? If so, what was it?

JakedaSnake

Discussion Starter · #4 · 9 mo ago

I need coffee said:
Those two codes get thrown when the MAF sensor is unplugged and the ignition switch is turned on. Unplug the MAF sensor and inspect the connector. If it looks o.k. (e.g. no corrosion or anything out of the ordinary) plug it back in and make sure it's secure.

This actually sounds like a rich A/F mixture.

BTW, did you do any work on the car recently? If so, what was it?

2009 SL 155k miles.
No real work has been done on it recently (within last 3 months) tomorrow ill be pulling the maf and hitting it with cleaner and running it, wether it works or not ill be taking off the intake to inspect for further vacuum leaks as i suspect there is one, along with taking off the throttle body and giving it a good clean cause it looks pretty nasty. I I taking it out to a buddy's house overnight which was about 40 minutes away had zero issues on the way there and back performance and fuel wise. I got the codes cleared and now it just came back with the misfire but I suspect it's just not being left on long enough to throw the p0102 code and the idle is restored with no fuel smell in the exhaust but the misfire is there. I will also be doing the valve cover gaskets and sparkies . My grandmother started it the next morning to go to garage sales and it started doing that so she brought it back to me.

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JakedaSnake

Discussion Starter · #5 · 9 mo ago

MuranoSL2003 said:
What year and how many miles?

I would start the troubleshooting process by having your alternator and battery load tested.

If you have a VOM, check the battery voltage (turn the headlights on for ~10 seconds first to dissipate the surface charge). The voltage should be over ~12.2-3 volts ideally, and around 12.6 or so if fully charged and new.

Also check the voltage just after a cold start. The voltage should be 14-14.8 volts or so if your alternator is healthy.

09 155k miles.
Both are good to go. Battery will probably need to be replaced next year but load tests good.

JakedaSnake

Discussion Starter · #6 · 9 mo ago

It would help if i had my own scanner, and my multimeters Battery is dead

JakedaSnake

Discussion Starter · #7 · 9 mo ago

Output device Telephony Mobile device Portable communications device Communication Device

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JakedaSnake

Discussion Starter · #8 · 9 mo ago

I changed the spark plugs, cleaned throttle body and the MAF sensor with no improvement. Maf is reading 8g/s idling at 1000rpm

MuranoSL2003

· #9 · 9 mo ago

You idle speed is high, it's usually 650 +/-50...

Reactions: 1

I need coffee

· #10 · 9 mo ago

High idle is probably from cleaning the throttle body. Do the idle air relearn procedure in the service manual (...there's videos on YouTube as well).

There should be freeze frame data for the misfire code. Post it here. Innova scan tool should be able to access the noncontinuous monitors. Check the misfire counters for all cylinders and see if any other cylinders are misfiring besides #3.

I believe your scan tool can read live data? With engine at operating temperature, what are STFT and LTFT values at idle for each bank (esp. bank 1)? You'll need to correct the idle issue first though before checking fuel trims.

Reactions: 2

JakedaSnake

Discussion Starter · #11 · 9 mo ago

I need coffee said:
High idle is probably from cleaning the throttle body. Do the idle air relearn procedure in the service manual (...there's videos on YouTube as well).

There should be freeze frame data for the misfire code. Post it here. Innova scan tool should be able to access the noncontinuous monitors. Check the misfire counters for all cylinders and see if any other cylinders are misfiring besides #3.

I believe your scan tool can read live data? With engine at operating temperature, what are STFT and LTFT values at idle for each bank (esp. bank 1)? You'll need to correct the idle issue first though before checking fuel trims.

I thought we weren't able to do the relearn procedure if we had check engine codes present, I believe I tried it yesterday but I don't think it worked so I'll probably need to try again. Tomorrow I'm going to be pulling everything back apart and swapping coil 3 with another one and switching injector 3 with another one as well putting it back together and running it to see what codes get thrown and if they move. I have a different scanner now I don't know if it's as good as the other one but I'm able to read some live data what should I be looking for? Yesterday when I was looking at idle I was taking in about 8 grams per second at a thousand RPM.

JakedaSnake

Discussion Starter · #12 · 9 mo ago

I'm also very weary about letting it run for too long because I don't want it to plug up cat bank one or 02 sensor because I just had the cats replaced not too long ago for the dreaded p0420 and it cost me about 1300 bucks at the stealership

I need coffee

· #13 · 9 mo ago

Relearn procedure is in attached PDF. It should still work with DTCs, but the main things are that the engine needs to be at operating temperature, wheels straight ahead, and all electrical loads off.

JakedaSnake said:
I have a different scanner now I don't know if it's as good as the other one but I'm able to read some live data what should I be looking for?

Which scan tool do you have now (brand and model number)?

Cryogenix1

· #14 · 9 mo ago

MuranoSL2003 said:
You idle speed is high, it's usually 650 +/-50...

Am I in a different universe than you guys? I don't see any posts or scanner pics that show the OP's engine RPMs (to indicate a high idle), or that he actually dismantled and cleaned the throttle body yet (that would contribute to a high idle). What are you and I need coffee referring to? Not trying to start a fight... I just don't understand the replies, and I re-read the OP's posts a few times very carefully.

Or were you implying that the fuel mixture and smell are indicative of a high idle, and informing the OP that the idle should be around 650?

Cryogenix1

· #15 · 9 mo ago

Have you tried switching out the #3 cylinder ignition coil with a different cylinder to see if the misfire carries over to a different cylinder? A compromised or dying ignition coil can definitely cause misfires, and depending on what the exact coil problem might be, it could be intermittent (say from a loose wire or torn stem or bad harness wire.)

I need coffee

· #16 · 9 mo ago

Cryogenix1 said:
Am I in a different universe than you guys? I don't see any posts or scanner pics that show the OP's engine RPMs (to indicate a high idle), or that he actually dismantled and cleaned the throttle body yet (that would contribute to a high idle). What are you and I need coffee referring to? Not trying to start a fight... I just don't understand the replies, and I re-read the OP's posts a few times very carefully.

Or were you implying that the fuel mixture and smell are indicative of a high idle, and informing the OP that the idle should be around 650?

Different multiverse

. See post #8.

Reactions: 2

Cryogenix1

· #17 · 9 mo ago

I need coffee said:
Different multiverse . See post #8.

WT....? I scrolled up and down so slowly so many times to make sure I hadn't missed anything. I wonder if post #8 hadn't loaded on my screen last time... Really bizarre.

JakedaSnake

Discussion Starter · #18 · 9 mo ago

I need coffee said:
Relearn procedure is in attached PDF. It should still work with DTCs, but the main things are that the engine needs to be at operating temperature, wheels straight ahead, and all electrical loads off.

Which scan tool do you have now (brand and model number)?

3040RS INNOVA SCAN TOOL i will try the relearn procedure again tomorrow, I probably need a charger to have the battery voltage in spec. I believe i said this before but tomorrow i will be changing the position of cyl 3 ignition coil to another one, probably #4 and i will also be changing the injector to another place. After that if it fixes it ill change it out but also gonna tear it back down and do the valve cover gasket since the RTV Ultra Black sealent needs 24 hours to cure before you can operate, according to directions. If i can fix the misfire id be more than happy to do the idle relearn so i dont mess up any o2 sensors.

JakedaSnake

Discussion Starter · #19 · 9 mo ago

I need coffee said:
Relearn procedure is in attached PDF. It should still work with DTCs, but the main things are that the engine needs to be at operating temperature, wheels straight ahead, and all electrical loads off.

Which scan tool do you have now (brand and model number)?

3040RS INNOVA SCAN TOOL i will try the relearn procedure again tomorrow, I probably need a charger to have the battery voltage in spec. I believe i said this before but tomorrow i will be changing the position of cyl 3 ignition coil to another one, probably #4 and i will also be changing the injector to another place. After that if it fixes it ill change it out but also gonna tear it back down and do the valve cover gasket since the RTV Ultra Black sealent needs 24 hours to cure before you can operate, according to directions. If i can fix the misfire id be more than happy to do the idle relearn so i dont mess up any o2 sensors.

JakedaSnake

Discussion Starter · #20 · 9 mo ago

Sorry about the double post, i also don't know how to delete it

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