[ThreeThirtyFiveXI]

I've got a CEL for the codes in the picture posted, i assumed it was my spark plugs since it was a misfire. Changed them and still have a misfire but a fuel code came up, what could it be?

[Basedtiger]

Do you have a recent data log through MHD? It could be your ignition coil or fuel injector.

[ThreeThirtyFiveXI]

Originally Posted by Basedtiger

Do you have a recent data log through MHD? It could be your ignition coil or fuel injector.

I didn't , what do i need to look for?

[Basedtiger]

Originally Posted by ThreeThirtyFiveXI

I didn't , what do i need to look for?

With a log you can see if the fuel injector is leaking. Compare the lambda 1 and lambda 2 readings after you left off the throttle. The readings should be about the same when you let off. I would try the easy thing first and replace the ignition coil on cylinder 4. Or at least swap the coil with another coil from a different cylinder. Then re-scan for codes.

[ThreeThirtyFiveXI]

Originally Posted by Basedtiger

With a log you can see if the fuel injector is leaking. Compare the lambda 1 and lambda 2 readings after you left off the throttle. The readings should be about the same when you let off. I would try the easy thing first and replace the ignition coil on cylinder 4. Or at least swap the coil with another coil from a different cylinder. Then re-scan for codes.

i did swap over the ignition coils after i changed the spark plugs. Definite fuel injector at that point?

[Emilime75]

Originally Posted by ThreeThirtyFiveXI

i did swap over the ignition coils after i changed the spark plugs. Definite fuel injector at that point?

And the misfire stayed on 4 after the coil swap?

I'd check compression, as well, before buying more new parts. Compression loss is quite a bit more rare than plugs/coils/injectors, but it does happen. Also need to confirm fuel pressure. After that, yes, likely to be the injector.

[HiRev335i]

Originally Posted by ThreeThirtyFiveXI

i did swap over the ignition coils after i changed the spark plugs. Definite fuel injector at that point?

just pull the plug on that cylinder to confirm if your injector is faulty or leaking..... if it is the spark plug the tip and threads will be wet with fuel . Also do this after the car has been sitting overnight or a long period of time. If your plug checks out and is dry then more likely it's not your injector and you can save the money on not replacing it. I see you have a 08 if it is an earlier build 08 there have been known issues with the mosfets to be defective in the DME to cause misfiring issues, so if you've exhausted all other avenues with no result that could be a plausibility. One other thing if you pull the injector and reuse it make sure to replace the Teflon seal on the end they are only a one time use.

[ThreeThirtyFiveXI]

Originally Posted by HiRev335i

just pull the plug on that cylinder to confirm if your injector is faulty or leaking..... if it is the spark plug the tip and threads will be wet with fuel . Also do this after the car has been sitting overnight or a long period of time. If your plug checks out and is dry then more likely it's not your injector and you can save the money on not replacing it. I see you have a 08 if it is an earlier build 08 there have been known issues with the mosfets to be defective in the DME to cause misfiring issues, so if you've exhausted all other avenues with no result that could be a plausibility. One other thing if you pull the injector and reuse it make sure to replace the Teflon seal on the end they are only a one time use.

I did end up replacing the ignition coils and looked in the cylinders, and plugs they were dry. The misfire did go away now but the car takes longer to start.

[Banzai250]

You might want to try to get a good log , from 3k-redline wot and check the reading on HPFP , long crank to start car are good sign that your HPFP maybe failing