CEL P0307 Cyl 7 misfire. Solved! Fuel Injector (1 Viewer)

[tahoejoe]

01 LX470 with 198K miles
CEL started blinking while on a 1500 mile trip. Hesitation and slight shuddering when going uphill or accelerating (when giving it gas). CEL stops blinking when going downhill. Pulled DTC codes and P0307 comes up after clearing codes. [Also P0305 in history but I am not seeing that one in current read]

Something going on with cylinder 7 (Why can it never be 1 or 3!!!!)

Things I tried...
- Replaced coil multiple times (5 and 7)
- Replaced plug (old plug was dirty)
- Cleaned fuel injector electrical connector and measured 15 ohms for the injector (same ohms as good #3 cylinder)

I know I have some exhaust issues. Exhaust manifold leak on driver side and muffler exhaust pipe has leaks and needs to be replaced. I am assuming these are not causing CEL.

Any ideas about what to check next? I am thinking about replacing fuel injectors but is there anything simpler that I might have overlooked?

If I have to replace an injector do I have to remove the fuel rail? Is there a write up for that procedure?

[Edit] The misfire comes up many many times per minute. I can see the misfire count in the OBD app count up as I am driving.

 

[Trunk Monkey]

Replace the cylinder 7 coil pack?

 

[tahoejoe]

Replace the cylinder 7 coil pack?

Thanks. I edited my post. I did replace both coils 5 and 7. It did not make a difference.

 

[awesomeissquid]

Have you checked the spark plug?

 

[tahoejoe]

Thanks. I edited my post. I did replace both coils 5 and 7. It did not make a difference.

Have you checked the spark plug?

Yes. I did replace plug on cylinder 7. The old one was dirty but a new one did not make any difference

 

[BullElk]

Yes. I did replace plug on cylinder 7. The old one was dirty but a new one did not make any difference

The coil pack and the correct nonfake spark plug are largely the answers to this type issue. Are both plugs you’ve tried the OEM Denso SK20R11? I have bought bad ones on Amazon.

 

[tahoejoe]

The coil pack and the correct nonfake spark plug are largely the answers to this type issue. Are both plugs you’ve tried the OEM Denso SK20R11? I have bought bad ones on Amazon.

Replacement coil packs are Denso. The original coil from #7 is now in #1 and not misfiring.
Replacement plug is NGK iridium from Oreilly because I was on a trip and had to buy replacement with whatever they have in stock

I always carry spare coils. So the coils I tried are 2 backup Denso that I carry with me plus an import coil Oreilly had in stock. All had no effect on the misfire.

 

[tahoejoe]

success.
I moved the fuel injectors around on the driver side and the misfire moved to cylinder 3, so I know I am dealing with a bad injector causing the misfire.

 

[Bisho]

NGK plugs are also OEM, btw.

 

[2001LC]

If moved FI wire housing connector #7 to #3, its likely wire.
If moved the FI, that does indicate a bad FI.

 

[tahoejoe]

8 "refurbished" injectors arrived today. I got them all swapped in. Cleared codes.
No more codes come up after a test drive.
Engine runs the smoothest since I got her 6 months ago.

This is a really satisfying fix for a diy'er. If new coils and new plugs are not making your 100 run smooth then do a compression test then look at the injectors.

The hardest part of the job was to reseat the injectors. I slightly damaged one of the new ones because it was not seated correctly in the hole. I think the best method is to get everything loosely in place after swapping injectors, make sure the injectors swivel slightly and then tighten down slowly and patiently checking the swivel movement as you tighten. If injectors dont swivel then its not seated in the hole and tightening can do damage. Use gas for lubricant.

I found this video to be helpful.

 

[2001LC]

I'll offer 4 tips for those contemplating doing FI in place:
1) First thing. Clean top of engine, paying special attention to area where FI seal/seat. We don't want and dust dropping into intake ports.
2) replace all seal. This included washer on fuel rail, which are seals
3) Use a torque wrench.
4) Replace fuel filter and green clip.

I use FIS (Fuel Injector Specialist) here in Denver. I spoke with Chuck (owner) yesterday. He's just purchase $30K in new equipment. His web page is down, but will be up soon.