J30 ECM Engine light Error Code 51

[fxgo]

I have a J30 with 120,000. I have kept up with the maintaince. All the injectors and plugs were replaced 5,000 miles ago.

When it is cold the engine is hard to start. Once she starts it runs a little rough, I do small some gas fumes coming from the exhault and some in the engine compartment. I don't see any injector leaks.

I do have an engine light error code 51, which means Injector circuitry. I performed the diagnostic steps in the manual. I check that all Injectors are clicking. I performed all the steps in the service manual. The ohms reading on the injectors are about 13 ohms. The cables from the injectors to the two connectos (F41 & F40) check out fine.

I disconnected ECM and cleaned the connectors and no change in the result. I didn't check from the F7 & F8 connectors and the ECM connector.

Has anyone have any experience with code 51?

I have another strange problem, battery. The last battery was 6 months old. The battery became bad and I had Advance Auto Zone replace it.

I installed a new one and after a week the battery is dead again. I didn't leave any lights on. I appears I have a current leak. The battery is being charged.

Thanks in advance for your help! -fxgo

[BoyWonder]

I'm by no means an expert, but the "Injector Circuitry code" coupled with the dead batter sounds like perhaps something is being grounded out somewhere that should not be getting grounded? I'd inspect the electrical system associated with the injectors a bit more closely. Wish I could help out more.

[fxgo]

Thanks for your reponse. Do anyone else have any input please? -fxgo

[Q45tech]

Measure the the car off current from a fully charged battery.Have alternator checked [properly and accurately].The ecu relay supplies +12 to all injectors in parallel , each injector is grounded by a separate transistor in ecu.

[fxgo]

Hi Q45tech,

Thanks for your reply, I took the battery out to charge it. It is completely charged. I will install it and test. I broke down and made an appointment with the Infiniti dealership for this Friday. I hope it's not the ECU. The good news is I will get a G35 for a loaner.

I will have them check error code 51 and the alternator.

Question from your experience a car 100K to 210K, which manufacture is more reliable? Toyota, Honda, or Nissan.

[Q45tech]

Depends on the model everybody makes bad ones in certain price ranges.

I really can only compare Lexus with Infiniti as we work on nothing else.

[fxgo]

Hi Q45tech & Boywonder

Problem is fixed! Before bring my car to the dealer, I checked out the the Injector circuitry right up to F40 and F41 connectors. It checked out fine. The only thing I didn't check was the wiring from the engine compartment to the ECM and the ECM itself.

I purchase a used ECM. Just before drive it to the dealer, I installed it. By the time I reached the dealer the problem want away, problem fixed.

Since I was at the dealer, I had them check the car out. The car was running perfectly, no codes. They found a problem with a leaking oil sensor and the variable dash light switch. I had them fix it, check the car out completely, and change the oil.

They did find a small oil leak from the passenger side dome cover. They said it wasn't worth fixing just keep an eye on it or add an oil sealer to the engine.

Should I add an engine oil sealer to the engine or live with it. It looks like it would be difficult to fix. What would you do?

By the way, when I told them that I also was experiencing a battery drain problem and that I though by replaceing the ECM it would fix it. The Dealer said, they experienced the same thing on another car two weeks ago and by replacing the ECM it fixed it too.

Looking at the orignal ECM, it looks like water damage was the culprit. I opened the old ECM. I had corrosion on the circuity.

It was from a small leak on the passenger side winshield. It is not the orginal windshield. I am having it replaced before I put back the ECM. The ECM is on the carpet floor.

It has been a long road. I hope my experience will help another J30 owner. When at the dealer, I like what I saw from all the new Infiniti models. They showed me a picture of the new redesigned M45. It looks really nice and it is faster then the Q45, 200lb lighter.

Thanks again for all your help.

Regards,

fxgo

[VimyJ]

You have added to the knowledge base here at NICO. We all thank you and good job on chasing that gremiln.

[fxgo]

Thanks VimyJ! I am only give back what NICO has given me. -fxgo

[VimyJ]

There seems to be a leak that is not atypical to Js from the right side of the wind shield. I noticed it once after going through a car wash.

[fxgo]

Was your winsheild repaced? -fxgo

[VimyJ]

Nope. Mine's OEM.