ECU Codes for idle problem

[firstq]

92Q45 with 101K miles

1. All of a sudden starting to vibrate at all speeds, even @ zero (idling).

2. Reving up the engine causes more vibration.

3. Vibration increase while driving when pressing the gas pedal. Letting the pressure off of gas pedal , lessend the vibration.

4. The car is starting fine.

5. I popped the hood up --> while turning the ignition on, I hear a clicking noise for a second - very easy to hear (as if two wires are shorting or something and then the clicking noise goes away).

6. New fuel pump and filter - 3months ago

7. All new 8 injectors 2 years ago @80K miles

Testing so far: (ECU testing --> Mode II)

- Turned the ignition to on- I can see the red light on ECU stay on- I turn the switch (screw) on the ECU to test mode- The red light on the ECU goes dark -- stays dark- no engine check light comes on during test

Seems like I am doing this wrong? Can anyone better explain the direction than what is in the Service manual?

Anything I can try before going to the dealership?

Thanks

[firstq]

Update: I think I was able to read out the ECU code, it turned out to be 55.

Where do I go from here?

Thanks

[Mayhem_J30]

i believe 55 means there's no detected problem...don't hold me to it for the Q.

does it vibrate in neutral? check thread below by 90Q45blue.

[firstq]

Yes it is vibrating in neutral - seems like as if the car is a tank - the car seat shakes as if on a sideways rocker setup.

Question: Can an injector go bad if the ECU code states 55?

Thanks

[firstq]

Injector #4 is showing no continuity (highest resistance). #1, #2, #3 tested well within limits (10-11 ohms).

Now - am I in for a plenum removal to get to the injector #4 or is it possible to get it out w/o having to remove the plenum.

I have not yet tested #5, #6, #7, & #8.

Your help is greatly appreciated.

Thanks

[Q451990]

The vibration you describe is the classic "dead miss" - after you replace the injector, you may need to clean or replace the spark plug on the same cylinder. Every time I had an injector failure I had to do this due to severe fouling that caused the plug not to fire (so the dead miss was still there).

Heath

[firstq]

Okay - so seems like the dreadful plenum removal is required to get to the 4th injector - bummer!

As far as spark plugs go, the car just got 8 new platinum plugs a month ago. Can a dead injector kill a new plug? I guess I will put the injector first and see how it works out.

Does anyone have directions and pics for the plenum removal process that I can get? I would really appreacite any help there.

BTW, plenum was removed @80K with all injectors and hoses were replaced by the dealer.

Thanks for your help.

[Sopdadope]

Firstq,

I had that problem before as well. Cured it with fresh injectors and plugs. Try searching this forum or the infiniti general forum, one of the members posted and INDEPTH how-to article on plenum removal along with pictures. It's not that hard, pretty straight-forward if you remember which hoses go where. Use some sort of labelling or marking system to keep track of the hoses. While you're at it, do a thorough cleaning of the intake plenum, any generic carb/throttle cleaner and a few shop towels outta do the trick.

I did all of this on top of a BG44k treatment and it makes a big difference. Hope that helps.

[firstq]

If I am trying to get to injector #4, do I have to remove all of the plenum and associated things - or just removign the few screws of the plenum would give me enough to get the injector #4 out. I can see the injector #4 but it is diffciualt as is to get the screw driver there to get the injector out. Also, not sure how high the plenum needs to be pulled up before the injector can be taken out.

Is it absolutely necessarry to get everyy thing out to get to the injector #4.

The reason I am hesitant is because about 20K miles ago the plenum got the service (all hoses were cahnged with the injectors) - so perhaps the need to redo the whole plenum service is perhaps not required.

Thanks

[DAEDALUS]

Most people remove the plenum to work on injectors 3-6; the injector is about 3" long. Not sure if it's worth trying to "cheat" on labor by removing the plenum partway. While you're in there, see if you can replace the 2 screws with cap or hex-head bolts. That'll make life a lot easier in the future should you have to remove it again.