What do the plugs say?

[daegrigg]

I've been chasing a poor idle and less than 100 percent performance for months now.

After doing all the usual stuff (MAF, BG44, SeaFoam, IAC, connectors, etc.), I replaced three injectors that had high resistance from 18-35 ohms.

Maybe a little better performance but still lumpy idle. ECU code is 55.

Replaced the Bosch Platinums with the correct NGK plugs.

You can view the plugs here: http://mysite.verizon.net/vzeri3wo/

CLICK ON "MORE PHOTOS"

I would appreciate input reading them. I am focusing on plugs 2 and 4 that seem to show poor ignition and/or too rich mixture.

Injectors bad even though resistance is ok?Coil or ignitor transistor are weak/bad?Other?

Thanks

Don
Modified by daegrigg at 6:53 AM 4/22/2006

[goody90q45]

Plugs 2 and 4 are definitely fouled from too much fuel. I had similar issues- sluggishness and poor idle. She ran great in the morning until warmed up. Plug 8 was fouled and the Fuel Injector lower o-ring was brittle and leaking. Replaced it and it solved all the problems we've discussed. In your case #2 is very easy to get to (as are #1 and #8). A set of o-rings has got to be less than $5 from the Infiniti dealer since it's less than $2 from Joe.

Which injectors have you replaced?

[maxnix]

Are those the Bosch? Hopefully not +4!

Difficult to make more than very broad generalizations from incorrect plugs. Pull and photograph your NGK in 5K miles if you have a good torque wrench with which to reinstall them..

[daegrigg]

The old plugs are Bosch FR8DPX. They were in there for about two weeks after I changed the injectors but injectors for 2 and 4 were not replaced.

I think I will replace #2 injector since it is the easiest to get to and see what happens.

[goody90q45]

If it's ohming OK try just changing the o-rings and reuse the injector. Make sure to clean up both o-ring mating surfaces on the fuel rail before reinserting the injector. You'll know as soon as you fire your engine up if a leaky o-ring was the problem.

[daegrigg]

I changed #2 injector with no change in idle or performance. The lower o ring on the old injector showed a little uneven surface but nothing to indicate it was pinched or crimped.

If a leaking injector (o ring) were the problem, I would expect to see noticeable improvement.

I have ruled out (but not checked) fuel pressure because that would affect all cynlinders not just 2 and 4. ???

The other cause of the "rich" condition shown by plugs 2 and 4 could be poor ignition. I am thinking the weak link would be the coil caps first and the ignitor transitor second.

Still 55 from ECU although I get the CEL occasionally.

What do you think?

Don

[squeefoo]

Try squeezing the fuel return line and see if it really runs like crap. Don't squeeze it too long, just 1 - 2 seconds, it forces the fuel past the bad rings.