J30 Questions

[juiceman]

I took my J to the Infiniti Dealer friday and they found a few things

The consult showed the A/F alpha on both banks is below 90% which they stated is running lean. The blamed this on the MAF.

I checked the MAF today and measured the voltage as per the book. At iginition on with car not running the spec is .8V and I was reading .45V. With the car running and warmed at idle the spec is .8 to 1.5V I was reading 1.4V

Does the low end of the spec really mean anything? I am assuming that the MAF is going and needs to be replaced.

The only other thing they found off is the HICAS sel diag. The steering angle sen was past or past/neut. He said the alignment was out on the car and was porbably causing some of my vibration. He blamed it on a bad rear passenger, steering ball joint where the seal is shot. I called joe @ Scottsdale and I can get the part but I wonder if this could be pressed on without removing the plate? There is a retaining ring on the back and I figured I could get a loaner tool from the local shop to press it in. Any suggestions? Should I also replace the tie rod ends while I am at it also?

He said that when I replace these items and get a balance done on the good hunter machine and a good alignmnet I should be good to go. Said that the car was in excellent condition.

Thanks for any input guys! BTW I was charged for one hours labor and got the printout. total 95.00 with tax and the 5.00 charge for the printout.. The tech took close to two hours going over car so I think I got a bargain.

PS the new G35 is sweet! I sat in one and fell in love but that will have to wait a few years.

[Q45tech]

At idle the engine is running at about 15% volumetric efficiency becuasr the throttle is closed and the air speed in the runners is dismal.

So a 3 liter engine fills every 2 rpm so at 700 rpm, 350 fills per minute but each fill is 15% [of what's is possible at 4,000 rpm WOT] maybe 450 cc of air.

The 0.8-1.4 voltage output from the MAF is purely a function of idle rpm and intake cleanliness all the way to the back of the intake valves.........of course air temperature and air barometric pressure can vary the voltage.

Nissan only uses the MAF voltage at idle as a double check.....the primary is rpm and coolant temp.....when warm the ecu tries to lean the injection time out to a miss then adds back some time........[make the idle as lean as possible to save gas].

The MAF usually don't fail unless abused.

[juiceman]

I was wrong they stated it was running rich not lean

Seld-Learning Cont 87%RPM 738A/F Alpha - R 93%A/F Alpha 89%Coolnat temp 181FO2S1 .05V

You say that MAF do not fail unless abused. I started exibiting signs of hesitation etc. I have cleaned MAF connector and no improvement. I know they are a simple mechanism but can they start to fail?

The tech claimed that a 10 yearold MAF will be at the end of its life. He was not pushing parts and did not even try to convinve me to get the work done there.

Everything else checked out at the consult

[Eswift]

if the heated wire on the MAF gets junk on it, you can get erroneous readings. if youve already fooled with the connections, thats the only other thing that should go wrong with it.

[juiceman]

Took a look in the MAF

The wire that runs in the protrusion, is that supposed to be just a wire? Mine has sort of a glob in the center of the wire.

Also, does anyone know about the stterin ball joint on the rear?

[Eswift]

if my memory serves me, there is a yellowish resin-looking ball in the center of the wire. it would be good if someone else could confirm the coloration. If yours is dark, that could be an indication that there is gunk all over the outside of your wire, which could definitley effect heat transfer rates, and hence, the MAF reading being offset. a less effective heat transfer would indicate to the ECU that less air was flowing than actual, so that could be the problem right there.

[Q45tech]

Anything within +-10% is normal. I you want it closer to brand new 100% [zero correction] you will clean the intake track, change all the injectors and O 2 sensors, make sure the valves and piston tops are shiny clean.

Since you are in Tampa we know the altitude but you didn't supply the barometric pressure when the test was done nor the air temperature /humidity passing over the MAF element....also need the idle vacuum at 738 rpm.

The oxygen sensor voltage says it is running lean [normal idle].........the correction factors are generated at cruise not idle where they are ignored mostly.

Save your money don't change the MAF. but if you want proof get one from a junkyard! to compare.

[juiceman]

Man unless you know this stuff yourself it can get real confusing. Who do you believe? It is real hit and miss.

BTW the car has 68K miles, with an induction service done very recently.

Then why did the consult show rich? I ordered a MAF but not at high dealer price, 219 delivered and it is the original manufacturer brand, just not from nissan/infiniti. Compared the numbers on the unit. I checked the connectors and tweaked them before. I tried running the car withou the MAF connected and the car would not really turn over let alone stay running.

The tech did a vacum leak test, by pinching the hose and the car immediately died. He said vacuum leak is out of the question

I know the plugs in the car are not the correct number and I have gotten them new also. Yes they are NGK PFR5G-11

I will try new one and deal with it if it does not help my situation. I will inform you all.

Thanks for all the input

[Eswift]

good luck!

[Q45tech]

Obviously you have not studied the 700 page manual that comes with the Consult. {Rich means make it richer because it is lean].

I didn't say a vaccum leak test but measure the actual vacuum in inches of mercury = 18"

Other than VVT their is nothing weird or sophisticated about this engine.

Nothing that a few years of trade school and/or a degree in automotive engineering can't let you fiqure out.

Don't assume that every Infiniti tech is an expert much less knows how things really really work.........lots of it is the senior guy helping the newbie..............the factory training books will make you laugh compared to the level of detail we sometimes go into on this forum.

Generally [9 out of 10 times] when you do a high pressure fuel rail/ injector cleaning the idle mixture returns near normal.......pouring something in th tank won't help much except maintain the status quo.

Tens of thousands of the engines were made for the NA 300ZX and the J30...........you need to take it to a Z specialist!

[juiceman]

I have got to find a z specialist around here.

I was told by the Service manager, talked to him numerous times about all my problems , and he promised me that their master tech 12yeasr experience and knows this car was working on it.

I appreciate everthing you have said it just gets confusing as I know alot about alittle but not a master of any. In other words, I know enought to get into trouble.

I got the part so I will just see if it makes any difference before I change the plugs so I can compare. I checked and the unit can be returned no questions asked within two weeks

Thanks again, let you all know how it goes