Doggus

2000 Maxima with 194K.

This started off with a P0400 which turned out to be the dreaded clogged EGR tube. I pulled everything out all the way to the intake manifold: air box w/MAF - intake - boot - throttle body assembly. Below all that I removed the EGR assembly (valve body, whatever you call it) and finally the tube itself. Got the tube cleaned and reinstalled everything.


The result was a very rough idle. It wanted to keep dying until it was warmed up. I removed the battery overnight so the ECU would be forced to reset (not sure if this was necessary).

This is extremely similar to a problem I had years ago when I found the boot just before the throttle body was split. When rev'd up the vacuum would cause the boot to close but at idle a small gap would open and it would rough idle.

The MAF is not new but it's not the original - this one probably has 65K on it. I was VERY careful with it when removing and setting down etc...

One thing that bothered me was the EGR valve interface to the block was metal-to-metal when I put it back together. Not sure if I lost a gasket there or if that's the way it was originally. Anyone know? Not against tearing this thing down again to make that part right.

Re-checked the pathway to the intake manifold and I don't see any gaps, all clamps are tight etc. Have to wonder if I missed something down by the EGR valve. There were a couple of coolant lines and the big pipe, can't think of anything else.


So now it's throwing code P0174 (system too lean - Bank 2). Any ideas?

DennisMik

iTrader: (2)

The causes of P0174 are:
Intake air leaks
Mass air flow sensor
Front heated oxygen sensor
Injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel

And yes, there are gaskets. Here is a link to the parts book diagram.

http://www.nissanpartsdeal.com/parts...egr-parts.html

Doggus

Well dagn, two gaskets down there. Not sure if the other one was there, I don't recall. I'll replace both regardless and hope like hell that's the problem.

One other question, how do you get to the temperature sensor plug? I couldn't get to it and had to carefully turn the sensor and make sure I didn't bind the wires. Wouldn't mind replacing that too if I can figure out how to get it unplugged.

DennisMik

iTrader: (2)

I never had to take mine apart on my 2000, so I'm not able to help you there. Hopefully someone else will answer that for you.

But I have an unrelated question. In your signature you have "2000 Nissan Maxima 5-spd auto". The stock auto trans in the 5th gen is a 4 speed - 3 speeds and overdrive. Is this a typo?

Doggus

Not sure where I got '5-speed's from when I wrote that?!? That fix is a lot easier than getting back into the EGR!

Doggus

So an update on this issue:

Pulled it all back apart. The gaskets were actually still on the EGR valve spacer body. They just looked like the rest of the block, dirty as hell except where the EGR valve assembly and the tube assembly mated up with them - it just looked like metal so I assumed I had assembled them back together metal-to-metal. Hard to see in there. I had new gaskets so I replaced the old ones. This didn't bode well as I really wanted to see I was missing those gaskets. Back to the thinking game.

I started putting the tube assembly back on and noticed the lock washers and the nuts kind of left a hole where the stud passes through the tube assembly. The diagram shows TWO washers, a 'washer spring' and a 'washer - lock'. Turns out I had put the 'washer spring'[s] back on the EGR valve assembly rather than the tube assembly. This should not have made a damn difference as the gaskets were in place and are what create the seal.

Anyhow, I put the washers back on the correct posts, slapped it all back together and the car runs. Dammit.

'Washer spring' is a weird name for those. They're nothing more than really thick washers. There is no 'spring' to them.

DennisMik

iTrader: (2)

That is some good eyeballing. At least you figured it out. Good work.