MrEous

iTrader: (11)

Did you do the install yourself?

Quick question...
Did you have an issue with the stock nuts not screwing on the 'whole' way?

In short...I am working on a friend's '98 Max and he had a shop install his Cattmans. They used the stock header nuts and the 'flange' around the nut actually rests up on the pipe welding and doesn't completely sit flush.

I wanted to see if this is a common problem or not.

He's having a fuel issue...running lean on the right bank. He has just about every bolt-on available for the VQ30 sans f/i or n2o. From the front (left bank) you can visually see that 3 of the nuts were not sitting flush. I am sure this is the case for the rears as well. I replaced the 2 nuts I could on the front with some smaller diameter replacements.

I looked up his code P0171 (aka 01-15), right bank fuel lean. He's already replaced the o2 sensors for both right and left banks so we know it isn't that. He has a MEVI too...all vacuum lines are ok, non-leaking. I'm just trying to do the 'cheap' fixes before I move onto testing fuel injectors for ohms. Any other suggestions? Also let me know if the nut issue is something you've come across.

Thanks!
Jeff

Jeff92se

iTrader: (82)

Is there signs of exhaust leakage at the flanges? That might cause a false a/f ratio signal. Look for sooty marks around the flange areas.

MrEous

iTrader: (11)

I'll definitely keep that in mind. Definitely helpful.

Do you think with a mild exhaust leak around the exhaust manifold that it would cause the fuel system to run lean?...or would you think there is a fuel delivery issue going on?

Jeff92se

iTrader: (82)

Well I don't think it's very good that the nuts don't sit flush. I would have ground down the welds flat if that were possible.

It might not be a case where that side is running lean perse. If the exhuast is leaking etc... it might cause the 02 to misread what is what is going on.

EZEMaxima

No, the car is actaully not runing lean but during accelaration and decelaration, the small leak act as a vacuum and extra oxygen is introduced into the exhaust system then the O2 sensor reads a much higher oxygen content which makes the ECU think the the engine is runnig lean.

Eric

MrEous

iTrader: (11)

Ahh...exactly the answers I needed.

Thank you both very much. I'll be getting in on this later tonight but wanted to get some info beforehand.

-Jeff

Jeff92se

iTrader: (82)

That is what I'm thinking also but wouldn't the ecu keep dumping fuel in there and actually make the car run rich?

MrEous

iTrader: (11)

^^ Jeff, he does have a black cloud of smoke while his car is 'crippled' with the 0115 code (running rich, right?). He has also gotten the multiple misfire code on seperate occasions.

Jeff92se

iTrader: (82)

Looks like you guys should fix the exhaust flange leakage problems. Then reset the ecu. See what happens. If you start changing stuff before you fix the leaks, you will be chasing your tail around replacing things.

I can't believe whomever designed the headers didn't account for the nut(s). You could use smaller nuts that have less "flange" on the bottoms but you really want and should use as wide of washers/nuts as possbile to distribute the clamping force. I'd grind the welds if you can and if it doesn't hinder strength. But it's going to be alot harder now that they are installed.

MrEous

iTrader: (11)

Unfortunately I have experience in pulling headers. I was the 2nd prototype for the Stone Racing headers and we ended up doing the install ourselves. I'll see what we can do about getting the welds ground down.

In the meantime I've sent an email to Brian (Cattman) in order to let him know about this problem and see if it is just an isolated case.

Thanks!
Jeff

Dave B

I hope you can get to all the nuts and replace them without any further issues. A lean condition with leaking headers/manifolds is common and can eventually burn out the valves. It's been my experience with LT1s/5.0s that if you get any sort of header leak, you must replace the metal gasket because they'll always leak. I'm sure your friend doesn't want to hear that because it means the headers have to come off for the gaskets to be replaced. This is the primary reason you don't see me buying Maxima headers. I've experienced first hand the problems associated with headers which include header leaks and constant retorquing of the bolts. With a transverse FWD V6, there's minimal room to work without removing a bunch of other things. I think the reason headers are so prone to leaks is because the metal in headers does a lot of shrinking and swelling whereas cast manifolds are pretty stable.

Jeff92se

iTrader: (82)

I agree Dave. The VE manifold flanges are probably good 2" thick.

MrEous

iTrader: (11)

Thanks Dave...I was afraid of what you're saying. Hopefully the only problem we face is getting the old nuts off, regrind the welds and getting the nuts back on.

*crosses fingers*

mitchman

Hey Jeff,

I agree with the gasket remarks that if there is a leak, the gasket is surely gone and no matter how hard you try to tighten the bolts, the gasket will still leak. Is the only gasket we have available the Nissan metal gasket? I don't know if you can buy just the material, but Mr. Gasket used to make a special heavy duty header gasket that was black in color and worked much better than any other header gasket available at the time. If that material is available, you could cut your own gaskets and have a much better seal.

Did you hear anything from Brian?

Off on another Cattman header question, can you remove the transmission without removing the headers?

Mitch

MrEous

iTrader: (11)

Ok...so I guess we're back to square one. Checked out the rear headers and only one bolt was not sitting flush. I checked the seal around both left & right headers and there was -0- soot. Looks like this is going to be a bigger problem.

We decided to change out his spark plugs. Take out left bank plugs and each of them look like they are running lean or hot (white-ish to gray coloring). We remove the rears and 2 of the coil packs look like they have some sort of moisture dried up on them, uh-oh. Remove the right bank plugs and each of them are black. All 3 of the right bank plugs have the same dried up moisture as 2 of the coil packs did.

I will post pics of one of the coil packs tomorrow and pics of all spark plugs as well.


Any suggestions?


P.S. Received email back from Brian (Cattman) and he explained the New Zealand guys already try and grind the welds down somewhat so the nuts fit. I posted this same problem on CaesarsChariots forums and they saw the post. As I type this they are going to start furnishing 'D' shaped washers to fit under the nuts to assure a flush-fit bolt-on.

MrEous

iTrader: (11)

Cattman furnishes a different type of gasket from the Nissan 'metal' gasket. It does provide a much better seal.

MrEous

iTrader: (11)

Pics...I said screw it and jetted home for lunch to get my camera/cf card.

Pic of the nut not seated completely...


Coil pack from cylinder 3...


Plugs from cylinder 1, 2 and 3 (in order)...


The corrosion = bad, right?

Jeff92se

iTrader: (82)

Odd. The rear bank is what is showing lean right? I bet there is something leaking into the cylinders making that side's o2 to read lean and the ecu is richening up the mix.
Or some type of moisture (ie.. coolant) is leaking into the cylinder preventing any decent combustion. ie.. coolant severly prevents combustion. Don't know why it would be leaking onto the coil pak. It's like it's not getting into the cylinder but leaking from above? You guys wash the engine down lately?

MrEous

iTrader: (11)

The rear (right) bank is the one that is showing lean.
He hasn't washed the engine in awhile, that I know of.

Do you know of any kind of coolant jacket that surrounds the coil pack or any other way some moisture could collect back there?

MrEous

iTrader: (11)

Another pic with all plugs...They are in typical order if you are looking at engine from the front.



The #3 cylinder plug is the one that worried me the most.

Jeff92se

iTrader: (82)

Only thing that I know of is the rear valve cover. But it would only leak oil down in there. Check his coolant level.

MrEous

iTrader: (11)

I'll check that too.

Joffe (seximagtr) unplugged the rear coil packs one by one to see if there was any difference in idle but everything checked out ok.

...after we changed all the plugs and reset his ecu we took some spirited 1-2-3 shifts and the black smoke exhaust was still present. I'm willing to bet he is still running rich on the rear bank. This diagnosis would be so much easier if we got any other codes besides the 'right bank running lean' 0115 code. Uggh.

Dave B

Does this guy wash his engine down? I think Jeff is on to something. I think the corroded spark plug and coil packs are a different issue unrelated to the current problems. There are no coolant jackets/ports in the vicinity of the pulg tunnel. If for some odd reason coolant had made it's way up there, I think you would smell it on the plug. To me, the corrosion looks like oxidized tap water. I'd still check the coolant just to be safe.

It sounds like the headers aren't leaking so I wouldn't bother. BTW, a header leak is pretty obviously because it is quite loud. The carbon covered rear plugs tell me the ECU is compensating for the lean condition. I guess I'd verify the condition of all the O2 sensors and any other component that affect the "lean condition code". How about a leak at the EGR plug?

MrEous

iTrader: (11)

Wouldn't an egr leak cause a code though? I'll check that and the coolant regardless.

My original thought on this issue before I even took a look was that there was a vacuum leak somewhere...but seximagtr took a look at all MEVI connections/hoses and everything looked just fine.

Dave B

Do any of you have a vacuum gauge? That could tell you a lot. A $30 MityVac from Sears is a great tool because you can do vacuum checks, brake bleeding, etc with it.

MrEous

iTrader: (11)

I think I can source one down here from James Vick.

Y2KSESteve

iTrader: (22)

You probably won't get a CEL light from an EGR leak.