I was looking at this thread:

http://forums.maxima.org/showthread....hreadid=188798

And I remembered the following:

1. Many people had their MAF fail approx 12K miles after installing a intake midpipe

2. Many people have seen oil on the factory's DRY PAPER filter

3. After a MAF fails, there is a noticeable amount of Oil in the intake tract & sensor

4. All intake midpipes have a return for the crankcase hole

6. Some people with crankcase Breather-filters have seen oil spill out

MY CONCLUSION

Could it be that the crankcase breather hole is spitting tiny amounts of oil back into the intake through the midpipe?...

This would easily explain why there's oil everywhere. Everyone with an intake midpipe, check and see if you can notice oil in the midpipe, etc. I'm going to check mine asap. Perhaps the 3.5vq is more likely to spit oil back out...

Nissan has been making MAFs for a long time & perhaps the 2k2 MAFS are ok after all... Let's look at that damn breather-return line!!!

I also think that the "over-oiling K&N fitlers" theory is not the reason MAFs are failing. People have been successfully re-oiling K&Ns for decades.

Please provide some valuable input guys... we may just be able to resolve the problem with a simple breather-filter installation. Of course, we'd also have to seal the midpipe hole.

People with a factory PAPER filter - could you check & see if there is any oil residue on your fitler element?

Thanks everyone!
G

 

Something to think about.

You would think the oil would be drawn into the motor not backward to the MAF.

Do other car makes have this problem with the MAF?

Why is it so pronounced with the Maxima?

My MAF blew with a totally stock intake down to the paper filter.

 

The engine oil residue in the intake tract is from the crankcase blow by gases. The EGR system draws them out to be consumed for cleaner emissions. However, once you shut down the engine the HOT oily vapors try to escape and the easiest path to take is towards the intake filter. That's why you find the oily residue both upstream and downstream from the crankcase vent tube.

 

So you're saying that "oily gasses" may be exiting through the crankcase breather hole?

Can a breather-filter stop this from happening?...

G

 

Yes, some of the gases.

During partial throttle, the intake manifold sucks the blow-by gases through the PCV(Positive Crankcase Ventilation) valve(located on the other bank), which also draws intake air through the crankcase ventilation tube to aide scavenging.

During WOT, the gases are drawn in the opposite direction to the intake tract through the ventilation tube and past the throttle plate.

So, if you add a crankcase breather, you are eliminating WOT scavenging and relasing the blow-by gases at shutdown into the environment, however you are also preventing the oily residue from building up in the intake tract, parts of the intake manifold, and the throttle body.

 

I have a custom mid pipe with no crank case breather connection, AKA I have a crankase filter, so no oil is getting into my mid pipe. With that said I have had 4 MAFS failures with my 2002.. You may want to reconsider your hypothesis

 

Will there ever be a solution to this on going problem???
I was going to do what emax did and purchase a 2K1 MAFS as a safety precaution when I install my Franken intake on,but all hope for that idea was scrapped when an Org. memeber had installed a 2K1 MAFS on his car and it threw an SES light. Why are our MAFS so poorly designed and so sensitive??? I never had this problem with my previous cars when I had an aftermarket intake installed or running the stock air box.

 

I believe your second question answers your first question.

 

I have to wonder if it's not vibration that is causing failures. Are any of these intakes dampenned with a rubber isolator on the bracket? I sincerely doubt it's oil that is causing the problem. That only leaves vibration. Those MAF's are VERY delicate.

 

We've already concluded that is ONE of the root causes(OVERoiling is another), however apparently the OEM setup is susceptible even with its rubber mounts under the airbox and the flex section on the OEM midpipe.

The dead horse is just being unburied and whipped for discussion sake.

 

 

That is my guess.

I installed the Franken with the stock flex piece that connects the stock mid-pipe. Then the MAF is solidly mounted with a rubber isolator to the strut tower. This install isolates as much vibration and movement of the MAF as possible. Not one problem yet!

 

I know for a fact that this past generation of Volkswagon Jettas has a serious problem with the car's MAF. My friend had to have his replaced twice, with no aftermarket intakes on his car.

 

But I have the Berk midpipe and I'm not using the Berk mounting brace... therefore, it is not secured to the chasis at all. The midpipe basicaly hangs off the rubber mounts connected to the intake manifold. So it would vibrate about as much as the stock-setup. I haven't had a problem yet... but I am worried I might find oil in the intake now.

Has anyone checked for oil residue, yet?

G

 

It's the ECU. I've done enough homework to be able to say that as a THEORY. I'll share my THEORY as to why I believe that it's the ECU

Actually.... it's a combination of 2 (or more) things. The MAFs on the 2002's had a defect. Their part number was 22680-6N200.

Nissan replaced it with a new part. Part number 22680-6N201.

Obviously, there was still something wrong with them too, as the 2003's had a new MAF. Part number 22680-AM600.

So I asked a tech why the failures were happening. He basically said that the input of the ECU (from the MAF) is looking for a certain voltage range. If the voltage rises or drops below that range, the ECU cries and the SES light shines it's bald head.

So why does the MAF blow? Well, the tech said that Nissan had to make some changes to the ECU to be less sensitive to the MAF signals (or maybe increase the range?). But in theory (key word THEORY), the ECU sends out a signal (of an unknown type) that makes the MAF heat up to the point that the element is fried. And now it's just anexoric chicken wire.

So how do I fix it? If you have the 22680-6N200, you're SOL. It will break. If you have the other two, ask your Nissan dealer to check into reprogramming the ECU the same way they would if the MAF had died. That should help with the problem.

Now, on another note, there is NO INDICATION OR PROOF that oil causes the failures. The majority of intake owners notice failures due to the following reason:

(This is an example and the numbers used are ONLY FOR ILLUSTRATIVE PURPOSES - they are NOT ACTUAL NUMBERS, only numbers that WERE MADE UP)
10 parts of air enter during 1 period with the stock box, generating 10 volts from the MAF to the ECU. When you replace the intake with an aftermarket intake, you increase the volume of air intake. So now you have 20 parts of air enter during 1 period which generates 20 volts. The ECU was designed to read only up to 12 volts. So when it gets 20 volts, it severs the connection to the MAF. It may also send out a ground signal on the same wire, which then damages the MAF. I have NO PROOF of the latter portion, it's only a theory.

So there you have it. A blown MAF and a sensitive ECU. If you can prove this theory wrong, go for it. Also, if you can prove it right, go for it. All in all, remember that it's only a THEORY and MAY or MAY NOT be correct.

 

EMAX,

Did you ever have your ECU reprogrammed? I did and have not had a problem yet after my first MAF failure.