update? still good?

 

yup.. transmission was fine. Found out it was a bad maf sensor, thats why it threw an SES code. it's all good now and running great

 

perfect!

 

That doesn't make a whole lot of sense. Fifth gear was slipping and so they replaced the MAF at which point fifth was still slipping. Then you put on your stock intake and it magically works? The problem may have disappeared for a short while but I would fully expect it to come back because changing the intake type will not affect your tranny performance. Not to mention the fact that the AF ratio fluctuates with engine RPM's not transmission gears meaning that a bad AF ration will be evident in all gears not just fifth.

 

It was due to the fujita intake. It making the engine run real lean. Not allowing enough fuel injected. More air and not enough fuel. Maf sesnor went bad. Replaced it and put stock intake back on. Been gone for 2 weeks now and running perfectly fine.

 

If it was running lean it would do so in all gears, not just 5th. This doesn't explain why only 5th gear experienced slippage.

 

haha dude... they ran a diagnoistic. Came up as a bad MAF sensor so they replaced it. I was fed up with the whole thing because I myself didn't believe it was only the MAF sensor. Got it back with the light off. So I took out the intake, sold it, and put my oem/stock intake in and never had a problem since. That is what I was told and what happened. I'm sorry if you don't believe it, but that was the case and it's working fine now. Its been 2 weeks and haven't felt a slip or anything remotely close to it. If it happens again, then we know its transmission issues. However, I know the car well and do not feel it will do it again.

Trust me. I didn't believe it at first and even took my dad out to show him what I was talking about (after I got a new MAF sensor and put the stock into in). It was totally fine and he thought I was crazy since it didn't even do it

 

I have an 03 sedan AT with 100,000 miles with the EXACT same 5th gear slipping problem. I just took it to AAMCO, and they quoted me $1700 just to look inside the transmission, parts extra. Well, after reading your post I am going to try and switch out my my z-tube/popcharger intake to stock...hopefully this will work for me too. I'll keep you posted...

 

Make sure the MAF sensor is seat properly. Could just be a bad maf sensor. It's not the transmission. At least not in my case. It was a simple fix. Keep us posted

 

How can I tell if it's a bad MAF sensor?

 

Replace it with a new one. But either way, you're going to have to go to the dealer to get the SES light (if it came on) off. If no light came on, then swap out intakes, and see what happens.

 

No SES light, I'm going to try the intake swap tonight and see what happens...thanks for your help!

 

Sounds good. Don't do any driving until you put the stock intake on. my ses light didn't come on until a couple days later.

 

Ok, swapped intakes back to stock last night...same problem. I don't have a check engine light on so I'm assuming my MAF is ok? Is this where I bite the 2 grand bullet? I read on another thread someone with the same problem that suggested it was the torque converter: https://g35driver.com/forums/g35-sed...-03-sedan.html

Any suggestions from here?

 

Hmm.. very strange. I really thought it was the transmission when I was going through it. I was very very shocked to find out it was only the intake/MAF sensor. Drive it around a bit. See if the car throws an SES. if it does, go in get a new maf and you're set.