lude-max-rx

I have recently purchased a 2k Maxima SE and I have a question about the powerband. Then engine feels great up to ~4K rpm and then falls flat. The power delivery from 4K rpm to redline is not very smooth and there is very little power. The transition at 4K is drastic. Is this normal? If not, any suggestions?
Thanks
Joel

Chinkzilla

ok that's not normal.

Your variable intake is broken... apparently the power valve is not making the switchover.

I will defaul to more knowlegable 2k-2k1 owner/members to elaborate.

LiquidhMax

Wasnt there a thread about this and a long pain in the behind dealership battle?

mad2kmax

iTrader: (4)

Yeah there was. Max_gator went through this (malfunctoning VIAS) about 2 years ago and I'm going through this now. Still trying to find out the fix, since dealer has no fucin clue.

However, lude-max-rx, if your VIAS (Variable Intake Air System) is malfuctioning, you should have power up until about 5k rpms. After that, the car will still pull, it just won't make anymore power. Your problem sounds different or it might be a combination of things.
Do you have a check engine light on? Do you drive an auto or 5spd? Any mods?
Give up some more details and we'll go from there.

lude-max-rx

mad2kmax, my car is a stock auto with no check engine light. I took the car out a few minutes ago and tried a few full throttle runs. My car has definate drops in the powerband at ~3700 rpm and again at ~4500 rpm and really runs out of breath by 5000rpm. Partial throttle runs actually yield a smoother power delivery. I am beginning to lean more towards the MAF rather than the VIAS. Do you have any experience with a bad or contaminated MAF?

I see from other posts that you are struggling with a possible VIAS problem. The fact that you see the rod actuating at 5K should prove that the vacuum solenoid, vacuum chamber and actuator are working correctly. Since theres is so little tension on the "butterfies", I seriously doubt that the key is broken. You should be able to remove the cover on the passenger side of the intake and verify movement of the "butterflies". Do you think you problem could also be contributed to the MAF. Incorrect speed/density readings could really show itself at upper rpm's.
Joel

mad2kmax

iTrader: (4)

Ah, but you are incorrect sir,

In all seriousness, it was my VIAS. It was broken internally. I don't want to let out any secrets yet, but my problem is more than solved. I will post a link describing my sucess shortly...

Loe max

iTrader: (6)

Don't rule out Coilpacks. Mine wouldn't pull anywhere when my coils were bad.

mad2kmax

iTrader: (4)

Go here.... http://forums.maxima.org/showthread....87#post2976387

Progress

iTrader: (26)

My car had very erratic power above 3500 RPM from the day I bought it (used). I got the MAF replaced and now it has power throughout the rev range. I think your power loss is due to the MAF that you suggested. Now I think my VIAS is malfunctioning because I feel no power gain after 5000 RPM.

lude-max-rx

It turned out to be my MAF. I took it out, sprayed it down with some electronic cleaner and reset my ecu. Took it out for a test drive and WOW, this thing moves. I can hear the VIAS kick in at 5K. Everything seems to be working fine now. Thanks to all for the suggestions.

PhilY

What does the VIAS kicking in sound like? Is it really loud and noticable?

Loe max

iTrader: (6)

If you have an aftermarket intake, you can hear a big change in pitch and sound quality once you past 5,200rpms. If the tone gets bassier (like a 4cyl civic with an intake, only louder and more straining, like the air filter wants to rip apart from its mount) your VI isn't working, if the sound changes into a snarl (like a power saw cutting through a block of wood) then your VI is working. This so far applies to 2k-2k1's. I'm not sure how 2k2+ intake note change after switchover. I've done this experiment with my 2k, I only wish I could explain it better or at least have a video camara to make a movie on how to test your VI.