recently when my car hits 5k rpms at WOT it almost feels like i stop accelerating but if i keep it floored it starts pulling hard again..... what could be causing my car to loose power after 5,000 rpms like this? no SES light..... thanks

will

 

Check to see if the VAIS is working, most likely it is not since the VAIS cutover switch is at 5k.

Dixit

 

its not that what else could it possibly be?

will

 

you should try and disconnect the VIAS and see if it runs the same. if it does then you know thats your problem. if thats not it then how many miles are on it and what kind of pertinent maintenance has it received?

 

im almost positive that its not the VIAS i can hear the car kick at 4k.... when im in traffic my car bucks back and forth terribly 1-3 gear after that its not so bad.... i am thinking that it might be something to do with fuel delivery or coils.... im gettin the stillen headers tomorrow and want to fix the problem so i can get an accurate dyno for everyone!!! anyone else have any ideas? 5,000 rpms is a wierd place to lose power. any help is appriciated! thanks

will

 

My guess would be VIAS

 

he has a 2k2.... not a 2k/2k1.

 

ha omg this is funny... looked up my tracking number for the headers and it says delivered i go outside and THERE IT IS A BIG BROWN BOX WITH HEADERS INSIDE!!!!!!!!!!!!!!! WOW i have been waiting for these things for a long time!!! sry for the random post just thought that i would share my happiness with others!!!!

will

 

........

 

i forgot the 2k2 had a lower crossover point for the manifold. without an ses light, i wouldnt know where to start. there are a few codes that wont trigger the light but could cause issues.

 

VIAS is really tough to diagnose... I have no clue about the 2k2/2k3 system...

 

Well according to the FSM this may be a VAIS problem. Cause on a 2k2 the VAIS cutover is at 3600. Which is odd why is so low, but then again the whole intake plenum and manifold design changed.

Id get Nissan to check that out before you get the headers put on otherwise do the check yourself. You would need to unplug the VAIS solenoid plug and check pin 1 and ground and it should read battery voltage. Then if you checked pin 27 on the ECM, between 1800-3600rpm the voltage should be 1.0 and then above that rpm range it should be battery voltage.

That doesnt mean it will work, still would need to make sure the valve switches over.

Dixit

 

wow this sounds like i might never find out whats going on.... i cant take my car to the dealership will all my mods and say i have a prob... done it a few times before and i think i have lost my FREE ticket in the service dept. has anyone else heard of the sentra or some nissan car having problems with the front pre-cat breaking away and pieces of the cat going back into the engine (when you hit a bump) causing increased oil comsumption and power loss? i ask this bc my front pre cat is "breaking away" and thought that maybe that could be a possibility as well.... any thoughts?

will

 

What the hell is a VIAS. have a 2002 and mine is laging a bit as well.

 

VAIS is a Variable Air Intake System. It basically uses longer runners for lower to mid rpms and then shorter runners for high rpms for more top end.

Dixit

 

I have 2k2 6spd and whenever I pass 4500RPM the car pulls like freaking crazy! Its almost like a sudden boost that kick in. So far I've done it only in 2nd and 3rd gear. I love it!

 

Hey Will its Adrian, Gregs old roommate. Anyway Ive been having a similar problem that your having. I noticed that it only does it when I have my version of the Frankencar intake but not when I have the stock intake on. I am thinking its a leak in the intkae somewhere but I've checked all my clamps and they are tight. Anyway if I come up with anything I'll let you know and if you find anything let me know. You have any pics of your ride haven't seen it in a while?

 

yo adrian its been awhile. i have had various intake setups at this point and for some reason mine still does it with all of em. i looked into the knock sensor (thanks SR20DEN) and the symptoms of the knock sensor sounds almost identical to what im experiencing... i dunno what the deal is. ill let u know if i figure this out.

would there be any gains by replacing the stock maf with a larger maf with a better quality sensor if that is even possible or exists. i know people take mustang cobra MAFs for 240s etc. can this be done with the max? thanks

will