I recently finished installing a 2003 Maxima VQ35/6spd into a 2003 Sentra.. The car starts/runs decently.. but it's down on power a good bit. It seems like in open loop, it's down more than in closed loop. I can partial throttle the car at low RPM, and it's got a good bit of pick-up.. but, as soon as I floor it, and it gets into open loop, you can feel the power drop off a good bit. At around 5K rpm or so, power comes back in.. it's before the 2nd runners open I believe. My tach isn't hooked up yet, so I can't verify exactly what RPM this boost in power occurs at. But, it's different than the spike from the secondary runners opening up. The last car that I swapped.. had a LOT more power down low/midrange than this car does. I've checked/replaced the following

MAF sensor
Fuel pump
02 sensors
Plugs
Cleaned ECU/sensor grounds (on top of front bank cylinder head/timing cover)
Verified that the CVTC system is working
Verified that the VIAS solenoid/valve is working


I know that the knock sensor, on the Sentra, will cause the ECU to pull a TON of timing out, up to around 5K rpm. Past a certain RPM (around 5K), the ECU ignores the knock sensor in open loop, and you get your timing back.. not sure if it's the same on the Maxima ECU.

But, can anyone think of anything else that I can check/try? I've done just about everything that I can think of for the "usual" suspects.

Thanks

Travis

 

There are no 2nd runners and it's more like 3800 rpms (switchover)

You're working at quite a handicap w/no tach and Sentra ECU..at least that's what I gathered from the post (you using Sentra ECU). Is it down on power recently, or just since the swap?

 

Sentra ECU powering a V6??

 

I'm talking about the valve that opens up at upper RPM on the VQ35 intake manifold..

I am using a VQ35 ECU from a Maxima.. How would a Sentra ECU power a VQ? lol..

 

I was talking about the same thing.

404 Upper RPM not found (3800)

I can't read well at night, nor do any of my more common senses work

 

I've got the tach hooked up... but the scale is WAY off... at redline, the needle is back around to 0 and on the stopper pin.. lol.. I'm hoping that I can recalibrate the cluster. I know on the older cars, there's a potentiometer inside the cluster that you can turn to adjust the scale. The last swap that I did... the cluster ran off of the CAN system.. but, this one still has analog for the water temp and tach.

I'm thinking that the knock sensor is the culprit.. just hoping someone can chime in who has had the same experience.

Travis

 

As far as I know everyone here who has a 3.5L still has a fucntioning KS.

 

Well, I'm going to try a 470K resistor to mimic a properly functioning KS in place of the actual sensor itself..