Well I went to the track tonight (just street tires, no slicks) and for some reason I was trapping 98-99 mph and running low to mid 14s, even with good 60' (2.1's and low 2.2s all night). WTF? Normally I trap 102-103 mph and sometimes 104. The car doesn't really feel slower, but if it's a gradual change (over the last month or so) then maybe I wouldn't notice it.

I put a new knock sensor on it (used a 4th gen KS on the VQ35) about 2 months ago, BEFORE I ran my 13.68@104.54 on the same damn street tires. I did 13.6 on a rather hot Sunday and tonight it was perfect, beautiful weather, no winds and everyone was doing good. Except me.

The car runs smooth, and IMO pulls like it normally does, but like I said if the change was gradual, I might not have noticed it (I haven't gone to the track in over a month because I blew my tranny). Since I put the tranny back in the trap speeds are lower, what the hell?

It seems it pulls a little harder at 3/4 throttle than 100% throttle, and if I'm on the highway doing 65-70, and decide to floor it, it kinda hesitates for a second and then goes. If I floor it gradually it doesn't do that, only does it when I floor it quickly.

Between my last time trial and eliminations I unscrewed the KS bolt just a little bit, and unplugged then replugged the battery in the process. Didn't seem to make a difference.

I know my timing must be crappy since I use the stock 95 ECU, but what's up with that?

I heard that if the ECU sees too high or too low of a signal from the KS, it will pull back into safe mode. Could it be that using a VQ30 KS on a VQ35 shows the ECU too low of a signal? Maybe I should put the VQ35 KS back on?

 

Try the VQ35 KS again, it is a differ KS. It is made for that engine so that might fix it.

WHEN ARE ANY OF THE 4th GEN VQ35's GONNA GET TUNED!!!!!!!!!!!

 

You read my mind. I did that after posting this. I am probably the only **** changing his KS at 7 AM on a Saturday morning. 30 minutes' worth of "F*ck! that hurts!" while the neighboors are trying to sleep.

Lol we're all broke. Actually I contacted the guy about the 300zx ecu again and this is what he said (English traduction for all you Americains):

''I did some research.

2 Solutions:

#1 Fit a CAS (Cam Angle Sensor) (see if we can fit one on one of the 2 cams) (in the front cover)

#2 The thoughest one... make an interface to take the signal of the 3 sensors (1 degree crank, 120 degree crank, and Cam reference) Basically divide the frequency by 2 and give it the good reference.

The #1 solution is the most simple, efficient and without trouble (except mecanical)

We're gonna have to look how we could fit that.''

Not an exact traduction, but that's close enough.

I've heard only good things about this guy, but it looks like we're stuck between two walls here. He doesn't seem to think solution #2 is the way to go, for some reason...

I really want the 300zx ecu to work, the tunability would be incredible. He says VQ35's are de-tuned in stock form, even the 350z/G35 versions...

 

Solution #1 was the conclusion I came up with when I was thinking of this. Im not mechanically inclined, so I would prefer an all electrical solution to a problem and as such I did not persue it any further. Do you have a copy of the 300ZX FSM? I would like to see the signals of the sensors to see how different they are to 4th gen ones.

 

If I weren't going to college soon, I would have my car tuned, headers, possibly an 00VI, and a new clutch.

Tuning would do wonders for us...

 

I'm gonna have to check.

If anybody has the 300zx FSM (1990-1993, OBDI), please let us know.

 

www.phatg20.net should have it.

 

Is this with the altima gearing?

 

The only real changes you've made are the altima gears since then right? Maybe somebody should use Cartest with the different gearing.

 

Well I went back this weekend and won the event on Saturday in Street Class. My highest trap was 103.61 on street tires. I also cut a TON of 2.08-2.13 60 foots on my Yokohama all-season street tires. I was running mostly low 14s to stay in the street class (14.00 and up) but 103.6 is definately normal.

I switched back to the VQ35 KS.

 

so it WAS the 3.0 KS??

 

Iam using the 3.0 knock sensor when i tried the 3.5 woulnd plug into the same harness as my 3.0

 

You have to change the plug, it's only one wire. Even on Sunday's super hot weather I was able to trap 102.90.

 

I don't know. I trapped 104 mph with the 3.0 KS, but that was a while back, maybe it got more sensible over the months. But the 3.5 KS must be at least as good as the 3.0 KS. Let's wait and see.

 

Maybe someone can chime in and advise the resistance values for the 3.0/3.5 KS. Should be in the test section of each manual.

 

Probably. Meantime, just by comparing them visually, it seems the 3.0 KS has a bigger surface plate or ''magnet''.

 

Resistance of a 2k2 KS should be 500-620 K ohms at 77*F, same as the 3L.

 

Same for both: 500-620 kOhms @ 77F

knock sensor p/ns:

22060-30P00
- Maxima 3.0 95-99
+ all the Z, Pathys, Sentras, Stanzas, etc prior to 2000

22060-2Y000
- Maxima 3.0 00-01
- Maxima 3.5 02-03
- Altima 3.5 02+
- Pathfinder 3.5 01+

22060-AU010
- Maxima 04+
- Sentra 1.8 03+

I would have thought that the difference in the sensors would be tuning for differing engine resonant frequencies. But that is obviously not the case as we have multiple configurations (ie I4, V6) using the same sensor.

 

Perhaps the 3.0 one was bad.

 

So if P/N 22060-2Y000 is for DE-K's too, the 3.0 KS should work fine on a 3.5

 

since you think your car runs slower under WOT that points to a tuning issue. the fuel and timming map under WOT (open loop) is most likely rich, thus rubbing power, but its safe. when the car is in closed loop the O2 sensors are helping to tune in a way, taking away fuel if you are indeed running rich.

 

jclaw- wat tire pressure were u @ when u pull those 2.18 60' s?

 

If anything he's running lean at WOT because the 3.5 fuel rail is supposed to see 53 PSI at WOT. But with the 3.5 swaps and the return-style setups with the 3.0 FPR the fuel rail is only seeing 43 PSI at WOT. Perhaps even less since the 3.5 injectors flow more.

 

well then thats even worse.... only one way to really know if hes lean or rich and since hes broke looks like we will have to wait.

He can be that lean since stock is quite rich, but then again im not up to date on the car.

JClaw, Which FPR are you using? ECU? what tuning devices are you using, any at all?

 

It was 2.08 actually. 25 psi front, 42 psi rear with a few zip ties on the front springs and the traction bars.

No tuning device at all. I don't even know what my A/F is.

 

Thats what i thought. so we will just have to wait on this issue, i mean for the true numbers.

 

I think the fuel pressure issue should be resolved via an adjustable FPR before he moves forward with a/f tuning IMO.

 

Update:

Today I took out my sloppily soldered 4th/5th gen knock sensor harness and 5th gen knock sensor, and replaced it with a brand new 1995 knock sensor harness and brand new 4th gen knock sensor.

It hauls.

 

Jclaw

Quick off topic question. How is your gas mileage with the 3.5L vs the 3.0L on normal driving use?

 

3.5 gas mileage:

Highway while keeping it around 65-70 mph: 400-435 miles on a tank.
City/mixed driving (what I normally do): 360-390 miles on a tank
City and flooring it 24/7: 300-325 miles on a tank

The most I ever got out of the 3.0 was 350 miles on a tank.

Thing is, the 3.0 had a bad KS, and bad oxygen sensors. Plus it was cold when I drove it. The 3.5 has 3 brand new O2 sensors, and the car is 120-150 lbs lighter. For a 13-second car it really gets good gas mileage, even when I drive like a f*cking maniac I can't seem to get less than 300 miles a tank. The fact that the car is 300+ lbs lighter than 2k2s and new Altimas really seems to help for gas.