I thought changing out the bad knock sensor would make a big difference. I sure felt like it's a big difference. Anyway, I went to the track yesterday to find out. If you check out Mardigrasmax's thread on the General Forum, that was my pathetic car he raced on the video. I ran a 15.6, what surprised me was I got a 2.2 60ft. I ran two back to back run of 15.6 with a 2.2 60ft. However, I couldn't achieve that again the rest of the night. WTH? I'm not sure if maybe do too many runs. I basically hot lapped. So, no time for the car to cool down a bit. The rest of the night I could not get better times than a 15.8 with a bad 60ft. When I got the 2.2 60ft, I think I launched at around 1500rpms. Another thing was my car seem to lose power at 3rd gear. The car pulled strongly in first and second gear. I left it in Drive all but one time with OD off. I wonder maybe I should have OD on? Whatever the reason, 3rd gear just seem weak. I tried later to launch at higher rpms around 2k, it didn't help, seem to got an even worse time. Also, I tried manually shifting it once, didn't help.

My mods:
hybrid intake(maybe I should switch back to CAI because the hybrid intake seem to perform better on the highway than on the street or 1/4)
ypipe
RT cat
Apexi catback exhaust
Don's VB

I had my tires set at 22psi, should be right. Hm...one thing I forgot though. I had about 3/4 to 1/2 tank of gas left. It was a last minute decision to race so didn't have time to prepare. I ran on my stock 15" SE rims with Brigestone Potenza RE950 215/60/15 tires. This was the first time I got to test out the tires on the track. Tires seem to grip pretty good.

Any ideas? I just don't know what's wrong. This is starting to get on my nerves. I ran a 15.4 at 89mph about a year ago I think, at the Hattiesburg track. I have about the same mods as I do know except for Don's VB and I had a full CAI at the time. Plus, I ran with the crappy stock tires. I manually shifted at the time because the lack of the VB upgrade. I ran also ran with about a full tank of gas too and didn't lower my tire pressure(was at 35psi all around). That's why I so confused. How come I ran even slower now than before?

Track condition was pretty good. It got pretty cold during the night which I thought would improve my times. NOT!

Help!

 

Btw, I just went outside to pulled the codes again to see if anything else is wrong. Nothing. Everything is fine, I got a 0505 code.


*sigh*

 

Come on, where are all the suspose experts?


I really really really wish I had the money to get another car. I would dump this POS in a heart beat.

 

I'm not a track expert but I do have some thought to this. I understand you lower your tire pressure to get better bite on the road for the launch. Is 22 a bit to low? Normal road tires are supposed to have a bit more air then slicks. I've seen some guys just run normal air pressure at the track as well. The lower tires do have much more resistance to roll then hard tires do. If you lower the front only say 5 pounds or so, but keep the rear nice and hard, 40 lbs maybe, that could probably add up to some 1/4 mile time changes. The less resistance to roll you have, the faster you'll go. I was always a bit skeptical when seeing guys run their tires so low at the track. These are road tires, not slicks. Maximum traction may not be at a pressure that low.

Anyhow, that my .02

 

what was your mph ?
that will say a lot about your problem.

Ant

 

Ummm, isnt 15.6 about what a automatic max should run? Whats your MPH anyway? Cause thats a better indicator of how much HP your car is pulling. Whos Y pipe do you have? Maybe its suffering from collapsed flex.

 

Here's one of the slip that I kept, this wasn't the one I ran the 2.2 60ft with.

R/T .838
60 2.332
1/8 10.113
MPH 70.94
1/4 15.675
MPH 87.89


Yeah, I kind of think my tire pressure might be too low. I'm running street tires, not drag or slicks. Actually my street tires aren't even ZR rated. They are direct replacement of the stock tires. They do grip a bit better, but nothing dramatic. I ran 22psi up front, but didn't increase the rear. Rear was about 35psi.

Like I said, I ran a 15.4 at 89mph before. That was without Don's VB, didn't lower tire pressure, almost full tank of gas, and crappy stock tires. Also, I had a CAI that time. This time I had the hybrid intake, not sure if that made any difference.

I have the WSP ypipe. The ypipe seem fine I think.

Further more is I'm don't know why I can even get close to the 15.6 I ran earlier later on in the night. I got some 15.8 and even one 16.0 later in the night. Also, my 60ft was no where near the 2.2 I achieved earlier.

I guess what upset me more was why I couldn't hit at least 15.6 later in the night. My launch was pretty consistent.

So all in all, I'm not happy with the 15.6 that I got, but I'm even more upset about not able to come close to that crappy time later in the night.

 

Are you caught up on everything like plugs fuel filter etc?

SuDZ

 

I haven't replace the fuel filter yet. How important is that? I only have about 50k miles. As far as plugs, I haven't check what condition they are in. I just changed them out a few months ago. I'll check anyway.

 

Fuel filter every 30k...very important.

 

Seriously? OMG...the fuel filter I have is still the original one. I never have it change ever since I got the car new. Hm...I think I better pick one up at the dealer soon. Might as well since I'm not going to race at the track any time soon because of this huge letdown.

 

i have a CAI YPIPE CATBACK exhaust HI FLOW cat , 97 se auto

i was always getting 89.xx MPH

your 2 mph slower, i do not have an answer, but 3rd gear not pulling seems wrong to me... honestly have you DYNO'd recently?

tranny fluid good?

trying to help

 

Yeah, 3rd gear not pulling strong is a bit weird. I thought our 3rd gear suppose to be very strong?

Do you have OD on or off at the track? I had OD off on all my runs. Thought it would help because it locks out 4th gear. I doubt having OD on would make any difference though.

Tranny fluid? Hm...got to check on that. Thanks.

 

theres a lot of things you're not taking into consideration...between you 15.4 run and now
temp, humidity...those make a big diff

i ran 15.6 @ 87 wit cai and 30deg
i ran 15.7 @ 87 wit cai, ypipe , don vb amd 65deg

different rims maybe ...


ant

 

Actually, condition wise this time was better. It was pretty cold later in the night, so I was surprised I couldn't do better.

 

One thing about the 3rd gear in autos...Last time I ran at the track (last week) I ran consistent 15.5s and 15.6s with a best time of 15.504 at 90.1 mph. To do that I hotlapped two runs which I think makes my Max perform better. The first run of 15.588 I left the O/D off. I noticed that at 3rd gear, the locking/unlocking of the 4th gear causes my engine to bog a bit at around 3k to 3500 rpm. This results in the revs not rising as fast and seriously slowing me down. For the second run, I tried running with the O/D on and got my best time and trap speed as a result. With the O/D on, I don't get that bogging condition. Something to consider.


BTW, The Fast Lane Performance Intake developed by Bruce a.k.a. "Papasmurf", and engineered by Richard (me) a.k.a. "NightRider" has now been proven to take .3 seconds off of my 1/4 mile time and add 4 mph to my trap speed.

 

That's exactly how the 3rd gear felt to me. The rev seem to rise real slow.

 

change the fuel filter...dat thing must be really dirty
filter costs like $13 and takes like 30 mins the most to do
but would take only about 10mins if nissan made it easier
to reach....good luck mike
hope u get the power back....if u run 15.6-16.0, how do
stock autos like my car do? mid to hi 16s??
can't be huh...something is seriously wrong with ur car

 

Stock autos? It varies. I say stock autos can go from high 15s to high 16s.

I'm going to change the fuel filter. Then I'll check out the plugs and tranny fluid too.

A side note, Don emailed me a long time ago telling me that the VB core that I sent back to him had rust. So, he warned me about my transmission. If the stock VB had rust, that's not good news for my tranny. It's just too expensive to have a mechanic open up the tranny to have a look, so it could be that. I'm not sure. There was a big flood down here before and I think I just drove right through it. Guess I will never know.

 

2 suggestions, 1st run some 205/50-15 tires this should lower your ET without anyother mods. Refer to this thread http://forums.maxima.org/showthread....que+convertor. 2nd if the car feels like its down on power do a power balance test. Find out if you have an injector/coil that isn't working 100%.

 

Hm...interesting. Ok, I understand the tire issue. Any recommendation?


Power balance test? How do I do that?

 

You do it by unplugging each injector as the engine is idling or running at a preset rpm (like 2000rpm or so). As long as all cylinders run as bad as the others the injectors/coils are fine. However if 1 cylinder doesn't seem to suffer as bad as the others then you have either a malfunctioning coil or the injector isn't working 100%. Also be sure to measure the resistance of all the injectors, if the resistance isn't between 10-14 ohms thinking about buying more injectors.

 

Thanks. I'll refer to the Haynes manual for futher clarification.

 

Would 205/50/15 tires work on 15x7 rims? I think my stock rims are 15x6.

 

Ok, I just checked out the resistance between the injectors. I got a 12.3-12.4 ohms. That's about right?

 

Well, my spark plugs are fine. I will have to get a new fuel filter that I'm sure. I also checked out my tranny fluid. The fluid was dark brown/gray color, not the reddish color like when it was new. So I will probably have to get a transmission flush. That's what I know so far.