Max_Gator here is a link to my dyno graph:
http://forums.maxima.org/showthread....hreadid=103321

I am gonna take my car in next week, but will probably have the same results as you did. Looks like I might be looking for a new car

 

Guys I too have that problem, took the car to nissan dealer and they said my car is OK.!!!!!!!!! BS I think.

This is also my first reply of the forum, so hi everyone.!!!!!!

 

You guys have to raise a collective hell! You aren't getting what you paid for. Remember how Ford's Horse Snake came out with a supposed "320hp" in 1999? The owners dyno'ed their cars to prove that it was overrated. The owners "got together" to complain. These actions forced Ford to fix the '99s and they weren't able to produce 2K Horse snakes because of this.

Who knows how many people have problems with their VQ30DE-Ks and not realize it (those who drive with weak ankles).

 

OK. I believe I have a new way to test and prove the existence of my problem.

Yesterday 2K2DEMAX (Jerome) let me use his factory service manual. It took me a while to determine what should have been evident without the manual.

The harness right in front of the VIAS assembly controls power to the assembly. I disconnected the harness and sure enough, the VIAS actuator does not move. That enabled me to compare the car's performance with the VIAS disabled and with it enabled. Guess what . . . big surprise . . . it was dead on the same.

The next step is to compare it to a properly operating 2k 5spd max. We'll do the comparison with my VIAS on vs. madmax2k's VIAS on. Then mine on vs. his off. I already know the results with his on - he pulls quite a bit. I'm betting that with the VIAS off he will no longer pull.

Can't believe it took me this long to figure out this test.

JP - You really need to take your y-pipe off. First, if they find it - forget about them EVER fixing your problem. Second, the y-pipe is giving you added performance. If you take it off your performance will be even worse - and therefore more evident. Don't forget, I'm losing 40 hp to the wheels at red-line from stock and I can't get them to admit I have a problem.

Ghase - can describe your problem and when you noticed it.

 

Thats what i did also about a week ago and my car feels the same. Hopefully you find whats wrong with your car, so I dont have to take off my y-pipe.

 

I have had my car at the dyno shop before. I don't see how your 2k 5'spd is making 197. I have a y-pipe, an exhaust, and the induction system. I am just hitting around 200. Most maxes should dyno out stock around 180 or a little lower. As far as your problems go, there are a couple of things that could be wrong. The "VIAS" that you are talking about is on the driver side of the engine bay. It is vaccuum operated. On the dyno you should see the hp curve rise steadily all the way to redline. I can tell you much more about this problem you have over the phone, so if you wish to call me and ask i have no problem. You can also call me at work. I like it when i get a break from a build. I could also fax you a copy of my dyno results if you want to compare them.

Cya for now,
Ryan
Roush Racing
313-294-8285 Work
810-567-7926 Cell
586-446-9254 Home

 

Did you take a look at my dyno or Max_Gators? Can you provide some quick info on what u think is wrong?

 

As I noted earlier in this post, I believe, it really isn't 197 because there is a blip at redline and the results on this plot were not smoothed. Smoothing out the blip made it 193. Madmax2k dyno'd his identical 5spd on the same dyno and the results were dead on. Most 5spd maximas dyno low 190s. Ours were done in 3rd gear. I believe that 4th gear gives slightly lower numbers. For my purposes, all runs have been done in the same gear.

Here's the dyno again for reference:

http://web.tampabay.rr.com/maxgator/oldVSrecent.BMP

The difference you mentioned is evident. At this point, it appears that there must be some internal problem with my VIAS. The actuator valve on the outside moves fully at 5k rpms. The only reasonable explanation I can think of is that the butterfly valves on the inside are not closing to shorten the intake suction length. I just can't get Nissan to admit there is a problem.

Have you seen this problem before?

 

The blip at the top of my graph would have put me around 210. But yes I have seen this problem before, but not from nissan. I have seen this in the DOHC taurus motors. They are cable operated, and the cable gets dirty and stops working. We, however, are vaccuum operated. check the hose that goes into the VIAS. make sure there are no cracks in it. That could be your problem right there

cya for now
ryan

 

OK. Latest update.

VIAS is DEFINITELY THE PROBLEM!!

Madmax2k (Larry) and I performed a little test at lunch today.

1. We ran with both of our VIAS variable intake systems enabled. We ran from mid-4k in 3rd through red-line and then into 4th gear. Once we hit 5k in 3rd, he simply walked away from me and the gap got even bigger once we went to 4th. Stopped around 6k in 4th b/c my radar went off.

2. We then disconnected his VIAS system and ran again. We were dead even all the way! All the way through 3rd and as far as we ran into 4th, we just sat side by side!

No doubt my VIAS does not function - even though there is power going to it and even though the actuator is working on the outside.

I then spoke to the service manager and explained the test results. He told me that after our last discussion, he had contacted one of Nissan's traveling technicians who is very knowledgeable about the Maxima. That tech had not heard of the problem before but was meeting with some other techs to discuss the issue. The service manager told me that he would pass on my test to the traveling tech and then get me an opportunity to talk to the tech directly.

I'm hoping that Nissan will fix the damn thing under warranty. If they don't Larry and I are going to pull apart the intake and fix it ourselves.

So, my dyno results reflect exactly what the variable intake system does for the 5th gen 3.0 maximas.

 

Good Work..Keep me informed on any possible fixes you get. I might take my y-pipe off this weekend and take my car into the dealer. Its supposed to be around 60 here

 

You may want to take off the y-pipe but wait to take it in. If I can get my problem resolved, I will be able to give you a specific person to refer your dealer to.

I mean it took me 2 days to get my dealer/tech to even understand what I was talking about. I'm probably 3 weeks into my battle with them. It is very unlikely you will get there any faster - who knows, though, maybe the people you take it to actually know something.

I'm just very fortunate to have another car that has been dyno'd stock against mine to test against.

 

My dealer doesnt employ the smartest group of mechanics. It took them 5 visits for them to figure out that I had a lazy tach. I am kinda procrastinating taking it in until you make any progress. I hope that I can get this problem solved. 30 wheel hp is a nice gain.

 

Is there a picture of what you are taking about. I am curious as to what you disconnected. btW good luck with everything.

 

Finally looked at your dyno.

You do realize that your dyno is almost identical to mine.

My dyno is here:

http://web.tampabay.rr.com/maxgator/oldVSrecent.BMP

We both have max hp around 5000 rpms just before the intake runners switch. HP stays flat until about 6k rpms and then at 6k rpms begins to fall off.

Torque falls off all the way to about 125-135.

Your max hp is 171/168 mine is 163.
Your max tq is 195/191 mine is 185.

In otherwords, your results are parallel to mine except a little higher. That most likely can be explained by the y and intake on yours but not on mine.

On the 5th gens, the y and intake really only show their effectiveness after the runners switch at 5200. Thus, it makes sense that your results are only a few hp/tq over mine instead of the 13 or so hp they would gain over a stock 5th gen with working VIAS

No doubt we have the same problem: the 5th gen variable intake system is not working.

 

I have been driving with the harness disconnected from the VIAS for two days now, with no difference in power. I am kinda looking forward to getting this fixed. I have spent 600 bucks on performacnce mods and never got to feel them. Does the intake sound any louder or have a different pitch when the runners swith over??

I have a feeling that as 5th gens age, there are gonna be a lot more problems like we are having. At least they will have a clue whats wrong and hopefully an easy way to fix it.

 

On the dyno, you can hear the runners switch. Sounds almost like a mini-vtech.

As far as going to the dealer, give it a shot. Who knows, maybe you'll get a tech right off the bat who will identify and fix the problem. Unfortunately, I doubt it.

I think it may be even harder for you because you don't have before and after STOCK dynos. Although they claim they won't accept my dynos as evidence of a complaint, I really believe that it has been the dynos that have given some credence to my claims.

What you really need, is someone who has a bone stock 5spd to compare against. I'd say find someone now and then do the tests that Larry and I did above. Then go to the dealer and arrange to do the same
tests. First, you'll have to educate them on what the VIAS is!!

If you had problems with getting your tach fixed, you are gonna have problems with this. Good luck.

 

I'm not sure I can add a lot to this debate but I just purchased a used Maxima 2000 with a 5 speed. I've raced cars for years and in my Maxima there is a noticeable power increase (rather dramatic) above 5,000 rpm. The car has 23,000 miles on it and the "check engine" light is on, which I havn't addressed. With or without dyno, the increase in power above 5000 rpm is VERY noticeable. In fact, I was surprised the engine was so "peaky". I noticed this PRIOR to reading any of the posts.

 

i was having the same type of problem caused from my stillen intake.I had no power i could dump the clutch at 6 grand and get just a chirp i had no power Nissan told me its because air was beieng sucked in from behind the sensor in the intake. Nissan tighten everything down reset the computer and my car has been running fine.

 

I noticed it when I loss about 350rpm from the factory shift point(6450rpm) to now a 6000, and sometimes 5900.!!!!!!!!!!!!!!

 

It sounds like you have an automatic. I recall that there was a problem with the auto transmissions slipping like that. You may want to search the archives - I'm pretty sure there is a TSB for that item and that Nissan will fix it.

 

Latest update:

I spoke to the service manager again today - and the traveling tech he is talking to asked the manager to confirm with me that I ran my car against Larry's (madmax2k) with Larry's Vias disconnected and mine connected and that the cars were dead even.

That tells me that I may be making some progress. Now, if I could only talk to the guy directly . . .

 

I thought that the service dept guy at the dealership said he was going to do that and get you an appointment to talk to the guy?

 

Yeah, I thought so too . . . .

 

Max_Gator,

Your definitely on target. I believe from reading the FSM on how the VIAS works that your Power Valve is not opening above 5K RPMs.

This is due to either:
1)Power Valve(PV).
2)Power Valve Actuator(PVA).
3)One-way valve in the Surge Tank(vacuum tank).
4)Vacuum lines from the One-way valve-->VIAS Control Solenoid Valve-->PVA-->PV.


Your ECU signal and "VIAS Control Solenoid Valve" appear to be working properly. I say this since you can see the "power valve actuator rod" move. However, just because it's moving doesn't mean the PV is actually recieving vacuum.

So, it has to be the vacuum signal to the PVA or the PV. However, I think the only way you can access/verify VACUUM from the PVA to the PV above 5K rpms is from the inside of the manifold, which means you can't be above 5K RPMs.

 

I also had my coils replaced at Nissan's expense, but the condition described here is different than I experienced. Before the coils were replaced, my engine was detonating and losing power at low rpms.

Every indication is that the VIAS is to blame for the power loss occuring above 5,000 rpm. I've had numerous interactions with Nissan USA (fuel cut issue, ignition coils, bumper scratches, etc.) My advise is to be patient and persistent. And don't antagonize your Service Rep. He can be your best friend if you get him on your side.

 

I'm almost positive I'm experiencing the samr thing but I'm wondering if I really need to get it fixed. I'm getting an SC in a few months and I imagine that the boost would overwhelm any "ram effect" from the shortening of the runners. What do you all think?

 

I've been reading the ESM as well. You've hit on the one part of the VIAS that I'm not sure I understand - vacuum and its function.

From reading the diagnostic procedure it appears that if the actuator on the outside "pulls" on the power valve and it opens then the entire system is functioning properly except for the possibility that the valves inside are not turning.

Can you explain how vacuum works in the system?

 

Could be somewhat true. However, losing 35 hp at peak is something in my book to get fixed. It is bound to have some effect on you even if you are SC.

 

As far as I understand, vacuum is what controls/activates the VIAS System. Basically, the VIAS Control Solenoid stops vacuum from reaching the Power Valve Actuator until the ECU signals you've reached 5K RPMs. Once the Power Valve Actuator recieves vacuum it activates the Power Valve.

So, inorder for the VIAS System to operate the "vacuum path" must go from the One-way Valve to the VIAS Control Solenoid, which is then activated by the ECU signal to open and allow vacuum to travel to the Power Valve Actuator, which then opens the Power Valve. If any of these components do not "open" or the vacuum lines are blocked/broken, then the Power Valve will not receive a "vacuum signal" to open.

Is this better? If not, I can simplify it once I get home tonight and have the FSM schematic in front of me.

Please keep me in the loop, since I'm very curious how Nissan is going to fix this. I'm betting they pull your manifold, unless it's simply one of the vacuum lines is broken.

One thing I'm wondering is if it's possible to bypass the VIAS Control Solenoid, by providing vacuum directly to the Power Valve Actuator. I poked around the manifold yesterday and couldn't find the vacuum line from the VIAS Control Solenoid to the Power Valve Actuator. If you were able to verify the VIAS doesn't work when you provided vacuum directly to the PVA, then you would reduce the possibilities to just the PVA, PV, or vacuum lines inbetween.

 

Ok. I think our understanding is the same. Unfortunately, the FSM (or Electronic Service Manual on CD that I'm using) doesn't provide very helpful diagrams.

If my understanding of the part names is correct, the actuator is a round black piece with about a 2 inch piece of metal sticking out of it and hooking up to the power valve. The actuator is located on the driver's side of the intake manifold toward the rear (passenger compartment side) of the engine. The metal piece runs out of the actuator and alongside the intake manifold (it is hard to see this piece) until it hooks up to the power valve.

You can watch both the metal piece attached to the actuator and the power valve move when your engine hits 5000 rpms (ECU sends signal). The actuator appears to pull the power valve open.

Since that is happening on my car, there shouldn't be a vacuum problem, right? The problem must be on the inside of the collector.

In the inside of the intake collecter there are flaps that move from allowing air to enter the intake from only a "straight down" path to, at 5000 rpm when the power valve moves, forcing the air to take an alternative route (for the sake of simplicity).

I do not believe the flaps are moving.

Are we on the same page now?

 

Any progress Max_Gator?? I am gonna take my manifold off tommorrow, I will let you know if I can find the internal problem and fix it.

 

I'm STILL waiting on the district service tech to get back to the service manager with an answer on how they will proceed. Getting quite impatient as well.

Let me know what you find. I am certain it is an internal VIAS problem and mine will also come off soon to locate the problem.

That is, unless I decide to make a lemon law claim (I think I may be able to squeeze one out of this situation !) or take some other action.

 

FINALLY!

Nissan has agreed to replace my variable intake. The caveat is that they will not do it under warranty . . . but they are doing it as customer goodwill. If that does not solve the problem - I give.

I will say that the service manager - Terry - has been very cooperative in helping me get this done. In short, I think he believed that I had a problem but did not want to confirm it because he could not determine what the problem was and didn't want Nissan to be stuck with it. Although I'm not pleased with that type of behavior in general, I'm pretty certain his hands were tied in that regard by Nissan.

Interestingly, I believe it was ultimately the fact that I let him know that I was seriously considering making a lemon law claim or breach of warranty claim, that may have given him a basis to get this done.

Overall, I really am not happy that I have had to work this hard to diagnose the problem and force them to fix it. And I am not happy that it has taken them this long to do it under goodwill. Unfortunately, it appears to be the result of an uncommon problem, lack of information about how their own cars work, and a bureaucratic system that makes it impossible to communicate with the people who can make the diagnosis.

I hope to attend the repair and if I ever figure out EXACTLY what is wrong, I will let everyone know. Looks like sometime next week since they have to order the variable intake.

 

GOOD JOB!

Your right about Nissan doing EVERYTHING in it's power to try and NOT fix the problem.

I feel bad for us Max owners who aren't Lawyers. I doubt anyone will have the same luck.

If possible, do a working VIAS POST dyno.

 

I will definitely re-dyno and post the results.

A working VIAS should be a stock dyno - and non-working should look like the lower hp below.

http://web.tampabay.rr.com/maxgator/oldVSrecent2.bmp

 

Max_Gator, when you get the intake installed and that definetly ures the problem. Can you give me the numbers of the people that you spoke with and the name of the nissan dealer you took your car to. I am gonna take my car in soon, but wanna provide them with enought info so they don't BS me and say "nothings wrong".

 

Update here:

http://forums.maxima.org/showthread.php?threadid=113198

 

What 2002 nissan maxima's do we have vias system as well.

 

Wow, I remember looking at 2k, 2k1 MTX Maxies back before I got my 99.5, and I test drove one that I noticed the 3.0VI wasn't losing massive power past 3,500+RPM, "what are you talking about.." said the salesman... eck, how common is this issue among 5th gen 00-01 owners?