My 02 SE (auto) seams to have a lumpy power band especially when compared to my dads Avalon (3.5L). There seams to be a lack of mid range torque with power not coming on until about 4500, which still isnt very impressive. Idle isn't very smooth either but is within specs.

Is this normal for a VQ? Ive also considered its just me becoming insensitive (right foot is generally heavy).

• Have NWP Spacers
• Replaced:MAF, Spark Plugs, Cam POS Sensor
• No codes

The car has thrown codes for timing over advance which led me to replace the camshaft sensors (no codes since). Im leaning towards the problem being clogged fuel injectors, but am also wondering if its a problem with the coil packs, knock sensor,VAIS, or variable timing control unit.

Any input is appreciated. Does your VQ feel slow/lumpy?

 

Just from experience, There really isn't much below 4,000RPMs.

 

From what I know toyota v6's generally head towards peak torque lowwe in the powerband and ends earlier compared to the vq35.

 

Problem is 4k+ isnt a whole lot better.

Im sure the shorter gearing in his car has something to do with it as well but the Toyota feels so much more linear. For me, my low end is ok but the mid doesnt really build much.

I know there isnt much anyone can tell without a dyno graph, but dyno runs arent cheap... Main thing im trying to determine is if its typical VQ or if Ive got a problem with something in my list above.

 

You should post a video of all the things you're describing.

 

Will do, should have one up by tommrow.

 

You should be able to check the vias operation pretty easily. Just use a manual brake bleeder or vacuum mechanism (harbor freight has them) and see if the vias is moving and staying in place properly.
Do you have a SRI? Did you keep the helmholtz?

 

The VQ tends to make more power uptop. It's just the nature of the motor. That's one of the reasons Nissan has the rev-up variant of the VQ.

My G coupe, for example, feels like a slug until about 3500 RPM. You can actually feel the torque pick up between 3 and 5 grand.

As far as lumpy, eh...maybe. In the NVH department, it's not exactly the smoothest motor around.

It's going to sound lumpy at idle because of the DOHC and adjustable timing on the intake cams.

 

I never really had that problem with my Maxima. I think it made nice power UNTUNED. But once it got tuned power came on more linear and smooth! Honestly. it seems to have alot more torque on the low end before the tune...but the tune made it much more smooth and keeps pulling up top. These engines love up top if you get it tuned right!

 

How many miles on the car? 6spd or AT? If it got some miles on it might be clogged cats, I know on my 03 **** was clogged like mug, after gutting, got some power back....

 

Longish post (sorry).

The videos as requested, also note I live in Colorado which definitely affects power.

0-60


2nd gear, let off early but this is the lumpiness that im describing.


Currently just running GAB, thought about testing operation by placing a zip tie on the shaft and checking to see if it moved (though not the best way of doing it).

Ive driven a G37, awesome motor, though it doesnt feel -that- much more torquey down low then my max. Love how the power keeps building instead of plateauing like it does in my max.


How much would the car benefit from a tune given its basically stock (and the fact theres no air up here in the mile high city)? Id love to throw in headers and exhaust but I just spent about $2000 on the transmission (new valvebody) and replacing the rear brakes. Its also difficult keeping the revs up with the gearing of the 4AT. Would be interesting though to get it a custom map for high altitude.

127K AT, anyway to check cats without ripping them out? And if they are indeed clogged is there a way that gutting them will still pass emissions (with 02sims)?

 

Looks and sounds fine to me. I have gutted my cats and used plug foulers. Keeps the ECU happy so no CEL. Not sure about it passing emissions thou. Really thou I think the car sounds fine. Your auto may not feel really torquey but my 6sp feels just fine. I mean if you where low on power you would not be able to loose traction when you nailed it from a stop.

 

 

Is that 2nd gear pull from D? It does seem a tad sluggish building the revs IMO.

 

Agreed, seems about right for autos, Im a auto got some vids in my Sig on youtube, different types 0-60 stock and what not, do you guys do emissions in your state like on the rollers or just check for CEL...if you want some good power get some Headers....And to check the Cats yeah they have to come off, the rear you can just drop y pipe and flash a light up there but front has to be taken off....

 

Auto 3.5 from a stop 0-60 6secs is fast. I would do a motor flush so the oil passages can clear out the built up gunk if you feel loss of performance and bad gas mileage.

 

You have no idea how bad I want a 6MT. Issue is they are hard to find in Colorado and Ive already dumped a fair bit in cash on repairs for this car. Currently working on connecting the drop resistor to a dash mounted switch to firm up the slushy shifts. When my trans does eventually die (given I can still afford to put gas in her) Ill prolly do a 6MT swap.

No sir, car was already in second gear before I started the run and I totally agree on the slow building revs.
They definitely do rollers so I'm not sure about getting headers...Whats the typical power gain on Cattman headers? Would headers+ high flow cat pass?

 

There have been a lot of people on here that have been able to pass emissions in the past with headers and a functioning main cat. The key was to let the car warm up to operating temperature so the cat was able to do it's job.

As for numbers ... it's also difficult to put a solid # on gains from headers, but my experience is a solid 20 hp, and typically, what has been seen in the past, is an intake will be felt a lot more when coupled with headers.

Normally, 4AT's dyno between 190-195 stock. I never dyno'd stock, but have enough faith in everyone before me, that it would have been in the 190-195 whp area (Dynojet). I dyno'd with headers as my only mod, and was able to muster 211. Threw in a GAB and was able to get 220. Advanced the timing (typical 2º BTDC) and added a JWT POP and was able to get 233.

With the aforementioned mods and lightweight 17's, I was able to clock a 6.3s 0-60 using the VSS, and I'm also above mile high (5600').

 

OBXs or Cattmans, people usually say between 18-22hp gain, I haven't tried to pass on the rollers and probably wont just have to pay a little extra when the time comes...

 

Vid looks perfectly normal to me as well...

 

I apologize for all the questions, modding cars is new to me.

Does this include a high flow main cat? If I did headers id probably do the whole dam exhaust system as ive seen it while the car was under a lift and its kinda wimpy. Also when you advanced your timing, was this done with the stock ECU? Would headers+catback+intake warrant getting a piggyback tune?

Meaning? Is there a way around the roller test?

Must be my frequent dips into the throttle that over time have made me think my car is irregularly slow lol.

 

The roller test is when the emissions folks put your car and get emissions info that way.

High flow main cat, sure, like the FastCat used on here by most. But even the stock cat should be fine, not going to get much HP from a HFC.

Usually, piggybacks are warranted since these cars are very conservative with respect to AFR from the factory (fairly rich, generally speaking).

The advanced timing that I speak of is only base timing, which can be done by a number of programs out there, or if you're lucky a dealer, it's not full out timing adjustments/tuning/dynoing, just BTDC.

Also, the numbers I just posted earlier are with no AFR conditioning. I would worry about getting some bolt ons and then moving on to some sort of tuning software/piggyback/stand alone, etc. These require deep pockets, and if you're not really into it that much, bolt on's should be fine.

 

I was just reading the piggyback/tuning thread and pretty quickly decided the money (for piggyback tuning) would probably be better spent on suspension-- Im still on the stock struts.

I saw a thread up on a cattman exhuast group buy, but does he still make headers?

 

He should just have to call him, his numbers on the 1st page, hes there till 5pm, I just got mine likeSept or Oct. Last year....

 

For auto and elevation that looks pretty quick to me.

It's just the long gearing that makes it feel bad. 6 spd (as you know :P) makes it a completely different car.

Any abnormal perf restriction would be the cats

 

Only one anomaly in those vids. You are going to need an HD2 kit my friend, especially driving like that. Just ensure your mounts are in good condition.

 

Yeah my trans shifts horribly soft from 1-2 at high levels of throttle. Actually in the vid, that was a relatively clean shift compared to what it has done in the past. Never had the rpms jump on me but Ive definitely had it shift so soft that the revs take a long time to fall and the power just kinda hangs there (like the ecu is limiting torque to complete the shift.)

Had the entire valve body replaced (by the dealer which was $$$$) in hopes it would cure it but it still shifts too soft when driving hard.

Im thinking about wiring in a dash mounted switch to disconnect the drop resistor when needed... What advantage does the transgo kit have over the drop resistor mod? (other then no CEL)?


Replaced all 4 mounts this year (front one was actually broken).

 

Get an intake to trick yourself into thinking you're accelerating faster
Its magic.

 

My Vq def aint lumpy suckafish

 

Defintely noticed this with GAB, but it also does tricks on my gas gauge aswell.

 

We can all sit here and tell you what we think you should, but it matters more what you want to do and what you want out of it.

I need to take a vid of my car one of these days. What kind of mount are you using for the camera?

My suggestions.

 

There's a guy in the for sale forums selling his entire valve body with the HD2 kit installed. Just swap it out and
Sell your rebuilt kit or keep it on the shelves if you decide
To demod your car.
The HD2 kit addresses several of the problematic areas that plague the auto tranny. It does this without using a band Aid approach. I would just suggest reading up on it through the numerous threads. If you see my posts about harsh shifts after, it was because I had a blown front motor mount.

 

Completely agree, though I appreciate the input as you guys know more then I do, which the info you provide ultimately helps me decide what I want to do with my car.

As for a camera mount, I used a piece of packing tape lol, which doesnt stick horribly well to the steering column.

In hindsight I should have just done the HD2 kit on my original valve body instead of replacing the whole thing. Would the none HD2 kit do the trick as well? One of the main reasons I bought a max, was because it seats people comfortably.I dont mind harsh(ish) shifts when Im alone but if Im riding with people id prefer it be smooth and unnoticeable.

 

Adding Polyurethane motor mounts will have it shift very smoothly, albeit very crisp.

I had the same issue as Chris, so I opted to change my motor mounts, and the difference was beautiful. I used to be embarrassed when I had to take co-workers somewhere and the damn thing felt like it would break something every time it shifted.

I also consulted with Aaron92se on this same subject and he also recommended the same.

I have a Stage II.5 VB mod, and before I realized about all of this VB mod/Motor mount stuff, I proceeded to purchase a stage II version(a bit softer). But, after the mounts were installed, I was completely satisfied and didn't need to install the new, lower level VB.

I went ahead and took the easy route (since this was before the HD2 option was "mainstream") and purchased a VB from Maxximumtuning.

 

I swapped my broken front electric mount with a cheap MT mount. I remember seeing someone on here having a thread up for motor mount inserts, just might have to order some, though dropping the cross member and getting the front through bolt to line up is a PITA.

Im admittedly leaning towards getting the HD2 kit installed, question is do I buy the one in the classifieds for $400 (aint bad deal), or do I have a shop do it to my current (supposedly brand new) valve body that has a 12000 mile warranty?

 

I would swap it. Also, refill the tranny with Amsoil ATF. I have extra for sale from where I bought a case when I had my HD2 installed.
* shameless plug!

 

I had the injectors flushed by the dealer today, huge difference and no more lumpy mid range. Power feels alot smoother and it even sounds healthier as well. I think it fixed the issue.

 

Do you have a pointer to the exact procedure that the dealer did? I do not know if our car has a convenient schrader valve port on the injector rail to do this procedure

 

I dont know the exact procedure, but you are correct that there isnt a schrader valve to do it. Id assume they undid the fuel lines to the fuel rail.

 

A hard blast on the highway would clear the injectors too. It's fun, and free

I would have suggested maybe your front O2 sensor is tired.

DW