2004 Coupe Performance Upgrade??

[Gman1950]

Looking for Bolt-on Upgrade options? I have installed a Stillen Ram Intake and was told to stay away from Chips and Oxy sensors. (voids the 92,000 mile warranty).

Any ideas are welcome.

Thanks

Gman

[pfarmer]

Looking for Bolt-on Upgrade options? I have installed a Stillen Ram Intake and was told to stay away from Chips and Oxy sensors. (voids the 92,000 mile warranty).

Any ideas are welcome.

Thanks

Gman

Stay away from any rotational elements attached to the engine. Stay away from cat replacements unless it is one for your house and not your car. Stay away from engine parameter modifications (ie timing).

Do not make changes to the stock car cabling system without consulting someone who understands the system and how to apply proper industrial standards. Do replace previously compromised cables with high quality like cables.

Perry

[Sentientbydesign]

Intake and exhaust are mostly for sound, but will yield 10-15 hp in parts of the powerband.

I keep wanting to get an intake, but seeing how both the Stillen and JWT use cotton gauze filter, I'm seriously turned off by them (too much evidence points to that technology being horrible for your engine). As such, I'll putter along with no intake until I finalize a design for a custom one (completely heatshielded with a MAF relocation).

I hate to advertise, but you can always look at the link in my signature and check out a grounding kit. It's cheaper than an intake and gives more noticeable change.

Oh, be sure to check out Motordyne's plenum spacers and MREV2.

http://www.motordyneengineering.com

[joe603]

First, what year is your G35? This will make a difference in some things you can do.

[Gman1950]

Hi:

It is a 2004 G35 coupe with an automatic trans.

Thanks,

[Sentientbydesign]

First, what year is your G35? This will make a difference in some things you can do.

It's in the Title, Joe. 2004.

[pfarmer]

Hi:

It is a 2004 G35 coupe with an automatic trans.

Thanks,

Do not do any wiring changes beyound fixing what may be broken with like components.

If you do insist on going with something like a grounding kit use one that doesn't use any method of stacked grounds which can lead to current loops, most notable on any type of in car module that doesn't use balance inputs.

What is your current mileage? There are some things you can do that will not void a warranty, others that will just guarantee it.

Keep in mind something like brakes can be a real performance enhancement and for track use can give more bang for the buck than any standard engine upgrade ever well (depends on the track). For example being able to get much deeper into a corner due to better brakes is often much better than having a marginal edge in being able to speed away from it. In the case of gaining 10 hp (and keep in mind your really want torque improvements with it) using an intake probably isn't as effective as spending similar bucks on brakes.

Perry

[tollboothwilley]

#1) Motordyne Plenum Spacer 5/16" iso thermal

#2) Grounding Wires, there are several custom wire kits. Don't waste on a STILLEN.

#3) Cat-back exhaust + HFC

[Gman1950]

I have 60k miles with a 92K Nissan Warranty.

Thanks,

GMAN

[Gman1950]

Gotta ask you if your pic is a Sheet-Sue?

GMAN

[Sentientbydesign]

Gotta ask you if your pic is a Sheet-Sue?

GMAN

Yah!!! Wish it was my shih-tsu, but it is one. One of the most oxy-moronish avatars I've ever seen.

[pfarmer]

Intake and exhaust are mostly for sound, but will yield 10-15 hp in parts of the powerband.

I hate to advertise, but you can always look at the link in my signature and check out a grounding kit. It's cheaper than an intake and gives more noticeable change.

Using a Stillen intake as an example I get a figure of about 2 hp per 100 dollars, slightly higher with the new version. I tried to do the same with a 100 dollar grounding kit and scientifically proven gains but every calculator in my house refuses to give me a number. Instead they give me some cryptic statements about 'Cannot..............'

Perry

[joe603]

It's in the Title, Joe. 2004.

Ya, ya...bite me.

Listen to these guys Gman...they know what they're talking about.

I'd go with this:

- Stillen PopCharger- Z-tube- Motordyne Plenum Spacer 5/16"- Grounding Wires- Cat-back exhaust (HKS or Stillen)

[pfarmer]

I have 60k miles with a 92K Nissan Warranty.

Thanks,

GMAN

First off read the terms of your Warranty and if necessary get some consultation from Nissan on what is permissible so as not to void it. You can probably go with a quality intake which will most likely give you a little bit on the top end but may hurt your bottom end as far as performance. Many do an intake purely for noise purposes. Various exhaust systems will probably be ok but I would be careful about anything that influences emissions both from the emissions standpoint and from possible issues with some engines, not sure on your older 'G'.

Be very careful about any modifications that have to do with rotational elements of your engine. Often they give very little in the way of performance and can cause some real issues with an engine. If this is your daily driver you want reliability. For example you can change a well balanced stock pulley with an equally well balanced aftermarket pulley that will usually be lighter. By doing so you may well have caused an issue with the longitude balance. A pulley may well induce a harmonic that over time can destroy shafts. They will possibly give you improved spool up capabilities but could give you a large repair bill down the road as well.

If there is an issue with your electrical system fix what the issue is. For example check grounds and if necessary replace with like grounds in exactly the same place and with the same size. This avoids any problems dealing with circular currents. While usually not a problem with a balance device such as a sensor (since a balance device has noise rejection characteristics) they can drastically affect an unbalanced device which doesn't. The 'G' has a mix of balance and unbalanced devices.

Perry

[4drsleeper]

First off read the terms of your Warranty and if necessary get some consultation from Nissan on what is permissible so as not to void it. You can probably go with a quality intake which will most likely give you a little bit on the top end but may hurt your bottom end as far as performance. Many do an intake purely for noise purposes. Various exhaust systems will probably be ok but I would be careful about anything that influences emissions both from the emissions standpoint and from possible issues with some engines, not sure on your older 'G'.

Be very careful about any modifications that have to do with rotational elements of your engine. Often they give very little in the way of performance and can cause some real issues with an engine. If this is your daily driver you want reliability. For example you can change a well balanced stock pulley with an equally well balanced aftermarket pulley that will usually be lighter. By doing so you may well have caused an issue with the longitude balance. A pulley may well induce a harmonic that over time can destroy shafts. They will possibly give you improved spool up capabilities but could give you a large repair bill down the road as well.

If there is an issue with your electrical system fix what the issue is. For example check grounds and if necessary replace with like grounds in exactly the same place and with the same size. This avoids any problems dealing with circular currents. While usually not a problem with a balance device such as a sensor (since a balance device has noise rejection characteristics) they can drastically affect an unbalanced device which doesn't. The 'G' has a mix of balance and unbalanced devices.

Perry

Dangit Perry, Every time I read one of your posts I feel like I'm getting kicked in the balls. Everytime I get in my car now I'm afraid it's gonna blow up because of my mods. I have a constant reminder in my head that repeats over and over "Intake's are bad, HFC's are bad, Lightened Pulley's are bad...catastrophic failure is upon you".

Can someone bring me back to reality?

[SteveTheTech]

Dangit Perry, Every time I read one of your posts I feel like I'm getting kicked in the balls. Everytime I get in my car now I'm afraid it's gonna blow up because of my mods. I have a constant reminder in my head that repeats over and over "Intake's are bad, HFC's are bad, Lightened Pulley's are bad...catastrophic failure is upon you".

Can someone bring me back to reality?

Drive it, enjoy it, but it is good to keep some realism in your head. Your car may not break but S*it happens. With mods typically comes abusive driving, the VQ is a solid motor but it is not indestructible. Perry and I are skeptics but by no means is fear the intent. We only try to enlighten. It worked though you think about the possible repercussions of your actions.

Looking for Bolt-on Upgrade options? I have installed a Stillen Ram Intake and was told to stay away from Chips and Oxy sensors. (voids the 92,000 mile warranty)

What are you looking for as far as modifications go? What is your overall goal for this car, daily driving commuter, weekend racer, ect. And what is your budget. The reason I ask is because everyone has their opinion on what is best for your car but when it comes to aftermarket modifications you should really try and do what will make you happy. If you are looking for presence, intake and exhaust (see the below note) are the way to go they will increase your fun to drive factor significantly.

Note- Since you are trying to stay within the guidelines of your extended warranty (kudos ) and it is up to the judgment of the dealer as to whether they will look past your modifications, you may still want to err on the side of caution. The G stock is a fun car to drive and with something simple you can get the most out of it without buying into the marketing hype of aftermarket parts companies that care more about your money than the performance of the part. Allot of the mods for the first gen G have superficial gains and overinflated claims. As Perry mentioned the cost per HP for many of these things is usually 1hp-$100 at best. http://nissansportmagazine.com...b.pdf This is a great article from a while back from a great group of guys

If it were my car I would go intake & muffler and then focus on the suspension and brakes that are already 5 years old, whether they are covered under warranty or not they are still aging.

[Gman1950]

Morning:

Thank you for your response.

I drive the car daily for business and no weekend amateur racing. Budget- We all have them but can find the money if i can. Will look into the factory warranty and can call my service rep at the dealership but they are pretty much conservative/no to any changes. Besides blacking out the windows, Billet front end, and chrome Infiniti rims (upgrade in size), I was looking to make some small mods in street performance. Had a J30 and never got around to making any changes and now got the bug.

Thanks for your advise

Gman

[pfarmer]

Dangit Perry, Every time I read one of your posts I feel like I'm getting kicked in the balls. Everytime I get in my car now I'm afraid it's gonna blow up because of my mods. I have a constant reminder in my head that repeats over and over "Intake's are bad, HFC's are bad, Lightened Pulley's are bad...catastrophic failure is upon you".

Can someone bring me back to reality?

I didn't state intakes are bad but keep in mind where most of the performance gains will likely be (and possible performance decreases). HFCs will likely give you performance gains and possible decreases as well.

One needs to determine where they expect the gains. It is entirely possible to experience a decrease where most of your driving takes place. It is also possible for something like HFCs to cause an unexpected failure if they fail. Most probably don't understand how 'FOD' can happen in this case, engine dependant of course.

Lighter pulleys will most likely give you spool up gains. There is no doubt that some rotational modifications can cause issues that most here don't fully understand, such as what occurs if you change a critical which will without a doubt change. They will however give you little benefit in the way of horsepower and may well decrease torque at steady states. An underdrive pulley (not to be confused with just lighter pulleys) may well give you a slight increase but may well cause other issues, these need to be considered, again where and how you drive. I never would rob cooling considerations if I lived in a hot climate, even where I live it is expected to be near 100 in the next couple of days, but then I could leave the car home during the hot weather.

All of these gains (and possible decreases) need to be considered in the overall picture. One is warranty, will it void it if something occurs? How important is that to the individual? If like many here they purchased an aftermarket warranty then that must be an important factor to consider.

If you are ok with voiding a warranty should a failure occur then I am fine with that, just don't expect to be covered if running outside of it.

There are other items that just do nothing at all in the way of benefits, can cause operational problems with a vehicle, that are a waste of time and money, and certainly I will point others away from them.

Perry

[SVTCOBRA]

Have you tried a grounding kit??? Have only heard positive results from this and it's just a little $$$

Hit up Nate for a set since he is a member!!

[pfarmer]

Have you tried a grounding kit??? Have only heard positive results from this and it's just a little $$$

Hit up Nate for a set since he is a member!!

And how much hp/dollar spent is gained. I just did some more research in various other forums including Nissans, Toyotas, Mazda, and others and more than a few don't see any benefit at all over a properly maintained factory system. A good many actually associated it with a certain type of oil which is interesting if you do a search on that phrase along with grounding kits. The point is that if you renew your factory grounds you will not need a ground capable of carrying 70+ amps to a 15 amp circuit. Many of the end connectors for example don't rely on pressure welded connectors and will suffer the same fate as poorly maintained factory grounds.

An interesting fact about the ECM is that the grounds to the various sensors are most often provided by the ECM and are separate from chassis ground. With the possible exception of a couple such as the crankshaft position sensor, the fuel tank level sensor, and one or two others even voltage measurements to the sensors have to be taken to chassis ground (referred to as body ground) instead of the ECM provided ground to avoid damage to the ECM circuitry per the FSM. This is consistant with balanced sensors which are designed for noise rejection purposes.

----------------------------------------

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damageto the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

----------------------------------------

So even if you directly ground the ECM you have not provided the ground to the sensor and the current flow to the ECM will be maintained at whatever the positive supply from the battery provides which we know is under 15 amps and could be provided with as little as a 16 gauge wire. While I would not recommend it you would be far better off addressing both sides of a power difficient problem (if it exists). To increase power to the ECM you would need to provide both the increase in ground size and the increase in positive size conductors. But then that is unnecessary since we know it doesn't go over what a 16 gauge wire can handle.

Perry

[SVTCOBRA]

To the OP,please use the SEARCH button and weigh the positive comments against the negative comments on any topic presented for discussion as it relates to the G35. Until now, I had only heard positive feedback here on the grounding kits on G35's.

[pfarmer]

To the OP,please use the SEARCH button and weigh the positive comments against the negative comments on any topic presented for discussion as it relates to the G35. Until now, I had only heard positive feedback here on the grounding kits on G35's.

Should be real easy to find the one with the problem with his car not operating after an install, cable had to be moved away from a couple of factory grounds removing stacked grounding.

Please go to the FSMs and figure out how a non-engineered set of add on grounds can make an engineered ECM and its sensors function better when the ECM has balanced sensors that would not be affected by any added ground as long as the factory ground is maintained. The same goes for nearly all sensors on the entire car.

As a reference car someone actually took before and after resistance readings on a Toyota Supra. The factory ground was showing .03 ohms maximum deviation between grounding points before and .01 ohms afterward. The internal resistance of many meters is 2 ohms. The Infiniti runs higher than the Toyota for many but the deviation is 1-2 ohms. I measured it on mine and can not measure any difference at all.

As long as the factory grounds are in good condition there will be no benefits and possible problems with circular currents by adding additional grounds. If the factory grounds are not in good condition then fixing them are the answer. Mother's highly trained engineeers knows best when it comes to the design of a grounding system. You can't increase the power capabilities to a D.C. system without addressing both the flow to and from a device.

I would support positive grounding on a theoretical basis, mostly for longivity.

Perry


Modified by pfarmer at 12:18 AM 7/27/2009

[SteveTheTech]

I have actually performed some semi scientific tests about this, but that is another point.

I noticed you mentioned the Fuel Pump circuit. If you look at the fuel pump circuit on almost all modern Infinitis you will see the ground circuit of the FP is actually detectable and there is a DTC for the grounding circuit for the fuel level sensor. Having clean and protected grounds is crucial.

This week I had an interesting case at work that followed these lines. The car was a 2001 QX4 with a lack of idle and a recent service history that included a replaced ECM and IAC valve. Active testing proved that the IAC was actually working when commanded appropriatly the linear soliod would activate but not correctly. However the main problem was the car was not throwing a CEL, which is extremely interesting since there was a serious issue with Open Loop operation and since there was not a fault in the IAC circuit. If you notice though the older models (w/o electric throttle bodies) IAC circuit does not have a ground, and all grounding for the two variable rate stepper motors is sourced through grounds labeled ECM. On this particular model there are two multiple grounding points located on the top of the inner timing chain cover. This specific vehicles grounds appeared to be ok and only showed between 2 and 3 ohms of resistance (my meter has a relativity setting to cancel out the meter and tests leads resistance) . Since Infiniti supplies no spec for resistance value it is on us to find a known good and test it. From what I have found anything more than 1 ohm may cause an issue. However in this case there was a very strong indicator that these compound grounds were being used as a load as the wire insulation and tape at the ends were charred and there was significant signs of corrosion. This inevidibly lead to a destroyed idle control processor inside the ECM which still allowed the IAC to operate but not to consistently. The two primary indicators were a burning smell inside the car and immediate stalling but if revved directly after cranking it would stay running. The fuel level sensor also works on a similar ground circuit but instead it is a little more involved. The grounds split and run too the ECM and combination meter. If there is a compromise in certain parts of the circuit the ECM will trigger a code for either increased or decreased resistance. However it will not detect the sensor not completely using the available electricity in the variable resistor and instead using the increased resistance in what is supposed to be a ground as a load it will cause some really interesting complaints.

What is the reason for my rant. To illustrate that grounds can and do cause problems sometimes but the symptoms are interesting and few and far between. But resistance alterations within the standard deviation can cause problems that may not be detectable to most.

[pfarmer]

I have actually performed some semi scientific tests about this, but that is another point.

I noticed you mentioned the Fuel Pump circuit. If you look at the fuel pump circuit on almost all modern Infinitis you will see the ground circuit of the FP is actually detectable and there is a DTC for the grounding circuit for the fuel level sensor. Having clean and protected grounds is crucial.

What is the reason for my rant. To illustrate that grounds can and do cause problems sometimes but the symptoms are interesting and few and far between. But resistance alterations within the standard deviation can cause problems that may not be detectable to most.

Actually what I mentioned was the fuel level circuit. In the post I was referencing a 2005 FSM detail of the ECM. I believe most of the key points are valid for the newer versions as well based on my preliminary review of the 2008 ECM. Both show that sensors generally reference ECM ground for signal purposes as expected. As far as shield grounds it gets a little interesting since there is a mix. For example it appears that the knock sensors use a ECM referenced ground for the device and uses the same ground in a series configuration for the shield, while the MAP sensor uses a chassis referenced ground for the shield.

It appears that only a few grounds for ECM sensors reference a chassis ground located in the engine room while the rest reference the ECM. The ECM reference grounds appear to be dual ended, that is used as the device ground. Some of these are also used for the shields. The chassis reference grounds (for shields) appear to be single ended. While not a surprise it is a practice I used back in the late sixties for sound systems.

Many car for performance reasons would have their plugs replaced with non-resistor plugs and cables. This often resulted in noise in the sound system which were a mix of AM/FM with AM still going strong. The fix then was to add in various components to the wires, plugs, coils, you name it someone had some device to sell you to fix the problem. What I was looking at is where the problem was being introduced to the sound system. In a good many of the the cases it was the plus lead which came off the accessory part of the battery cable. I found that by disconnecting the normal power lead to the radio and replacing it with one of two difference types of coax or shielded flat lead cables. In the case of the coax you used one large enough to carry the load with the center conductor. In the case of the shielded flat lead you had a two conductor cable located withing a foil shielded outer layer. In its case one lead was used for the negative, one for the positive depending on the radio, some of which did not used a chassis ground.

What was common to both however was that you needed to avoid the temptation to ground both ends of the shield. Doing so would introduce noise into the system. Few seemed to understand why I was not doing so, it appears Infiniti engineers have a handle on the why.

What I am seeing here is the use of the same concept combined with noise rejection capability provided by the ECM.

Perry

[pfarmer]

I have actually performed some semi scientific tests about this, but that is another point.

I noticed you mentioned the Fuel Pump circuit. If you look at the fuel pump circuit on almost all modern Infinitis you will see the ground circuit of the FP is actually detectable and there is a DTC for the grounding circuit for the fuel level sensor. Having clean and protected grounds is crucial.

It would be interesting to know the inner workings of how they detect ground. On an industrial application this is often done with a floating ground for the device. The idea here is normally to detect a malfunction that is taking current flow to the earth (chassis ground). The device is isolated from earth ground. One method involves measuring current flow between the chassis ground and the device ground. The other measures the total current flow in the power lead against that in the floating ground.

Of interest is an engine ground being provided through the transmission input shaft to the crankshaft on a engine with a faulty ground. Besides causing running issues it can cause bearing damage if current flow gets high enough.

Perry

[SteveTheTech]

http://www.nicoclub.com/FSM/pa...c.pdfEC-435

Although the book does not seem to specify directly I am going to make an assumption that the ECM uses normality checks of the FL circuit and references that with stored values to determine the status of the FL gauge. The one problem I saw with this circuit had perfect grounds and a complete signal and the logic inside the ecm was perfect.

Nissan is famous for using normality checks on several legs of both power and ground signal of vital engine sensors. There are also many DTCs that are logic based, meaning the input (to the ECM) value does not match what the computer thinks it should be. This is where many, even highly experienced, techs go off in the wrong direction. Whenever you pull a DTC the first step should be checking the DTC logic to see what exactly this code is indicating. In the old days there were less than 20 primary DTCs and they were normality only. Logic codes came with OBDII and became more advanced with the introduction of CAN lines. The new FX50 has a CAN-BUS junction to direct traffic among the myriad of controlled and controlling devices.

I find the example in the link above interesting because if you look at the circuit diagram for the gauges it does not show that the ground runs through the ECM. Testing the circuit incorrectly could yield incorrect results and possibly damage the ECM. I really do not know why they don't even reference the real diagram. Instead they wait till we get burned on something like this and say oh yeah didn't you know. It's sort of like a right of passage for young techs.