Somethings up with my coupe.

[mikethemike]

So my dad has a 2012 AC as his rental car (great taste right?). Its a 2.5s with only 12k miles. Obviously stock. Now one would think that these cars carry the same power, torque, etc. So I took this car out to see if theres a difference in performance with the intake+exhaust my coupe has and now I'm concerned because this rental coupe FLIES! I mean this thing is a torquey bastard compared to my engine and unless they changed the throttle response with the engines between 2010 and 2012, somethings up with my coupe. Mine is just so damn slow from a stop and I thought thats just how they designed the engines. Unless I need to wait a few thousand more miles to break the engine in (8k miles right now) I should probably take it into Nissan to have it checked.

Now what should I do being that I have an intake and exhaust? I doubt the intake is the reason why its doing this, in fact i know its not because it was like this before i put the intake and exhaust in. But I don't want it to void the warranty, though i doubt it will. But to be on the safe side should I just replace the intake for the time being and take it in?

This is weird.

[wade001]

I dont think they made any real changes between your year and that one. I guess there could be a few things to consider though. All 2.5's are built the same but theres a saying that every engine is different ! What I mean by this is that 2 engines won't be the same on any car. Things like how the engine was broken in, how it's been driven (ECU is adaptive), what size wheels, maybe a lil lighter, even possibly the oil used can affect the cars acceleration ! Theres a ton of things!

As for your mods, they probably affect it somewhat. Engine mods are based off of getting air in and out, most gains are in the higher rpm range but may sacrifice low rpms. So that maybe could be why your car feels slower, but it would be faster in the high range. For example, I know when I put an intake on my car and dynoed it, my peak hp went up about 200rpm. Add an exhaust for you and it could be a little higher but who knows !

I dont think the dealer will do much if there's no code unfortunately. But I would swap the stock intake to be paranoid cuz it's not too hard to do lol.

A couple things you can try though ! Clear the ECU by disconnecting the batt for 10-15min, and try driving a lil more aggressive. The ECU will learn the new style and could respond better after you put miles on . Maybe try it without the intake as well and see if theres a difference with the ECU cleared as well if you want. If you have heavier then stock wheels that will definitely affect performance as well. I raced someone who has the same car but has an exhaust as well, but had 20" rims. We did a 60-100 run and I pulled on him real good for a couple cars (2-3) before he let off .

[DAAN.]

I'd do that first (Clear the ECU / put your foot down afterwards) before scanning it. Codes will tell is something is out of order

[mikethemike]

Thanks guys I'll give that a try. I wouldve done the whole disconnecting the ECU thing if it were an older car, but I was told (back when I had my 04 altima) that with newer cars its not like that anymore. But it couldn't hurt and you both may be right. =)

[AlexM.]

Clear the ECU by disconnecting the batt for 10-15min, and try driving a lil more aggressive. The ECU will learn the new style and could respond better after you put miles on . Maybe try it without the intake as well and see if theres a difference with the ECU cleared as well if you want.

I'm gonna try that, never heard of that. Thanks!

[DJ_B_Easy]

Engine mods are based off of getting air in and out, most gains are in the higher rpm range but may sacrifice low rpms. So that maybe could be why your car feels slower, but it would be faster in the high range.

[mikethemike]

This is true ^

How about just getting a basic tune? I've never gotten a tune up before so someone walk me through this. Would any local mechanic do this or should I bring this to a performance shop? What would getting a tune up entail? Could I have them remove the governor and improve the throttle response with a tune up?

I doubt I'll be spending the money for a BD Tuner as fun as it may be, but if I could get a shop to eliminate some of the restrictions and free up some power that would be great. Or at least throttle response. Again, never had a tuning job done before so I could be dead wrong.

[RicerX]

Another thing to consider is that if you're driving your car on a hot day, that Takeda intake doesn't have a heat shield of any sort, so you may be experiencing heat-soak with the intake.

[mikethemike]

Restarted the ECU and drove it just now. i dont think anything changed, as expected. Then again, its pretty out outside so it could be just sucking in hot hot air.

Guess I gotta just live with it, which is fine =)

[CoupeVQ35CVT]

Most aftermarket mods that increase airflow, usually end up causing a stock ECU/engine setup to "feel" sluggish at low rpm/take off. I've experienced this for sure with at least 2-3 different cars with near similar hp/weight - one of them complete with before and after an intake, headers/exhaust. The difference is usually not much more than a momentary jolt you might feel with a "stock" car, but the modded one might have more pull at the higher RPM, which is less noticeable since it is not as sudden. That's my theory anyway.

[wade001]

This is true ^

How about just getting a basic tune? I've never gotten a tune up before so someone walk me through this. Would any local mechanic do this or should I bring this to a performance shop? What would getting a tune up entail? Could I have them remove the governor and improve the throttle response with a tune up?

I doubt I'll be spending the money for a BD Tuner as fun as it may be, but if I could get a shop to eliminate some of the restrictions and free up some power that would be great. Or at least throttle response. Again, never had a tuning job done before so I could be dead wrong.

About the ECU, the guy said that because they have a backup reserve to keep power to it so it doesn't reset. But if u leave it long enough it will die and you will have reset it !

Cars of our year dont really need tune-ups like the older ones fortunately . I believe our plugs are iridium, should be good for an easy 60k, car is also coil over plug so theres no need for wires. Fuel filter should be good for a long time as well ! I dont see a gain for you with low miles doing this ! the factory scantool can change to speed limiter and a few other things, but u have to go in the back door if u know what I mean lol ! The throttle response idk, might need uprev for that !

As far as clearing the ECU, it will take time, like 100+ easy miles before it relearns. It wont happen right away. Off the top of my head things you can do would be to switch to synthetic if you have relatively low miles, also put in a coolant additive to drop running temp a bit ! I use Amsoil for both as I have had great results with them. The mods will affect your performance, u never really know unless you dyno though!

[wade001]

Most aftermarket mods that increase airflow, usually end up causing a stock ECU/engine setup to "feel" sluggish at low rpm/take off. I've experienced this for sure with at least 2-3 different cars with near similar hp/weight - one of them complete with before and after an intake, headers/exhaust. The difference is usually not much more than a momentary jolt you might feel with a "stock" car, but the modded one might have more pull at the higher RPM, which is less noticeable since it is not as sudden. That's my theory anyway.

Ill add a lil to that ! When you do any kind of engine modification to your car it can "confuse it". Possibly taking away performance gain until it adjusts. The problem is though, even though it is a performance part the engine is designed to run a specific way. So if you do I/H/E you will get more airflow, more then the ECU expects which is the problem ! This being the case, the ECU will take this and change the fuel map and timing to bring it "back" to what it is set for, essentially "de-tuning" the car in a sense ! This it why people say do the mods first and then tune as it corrects this! Our car is purposely de-tuned by nissan! The over-riding reason for this is to meet emissions! Cars today are tuned for emissions and not performance, and it's going to get worse ! A cars behavior in driving can be greatly changed with a pretty good tune! But you cant compair 2 cars exactly though as a comparison, the programing for the engine and transmission could be different (like an updated one). There are so many factors it can drive u crazy !

[mikethemike]

Yes, so since I already have I/E, should I get a tune up so the ECU can correct this? Or are you referring to geting an Uprev tuner?

[mikethemike]

And IF I were to go with an Uprev tune program, which one would be the product to get? Actually what would be recommended for a 2.5 with the mods I have? BDTuner or this? I doubt I'll get it, but its always good to know and do the research since I sometimes just end up throwing in the towel and end up buying s*** i say i dont need.

http://uprev.com/secure/osiris-engine-management

[wade001]

A regular tune-up wont net you much of anything , and do the BD tuner, you would need an UpRev tune to get something real.
I would do a few other mods first before you spend good money on a tune. Anything could help, but I would add the header since u have the other two, a LW pully will help as well for a lil quicker response.

When looking for someone to do it, look real good into their rep. Not just what a few people say but to really decide yourself! A real tune can give a real nice difference in performance.

Before anything else is said, I dont know really what is the difference btwn the cars and what you expect ! IDK, even after the other mods and tune you still may not get what you exactly want . If it's low end you want the I/H/E wont give you that, they will give you high end. A tune can definately change it to a good degree but IDK for sure! You will gain and lose at different points in general. You honestly just need to really look into it for yourself to decide, dont go just by me lol . Just trying to try n help explain what you might have felt as the difference ! Let us know and hope this helped !

[mikethemike]

A regular tune-up wont net you much of anything , and do the BD tuner, you would need an UpRev tune to get something real.
I would do a few other mods first before you spend good money on a tune. Anything could help, but I would add the header since u have the other two, a LW pully will help as well for a lil quicker response.

When looking for someone to do it, look real good into their rep. Not just what a few people say but to really decide yourself! A real tune can give a real nice difference in performance.

Before anything else is said, I dont know really what is the difference btwn the cars and what you expect ! IDK, even after the other mods and tune you still may not get what you exactly want . If it's low end you want the I/H/E wont give you that, they will give you high end. A tune can definately change it to a good degree but IDK for sure! You will gain and lose at different points in general. You honestly just need to really look into it for yourself to decide, dont go just by me lol . Just trying to try n help explain what you might have felt as the difference ! Let us know and hope this helped !

Thanks man. Yea its the low end torque I want. Before I go any further, rest assured, I'm not looking to make this car a race car by any means. I dont even drive that fast to be honest. If I did, I'd have gotten a 6 cyl. However, low end torque is a must whether its a 8 cyl, 4cyl or a friggin 3cyl geo metro.

Now heres where another mixed review comes in. I've been told there is no actual use for a lightweight pulley for the 2.5's even though they have em. According to LongBeachCoupe " a 3.5 pulley is "under driven" the 2.5 pulley is just lighter" which doesn't do too much for a 2.5. But like you said, maybe once I get the tune, I'll feel the power coming from that pulley. And I do intend on getting headers sometime.

As for finding someone to tune, now that I think of it, I know a few guys who own a performance shop. I'll look into them

[Irvxing]

I had an aftermarket exhaust set up with my coupe and this weekend i installed the OEM exhaust back on and i feel like it flies. Low end torque is more punchy rather that with my other exhaust. Could be in my head though.

[wade001]

No problem! at this point I would change what I would do perhapse lol. The other car had the lower grunt, part of this was designed through the exhaust and intake, again, something many I think simplify to much . Everything is a specific way stock, when you change a few things it makes an effect on the power curve. Since you have I/E, you could tune for that n the pulley, wont give super numbers but I wouldnt care as it's the power delivery you want worked better:)!
The statement of the 2.5 pulley being pointless I highly disagree, if anything from a simple physics perspective as my basis with it being lighter. PLUS, it wont affect the power curve at all !! An underdrive will give a bit more, but as a result the serpentine belt will turn slower effecting the alternator output to lower , if you have stock sterio/lighting your pretty ok, but if a high power stereo system/etc. and you could have issues ! I hope this seems beneficial .

[mikethemike]

No problem! at this point I would change what I would do perhapse lol. The other car had the lower grunt, part of this was designed through the exhaust and intake, again, something many I think simplify to much . Everything is a specific way stock, when you change a few things it makes an effect on the power curve. Since you have I/E, you could tune for that n the pulley, wont give super numbers but I wouldnt care as it's the power delivery you want worked better:)!
The statement of the 2.5 pulley being pointless I highly disagree, if anything from a simple physics perspective as my basis with it being lighter. PLUS, it wont affect the power curve at all !! An underdrive will give a bit more, but as a result the serpentine belt will turn slower effecting the alternator output to lower , if you have stock sterio/lighting your pretty ok, but if a high power stereo system/etc. and you could have issues ! I hope this seems beneficial .

So many sad faces

This is a huge help. Luckily I dont have a sound system in the car. Just basic stuff. Well I guess I'll look into getting the OBX lighweight pulley for the Sentra since its the same thing.

[DJ_B_Easy]

I would try an idle re-learn before spending any more $$$.

[wade001]

idle re-learn wouldnt be a bad idea !

The sad faces are because I figure people may not like some of the stuff I'm saying lol. the 2.5 pulley is the same diameter, so no affect on the alternator !

[mikethemike]

Great I'm gonna try that out. Just read the directions. Before I go any further, whats the worst that could happen if I miss time myself in the relearning process?

[DJ_B_Easy]

^I believe you just get a CEL or SES light until you do it properly. Its not difficult, but you should definitely use a stopwatch or get some to count it off for you.

[mikethemike]

Wait a second, this is a similar procedure I had to do when I would clear the CEL light from my other Altima. If I'm not mistaking, this is the same. If thats the case then this should be cake since I've done it numerous times. The only difference is instead of a turn key, its a push button =]

[mikethemike]

Wait a second, this is a similar procedure I had to do when I would clear the CEL light from my other Altima. If I'm not mistaking, this is the same. If thats the case then this should be cake since I've done it numerous times. The only difference is instead of a turn key, its a push button =]

[Throckmorton]

... Things like how the engine was broken in, how it's been driven (ECU is adaptive)

A couple things you can try though ! Clear the ECU by disconnecting the batt for 10-15min, and try driving a lil more aggressive. The ECU will learn the new style and could respond better after you put miles on .

Wade,
You have provided a ton of useful information, but I must disagree with your ECM comments.
No, it will not adjust depending on driving habits. The factory settings of the ECM control all aspects of the driving cycle. There is no provision for the ECM to "learn" your driving habits.
The ECM has a memory function, which stores the driving condition such as fuel system status, calculated load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle speed at the moment the ECM detects a malfunction. TM-264 Factory Serice Manual

The manual also says this: ECM EC-120

If the battery is disconnected, the emission-related diagnostic information will be lost within 24 hours.
• The following data are cleared when the ECM memory is erased.
- Diagnostic trouble codes
- 1st trip diagnostic trouble codes
- Freeze frame data
- 1st trip freeze frame data
- System readiness test (SRT) codes
- Test values

Nowhere in the Nissan Factory Service does it mention that the ECM can be “reflashed”, nor does it mention that the ECM ‘learns” or “remembers” how you drive your car. All that is removed is the DTC information when the battery--or power source -- unhooked for 24 hours.

Another example is here in the Fuel injector section:

The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the ECM memory. The program value is preset by engine operating conditions. These conditions are determined by input signals (for engine speed and intake air) from the crankshaft position sensor (POS), camshaft position sensor (PHASE) and the mass air flow sensor.

But hey--I could be wrong!

[DJ_B_Easy]

^So yeah, do an idle re-learn.

[wade001]

... Things like how the engine was broken in, how it's been driven (ECU is adaptive)

A couple things you can try though ! Clear the ECU by disconnecting the batt for 10-15min, and try driving a lil more aggressive. The ECU will learn the new style and could respond better after you put miles on .

Wade,
You have provided a ton of useful information, but I must disagree with your ECM comments.
No, it will not adjust depending on driving habits. The factory settings of the ECM control all aspects of the driving cycle. There is no provision for the ECM to "learn" your driving habits.
The ECM has a memory function, which stores the driving condition such as fuel system status, calculated load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle speed at the moment the ECM detects a malfunction. TM-264 Factory Serice Manual

The manual also says this: ECM EC-120

If the battery is disconnected, the emission-related diagnostic information will be lost within 24 hours.
• The following data are cleared when the ECM memory is erased.
- Diagnostic trouble codes
- 1st trip diagnostic trouble codes
- Freeze frame data
- 1st trip freeze frame data
- System readiness test (SRT) codes
- Test values

Nowhere in the Nissan Factory Service does it mention that the ECM can be “reflashed”, nor does it mention that the ECM ‘learns” or “remembers” how you drive your car. All that is removed is the DTC information when the battery--or power source -- unhooked for 24 hours.

Another example is here in the Fuel injector section:

The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the ECM memory. The program value is preset by engine operating conditions. These conditions are determined by input signals (for engine speed and intake air) from the crankshaft position sensor (POS), camshaft position sensor (PHASE) and the mass air flow sensor.

But hey--I could be wrong!

Well.... Legit statement and disagreement. But I stand by what I say, and I'll try to explain .

The info you stated from the manual, all true and I know that. However..... You will not find what I said in the service manual.. The manual is for trouble shooting, it will not tell you anything about what I said. And 90% of people dont know about this either so it will be hard to find out about this bit of info.

The ECU has what is called "adaptive learning", which means it can make permitted changes to mapping,etc. I also didn't say it will re-flash.. I said re-learn, there is a difference. ECU's are designed now so that they can adjust their mapping to the drivers style of driving, for various reasons. I am not saying that oh.. the AFR will go from 14.7 to say 13.0 or anything. However, AFR on a fuel mapping is NOT a solid 14.7 throughout on the table, it is different in almost all cells of the table! What changes is that! This is what a re-flash or tune does, you can change the cell values, which is why the HP may not drastically change but the power delivery changes greatly as all the cells are closer to the desired AFR! Thats why people say they feel a huge difference at certain rpm's. A re-learn is kinda like this, but keeps to the programed parameters of xx.x-xx.x AFR, it just changes the AFR in the cells slightly from the base map ! If you drove two exactly the same cars but the owners had completely different driving styles you would see a difference in how the car performs. Eh, it's early, I guess this is enough, If you see what I am saying is not being pulled outa my as* maybe consider I have a valid point !

[mikethemike]

I'm doing the idle relearn after work. Chances I'll feel a difference is slim to none but no worries. It's good to know the stuff so thank you guys

[AlexN09]

I think it would be so freaking funny if the rental was a 3.5 :p

I also realize you stated it was a 2.5