General Info: A Quick Reference Guide for Modifications and Common Problems - Nissan Forum
QR25 2.5L Engine Engine Discussion: 2002+ Sentra SE-R and SpecV

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post #1 of 25 Old Jan 29th, 2005, 02:54 AM Thread Starter
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Post General Info: A Quick Reference Guide for Modifications and Common Problems

A lot of questions are redundant so I figured I would put the general questions into it's own thread. If you just got your QR powerd car and are not sure where to start, reading this may help you out a bit. Feel free to add on or to merge this with a another thread. Hopefully, this will help people get a better idea of what is available for their car and help avoid repeat questions and threads.



Performance Modifications that will help your engine gain power (these are almost all bolt on modifications):

-Intake-You can do this with a short ram, cold air or remove the stock airbox silencers and install a high flow box filter such as a K&N. For the sake of it being where most people go, we will discuss the cold air intake (AKA CAI).
.....Makers of quality CAIs: Injen; AEM; NISMO; HotShot; Place Racing
.....Notes: It is important to buy a good CAI. Lesser models can and probably will bounce around eventually destroying your MAF. This in the long run will cost more money than buying a quality intake. The good names have excellent mounting designs, better filters and are better researched hence they are built better. When installing a CAI, it is a good idea to put weatherstripping on the CAI where metal will touch metal. This will prevent vibration and a god awful noise. NPM dynoed 3.2 WHP, and 2.3 WTQ with an AEM. Keep in mind a CAI does not add as much power as many people claim.

-Header-This is the biggest modification for our car. The 4-1 design header will give more top end power and the 4-2-1 design will give more low end and mid range power. Depending on the model, you can gain close to 20 WHP with a header.
.....Makers: AEBS (down pipe included with high flow cat); HotShot; NISMO; Stillen (down pipe included); DC Sports (down pipe included); OBX; SS Autochrome; Kamikaze (I wouldnt reccomend this one at all lol)
.....Notes: Installing a header will throw a CEL (check engine light). Various ways of fixing this exist, with the most common being the installation of a sim.

-Downpipe-If your header does not have a downpipe, then getting one will add a few horse power. A downpipe without a cat will most likely mean you are running catless. This has pros (more power and less expensive) and cons (loud as heck and not a goood sound, somewhat stinky, not emissions legal, and almost 100% chance of throwing a CEL)
.....Makers: Stillen; VRS; HP Autoworks

-Exhaust-A million and one makers make exhausts for our cars but they sound very different. Resonators will help make the sound deeper and quieter. Mandral bent piping is much better than crush...especially for our cars. Muffler selection will also play a big role in the sound.
.....Makers: VRS; Stromung; Greddy; APEXi; Magnaflow; Megan Racing; NISMO

-Camshafts-This is also a big modification for our car. If they are installed correctly, not only will you not lose any low end power but you will gain about 8-10 WHP and it will show on top end big tyme!
.....Makers: NISMO; JWT (slightly more aggressive than NISMO)

-SAFC2 (Super Air Fuel Controller, made by APEXi)-The gains from this are higher on the 02-03 than the 04+. To see real gains, dyno tuning is needed. This is not something anyone can do and if done incorrectly, you could seriously damage your engine. On the 02-03, a gain of 7-9 WHP on a bolted QR is very possible.

-Grounding kit-This mod seems to help smooth the idle and help the electrical system more than anything else.
.....Makers: NISMO; Stillen; Vytor; a million and one custom companies

-Crank Pulley-While the dyno has only shown about 2-3 WHP, an aftermarket crank pully will be lighter than your stock one by over 3 pounds. Since they are the same size as the OE pulley, no new belts are needed and ammenities such as A/C will not be compromised.
.....Makers: Unorthodox Racing; Impulse Mechanisms

-Nitrous Oxide-A 50-75 shot has been proven to be safe. Having knowledge of what you are doing is important. Using spark plugs that are not platinum and one step colder is a must. I will not go into further detail as much information already exists.

-Balancer Shaft Removal Kit (made by Jim Wolf Technology)-This modification will be good for 8 WHP and only costs about 90 bucks. NPM has shown that it takes time for the ECU to ajust so you will not get the full benefit immediately. Your car will also hold over 1 QT more of oil. The big downside of this mod is it will prettymuch kill your warranty and your car will have some increased vibration.

-Hondata intake gasket-This is a high temp insulating intake gasket which claims to lower the intake temp. Gains on Honda engines have been proven but no dyno sheets to my knowledge exist for the QR.
.....Maker: Hondata

-Throttle Body Bypass-I do not reccomend this modification but the idea of it is to have cooler coolant. The only possible way to see even the slightest gain with this mod would be to do this and the Hondata, which after a few hours and about 70 bucks may not give you more than 1-2 WHP, if that. Also, keep in mind people have had problems with this mod. See here http://www.b15sentra.net/forums/showthread.php?t=63742

-ECU-An aftermarket ECU for our engine does not exist, and probably never will. If someone claims to have one, they are probably lying. A few companies are claiming to develop a reflash for our ECUs, but currently, nothing exists except a piggyback ECU from Stillen called the QR pro. Considering gains from an SAFC2 are higher and the SAFC is a few hundred dollars less expensive, the QR Pro is not really worth the money, at least in my opinion.

-Wheels-said in a nutshell, you dyno higher with smaller and lighter wheels. This is a fact. If you want to dyno higher, drop those big wheels.
.....Makers: Too many.

-Knock Sensor-Many people will ground and or relocate this in the 02-03 due to oversensative knock sensors. Mind you those years will knock if they are not fed premium gas. The knock sensor is their for a reason, to retard timing so you dont screw up an engine. Using caution with this mod is always a good idea.
http://forums.thevboard.com/viewtopic.php?t=7339

-Spark Plugs-The OE plugs are platinum, switching to irridium or copper is not a bad idea at all considering they are more performance oriented and platinum is more oriented toward long life. By all means, avoid Bosch and lean towards Denso or NGK. For every 50-75 extra horsepower, make your plug one step colder.

-Nology Hot Wires-While claims are made about higher HP, TQ and even top speed, I have never seen any dyno sheets to back this up. The idea is that Hot Wires creates a more powerful spark. I truely dont understand the logic for our cars because of the existing way the plugs are set up. For 200 dollars, I would personally spend it on something else.

-Turbochargers-FI-R and PTI make a kit. This has been discussed extensively.

-Superchargers-No production models exist currently. Any past supercharger attempts were either failures or simply a way of attracting attention to a company. Revolution Autoworks claims to be in development of a supercharger that will be released around the summer of 2005.



Other related items that will help your performance indirectly:

-Motor Mount Inserts-While these will not help your dyno gain, they lessen wheel hop and help smoother shifts on a transmission. If you launch hard, your stock mounts may be torn. You can install these even if your stock mounts are already torn. The downside of these is vibration is significantly increased at low RPMs. This is easy to install and uninstall.
.....Makers: Energy Suspension; Power Tech Imports; Place Racing

-Short Shifter-Self explanatory.
.....Makers: NISMO; B&M

-Stainless Steel Clutch Cable
.....Makers: Crown and many others

-Clutch Fluid (Redline MT-90 and MTL mix, 1 bottle MT-90, 1 bottle MTL and about 1/2 bottle of MT-90 or to where the proper level should be). This has helped people shift smoother.
.....Maker: Redline



Common Problems:

-Pre Cat failure, most common in the 02-03 models although it has occasionally affected the 04+...see https://www.nissanforums.com/showthread.php?t=41855

-Transmission shifting problems-If you are experiencing tranny problems, you are not alone. Many threads exist on this problem and what can be done.

-ECM recall and floormat recall-this is well discussed as well.

-Butterfly Valve Screws-Recently, owners have been having screws being literally sucked up into their engine, sometimes even destroying it because of butterfly valve screws becomming loose and eventually completely dislodged. No recall to my knowlege has been issued yet, but many owners have removed the intake manifold, removed the screws and reinstalled them with loctite to ensure that this will not affect them. See here http://forums.thevboard.com/viewtopic.php?t=29162





As I said, add any info you have or correct me if I am wrong on anything. Hope this helps clear up what is and isnt available for our car and happy modding!


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post #2 of 25 Old Jan 29th, 2005, 11:04 AM
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Nice Write-Up!

2004 Molten Silver SE-R Spec V l AEM CAI l DC Sports Racing header l
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post #3 of 25 Old Jan 29th, 2005, 06:05 PM
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im thinkin STICKY!!!!!!!!
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post #4 of 25 Old Jan 29th, 2005, 06:20 PM
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sticky indeed. Now we do not need extensive threads again and again about intakes and exhausts.

Refer newbie questions here!




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post #5 of 25 Old Jan 29th, 2005, 06:20 PM Thread Starter
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Quote:
Originally Posted by chimmike
sticky indeed. Now we do not need extensive threads again and again about intakes and exhausts.

Refer newbie questions here!
Thanks Chimmike

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post #6 of 25 Old Jan 29th, 2005, 09:55 PM Thread Starter
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Reading and Resetting the ECU

If you are having a problem, you car read the malfunction code. You can also set the ECU manually. Unplugging the battery will not reset a Check Engine Light on the QR25. This is how you pull codes and reset the ECU. Keep in mind, this is for the 02-03 models. I am not positive if the 04 is different.

Pulling codes:
1) Without starting the engine, turn the ignition key to the ON position and wait three seconds.
2) Fully depress and release the accelerator pedal five times in less than five seconds.
3) Wait exactly seven seconds. Fully depress the accelerator pedal for ten seconds until the MIL (SES) light flashes.
4) Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code. All codes will be 4 digits.

Long flashes (0.6 seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.)
The next three digits follow in turn in the same fashion except with faster blinks (0.3 second) and a 1.0-second pause between digits.

The blinking will continue until you turn the car off. Then the car will be good to drive again.
In the ESM, refer to page EC-639. I warn you, there are hundreds of codes.
If you get four blinks of ten (0000), the ECM is indicating no malfunction.

Clearing the CEL:
While the ECU is flashing these diagnostics, depress the accel pedal and hold for over 10 seconds. You are good to go and the code has been cleared.



This info is from the VBoard. http://forums.thevboard.com/viewtopic.php?t=24691
They list the majority of the malfunctions numbers and an explanation of what they mean.


Autozone will do this for you for free, except they will simply plug into an OBD2 port and read the code. Considering this is free and faster, I think it can be ruled slightly easier. If you arent near one or are eager to know what is wrong, this procedure is just for you.

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post #7 of 25 Old Jan 30th, 2005, 07:28 PM Thread Starter
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Abbreviations For Modifications

Aparently I can't edit my posts in this thread??

Anyway, another thing that new commers need to know are the abbreviations for modifications.

I/H/DP/E/P/MM/BSR/TB/C/SS/AFC/KS may not mean much to you, but it is actually the abbreviation for modifications. If someone says to start your mods with the I/H/E combo, this actually means something.

I=Intake
CAI=Cold Air Intake
SRI=Short Ram Intake
WAI=Warm Air Intake
H=Header
DP=Downpipe
E=Exhaust
P=Pulley (can also be CP for crank pulley)
MM=Motor Mounts (rare and people commonly think they have mounts when infact they have inserts)
MMI=Motor Mount Inserts
BSR=Balancer Shaft Removed
TBBP=Throttle body bypass
TBP=Throttle body porting
C=Camshafts
SS=Short Shifter (SS can also mean stainless steel lines so it is comminly confused
AFC=Air Fuel Controller such as the APEXi SAFC2
SAFC(2)=APEXi's AFC
KS=Knock Sensor (relocated or grounded)
G or GW=Grounding wires
HW=HotWires (uncommon abbreviation)
H=Hondata intake gasket
HID=High Intensity Discharge (generally relates to headlights)
NOS=a brand of nitrous oxide but people commonly call it NOS, just like how people call tissues kleenex
N2O=Nitrous Oxide

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post #8 of 25 Old Feb 1st, 2005, 12:35 PM Thread Starter
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Performance Chips

There are 'chips' which claim to add horsepower and increases gas mileage and they cost from about 2-40 bucks. The patented design is called the Tornado. Some people claim to get 2-4 more MPG, but I highly doubt it as the physics of these things simply do not work. These claims may be fueled by the power of suggestion more than actual results. This thread explains a lot of it.

https://www.nissanforums.com/showthread.php?t=84256

Summed up: Those cheap performance chips are worthless and depending on the design they can actually harm your engine and significantly decrease gas mileage. The only things that help performance that is similar to a chip is a piggyback ECU (As stated earlier, aftermarket ECUs for the QR25 do not exist and probably never will. People have claimed JWT is developing one but to what I understand, they have no plans currently in line or down the road). Stillen makes a piggyback ECU called the QR Pro. Considering that gains from an SAFC2 are higher and the SAFC2 costs less, the QR Pro is at least in my opinion senseless unless you dont want to pay for the dyno tuning that is needed to see the full advantages of an SAFC2.

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Last edited by NickZac; Feb 1st, 2005 at 12:38 PM.
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post #9 of 25 Old Feb 18th, 2005, 01:33 PM Thread Starter
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Might as well add on to this as I just got back from the Nissan dealer. The master mechanic told me butterfly screws on the Sentra is not really a problem unless you mod to hell and drive hard. Considering who this is comming from (master tech at a very high volume dealer/service), I think I may have overreacted to the possible problem with the screws. He said on the 92-94 Max IIRC that the screws were a huge problem and he had to Loctite all 3 that he owned. He also said blue Loctite is the best to use on this.

I went in because I was losing coolant. I wasnt getting any air bubbles, not burning any oil, no leaks, no sweet scent, nothing. So I assumed it to be the rad cap and got a 1.3 bar NISMO cap. Turns out I was correct as they showed me where coolant had leaked and the tests they ran all came out excellent. Aparently having the caps going bad is not all that rare.

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post #10 of 25 Old Feb 19th, 2005, 07:56 AM
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I may be having a similar issue as well if that's the case. I had to add about 2.5 gallons of coolant about 2 weeks ago. Coolant was down to Min HOT Line.

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post #11 of 25 Old Feb 19th, 2005, 12:03 PM Thread Starter
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Quote:
Originally Posted by vector03
I may be having a similar issue as well if that's the case. I had to add about 2.5 gallons of coolant about 2 weeks ago. Coolant was down to Min HOT Line.

I wasnt losing nearly that much (2.5 gallons!!!!!!). How does your coolant look, how does it reflect and when you crank the car cold, does the rad hose have any air bubbles?
I have heard of head gaskets going on our cars...

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post #12 of 25 Old Feb 19th, 2005, 01:31 PM
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remember Royal Purple also makes good oils and dont require any mixing. remember do not use synchromesh

Southwest auto works makes a pully

megan racing has a downpipe

04/05 models have netted very good gains from a safc-II each vehicle no matter which year model is different in its own way

otherwise very good write up and very informative


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post #13 of 25 Old Mar 10th, 2005, 01:37 AM Thread Starter
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Nissan TSBs

http://www.nissan-techinfo.com/nissa...Sentra_B15.asp

This is the Technical Service Bulliten for the B15 Sentra. If you have a problem, it could easily be listed here as well as the solution. For example:



Quote:
NTB02053

This bulletin introduces 3M Plastic Polish # 39010, which should be used to clean and polish headlamps with cloudy, hazy, or other poor appearance

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post #14 of 25 Old Mar 10th, 2005, 01:55 AM Thread Starter
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OBD2 Codes

This is a list of EVERY OBD2 code...there are a lot
http://www.obdii.com/codes.html

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post #15 of 25 Old Apr 19th, 2005, 10:19 PM Thread Starter
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Arrow ECU Idle Relearn

I did this tonite and it helps. I have been meaning to do it for ever. If you cleaned the TB, did other bolt ons (especially cams), or have a rough or loopy idle, then do this. It will generally correct it. Use a stopwatch when doing this as the times must be relatively accurate:

-Warm up engine.
-Turn ignition switch “OFF” and wait at least 10 seconds.
-Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
-Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
-Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops
blinking and turned ON.
-Fully release the accelerator pedal within 3 seconds after the MIL goes ON.
-Start engine and let it idle.
-Wait 20 seconds.

Source: http://forums.thevboard.com/viewtopic.php?t=29384&

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