Danial
11-23-2011, 05:19 AM
Ok so I had to do some research on why my car was acting up and I thought I'd throw it here in one place and hopefully it helps someone spend less time on a dumb problem
So your car won't drive past 2500 rpm? BOM BOM BOM BOM I almost made a girl on a vespa crash when it started happening to me lol
**I didn't actually write 99% of this shit, I just compiled it here. **
Fuel cut issues
check
-ECU limp mode/ how to check codes on ecu
http://www.zilvia.net/f/archive-faqs/10007-ecu-location-reset-codes.html
[some of the common ones that I wrote down for this]
12 Air flow Meter/circuit open or shorted
22 idle speed control valve or circuit
23 Idle switch (throttle valve switch) signal circuit open
25 Idle speed control valve circuit is open or shorted
29 Fuel system rich
33 egr malfunction
98 Coolant temperature sensor
resetting the ecu
to reset the ecu/ simplest explanation of reading codes
1) There are 2 screws that hold the ECU in place, one at the top just underneath the bottom of the dash, and the other is beneath the ECU to the side of the panel. Once these are taken off, take the dash screw off (right above the first ECU screw). Lift the dash a little bit while wiggling the ECU out, it's tricky but it'll get out.
Turn the ECU around and get to the back of it, you will see a knob with a notch in it beside a caution sticker. Follow directions, but if you want to know what threw the code, follow this:
-Turn ignition to on position (where most of the lights are on, brake, airbag, etc)
-Turn knob fully clockwise, wait two or more seconds, then turn knob fully counter clockwise
-The service engine light will start blinking, count the blinks. The first blinks are slow, this will represent a first digit.
-There will be a short pause, then the light will blink fast, these blinks will represent a second digit.
-For example, light blinks slow 5 times, and blinks fast 5 times, this is code 55
-If there is only one code, the light will just repeat the code over and over. If there are more, the light will also repeat each code one after the other.
-Once you know what the problem is (or if it's just general maintenance) fix it, and clear the code by starting the car.
2) (with key at on position but not running) turn the little screw thingy on the back all the way clockwise, the slot will point to a line on the unit wat 2 or more seconds (if you don't wait you'll just get different codes)
3) start motor
4) turn screw thingy back
5) drive
[other opinions that might be helpful]
disconnect the battery for 5 min and press the brake pedal a couple times with the batt disconnected.
Once 5 minutes is over, start the car and let it idle for 1 minute. Do not rev, or drive the car until it has idled for 1 minute.
For 97 240sx (s14 ka24de)
2) Turn the screw full clockwise, hold 2 seconds, turn back
3) read the codes
4) Repeat step '2' to erase codes, start car to store them
-speedo/tach issue? Sending bad signal to ecu?
[obviously you should know if your guages are working or not, and even if they are check the wires with a voltmeter and your eyeballs]
Coolant temp sensor
Buy BWD Coolant Temperature Sensor WT607P at Advance Auto Parts (http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Coolant-Temperature-Sensor-BWD_3995232-P_425_R|GRPSESWAMS_____)
item # WT607P
[they're cheap as hell just buy one]
MAF issue [not working correctly or unplugged/badly wired]
-if your MAF is not connected
jiggle the connection to the MAF and your check the throttle. Your car is going into safe mode and rev limiting you at 2500 rpm. Typical of the car running with NO MAF plugged in.
If the MAF were bad then it would not run at all. It would either just flood out and die or not even start. With it unplugged it goes into safe mode and will run decently untill 2500 rpm at wich point it will hit a rev limiter.
It being un plugged could mean one of two things....
1. Either the MAF connection is loose/corroded and it has become unplugged or have such weak intermittent signal that ignores and goes into safe mode assuming broken MAF
2. The MAF IS broken and either it broke in a way that dissables the circuit and gives no signal. OR it was broke in a way that makes the car undriveable/flood out and was disconnected to make the car driveable enough to make it home safely. (Hense: Safe Mode)
Now you have a few options from here...
1. You can just spend mad money and buy a new MAF and Connector (just to be safe) and fix the problem now. It'll cost you around $400 btw for new ones.
2. Or you can do some diagnostics to save your self some money at the expese of work and time. You can get a Digital Multi Meter and check the wires per FSM for the proper voltages per FSM. You should find a variance. This will tell you if the wiring is bad or if the MAF/Possibly both are bad. Make sure it's plugged in when you check. If its the wiring you will know. If it's not that then it could be the MAF being broken in a normal way or the wiring is corroded or loose. work on the wiring to tighten the terminals if lose or clean them if they are in any way corroded. Connect tightly and check again. If still same then it's probably your MAF. If it's still no good you need to replace the MAF. Go to a junkyard and pay them for a used one. it's $50 around here.
From autozone they are $300 with a core charge of 35. I DON"T WANT TO KNOW how much they are at the STEALERSHIP. Install new one and check again. If still now good take that one back cause it didn't solve the problem meaning its etiher broke or your wiring is really just no good. Junkyards will give you the harness connector with it for free also btw. And they are gaurunteed to work or your money back. If you tried the new MAF but didn't replace the harness with it chances are you still have a wiring issue. The connection is very hard to repair once the terminals have been damaged by corrosion. A new harness only costs 20 bucks on ebay if one didn't come with your MAF. So I HIGHLY recomend replacing it if it's corroded in any way at all.
I have never owned a nissan that didn't have MAF problems, they are the main source of engine control in all nissans. That connection controls how much power your car makes or if it runs at all. The better that connection and more accurate that signal is the more power your car will have. PERIOD.
Heres a link that gives you info on how to check your maf and how to read your a/f ratio(02 sensor):
Important tech stuff if you own a 240. Or any car really. MAF CTS TPS O2 AFR A/F : 240SX Technical Forum (http://forums.nicoclub.com/important-tech-stuff-if-you-own-a-240-or-any-car-really-maf-cts-tps-o2-afr-a-f-t476094.html)
BTW an AFC works by altering the MAF output signal (control wire) before it reaches the ECU. This makes the ECU add or reduce fuel making the car either richer or leaner accordingly. With a good fuel pump and a A/F ratio meter you can gain 15hp easily with a good AFC by fine tuning it.
REPLACING THE MAF
Yes that is correct, pay close attention to the notches on the top and bottom of the maf, there are 2 notches on one side and 3 on the other, this is critical so you get the wiring right. When i first did mine it was wrong and i smoked the MAF.
Wiring: running an Ecu set up to run stock maf then it should be 02 in 05 out. If you have tuned ecu for z32 maf then it should be 02 in 02 out. Stock maf and stock ecu are o5 in and 05 out.
signal which is thin white wire , then you got power which is super thick white wire...rest are grounds
BUT someone said extra ground should go to the chassis
according to JWT guide
12 Volt
KA Black/White wire goes to Z32 E
0-5V Signal Wire
KA orange wire goes to Z32 B
Ground
KA black goes to both C and D on Z32
I'm unsure of the Z32 colors, as some are different. Follow the JWT guide as it works.
Fuel Pump
[test the pressure, if its bad then spend 75 bucks on a Walbro]
For part sourcing at the junkyard
Ka24de Applications
2000-2004 Xterra
1998-2004 Frontier
1993-2001 Altima
1991-1998 240SX
1997-2000 R'nessa (4WD model, Japan)
1998-2001 Presage U30 (Japan)
1999-2001 Bassara U30 (Japan)
1993-1997 Bluebird U13
Isuzu COMO (Japanese: Isuzu COMO)
Nissan Largo
Feel free to correct anything thats wrong
So your car won't drive past 2500 rpm? BOM BOM BOM BOM I almost made a girl on a vespa crash when it started happening to me lol
**I didn't actually write 99% of this shit, I just compiled it here. **
Fuel cut issues
check
-ECU limp mode/ how to check codes on ecu
http://www.zilvia.net/f/archive-faqs/10007-ecu-location-reset-codes.html
[some of the common ones that I wrote down for this]
12 Air flow Meter/circuit open or shorted
22 idle speed control valve or circuit
23 Idle switch (throttle valve switch) signal circuit open
25 Idle speed control valve circuit is open or shorted
29 Fuel system rich
33 egr malfunction
98 Coolant temperature sensor
resetting the ecu
to reset the ecu/ simplest explanation of reading codes
1) There are 2 screws that hold the ECU in place, one at the top just underneath the bottom of the dash, and the other is beneath the ECU to the side of the panel. Once these are taken off, take the dash screw off (right above the first ECU screw). Lift the dash a little bit while wiggling the ECU out, it's tricky but it'll get out.
Turn the ECU around and get to the back of it, you will see a knob with a notch in it beside a caution sticker. Follow directions, but if you want to know what threw the code, follow this:
-Turn ignition to on position (where most of the lights are on, brake, airbag, etc)
-Turn knob fully clockwise, wait two or more seconds, then turn knob fully counter clockwise
-The service engine light will start blinking, count the blinks. The first blinks are slow, this will represent a first digit.
-There will be a short pause, then the light will blink fast, these blinks will represent a second digit.
-For example, light blinks slow 5 times, and blinks fast 5 times, this is code 55
-If there is only one code, the light will just repeat the code over and over. If there are more, the light will also repeat each code one after the other.
-Once you know what the problem is (or if it's just general maintenance) fix it, and clear the code by starting the car.
2) (with key at on position but not running) turn the little screw thingy on the back all the way clockwise, the slot will point to a line on the unit wat 2 or more seconds (if you don't wait you'll just get different codes)
3) start motor
4) turn screw thingy back
5) drive
[other opinions that might be helpful]
disconnect the battery for 5 min and press the brake pedal a couple times with the batt disconnected.
Once 5 minutes is over, start the car and let it idle for 1 minute. Do not rev, or drive the car until it has idled for 1 minute.
For 97 240sx (s14 ka24de)
2) Turn the screw full clockwise, hold 2 seconds, turn back
3) read the codes
4) Repeat step '2' to erase codes, start car to store them
-speedo/tach issue? Sending bad signal to ecu?
[obviously you should know if your guages are working or not, and even if they are check the wires with a voltmeter and your eyeballs]
Coolant temp sensor
Buy BWD Coolant Temperature Sensor WT607P at Advance Auto Parts (http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Coolant-Temperature-Sensor-BWD_3995232-P_425_R|GRPSESWAMS_____)
item # WT607P
[they're cheap as hell just buy one]
MAF issue [not working correctly or unplugged/badly wired]
-if your MAF is not connected
jiggle the connection to the MAF and your check the throttle. Your car is going into safe mode and rev limiting you at 2500 rpm. Typical of the car running with NO MAF plugged in.
If the MAF were bad then it would not run at all. It would either just flood out and die or not even start. With it unplugged it goes into safe mode and will run decently untill 2500 rpm at wich point it will hit a rev limiter.
It being un plugged could mean one of two things....
1. Either the MAF connection is loose/corroded and it has become unplugged or have such weak intermittent signal that ignores and goes into safe mode assuming broken MAF
2. The MAF IS broken and either it broke in a way that dissables the circuit and gives no signal. OR it was broke in a way that makes the car undriveable/flood out and was disconnected to make the car driveable enough to make it home safely. (Hense: Safe Mode)
Now you have a few options from here...
1. You can just spend mad money and buy a new MAF and Connector (just to be safe) and fix the problem now. It'll cost you around $400 btw for new ones.
2. Or you can do some diagnostics to save your self some money at the expese of work and time. You can get a Digital Multi Meter and check the wires per FSM for the proper voltages per FSM. You should find a variance. This will tell you if the wiring is bad or if the MAF/Possibly both are bad. Make sure it's plugged in when you check. If its the wiring you will know. If it's not that then it could be the MAF being broken in a normal way or the wiring is corroded or loose. work on the wiring to tighten the terminals if lose or clean them if they are in any way corroded. Connect tightly and check again. If still same then it's probably your MAF. If it's still no good you need to replace the MAF. Go to a junkyard and pay them for a used one. it's $50 around here.
From autozone they are $300 with a core charge of 35. I DON"T WANT TO KNOW how much they are at the STEALERSHIP. Install new one and check again. If still now good take that one back cause it didn't solve the problem meaning its etiher broke or your wiring is really just no good. Junkyards will give you the harness connector with it for free also btw. And they are gaurunteed to work or your money back. If you tried the new MAF but didn't replace the harness with it chances are you still have a wiring issue. The connection is very hard to repair once the terminals have been damaged by corrosion. A new harness only costs 20 bucks on ebay if one didn't come with your MAF. So I HIGHLY recomend replacing it if it's corroded in any way at all.
I have never owned a nissan that didn't have MAF problems, they are the main source of engine control in all nissans. That connection controls how much power your car makes or if it runs at all. The better that connection and more accurate that signal is the more power your car will have. PERIOD.
Heres a link that gives you info on how to check your maf and how to read your a/f ratio(02 sensor):
Important tech stuff if you own a 240. Or any car really. MAF CTS TPS O2 AFR A/F : 240SX Technical Forum (http://forums.nicoclub.com/important-tech-stuff-if-you-own-a-240-or-any-car-really-maf-cts-tps-o2-afr-a-f-t476094.html)
BTW an AFC works by altering the MAF output signal (control wire) before it reaches the ECU. This makes the ECU add or reduce fuel making the car either richer or leaner accordingly. With a good fuel pump and a A/F ratio meter you can gain 15hp easily with a good AFC by fine tuning it.
REPLACING THE MAF
Yes that is correct, pay close attention to the notches on the top and bottom of the maf, there are 2 notches on one side and 3 on the other, this is critical so you get the wiring right. When i first did mine it was wrong and i smoked the MAF.
Wiring: running an Ecu set up to run stock maf then it should be 02 in 05 out. If you have tuned ecu for z32 maf then it should be 02 in 02 out. Stock maf and stock ecu are o5 in and 05 out.
signal which is thin white wire , then you got power which is super thick white wire...rest are grounds
BUT someone said extra ground should go to the chassis
according to JWT guide
12 Volt
KA Black/White wire goes to Z32 E
0-5V Signal Wire
KA orange wire goes to Z32 B
Ground
KA black goes to both C and D on Z32
I'm unsure of the Z32 colors, as some are different. Follow the JWT guide as it works.
Fuel Pump
[test the pressure, if its bad then spend 75 bucks on a Walbro]
For part sourcing at the junkyard
Ka24de Applications
2000-2004 Xterra
1998-2004 Frontier
1993-2001 Altima
1991-1998 240SX
1997-2000 R'nessa (4WD model, Japan)
1998-2001 Presage U30 (Japan)
1999-2001 Bassara U30 (Japan)
1993-1997 Bluebird U13
Isuzu COMO (Japanese: Isuzu COMO)
Nissan Largo
Feel free to correct anything thats wrong