WHAT YOU DO WHEN YOU RESET YOUR ECU! - can some one make this a sticky?
09-24-2003, 01:28 PM
#1
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Join Date: Jun 2003
Location: mostly at work
Posts: 147
Car Info: 93 impreza
WHAT YOU DO WHEN YOU RESET YOUR ECU! - can some one make this a sticky?
Ok, honestly, i am getting tired of every one pretending to be an expert and calling for an ECU reset with wiper fluid refill.
Every time ECU is reset it looses system status, and has to go through a set of internal tests to verify internal system functionality, mostly emissions control. Until these tests are complete (drive cycle tests) your car will run in a safe mode (default mode, almost a limp mode). This results in your car running much richer then normal to be on a emissions safe side, and on average for all test conditions to occur it takes 2-6 weeks. Which brings me to a point, every time ECU reset is done, it does more harm then good, but if one is determined to reset ECU every time a new gauge is installed, this will help you:
I would also suggest purchasing or renting an OBD II scan tool so you can verify all tests have been ran.
RUNNING AN OBDII DRIVE CYCLE
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you’ve erased any trouble codes from the PCM’s memory, or after the battery has been disconnected. Running through the drive cycle sets all the system status "flags" so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at ¾ throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
Thanks
Alex-
Every time ECU is reset it looses system status, and has to go through a set of internal tests to verify internal system functionality, mostly emissions control. Until these tests are complete (drive cycle tests) your car will run in a safe mode (default mode, almost a limp mode). This results in your car running much richer then normal to be on a emissions safe side, and on average for all test conditions to occur it takes 2-6 weeks. Which brings me to a point, every time ECU reset is done, it does more harm then good, but if one is determined to reset ECU every time a new gauge is installed, this will help you:
I would also suggest purchasing or renting an OBD II scan tool so you can verify all tests have been ran.
RUNNING AN OBDII DRIVE CYCLE
The purpose of the OBDII drive cycle is to run all of the onboard diagnostics. The drive cycle should be performed after you’ve erased any trouble codes from the PCM’s memory, or after the battery has been disconnected. Running through the drive cycle sets all the system status "flags" so that subsequent faults can be detected.
The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of one another).
NOTE: The ignition key must not be on prior to the cold start otherwise the heated oxygen sensor diagnostic may not run.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.
2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.
3. Hold at a steady state speed of 55 mph for three minutes.
OBDII monitors EGR, air pump, O2 sensors and canister purge.
4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.
5. Accelerate back to 55 to 60 mph at ¾ throttle. OBDII checks misfire, fuel trim and purge again.
6. Hold at a steady speed of 55 to 60 mph for five minutes.
OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.
7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge.
Thanks
Alex-
09-24-2003, 02:57 PM
#3
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Thread Starter
Join Date: Jun 2003
Location: mostly at work
Posts: 147
Car Info: 93 impreza
my brother is in college for auto mechanic, I originally found info on OBD II drive cycle in his books. For the lack of motivation to retype the page i copied this patricular info from: here (http://members.aol.com/carleyware/library/us796obd.htm)
also here: http://www.obdii.com/drivecycle.html
also here: http://www.obdii.com/drivecycle.html
Last edited by awd4ever; 09-24-2003 at 03:00 PM.
09-26-2003, 07:55 PM
#8
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Join Date: Jun 2003
Location: mostly at work
Posts: 147
Car Info: 93 impreza
on the contrary, the more things are computer controlled, and computer limited, the easier it will be to modify.
A reletevly simple piggy back can unlock your cars full potential by lying to your computer about sensor readings.
A reletevly simple piggy back can unlock your cars full potential by lying to your computer about sensor readings.
09-30-2003, 04:01 PM
#10
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Posts: n/a
Thanks for the info...
Shouldn't the ECU be reset whenever a change is made? Cats taken off, uppipe, more boost, race gas, for example? Any ideas on what the WRX ECU does when it sees missing cats ?
Shouldn't the ECU be reset whenever a change is made? Cats taken off, uppipe, more boost, race gas, for example? Any ideas on what the WRX ECU does when it sees missing cats ?
Which brings me to a point, every time ECU reset is done, it does more harm then good, but if one is determined to reset ECU every time a new gauge is installed, this will help you:
10-02-2003, 06:02 PM
#11
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Posts: n/a
i got a powerflow catback exhaust fitted on my 95 wrx *** import
but the company accidentally removed my 3rd cat(rear cat in midpipe) my ecu is now going mad all the time
backfires, loss in power ,hesitation and all round very rich
it goes away after an ecu reset but comes back after a day or so
this must be coz the ecu eventually reads the 3rd cat missing hence problems
but the company accidentally removed my 3rd cat(rear cat in midpipe) my ecu is now going mad all the time
backfires, loss in power ,hesitation and all round very rich
it goes away after an ecu reset but comes back after a day or so
this must be coz the ecu eventually reads the 3rd cat missing hence problems
10-03-2003, 03:39 AM
#12
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Join Date: Jan 2003
Location: 1
Posts: 52
Car Info: 95 1.8 fwd auto -> 95 2.5 awd 5sp
get one of these O2 fixes off ebay. I hear they work, no phun. it just reads back to ecu the voltage it would get under normal conditions... you should be able buy one of these from a boat store for 5$
10-04-2003, 12:09 PM
#13
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Originally posted by Captain Ned
Ye Gods, I hope that the OBDIII system described in that linked article never comes to pass. If it does, and as described, you'll never be able to mod anything.
Ye Gods, I hope that the OBDIII system described in that linked article never comes to pass. If it does, and as described, you'll never be able to mod anything.
Personally, I don't want people knowing where I am. That could also end up being used for traffic enforcement as well. The GPS sees you going 100 in a 55, and you get mailed a ticket.
10-05-2003, 11:45 PM
#14
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Join Date: Jan 2003
Location: 1
Posts: 52
Car Info: 95 1.8 fwd auto -> 95 2.5 awd 5sp
If i am not mistaken such a law got declined, but i do think it's only a matter of time till it passes. Then we'll have to have a chip to remove RPM fuel cut, Governor, and GPS monitoring... Did you know that a law has passed that every new cellphone should have a GPS locator to allow emergency responce units locate you within 3 meters?
