Nissan Primera P11 ECU recalibration procedure

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   Hey guys and girls,

I need to reset my ECU after I'm done fiddling with my crankcase vent and air intake. Now this is what i know:

Disconnect the positive part of the battery
Wait around 30 minutes
Then reconnect the positive part of the battery
and then?

There has to be some procedure to recalibrate my ECU on the modified air intake of my car. It's probably stated in some service manual, which I don't have.

Any help is greatly appreciated.

Greetings,
Bas Kapteijn

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baskapteijn Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 19 Mar 2010 Online Status: Points: 114	Post Options Post Reply Quote baskapteijn Report Post Thanks(0) Quote Reply Topic: Nissan Primera P11 ECU recalibration procedure Posted: 14 Jul 2010 at 10:11am
	Hey guys and girls, I need to reset my ECU after I'm done fiddling with my crankcase vent and air intake. Now this is what i know: Disconnect the positive part of the battery Wait around 30 minutes Then reconnect the positive part of the battery and then? There has to be some procedure to recalibrate my ECU on the modified air intake of my car. It's probably stated in some service manual, which I don't have. Any help is greatly appreciated. Greetings, Bas Kapteijn

Ant-Dat Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List NPOC Legend 1998 Primera GT Joined: 15 May 2003 Location: In workshop Online Status: Points: 16125	Post Options Post Reply Quote Ant-Dat Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 10:16am
	nissan ecu has self learn, if you want to clear the ecu it need disconnected for 24 hours, or done via a consult
	SB "he isn't human, he is a machine that never falter

jayc Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 01 Feb 2009 Online Status: Points: 579	Post Options Post Reply Quote jayc Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 11:12am
	There's little point in reseting the ECU. All the ECU does is work on short and long term fuel trims. A fuel trim is the percentage the injection duration is altered from the factory map to keep the motor stoich. The short term trim will change instantly the motor is up to temp as this is trim'd on the fly. The long term trim is what the motor learns over a peroid of time (usually takes around 50 miles for the trim to settle). So lets say for example your existing long term trim is at say 9% (this is just my estimation and takes into account gerneral wear and tear) and you reset the ECU back to 0%. Now you've added a modified air intake to I assume suck in more/cooler air? Now with more air coming in the ECU will need to increase the injector duration to keep the motor stoich. With the fuel trim at 0% it will take slightly longer for it to settle as it has to start at a lower figure (it's based on average short term trim over time). If you'd left it the same it would likely just increase by 1 or 2% a lot quicker.

baskapteijn Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 19 Mar 2010 Online Status: Points: 114	Post Options Post Reply Quote baskapteijn Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 12:13pm
	Hello Jayc, Thanks a lot for your reply(both of you). That's really great information! The reason why I wanted to reset my ECU is because I will remove the crank vent from the air housing and close the holes on the air housing. I don't want those hot oily gasses in my air-intake. Most reactions on ECU questions about P11's (all over the web) suggest to reset the ECU(by battery disconnect or a screw on the ECU). However, I really think that what you tell me is true so I'll first try that. Ill modify my air housing and just drive for an hour to a distant friend to stabilize the long term trim. That's it for now, I will post a reaction when I'm done or having problems ;). Greetings, Bas

Ant-Dat Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List NPOC Legend 1998 Primera GT Joined: 15 May 2003 Location: In workshop Online Status: Points: 16125	Post Options Post Reply Quote Ant-Dat Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 12:22pm
	there is no screw on P11 ecu, hasn;t been on a nissan ecu from the late 80's early 90's. The screw on the older ecu was there to put the ecu into service mode not reset. Rest was also done by disconnecting battery for a period of 24 hours. Expect running issues if you do that with the crank venting btw.
	SB "he isn't human, he is a machine that never falter

jayc Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 01 Feb 2009 Online Status: Points: 579	Post Options Post Reply Quote jayc Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 2:24pm
	There are enviromental factors to consider before venting crankcase fumes to the atmosphere. Personally I wouldn't do it but then again I'm a bit like Dave Angel :)

twelve Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Legend Elite Top Tosser Joined: 04 Oct 2008 Location: Frimley Online Status: Points: 9688	Post Options Post Reply Quote twelve Report Post Thanks(0) Quote Reply Posted: 14 Jul 2010 at 2:38pm
	I wouldn't bother. You really wont get any gains from it.


baskapteijn Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 19 Mar 2010 Online Status: Points: 114	Post Options Post Reply Quote baskapteijn Report Post Thanks(0) Quote Reply Posted: 19 Jul 2010 at 7:58am
	Hey guys, Thanks a lot for all the advice. I couldn't help myself however to reset my ECU by removing the (+) cable on my battery and letting it off for one hour. Then I reconnected it and let my engine run idle until the fans did turn on. Then I took it for a 70 km (43 miles) drive, driving fast and slow on regular intervals. I must say that the engine seems to react a bit quicker than when I did the mod of my crankcase (the day before) and didn't reset it (and also drove 43 miles). However this could also just be some human feeling that's not based on any facts so don't hold me to it ;).

baskapteijn Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 19 Mar 2010 Online Status: Points: 114	Post Options Post Reply Quote baskapteijn Report Post Thanks(0) Quote Reply Posted: 19 Jul 2010 at 8:00am
	Oh and Jayc, As you'd probably already guess, environment issues are considered but not a real decisive factor in modifying my car.