Idle Relearn not working

[ballbluehorse]

Hi All
I have 2008 2.5 Elgrand bought recently with problem Idle. Engine idles and hunting between 1500 - 2200 RPM. I thought this will just need an Idle relearn using the NDS11 app.
I tried the idle relearn using the app with all conditions satisfied i.e engine warm, electrical loads off, steering straight etc. It keeps saying ECU Busy then it times out and says IVAF failed. I have checked for vacuum leaks, cleaned throttle body etc but no luck.
I have heard that if the idle to start off with is too high above 1200 RPM or hunting badly then idle relearn with the NDS11 app will not work. On some websites it suggest disconnecting one or two injectors to bring the idle down before doing the Idle relearn with the app might be the solution to get it to work.
Anyone who has heard or tried this procedure or anyone with any ideas of solving this problem
Help is much appreciated.

 

[LeStempy]

Try going to the active test page and start and stop each function other than the fuel pump. When you then turn the ignition off and start again it should reset any values that might be corrupt.

 

[ballbluehorse]

Try going to the active test page and start and stop each function other than the fuel pump. When you then turn the ignition off and start again it should reset any values that might be corrupt.

Thank you very much for your advice. do you mean start and stop on the active test page functions of the NDS11 the app?

 

[LeStempy]

Thank you very much for your advice. do you mean start and stop on the active test page functions of the NDS11 the app?

Yes, NDS2. You can have a play with the settings on that page as the changes aren't permanently memorised and will reset to default once the ignition is switched off.

 

[Lpgc]

Are you reading RPM from the revcounter or from NDS2? I see a lot of incorrect revcounters... Seems that when people change dials to mph dials they're more likely to try to get the speed pointer but back on in the correct position than the revcounter pointer lol. I wouldn't doubt the range of fluctuation you've said but I'm asking is it hunting between 1500 and 2200 or could it be hunting between (say) 900 and 1600? Heh, the 2.5 I've just finished converting to LPG shows 1100rpm on the revcounter when really it's idling at 730rpm (at 80C with no loads).

A common cause of idle hunting (periodically rather than quickly switching between slow/fast idle), particularly on 2.5's, is due to fuelling going rich (quick idle) / lean (slower idle). If, say, there's a problem with the MAF, or false air (vacuum leak or intake ducting leak), or a range of other problems, what can happen is: The fuel system runs closed loop during which fuel trims will be applied and mixture gets nearer to correct, but then when fuel trims peak at maximum for a while the system sees it as a fault condition and switches to open loop mode in which the fuel trims are not applied and then the engine suddenly gets a lean mixture which reduces the idle rpm. Then after a while of open loop the system tries closed loop again and we go back to the start so the hunting continues.

If there's been an error such as fuel trims maxed out IAVL often won't run. 2.5's Won't necessarily learn idle fuel trims until certain runtime (engine operation during actual driving) tests have been passed behind the scenes.

Could try taking it for a drive (if it will drive OK), then turn it off, restart it and see what idle speed is and what fuel trims are doing at idle. If trims are OK (not maxing out), engine temp is within correct range for running the IAVL, no electrical loads such as the cooling fan(s) running, then try running the IAVL at that point.

You can turn injectors off but there's little chance of successfully running the IAVL with any turned off and even if it did run it wouldn't give correct idle speed after you'd turned injectors back on again... But you can try things like turning injectors off to see if idle speed remains lower or doesn't surge after you've turned them back on again. Could also maybe turn off the only main electrical load you can't usually manually control using NDS - the electric fan. Idle speed varies quite a bit on 2.5's for electrical loads and the cooling fan draws a lot of amps. Does the cooling fan normally work as it should?

If you leave a 2.5 idling the engine temp will eventually become too hot for the IAVL to run.

 

[ballbluehorse]

Are you reading RPM from the revcounter or from NDS2? I see a lot of incorrect revcounters... Seems that when people change dials to mph dials they're more likely to try to get the speed pointer but back on in the correct position than the revcounter pointer lol. I wouldn't doubt the range of fluctuation you've said but I'm asking is it hunting between 1500 and 2200 or could it be hunting between (say) 900 and 1600? Heh, the 2.5 I've just finished converting to LPG shows 1100rpm on the revcounter when really it's idling at 730rpm (at 80C with no loads).

A common cause of idle hunting (periodically rather than quickly switching between slow/fast idle), particularly on 2.5's, is due to fuelling going rich (quick idle) / lean (slower idle). If, say, there's a problem with the MAF, or false air (vacuum leak or intake ducting leak), or a range of other problems, what can happen is: The fuel system runs closed loop during which fuel trims will be applied and mixture gets nearer to correct, but then when fuel trims peak at maximum for a while the system sees it as a fault condition and switches to open loop mode in which the fuel trims are not applied and then the engine suddenly gets a lean mixture which reduces the idle rpm. Then after a while of open loop the system tries closed loop again and we go back to the start so the hunting continues.

If there's been an error such as fuel trims maxed out IAVL often won't run. 2.5's Won't necessarily learn idle fuel trims until certain runtime (engine operation during actual driving) tests have been passed behind the scenes.

Could try taking it for a drive (if it will drive OK), then turn it off, restart it and see what idle speed is and what fuel trims are doing at idle. If trims are OK (not maxing out), engine temp is within correct range for running the IAVL, no electrical loads such as the cooling fan(s) running, then try running the IAVL at that point.

You can turn injectors off but there's little chance of successfully running the IAVL with any turned off and even if it did run it wouldn't give correct idle speed after you'd turned injectors back on again... But you can try things like turning injectors off to see if idle speed remains lower or doesn't surge after you've turned them back on again. Could also maybe turn off the only main electrical load you can't usually manually control using NDS - the electric fan. Idle speed varies quite a bit on 2.5's for electrical loads and the cooling fan draws a lot of amps. Does the cooling fan normally work as it should?

If you leave a 2.5 idling the engine temp will eventually become too hot for the IAVL to run.

Hi Alan
Thanks for the reply. The car is hunting between 1500 to 2200 RPM. You can actually hear the the engine loudly as it hunts/surges so rev counter is accurate

 

[Lpgc]

Hi Alan
Thanks for the reply. The car is hunting between 1500 to 2200 RPM. You can actually hear the the engine loudly as it hunts/surges so rev counter is accurate

It's Simon but no worries, you're welcome.