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2002- Altima 3.5L - high idle speed

Posted: 29 Mar 2022, 18:02
by Jojo99
I purchased the NDS software with the hope that it would help with getting the idle speed back on track (P0507 code). But so far it has failed.

Why does the Idle learn function have to run to a count of 5000 before it fails? What is it doing over these 5000 units? Is there some way to reduce or control this number?

My buddy, who used to work as a Nissan mechanic, says their Consult software did not count to 5000 like this.

I have made sure that I meet all the required parameters before starting the Idle learn function. I have replaced the PVC valve, cleaned the throttle body wire connections and checked for loose wires, cleaned the throttle butterfly area, ensured it closed fully and have not been able to find any obvious vacuum leaks.

Now I sit around watching the count climb to 5000 multiple times but get rewarded with this unhelpful message:

"ECU unable to complete IAVL procedure. Check service manual for possible causes."

As I mentioned previously with the connect cable issues, here must be some error code returned as to WHY the process won't complete. Is there an error code that ID's WHAT the problem is that you are not returning?

Anyway, I looked at the EC manual but don't see anything that points to why the idle speed will not "learn".

So what now?

Re: 2002- Altima 3.5L - high idle speed

Posted: 31 Mar 2022, 18:13
by Jojo99
It might be helpful to get a reply Tom.

Re: 2002- Altima 3.5L - high idle speed

Posted: 03 Apr 2022, 16:58
by Jojo99
Are you still researching the points I raised, Tom? Waiting for the developer to get back to you?

Re: 2002- Altima 3.5L - high idle speed

Posted: 04 Apr 2022, 16:30
by Tom
So you have tried all the suggestions in the service manual and everything checks out? Did your Nissan mechanic friend have any suggestions?

How high is your idle?
What are your fuel trims: Short Fuel Trim, Long Fuel Trim, A/F Alpha, A/F Alpha stored? You should have some of them but probably not all.

Eagerly waiting for your next reply

Re: 2002- Altima 3.5L - high idle speed

Posted: 05 Apr 2022, 10:21
by Jojo99
Eagerly is good!

Yes, so far everything checks out I think. We can't find any leaks after taking apart the top of the engine again a couple of days ago and checking every hose within reach (also pulling it off the nipples and putting it back on again). We cleaned the TB. Also replaced the PVC valve.

The idle stays between 925-1025.

Don't know about fuel trims. See them defined in the appendix of the UM but don't see any other reference in the manual to these. Where are they in the software?

Re: 2002- Altima 3.5L - high idle speed

Posted: 07 Apr 2022, 16:58
by Jojo99
I took my car to the shop (independent, not Nissan), wound up being charged 350 (2 hours work) and they got the idle set correctly. Car running nicely now.

It's sad that the NDS software wasn't up to the job and all it could offer was unspecific errors.

Re: 2002- Altima 3.5L - high idle speed

Posted: 10 Apr 2022, 21:36
by Tom
So the mechanic was able to lower the idle RPM without performing the IAVL?

Re: 2002- Altima 3.5L - high idle speed

Posted: 12 Apr 2022, 13:52
by Jojo99
No, he did an IAVL using something he has in his shop (I assume the smog machine). He told me he had to remove 3 injectors (tried one at a time) to get the RPM low enough for the IAVL to take.

My buddy & I had removed only 2 injectors to get the RPM below 1000, which everyone says is th enumber necessary for the reset to take. We would have tried more but he didn't have the time to sit around waiting for whatever the NDS software is doing while it counts to 5000 with fingers crossed that it might work. Instead, he stated that the NDS software probaby is the failure point.

As a former programmer with a strong technology background, none of this makes any sense to me.

- WHY is RPM below 1000 a necessity for the IAVL to work? Is this a NISSAN programmed requirement?

- WHAT is the NDS software doing for apparently 5000 tries in attempting to do an IAVL? Retries of something? Why not quit after 10 or 20 failures?

- It would have been helpful if NDS could have returned a status of "RPM too high" for the IAVL to work. If such status isn't available, then that seems to be a failure in NISSAN's programming. If it is available and you don't pick it up, then the failure would be on you.

Re: 2002- Altima 3.5L - high idle speed

Posted: 21 Apr 2022, 16:38
by Tom
The NDSII software is counting while the ECU is returning "ECU busy" message. There is no other information provided by the ECU. After counting to 5000 it just gives up.

It would be good if the ECU provided some more information about why it can not complete the IAVL but this unfortunately is not the case. That's why its important to follow all the prerequisites and fault finding steps in the service manual.

So the mechanic could not complete the IAVL procedure with the "smog machine" until disconnecting 3 injectors?
And you only tried to disconnect 2 injectors with the NDSII software right?

Re: 2002- Altima 3.5L - high idle speed

Posted: 23 Apr 2022, 18:42
by Jojo99
"So the mechanic could not complete the IAVL procedure with the "smog machine" until disconnecting 3 injectors?"

That is what he told me. If accurate, it implies that he had to keep reducing the unadjusted idle speed to get it to work.

So what is magic about the 5000 number? Why not 1000, 2000, 0r 3300 retries? Apparently that number is hard coded in the program. It should be set via a parameter.

If the ECU doesn't provide status info, then that is on the team at Nissan that developed the code. Hopefully, they do a better job with newer cars.