torsteinvh

Hi!


After a recent ECU reset my idle speed is fluctuating between 640 and 940 RPM.
I did some DeltaDash logging, and noticed that the Front O2 Sensor Voltage never drops below about 0.875 V.

I compared the log to another log where the idle is OK, and there the O2 voltage varies between 0 and 0.825 V.

I'm no expert on this, but I suspect my O2 sensor is gone bad?
My car is a MY00 Wagon.

Anyone willing to take a look at the following logs and offer some advice?

Erratic idle
OK idle


Best regards,
Torstein

The_Judge

Looks like lambda to me as well. However, when mine went (MY00), the AFR readings (I don't have DeltaDash) were all low - around 0.3-0.4 - and were very static. I replaced the sensor, and the lights were all over the place; doing what they should be.

Regards,

Ade.

WREXY

Was the "erratic" log done immediately after engine start up? You have to wait a few minutes idling before the readings start fluctuating.

It may be your MAF instead. I'm suspecting this because your problem started after the ECU reset. The ECU can learn to operate the car with a failing MAF in some cases and you don't realise there is a problem. Once the reset's been done the problem shows up.

Try the log again, but give it a few minutes before determining that there is no fluctuation. If say after 5 minutes there is no fluctuation, it probably is the lambda.

Cheers,

George.

[Edited by WREXY - 10/27/2003 2:32:58 PM]

messiah

this sounds familar to my "Am I running lean" thread

my MAF looking spotless the other day and I've also have lambda sensor suggested to me - how much are these to replace?

torsteinvh

Wrexy, I did several logs on the the way to work, I have another 'idling-log' done five minutes after the one I posted.

I started this log when I arrived at work, just prior to turning off the engine.

Idle RPM are steady at just below 800 for about 10 second, then it starts fluctuating.

Erratic idle 2

My local garage also suggested the MAF, they will look at my car on Wednesday, I guess I will now for sure then.

-Torstein

WREXY

Have a look at the diagnostic trouble code reader in DD. Have a look to see if there are any fault codes. Also to test MAF, do a run at WOT in 3rd gear from around 2500rpm to below redline and post the results on the same link. We'll see if it's running lean.

How does the car drive since the reset?

Cheers,

George.

torsteinvh

Wrexy and others, thanks for your input

No fault codes, already checked that.

The reason for the reset was that the car seemed to hesitate a bit, and also felt a little 'juddery' (I don't know how else to describe it) on lower RPMs, especially around 3000.

After the reset it behaves mostly the same, with the additional idling problems.

I'll see if I can manage a WOT-run tomorrow, but winter has arrived with a couple of centimeters of snow, and I'm also a bit worried about running the car lean on purpose...

-Torstein

WREXY

OK m8. Don't risk it. From the idling logs it points to lambda I'd say. But there's still a chance it may be the MAF. It would be good if you could borrow a MAF off someone, install it to your car to see if the problem goes away. If it does then you know it's the MAF if it doesn't it should be the lambda.

Cheers,

George.

torsteinvh

Garage just called, they say it is the MAF. They are changing it now, so I will now for sure if it is OK when I pick up the car later today.

-Torstein

[Edited by torsteinvh - 10/30/2003 1:20:19 PM]

WREXY

Let us know.

torsteinvh

Just picked up the car, it felt a lot better on the drive home. Rock steady idle, and acceleration seemed smoother

Seems like the MAF change fixed the problems, I'll do some logging in a couple of days and compare with the logs with the faulty MAF.

But so far so good

-Torstein

WREXY

Good one.