High tick over after changing air flow meter

[jamie74]

Hi folks,

Just wondered if anyone could advise me with a problem with my 2.5!

Over the last couple of weeks my car has been hesitating when pulling away and also doing a bit of kangarooing whilst creeping along at low speeds. On friday when I was stook in traffic on the motorway the idle tick over was all over the place ranging from 1500rpm down to virtually cutting out and then settling back at it's usual idle of 800rpm. I was told that it was more than likely a faulty air flow meter and told to try changing it as it's a common fault on m20 engines. Yesterday I changed the afm and it cured the hesitancy and low speed kangarooing, just one problem now, the car will not tick over any lower than about 1200rpm even when it's warm and up at normal temperature!! Have I fitted another faulty afm or is this something the ecu might cure over the next few days or so?

Any help will be much appreciated!

Regards

Jamie

[jamie74]

I'm thinking maybe the afm wasn't the problem to start with. So questions are:

1. Do I change the afm for another one or leave it to see if it settles?
2. Could something else be causing the original problem(1st Post)of bad idle/kangarooing?

Jamie

[Brianmoooore]

Since it costs nothing, in money or effort, I'd just drive it for a few days, in case it's just the ECU has completely lost the idle settings.

[jamie74]

I was thinking of leaving it for a few days to see if it corrects itself, I remember when I had the battery taken off my other touring(2.0 Auto) that took days to reset itself!! Do you think I am on the right track with my original problem of bad idling/kangarooing? I'm no E30 or mechanical expert so apologies if I'm being dumb, thanks for the reply.

Jamie

[Brianmoooore]

Your original fault sounds typical of a slightly weak mixture, which can have many causes - minor air leaks, less than perfect injectors can all contribute to this, as well as a possibly faulty AFM.
First thing to check is the condition of the large air hose from the AFM to the throttle body, and whether the throttle position switch is doing what it should.

[jamie74]

Thank you Brian for the advice, yesterday whilst swapping the afm I did check the large air hose which seems ok, I will look in to the throttle position switch. Will have to revert to my recently purchased Bentley Manual for the TPS operation as I'm an E30 novice! I will look down the injector fault route last as I'm presuming this would be the most expensive.

Regards

Jamie

[Brianmoooore]

I will look down the injector fault route last as I'm presuming this would be the most expensive.

Have a look in our 'trader' forum.