Poor cold start,,,a clue!

[toughguych]

Hi All,
I have been having problems with my 325i not wanting to start when its cold.
Its becoming a daily grind, siting in the car playing with the throtal and hoping the car will stay running. Its very rough when cold.
Done loads to it, all the usuall bits replaced and checked.
I noticed whilst warming her up this morn that when she is about to die, like all power to the engine has been cut for a split second. The mpg needle goes all the way over to the left: 50+ miles per gallon.
Would this indicate Fueling problems when she is cold and how can I do a full injector test. Is there an artical on how to do it from start to finish?

[toughguych]

Come on, someone must have an idea?

[rj]

Hi

If I remember correctly, if the econometer shows a fuel cut, the problem can be in the air flow meter.

If the problem occurs only when cold, there is an intake temp.sensor in the meter which could be causing the cold start prob.

To measure the resistance of the sensor, connect, if I remember, pins 9 and 8. At room temperature it should be about 2.2 to 2.7 kOhms. Then apply heat from a hair dryer and blow warm / hot air through the meter. The resistance should drop down to a couple of hundred ohms or thereabouts.

[toughguych]

Thanks rj, I will give it a go.

[toughguych]

Ah, just one thing, are pins 8 & 9 on the ECU?

[tonyppe]

im not sure here, but connecting stuff up straight to the ecu dont sound right. it may be the little plug on top of the engine under that screw cap.... but i dunno

[toughguych]

Just checked Haynes.
Now I know where about those pins.
Will do the tests soon.
Not 2morrow, it Christmas day! ( well maybe if I get time in the morning! )

Cheers all.

[rj]

There are obviously pins which correspond on the ecu but they are not the ones numbered 8 & 9. I think one is pin 44 but I'm not sure. On the connector to the air meter they are the extreme right pin and third from right I think.

Keep us posted as to the diagnosis.

[toughguych]

Ok, well,
did some tests on the afm and sure enough there was not continuty of resistence when I opened the afm door.
In fact resistance went up then down then up again during the coures of the flap being opended.
I put in my old afm which I replaced when I was having similar problems 2 years ago! ( with a second hand one )
Well, it now starts ok but revs to 1.5 rpm when warm. Only after you come to a complete rest for about ten seconds does it settle back to normal tick over.
A new afm is £400 from my local dealer. This seems abit expencive as I have heard around here they should be £250. Is that correct?
But we are getting there as far as getting the car to run properly goes!

[rj]

I have never bought an AFM, but I thought the dealer price was about £330-350.

At least after you have replaced the AFM with the older one, the engine is now starting ok.

Have you checked the coolant temp.sensor and is the throttle position switch set correctly. Does the engine perform normally otherwise or are there other symptoms? I presume your ICV is cleaned?

[toughguych]

Thanks, yes all that is ok.
Prob was with the afm but I dont think the old one which is now back in is 100%.
But its a lot better.

Cheers.

[toughguych]

Well, it was a lot better but last two days starting has become worse then B4.
It seems the gemlins under my bonnet have found the AFM and started eating it!
Well, I need to find someone to lend me a good one for a day.
But I am not UK Mainland. I Live in the Channel Islands so will have to ask around here,
Will keep ya posted......

[Speedtouch]

Why not take the cover off one of your AFMs and try cleaning it out with contact cleaner or similar...AFAIK,, it's only a relatively crude rheostat (variable resistor).

[toughguych]

Thats an idea, thanks.
I had the opinon from what i have read that when they dont work anymore you just have to replace them but I will give it a go.

Cheers.