Poor starting and idle.

[mikesmith]

Hi all, has anyone come across this before? When I start my V8 it winds over for a while before it starts then pops the head lights up then down again. The idle is very hit and miss sometimes at 2000 rpm some times not at all, new IACV fitted and all other sensors appear to be working ok? Do the ECM's give trouble? and can they be tested? if so who can do this reliably? Also when the AC is on it doesent always pick the idle up correctly and the cooling fans run all the time. Do V8s typicaly take some winding up to get them started? as in 3-4 secs? hot or cold. Many thanks. Mike.

[matk]

I'm not a V8 expert but from previous posts, the headlights do that when you're battery is getting low. As far as the cooling fans go I believe (someone correct me if I'm wrong) they do run all the time with aircon switched on.

Can't help with the other stuff......

[redshift]

Yes the headlights popping up while cranking is a sure sign that the battery is about to expire.

I just wonder whether the voltage drop that causes this goes low enough to reset the ECU base settings?

Mine did act a little strangely just before I changed the battery (not quite as extreme as your symptoms) but definately the headlights/odd idle part.

Since fitting the new battery all has returned to normal.

[superdavelotus]

It's not necessarily a dead battery more a large drop in charge from the battery. This can be from lack of use. I'v ehad this sympton for past two years but it's only through lack of use. If I go on a long run or use my car for a few days on the run, the battery charges and symptoms go away. It's the alarm, imobiliser and tracker all taking a drain.

If you do use your car regularly then it's likely it's the battery, although, a bad earth to chassis can emulate these symptoms too!

Regards,

Dave Walters

[mikesmith]

It's not necessarily a dead battery more a large drop in charge from the battery. This can be from lack of use. I'v ehad this sympton for past two years but it's only through lack of use. If I go on a long run or use my car for a few days on the run, the battery charges and symptoms go away. It's the alarm, imobiliser and tracker all taking a drain.

If you do use your car regularly then it's likely it's the battery, although, a bad earth to chassis can emulate these symptoms too!

Regards,

Dave Walters

I have had a look at the battery and found it to be a Halfords special Going to change it and go from there. You lot are just too helpful Thanks, Mike.

[Bibs]

As far as the cooling fans go I believe (someone correct me if I'm wrong) they do run all the time with aircon switched on.

Not a correction as such but a point of order, the fans run with AC on under 30mph, over that the airflow does the work and the fans switch off.