440 2.0 B20f idle issue when cold

[RadSpeed]

Hi

Have recently bought a 1995 440 2.0 auto with the B20f engine.

Have already changed the timing belt, plugs, leads, distributor parts, as well as new oil and coolant as was in need of a good service.
Managed to drive it home with what was later discovered as two teeth jumped on the timing belt!

Now the car runs pretty well, good power when driving- however when starting the car from cold it idles very lumpily and RPMs drop down and stalls after a few seconds.
Eventually will run after a bit of revving, but then after a decent drive seems to idle too high ~1300.

Have removed the Bosch ICV to clean and test- 12v applied to it on the bench makes it snap straight open. Have also measured the plug in the engine bay and ~13.5V showing there whilst running.

However when connected the valve doesn’t seem to open or close- had the car idling by putting thumb partially over the disconnected idle valve inlet so I could look into the valve and it remains in the off position when idling or throttle open.

Anyone have experience with these idle valves, or suggest anything else that might be causing the rubbish idle?

Thanks in advance

[dcw]

Hello

Good cars, aren't they? Lucky to get away with two teeth out on the cambelt though!

Check the resistance on the ICV - it should be 8 ohms. Also, is it clean inside? they're renowned for gunging up. Petrol is often the best to get them clean and shiny again...

In case it's something else there is an OBD 1 error code system in these cars via the little black box in the NS strut tower under the bonnet. If the ICV isn't the answer come back and I'll enlighten you further on reading the codes...

Good luck

David

[RadSpeed]

Hi David,

Thanks for such a speedy reply!

I have made sure the valve is clean, and resistance is as expected. It definitely opens if I put a battery across it.

I did also test the plug again, this time with a 21w bulb across it instead of open circuit and only got 6V whilst running- not sure if this is a valid test as I’m not an electrician! But could this signify that there is an issue with the feed too the plug?

I did also have a read up on the diagnostic block and only got 1-3-2 out of plug 2, which I believe is ‘incorrect battery voltage’. Let me know if that’s not right, but it didn’t seem to make much sense as the battery is fine!

Thanks again

[RadSpeed]

Just to add some other info:

Disconnected the ECU plug in the footwell- no corrosion or water so looked good.
Put a multimeter into each wire out of the ICV and into each pin of the ECU plug and found:

ICV wire Gray-Red to Pin 13 : 20 ohm
ICV wire Gray-Red to Pin 1 : 1.6 ohm
ICV wire Gray-Red to Pin 25 : 1.4 ohm
ICV wire Green-Brown to Pin 24 : 0.7 ohm

Haynes diagram shows pin 1 as ground
Pin 13 and 25 not listed
Pin 24 links to the Gn-Br so no issues there.

Will try and trace the wires and see if any damage along them today.

[RadSpeed]

Problem solved!

A wire had chafed through in the footwell to drivers door area- bizarrely it seems to have been connected to the boot lock as this now functions with the central locking, but the ICV now audibly clicks open on ignition too.

Thanks for reading !

[dcw]

Pleased it's sorted!

You'll find all sorts of strange connections between random things with the electric wiring in these cars. Quite why a drain to earth on boot lock wiring should trouble the ICV is anyone's guess....

David