Poor idle after battery change
 

Hi, I have searched and read a few posts on this, but they are mostly related to diesel engines.

Car: 2002 V40 1.8i Petrol 122bhp

My problem: After returning from a 2 week holiday, someone had tried to break into my V40, and as a result, the alarm flattened the battery. The battery completely died and would not re-charge, so I have replaced it, but now the engine will not idle very well. It stalls after revving, and during idling it raises and drops engine speed.

I have seen posts relating to Idle control valves and others about the ECU resetting due to the battery change, but I am not sure which is applicable to my engine.

Any help will be gratefully received.

Thanks, Richard

It's not something as simple as dirty or loose battery terminals?

Possibly, they were very dirty. Can you explain how this would affect idle speed? I'll check this tomorrow.

Thanks,

Richard

You have a GDi and would benefit greatly from using the re-learn.
Here you go:thumbs_up:

Learning function if GDI engine.
On GDI equipped cars, when the ECu is replaced or the battery is reset (disconnected), an idle
learning function for the ECU will be required

Idle Learning Procedure

1. Start the engine and warm the engine until the coolant temperature reaches 85c or higher.
When the coolant temperature is 85c or higher, you only have to switch the ignition to the
ON position.

2. Turn the Ignition to the LOCK position to stop the engine.

3. After 10 or more seconds, restart the engine.

4. Run the engine at idle for 10 minutes with Transmission in nuetral (P for Auto), air con
and heater off.

5. Stop the engine.

6. Restart the engine and run it at idle for 10 minutes with Transmission in neutral
(P for Auto), air con on at
max cool, fan high speed and windows open.

7. Repeat steps 5 and 6.

Note:
1. When ambient temp is 20c or higher and the air con has been continually operated, step 7
may be omitted.

2. During idle in steps 4 & 6, when engine operation switches from lean operation to
stoichiometric operation,
engine stall can occur. In this case, clean the throttle body (throttle valve) thoroughly
and repeat step 1 and
the subsequent steps.

Thanks,

Could someone post a guide to clean the throttle body? I have seen one on a previous post by gatos, but the link has been removed.

I am sure the car will stall when idling

It probably will but stick to the system and it will work, as for a guide i cant really help but its not that hard. Take of the corrugated air hose and you will see if you need it or not. Like i say, if it stalls just start it again and carry on.

So I tried your procedure yesterday, it stalled a couple of times whilst doing it. I checked the throttle body and it seamed fairly clean. The butterfly value moved okay and sprung back into position.
Is still has a terrible idle, but improves a little when warmed up, and still stalls a lot.
The problem I had with your procedure, the air con pump is broken and makes a noise when turned on. I don't want it to run too long, but I did for the 10 minutes you suggested. I am reluctant to turn it again as now the noise has increased.
Any ideas?

The only thing i can say is fix the aircon or buy the belt to delete it, you dont need that seizing on you.
Mine also looked ok till i took it off. Clean the throttle body and do it a gain. The procedure is copied from a Mitsubishi service bulletin and i have used it a few times as a sort of annual service.

Interesting that it's 10 minutes. My Sierra used to reset the same way, but without the aircon step(s).

I think you could repeat the procedure, exactly as described, but leave the aircon out.
It probably just needs to know how much load the engine has with everything switched on, so if you're not using the aircon at all ever it'll be fine. Probably. :-)

I never use the aircon, and am considering removing it all. Besides, I like to have the window open so it's useless to me.

It mentions somewhere in my Haynes Manual about a re-learn for all X40s. If i can find it ill write it down


ok the manual says, To allow the ECU to learn running values,
1. Start the car and hold as close to idle speed as possible until operating temperature is reached.
2. hold at 1,200RPM for approx 2 minutes.
3. take the car on at least a 5 mile varied drive to allow the ECU to finish the relearn process.

This should be sufficient for the ECU to relearn the running and idle values.