Activa refuses to idle, keeps stalling.

zz9 · Post by **zz9** » 12 Mar 2009, 15:17

Hi there

Long time lurker here with a S reg S2 Activa that I'm trying to coax back to good health.

Just fitted a new hydraulic pump and HP pipe and had to take the Bosch engine management computer out to get the pump out.

The manual says it now needs to learn it's settings again and will run and idle rough for a while. I've driven it for an hour and it runs fine but will not idle, or sometimes just barely ticks over at very low revs.

Any ideas? I've checked all leads, hoses, connections I can and there are no warnings on the dashboard.

ACTIVE8 · Post by **ACTIVE8** » 12 Mar 2009, 15:34

Hi zz9 welcome to the forum.

I had similar problems with mine previously I.E. rough idle etc, so thinking back I now don't seem to have the problems.

The difference between now, and then is that there was a battery on its way out, with the new battery the voltage is what it should be, and stable which it was not before, so I feel this has helped a problem, I was going to attend to, but now do not need to.

ACTIVE8 · Post by **ACTIVE8** » 12 Mar 2009, 15:39

It might have been rough for a little while, and then improved.

As the battery had been off, it has the same effect as taking off the E.C.U as it's in each case removed, from its power source for a while.

I also had no loose connections, warning lights etc.

zz9 · Post by **zz9** » 12 Mar 2009, 16:57

Good point Active8, The car has been off the road for six months so the battery may be not as good as it should be. I'll test it with another battery, after I've replaced the accumulator sphere. That's a job for tomorrow.

ACTIVE8 · Post by **ACTIVE8** » 12 Mar 2009, 17:14

Good luck with the repair, I hope you manage to sort it out.

Post by **CitroJim** » 12 Mar 2009, 18:53

It could also be a sluggish and lazy Idle Control Valve. That's the lump on the side of the rubber hose going to the inlet manifold. Good idea to have it off and give it a good clean with carb cleaner.

The other possibility is, given the ECU has been out is damage to the MAP sensor pipework going to the MAP sensor inside the ECU. This pipe can get crimped/pinched on the lastic or the rubber bits between the ECU and the riund plastic damper device can perish and let in air if disturbed.

Does the car fast idle OK when cold and then refuse to idle when warm or is the symptom there all the time irrespective of engine heat?

If te battery is good enough to fire the car up, it should e fie for the ECU as the ECU compensates for low battery voltage by increasing the injection pulse width.

Does it start OK?

zz9 · Post by **zz9** » 12 Mar 2009, 19:02

Jim,

Fires up okay but needs throttle where before it would start with just the key. Once running it needs throttle to stop it from stalling, hot or cold. It might idle slightly better when hot but that could be my imagination. While driving it's perfect.

The few times it idled by itself it was so slow that the headlights lights dimmed drastically, maybe 400 rpm.

I'll check out the ECU and it's pipes etc again tomorrow and have a look at the idle control valve.

I'm far from being the most mechanically minded person but have always managed to do basic stuff myself like replacing brake pads etc. Changing the pump is about the biggest job I've ever done, At least that appears to be running fine!

Thanks again, I'll let you know what I find tomorrow.

Post by **CitroJim** » 12 Mar 2009, 19:08

Going on that, chances are it'll be the Idle Control Valve. Before having it off to clean it, have a quick check of its electrical connector.

Sorry for the bad typing in my last post

My daugther has nabbed my main PC and I'm reduced to a laptop

Typing on the silly little keyboard is horrible...

zz9 · Post by **zz9** » 12 Mar 2009, 19:17

I hate laptops as well, especially trying to use the numbers along the top!

DickieG · Post by **DickieG** » 12 Mar 2009, 19:39

Have a good look around for a dislodged vacuum pipe as such symptoms are invariably caused by excess/unregulated air entering the engine and upsetting the mixture at idle. Once beyond idle the additional air allowed to enter the engine balances out/reduces the effect of the unregulated air to the extend that the engine performs relatively well. I take it that you re-connected the vacuum pipe to the ECU?

A very common occurrence after working on an engine.

zz9 · Post by **zz9** » 12 Mar 2009, 20:07

As far as I know everything that came off went back on. But I'll check it all again tomorrow.

Thanks for the tip, another thing to check...

zz9 · Post by **zz9** » 13 Mar 2009, 20:36

Okay, there was a wire loose....

While fitting the new pump I had a look at how accessible the accumulator sphere was, and unplugged an electrical plug from a hose just above and to the left (as you look at it) of the sphere.

Any idea what plug that is? And if that could cause the idle problem?

The battery was flat so until it's charged up I can't test it.

zz9 · Post by **zz9** » 14 Mar 2009, 17:47

Okay, now starts and idles perfectly.

And managed to change the accumulator sphere. Even with the tool that was hard work getting the old one undone!

Thanks everyone for all the suggestions. Just me being an idiot for overlooking a lose connection in plain view.

Post by **CitroJim** » 15 Mar 2009, 09:42

Don't be hard on yourself, we've all been there

Pleased all is now OK