Xantia revs

egg · Unread post by **egg** » 06 Apr 2004, 02:41

Hello all. I have a xantia 2.016v, 1996 with low miles. Intermittently the car develops a nasty fault. Symptoms as follows:
1. When i decelerate the revs stay high.
2. When i brake and dip the clutch the revs increase (even when fully warmed)and stay at approx 1400 rpm ish before very slowly coming down.
3. The car runs dog rough and drinks fuel (£40 is good for approx. 200 miles)
4. When i take foot off throttle after approx. 1 second car 'kangaroos'.
Problem has sometimes been resolved by filling with fuel and/or unplugging the engine management system for a while. Problem has returned and will not now go away. Main dealer worse than useless as engine mangement light does not stay on.
Am at end of my tether! Help please.

Stempy · Unread post by **Stempy** » 06 Apr 2004, 03:05

Sounds similar to the symptoms cause by a jamming air bypass stepper motor. I'm not sure if the 16v engine has a similar set up to the 8v, but if it does it might be worth taking it off a giving it a good clean.

egg · Unread post by **egg** » 06 Apr 2004, 03:14

The set up is very different to the 8v engine. The engine is the one without a distibutor - very strange. Nonetheless if i can find the stepper motor i'l give it a clean! Thanks for the advice.

Stempy · Unread post by **Stempy** » 06 Apr 2004, 03:21

On the 8v the stepper is bolted to the back of throttle body.

egg · Unread post by **egg** » 06 Apr 2004, 03:27

Cheers. I'm a novice with a spanner, and definately with these french things. I'll do my best!

alexx · Unread post by **alexx** » 06 Apr 2004, 03:45

On my 1.8 16v, stepper mottor is on the upper side of the throttle body, 3-4 cm in diameter, 3-4 cm long. It's black and 'Made by Airpax for Magnetti Marelli' is stamped on it. It should be similar on the 2.0 16v (maybe some other manufacturer like Bosch). I think it's the only element on the throttle body with 4-pole connector, so you can't miss it.
Disconnect the battery before disconnecting the idle motor.

egg · Unread post by **egg** » 06 Apr 2004, 03:54

Thanks, will give it a go. Only one thing - what is in Idle motor? (sorry if i sound thick, but really am a novice!)

alexx · Unread post by **alexx** » 06 Apr 2004, 04:19

It's a 'stepper' motor - a special kind of electric motor, driven by engine management computer with voltage pulses. It opens and closes air bypas around throttle valve, regulating engine speed at idle, when throttle valve is closed. It's a sealed unit and usually there's no need to dismantle it, but only to clean it's outer mechanical parts (a kind of a pushrod)