xantia hesitation

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pollc
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xantia hesitation

Post by pollc »

hi all
i recently baught a 97 1.8 16v xantia, it has only 28000 miles from new and it came from a good home which had it fully citroen serviced.
When driving the car, ive noticed a big flat spot just after u change gear, its like a hesitation if u take ur foot off then back on!!! it sometimes misfires once when this happens, and its usually below 3000 rpm. the ecu fault codes have been tested by citroen but none show, ive just changed the plugs and air filter, but to no avail.
Has anyone else heard of this problem on 1.8's?
?
?
rsmith
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Post by rsmith »

This sounds like a similar problem to mine. I have had exactly the same symptoms - and citroen dealer could find no fault code. i have noticed an addition idle problem on mine when the probem occurs - see my previous (5 days old ish) posting "xantia 2.0 16V engine niggles".
Have you noticed the idle problem as well?
I have been told it might be the engine speed sensor that is causing the problem, which are not too expensive and I think it is very easy to access on the 1.8 16v - and just 2 screws (can anyone confirm this?). On my 2.0 16v its hidden underneath the throttle housing, but still not too hard I think, just haven't got round to fixing mine yet because it doesn't happpen very often, but it is bloody annoying when it does.
I'll keep you posted if I manage to get it done at the weekend.
Hope this is of some help and we can both get it sorted!!?
Rupert.
David Goddard
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Post by David Goddard »

Assuming that this problem is not only when the engine is cold - which would indicate the coolant temperature sensor (£13.00), it sounds like a fault with the MAP sensor (Manifold Absolute Pressure sensor). This is mounted on the o/s bulkhead. It measures the manifold vacuum. If is fails, the ECU doesn't know the engines running! Tell tale signs are flat spots and backfires under acceleration.
They are not cheap so it's worth having yours checked.
Check that the vacuum pipe connecting it to the manifold is not disconnected.
It's a bit tricky to check electically. It has three wires going to it. One is a power supply 5V. One earth. The other is the output which should be 3.5V with respect to earth when the engine is static; and 1.6V when at idle.
I have checked one by sticking pins through the wires!
pollc
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Post by pollc »

rs smith>>
I have an idle problem in that the car sits at dead on 1000 rpm when it is warm, never higher, never lower.
david goddard>>
surprisingly the problem doesnt seem to occur when the engine is cold, runs perfect when cold, but as soon as its warm, each and every gear change is accompanied by a big hesitation and 30% of the time 1 misfire.
The map sensor on mines is attached to the underside of the inlet manifold, i think the earlier ones were connected using a pic, mines goes straight in. the access to this is near impossible while engine running. A citroen specialist quicky looked over the car and suggested also, the throttle steppet motor, (used to bypass the throttle vale to give extra air) or the throttle potentiometer.
Had the car rolling road tested and the result was 111.5 bhp, only 0.5 bhp down on new. Whic i think confirms the engines good condition.
spanners
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Post by spanners »

IT SOUNDS A LOT LIKE A STEPPER MOTOR FAULT (MOT VALVE) IT WILL NOT ALWAYS SHOW UP ON CODE TESTERS BEAUSE THE FAULT IS MECHANICAL NOT ELECTRICAL. THE PART IS QUITE EXPENSIVE APPROX £70 AND SHOULD BE FITTED BY CITROEN ENGINEER SO THEY CAN DO AN ACTUATOR TEST ON IT TO SET IT UP.
David Goddard
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Post by David Goddard »

I would agree with "Spanners". Sounds like a mechanical failure the Idle Speed Control Valve. This may also explain why you tick-over is a bit high at 1,000rpm.
Could be throttle position sensor wear. This is easy to check with a multimeter. It is a variable resistor connected to the throttle butterfy. After unplugging the connector, and operating the throttle, the resitance should vary smoothly, with no sudden movements or variations. A digital meter is not good at showing such glitches - the old fasioned type will be better!
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