Xantia 1.8SX rough running

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Makka Pakka
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Xantia 1.8SX rough running

Post by Makka Pakka »

Couple of weeks ago my 1996 Xantia 1.8SX (owned 4 years) started to give the odd hiccup when cruising which it has never done before - nothing too serious thought maybe damp. But today when driving really went quite lumpy and hesitating. Worse when accelerating. Can hold 2-3000 rpm quite smooth but still not pulling well. Replaced plugs with new. Old number two plug from left hand end was very sooty others light brown. Went well with new ones for half mile then same problem. My guess is ignition coil. Any way to test this - would this show up in diagnostic code? I'm guessing the coil is an all in one unit and not a servicable item. Appreciate any ideas or comments.
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Old-Guy
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Post by Old-Guy »

Depends on 8 or 16-valve engine.

8-valver I'd say classic symptoms of a duff HT lead. Do change them as a set.

16 valver According to Haynes BoL, the individual coils in the unit on top of the cam-box can be removed/replaced. Disconnect the battery negative lead first! 20K(iler)Volts really hurts! Try swapping nos 1 and 2 coils - if No1 plug then sooty, duff coil. Certainly worth a look and cleanup inside the ignition unit for loose connections, HT tracking.
2011 Grand C4 Picasso VTR+ 1.6HDi in Kyanos Blue
1995 Xantia Estate SX 1.9TD in Vert Vega "The Green Lady" - after 11 years now owned by XanTom
1998 Xantia 2.1 VXD Estate in Mauritius Blue - R.I.P. (terminal tin-worm)
Makka Pakka
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Xantia 1.8SX rough running

Post by Makka Pakka »

Thanks. Have taken the coil unit off and cleaned it all round. Looks like this is a sealed unit though - cant see how to take the individual coils out as looks like there are no screws or clips. Checked plugs again. Today they are all clean. Put all back together but still hesitates on trying brisk acceleration. Smooths out though at constant revs. If I push gently on the pedal the hesitation is barely noticable which is why I think the plugs have stayed clear today. I put in some injector cleaner (Wynns) in the tank today I'm thinking maybe injector problem. Will run it though till weekend to see if that works, if not start looking again.
Makka Pakka
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Xantia 1.8SX still rough running on acceleration only

Post by Makka Pakka »

Update: Removed MAP sensor and cleaned out. Removed throttle position sensor inspected and cleaned up to check its function mechanically. Checked and cleaned wiring plugs to both. Took off throttle body inspected and cleaned. Problem remains. No MIL light indication that there is anything wrong (does work). Does anyone know - does it follow that a diagnostic code would only be indicated by MIL light coming on or can codes be present without MIL light coming on. Dont want to waste money on diagnostic test if not necessary for this reason.
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Clogzz
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Post by Clogzz »

Diagnostics don’t know what’s happening on the high voltage side of the ignition.
One of my old bombs with 6-cylinder engine had 4 open plug leads, and was struggling uphill at speed.
The leads may measure 4K Ohms each.
They go open at the plug end, so ‘re-terminating’ them should help.
An earthed wire made to touch the outside of a spark plug lead will have slight arcing … ‘corona’, so indicating that the high voltage reaches that far.
You can also unplug the leads in turn, and spark-test them to the metal of the engine.
Hold the leads with a rag or insulated pliers because any leakage or static will give you at least a ‘tingle’.
When the sun isn’t shining too brightly, 8) you could see if there’s any leakage causing blue sparking around the ignition coil and spark plug leads.
There are also cheap test screwdrivers with neon lamp that lights up when touching the outside of the leads.
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