OK, this has been annoying me for weeks, but it's still getting worse, and I wonder if any of you have any suggestions.
My Xantia has developed a misfire. I first noticed it on the motorway and it seemed to stutter a little under acceleration from about 2,500 rpm. Recently, it's now happening pretty much at all speeds and when it's cold as you change from first gear to second it all but cuts out (no warning lights come on, not even the STOP light) but then carries on as normal.
If you listen to the exhaust pipe note you can here the normal sound then probably about every 20 seconds or so, you can hear it really stutter (a second or so of near silence).
So far I've tried some injection cleaner; replaced the spark plugs and air filter. I was going to change the HT leads but they are main dealer only and about £45.00 (plus they said they don't go wrong very often). I did by a fault finder machine, but I can't find a 2 pin socket to plug it into.
The car is a 1999 Activa 2.0 T
Any suggestions of anything else I could try is greatly appreciated. If all else fails, I'll take it to a decent specialist, but I want to eliminate all DIY possibilities first.
Rob
Activa Misfire
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steveallmond
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I'll try the revving in the dark suggestion (never thought of that!) - I don’t know whether it has individual coils? how would I tell.
We also tried hooking it up to one of those (I'm sorry I don't know what they are called) guns which fires a pulse of light along with the ignition - some cylinders seemed to fire much quicker that others (could that just be it picking up stray signals from degraded leads)?
Every sorry often you could see the light flash just stop as it misfired. I'm thinking it's defiantly an electrical problem.
Cheers for your help so far.
We also tried hooking it up to one of those (I'm sorry I don't know what they are called) guns which fires a pulse of light along with the ignition - some cylinders seemed to fire much quicker that others (could that just be it picking up stray signals from degraded leads)?
Every sorry often you could see the light flash just stop as it misfired. I'm thinking it's defiantly an electrical problem.
Cheers for your help so far.
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Stuart McB
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Richard Gallagher
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The 2.0 turbo engine does not have individual coils, just the one on the N/S end of the engine where the HT leads sprout from. The ignition system does have what is called a 'wasted spark' system which in english means that the ignition fires not only on the usual firing stroke but also the exhaust stroke, so that may explain the 'quick' firing described above.
Needless to say, all cylinders should fire the same amount, so it is well worth cleaning any dust/grime away from the coil towers (where the HT leads connect) and also the leads themselves to reduce tracking.
Unless I'm mistaken, I thought the HT leads were the same for the turbo as the normally asperated 2.0. The coil is different in spec, but the engine will work if substituted with a normal 2.0 coil. I know this because I did this on my old Turbo CT estate with the same engine.
Whilst the problem may feel like an ignition problem don't rule out fuel, the problem could be other items such as the Lambda sensor not switching correctly making the engine run weak, the coolant temperature sensor, the list goes on and on. Modern petrol engines can be a nightmare to diagnose with misfires.
Have you done the basics of a compression test in case you have something such as a 'sticky' valve?
The 2 pin code reader you have bought will not work with your Xantia due to it having either a 16 or 30 pin diagnostic socket within the fusebox situated by the drivers right knee. The only type of code reader that will work is a 'professional' one which is rather expensive to purchase.
I have one of these and can vouch for their usefulness in cases such as yours. If you are not too far from Langley/Uxbridge I could do a 'code reading' for you to see if you have any fault codes recorded within the ECU and also check what signals the ECU is receiving from the various sensors etc. If you are too far away then £30-50 spent on a code read elsewhere could possibly a good investment to avoid buying 'unneeded' HT leads etc as you stab in the dark!
Needless to say, all cylinders should fire the same amount, so it is well worth cleaning any dust/grime away from the coil towers (where the HT leads connect) and also the leads themselves to reduce tracking.
Unless I'm mistaken, I thought the HT leads were the same for the turbo as the normally asperated 2.0. The coil is different in spec, but the engine will work if substituted with a normal 2.0 coil. I know this because I did this on my old Turbo CT estate with the same engine.
Whilst the problem may feel like an ignition problem don't rule out fuel, the problem could be other items such as the Lambda sensor not switching correctly making the engine run weak, the coolant temperature sensor, the list goes on and on. Modern petrol engines can be a nightmare to diagnose with misfires.
Have you done the basics of a compression test in case you have something such as a 'sticky' valve?
The 2 pin code reader you have bought will not work with your Xantia due to it having either a 16 or 30 pin diagnostic socket within the fusebox situated by the drivers right knee. The only type of code reader that will work is a 'professional' one which is rather expensive to purchase.
I have one of these and can vouch for their usefulness in cases such as yours. If you are not too far from Langley/Uxbridge I could do a 'code reading' for you to see if you have any fault codes recorded within the ECU and also check what signals the ECU is receiving from the various sensors etc. If you are too far away then £30-50 spent on a code read elsewhere could possibly a good investment to avoid buying 'unneeded' HT leads etc as you stab in the dark!