Saxo bad jerking when cold

mgoodlad · Post by **mgoodlad** » 30 Jul 2004, 02:07

Car is 1996 Saxo 1.1 with 53,000 miles owned since new by my parents and serviced on time at a Citroen garage all the way through, including recently.
Recently has taken to giving a fairly violent jerk when accelerating when cold - usually at low revs when starting off in a gear. It is really annoying and does it pretty much every time. Once the car has warmed up it drives fine.
Asked about it at the last service but it didn't do it then. Dad has changed the spark plug leads recently. I had a look at it last night and took every multi plug off I could find and give it a squirt of contact cleaner. From the distributor there was a unattached earth lead thingy with a plastic box at the end which I reattached (it had a recent head gasket replaced due to coolant problems which is another story - looks like they forgot to reattach it).
I assume it has had recent spark plugs and fuel filter but not looked at the last service invoices.
My tinkering made no difference at all.
Any thing else I could try?
Regards
Michael Goodlad

wheeler · Post by **wheeler** » 31 Jul 2004, 05:41

the wire with the black box thingy is just an interfearence supressor.as for your problem its possibly a coolant temp sensor (green one) for the ECU problem.

Paulxmski · Post by **Paulxmski** » 01 Aug 2004, 05:36

Hi Michael,
I don't know how the Saxo is set up with regards to fuel delivery but if it is injected then the problem sounds very similar to mine. In fact it seems that mine also developed this effect after a head gasket job.I changed over my coolant sensor for a known working one and it didn't improve. In fact I've changed virtually all the sensors and relays apart from the Lambda and idle valve which I have blown through. It might be worth having the car computer tested because the complications between the various sensors and control valves are so acute that only a read off from the engine when started from cold will I think put a finger on the problem. I'm just letting mine warm up and driving it after that until I can afford to take it to a diagnostician. My independant expert has pointed me at one of these who charges £40 an hr and my well fix it in that time or at least be able to put his finger on the problem and as that is all he does everyday it most likely is very worth it.

Paulxmski · Post by **Paulxmski** » 02 Aug 2004, 01:54

Hi Michael,
I fixed the chugging I was getting on my car today. There was a lot of dirt around 2 of the male connectors on the ECU and it wasn't bolted down to the back plate in the box. Have you tried taking the connector off and reconnecting it? I think this may have happened in my case because when they rebuilt the engine (before my ownership) they may left it dangling around and then rushing to finish the job didn't look to see everything was clean and tidy.
Best Regards,
Paul.

mgoodlad · Post by **mgoodlad** » 24 Aug 2004, 16:51

Thanks Paul and Wheeler for the comments - much appreciated.
I took off the connectors to the ECU and no dirt at all was apparent and all looked perfect - I put it back together and made sure it was properly reconnected.
It was at the Citroen dealer for something else and we asked him to replace the coolant sensor.
Neither of these have had any effect - still a bad jerking, mainly when cold.
Anything else I could try? Could it be the distributor? Or whatever its called these days - on an older car I would have said it was a poor spark - its had new plugs, new plug leads so the next bit is the black box thingy the leads get plugged into? Looks an easy swap out but I guess it costs a fair bit? Or are there any other sensors which if they go bad can cause these symptoms?
Regards
Michael

AndyP · Post by **AndyP** » 24 Aug 2004, 18:56

My Xantia often does this and I have noticed that it's definitely not as bad when a hotter grade plug is fitted. When I got the car it had 5's, I bought some new ones which I believed were right for the car (according to Halford's) and got 7's I think - it was awful. Then I tried some old plugs out of my Nissan (super expensive platinuim jobbies - about £20 ea. !!!) which were 6's and it was definitely better. Have now moved back to the original 5's and I think it's just about the best yet, but certainly not perfect. Once warmed up properly it's absolutely fine, but running cold between 1500-2000rpm can be pretty lumpy.

mgoodlad · Post by **mgoodlad** » 07 Oct 2004, 17:29

Problem sorted - it was simply the spark plugs - thanks AndyP and other respondents.
However my dad took it to the Citroen dealer who took it for a run and plugged in a machine at the same time and diagnosed a faulty throttle potentiometer - he did not think it would be the plugs. £200 quoted for the part - we got a complete throttle housing for £65 from a breakers yard and swapped it over. But no difference at all. Getting desparate so bought plugs and running perfect.
So go for the simple things first.....
Regards
Michael

Rob Marshall · Post by **Rob Marshall** » 07 Oct 2004, 19:28

The throttle body is common to go wrong. Lucky you found one from a breakers. Had the same problem with an AX belonging to my neighbour!