Rough Idle and cut out when warm.

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Colin2206
Posts: 6
Joined: 31 Oct 2019, 12:31

Rough Idle and cut out when warm.

Post by Colin2206 »

My wife's car is the 207 CC, 1.6 Vti petrol model on 08 plate.
We've had it for a number of years and it has generally run well and is at 100,00 miles now.
It has recently started to run rough on start up idle although it revs up smoothly and runs evenly going down the road. Yesterday though, when warm, it cut out at traffic lights etc. but will restart at the first attempt.
I have taken out and cleaned the spark plugs, checked the gap (although they are the not-adjustable type). No.1 cylinder was very sooty, the others less so but not as clean as they usually are. Checked the air filter, all ok. Still lumpy on start up. I have a basic code reader but no faults are recorded, other than the O2 sensor P0135, pending, which it has had since the last MOT. A new O2 sensor has been fitted, this fault predates the current problem.
Haynes suggests fitting a new seal at the throttle housing, which I try and get this week.
Anyone had this problem before and any pointers on how to fix?

Regards,
Colin.

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Pug_XUD_KeenAmateur
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Re: Rough Idle and cut out when warm.

Post by Pug_XUD_KeenAmateur »

I don't much understand these modern cars with their fancy electronics and emission systems

....but sootiness on the Plugs suggests its running rich

...and one of the things I did in the quest to track down a rough idle on a temporary vehicle of similar new-ness that I recently owned was to pull off a Hose while idling so that the engine was pulling fresh air for a short period , see if it made any difference; specifically with regard to the EGR.

...in my case I established that if this was playing silly b****rs, it'd cause a rich mixture,

...an easy and worthwhile experiment

In my case doing so made no difference, so I could eliminate the EGR

Don't let it breathe 'fresh air' for very long, just long enough to test it

Also might be interesting to see if its thirstier than usual, to 'Double-Confirm' its running rich

Colin2206
Posts: 6
Joined: 31 Oct 2019, 12:31

Re: Rough Idle and cut out when warm.

Post by Colin2206 »

Just an update.
Stuck a bottle of cleaner in the tank, no real difference. Went back to the O2 Sensor fault reading. P0135 which indicates the heater not working. Checked the heater supply and earth and both there but only getting 9v on the supply. Battery is at 12.5v not great but good enough I would have thought. I can't find a decent wiring diagram anywhere, so if anyone has one for the 207, please let me know.
Going to order a seal for the throttle body. I'll clean, check and refit with new seal. Only other items I've been advised to look at are the vacuum hoses, but again no diagrams so don't know how extensive the system is. After that the injectors themselves, I guess.
The original sooty plugs seem to have been a symptom of the problem, now running clean. The rough running seems to have a pattern. When it is running rough at idle, it hunts between 900 to 1300 revs., although when all ok it idles at 800 rev, quiet and steady. Still cuts out when coming down from higher revs. I can manage it if I slow down with the gears so the engine is constantly engaged.
Any suggestions appreciated.

Colin.

Colin2206
Posts: 6
Joined: 31 Oct 2019, 12:31

Re: Rough Idle and cut out when warm.

Post by Colin2206 »

Hopefully the final update.
The rough running continued, although not so bad and the cutting out became sharper, coming off the motorway, roundabouts etc. Also, getting multiple fault codes on the log. I went back to basics. I have a small garage with a short steep ramp up and with the low clearance on the 207, it goes in slowly with a lot revs and clutch slipping. It did not like it, terrible smell off the exhaust and flashing engine warning lights.
I change the plugs for old good set, new air filter. The other thing on the air side is the throttle valve which is working as the engine rev’d well enough. Internet recommend cleaning the butterfly flap inside. Also the seal is a possible air leak. New seal ring is £11, which is steep for a 75mm rubber ring.
Getting the Throttle Body off is the usual fun but doable if you can change spark plugs & fit new brake pads etc. Pictures below are the tools used, nothing special.
Tools.JPG
Access is awkward. All the air filter boxes need to be removed but it is just screws and clips (speed gun for the screws). The Throttle Body is at the outlet from the air filter, lhs side. I took off the engine lifting bracket for access. There are two breather pipes which you split at the union to push out of the way. The Throttle Body is held by 3 x long screws (female splined heads). I could not get good access and used different drivers & bits until they came off. I needed the Peeping Tom to see what I was doing. Photo of Butterfly Flap on inlet side, moderate/heavy coating.
Throttle Body 1.JPG
I cleaned the outside with simple non-abrasive kitchen cleaner, inside white spirits & check for cracks and the butterfly for ease of movement. All ok. Re-assembly, as they say, is the reverse.
You can’t really see the sealing ring groove and have to feel to ensure it is seated. There is maybe a clip against the engine block, I could feel it but could not get round to see it. Then seat the body on top. As usual, struggled for an hour or more to get the thing to seat and it would not go, went in for a meal and then it clicked in first attempt. Screws are difficult to line up and when you drop one down the back you will need the magnet on a stick to retrieve it and if it goes behind the steering rack gaiter, jack the car up, remove the road wheel, remove the inner wing liner and use something, anything to get it out; but once in they are in. Then all the air filter boxes etc. If doing it again, I would remove the plastic rocker cover thing to get better access. It looks fiddly but should make the difference.

I had replaced the O2 sensor earlier and with the old one off the car, tested it as best as I could. Part of the test is heating with a blow torch until red hot and check with a basic multi meter. Internet also says it may burn off any contaminants. Passed ok and refitted. You need a special socket for this, I got the 75mm deep and it is just undersized, so get 100mm if you can.

Put everything back and the car runs perfect, except new fault code P0014, Camshaft Sensor, which was not one of the many I had previously. Cleared it and it came back a week later. Have now fitted new Sensor <£15 off eBay. All seems to be running ok.

Still don’t really know what the cutting out was about. Possibly too much oil as per the Butterfly Flap coating, maybe soiling the O2 sensor etc. The Camshaft Sensor should not have caused this but don't know for certain.