Citroen C2 1.1 Idle Misfire [SOLVED]

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Dibber
Posts: 56
Joined: 19 Mar 2019, 11:26
x 4

Re: Citroen C2 1.1 Idle Misfire

Post by Dibber »

Thanks Nemo

Dibber
Posts: 56
Joined: 19 Mar 2019, 11:26
x 4

Re: Citroen C2 1.1 Idle Misfire

Post by Dibber »

I think I probably have finally found the problem and it's rather annoying..

Today I thought I would try once again checking for a vacuum leak. I have been down this road a few times. Weeks ago I discovered a leaking injector o ring and ended up replacing all four injectors o rings.

I have done smoke tests as well in the past which yielded nothing.

Today by chance I thought I would try something different. I used a length of tubing as a means to listen for a vacuum leak and immediately heard hissing in the area of the inlet manifold to head, in the centre. I then mixed up some soapy water in a spray and sprayed the same area. Right away the engine revs dropped. I then sprayed around injector number 2 and it had the most reaction. Strangely after a minute or so after spraying it the engine evened itself out and started running really smooth. The best it's ever been truth be told.

So I definitely have a major vacuum leak. Possibly the injector o ring and also the inlet manifold are at fault or maybe even a crack or distorted inlet manifold. I will be more than a bit pissed if the injector o ring is at fault as I renewed them. Anyhoo now I have some positive direction. It makes perfect sense. Long term fuel trims showing a lean condition, the gas analyser test showing lean at idle but perfect beyond idle.

It's going to be injectors out yet again and inlet manifold off. Fortunately I have a spare manifold if it turns out to be cracked or distorted. So it's going to be another set of injector seals and manifold o rings next week. Fingers crossed.

User avatar
NewcastleFalcon
Posts: 11641
Joined: 25 Feb 2009, 11:40
x 1022

Re: Citroen C2 1.1 Idle Misfire

Post by NewcastleFalcon »

Dibber wrote:
06 Apr 2019, 16:51
I used a length of tubing as a means to listen for a vacuum leak and immediately heard hissing in the area of the inlet manifold to head, in the centre. I then mixed up some soapy water in a spray and sprayed the same area..............


Like that. I've got one of those too.....15mm plastic water pipe and a wider diameter tube at the top for your ear! joined together professionally with insulating tape. A tube and soapy water! Give me that any day over your computer diagnostics.

Hope it helps you fix your misfire, and you can edit your title to "Citroen C2 1.1 Idle Misfire....Solved" :-D

I did start a thread some time ago to act as a receptacle for such things

"Toolbag Tales-Homemade and improvised tools" viewtopic.php?f=2&t=57231

I'll revive it with a picture of my listening tube! Feel free to join in

REgards Neil

Dibber
Posts: 56
Joined: 19 Mar 2019, 11:26
x 4

Re: Citroen C2 1.1 Idle Misfire

Post by Dibber »

On removing the injectors I discovered one o ring was split. That's very disappointing as I had replaced them a few weeks back and had been very careful refitting them into the head.

I had a couple of spares so fitted another and put it back together. As I was awaiting new o rings for the manifold and injectors it was only to see if it would make any difference to the idle. It did not make one bit of difference. I conducted a leak test with soapy water and discovered every injector had a tiny leak. That is unlikely to have a significant impact as a MAP system will detect the change in pressure and the ECU will adjust to compensate.

I had a spare inlet manifold and whilst I had a day or two before the parts arrived I decided to clean it up with the view to using it. Putting a straight edge on the face of the manifold revealed a problem with brass looking inserts in the plastic that the studs sit in. One was sitting proud. Using a sheet of glass and a length of sandpaper attached to glass I rubbed the face of the manifold against the sandpaper. After about 15 mins the high spot was removed.

I took all the injectors out the fuel rail and gave the rail a good blow out with compressed air. The old manifold was removed and the throttle body transferred to the donor manifold.

My friend had told me when working for PSA they had issues with wiring due to a silicone substance the factory put on electrical connections. The silicone would go hard and cause bad connections on plugs. With this in mind I pulled all my ECU multiplugs off and spent a bit of time with a piece of Mig wire cleaning each contact pin in the plugs. There definitely was a couple of pins that had tiny solid pieces of silicone that came out.

My parts arrived today so I pieced everything back together. I was careful to distribute the pressure evenly whilst tightening the inlet manifold. With new seals fitted to the injectors I went to refit them to the head. They were very difficult to get in even with some soapy water on the o rings. I did not remember them being that tight the last time I renewed them. It took quite a bit of time to insert them. Always mindful not to apply too much force which could split them.

Finally all back together I fired it up. Well... it's definitely running better at idle. There are far fewer fluctuations than before so it's been worthwhile. As to what has contributed the most to the difference that's hard to pin down. The injectors are definitely sealing better. The manifold o rings may have had an impact but there is no evidence to back that up. Possibly cleaning the ECU pins was ultimately the fix.

Personally I would still like it a tad better but I am supper fussy :rofl2: . The truth is, for 99 percent of folk they would be quite happy so I therefore would conclude this as having been finally solved! =D> =D>