Serious Misfire - HELP!!!!

12th April 2010, 20:44

Hi guys,

Before I start, I know this is a very common fault - couldnt find any specific answers.

I have a mk2 vts with a magnex system with decat, enclosed green filter, and have now recently fitted a 4-2-1 manifold.

The car has been idleing weird for the past week or so, and today cut out, then when I started it up again the idle was very rough - sounded like a heartbeat! I disconnected the battery to reset the ECU and the car seems to be running fine again, however I want to prevent the car idleing rough.

I was wondering, I think the car is running rich, so I have got a sleeve for the lambda from GMC. My car only has 1 lambda sensor which goes into the manifold, not 2 like most mk2 vts's.

If I fit a blanking plug to the manifold and put the sleeve on the lambda, will the car run a bit better??

Also, the car has just had a full service, oil, filters, plugs (gapped properly) etc.

Cheers

Chewy

12th April 2010, 21:16

Nope, the lambda sleeve is only for cars with two sensors that have been decatted.

It makes the ecu think that there is a difference after the cat as that is the one that is sleeved.

12th April 2010, 21:18

Does your car have a single plug or 3 plug ECU?

12th April 2010, 21:36

1 lambda would be a single plug ecu.

12th April 2010, 22:04

Single plug ecu. Is there any way that I can stop the car running as rich then??

Chewy

12th April 2010, 22:16

No need for a lambda sleeve then. The lambda sensor must stay in the exhaust otherwise it will overfuel.

The cause of your issue must lie somewhere else. Was it misfiring or just idling lumpy?

12th April 2010, 22:35

Bit of both mate.

Chewy

12th April 2010, 22:40

Is/ was the engine management light on? Coil pack might be a good place to start.

12th April 2010, 23:25

I'd say check the manifoid, particularly at the header, if there's an leak there you're going to get some odd signals from the lambda and one seriously confused ECU.

13th April 2010, 11:06

Engine management light has never come on, I took all the plugs out this morning, re-gapped them, and put it all back together, car seems to be running ok just now.

Chewy

13th April 2010, 19:10

Just been out in the car and seems that the car is misfiring, couldnt get past 20mph at one point!

Had a look on here and the coil pack seems to be the common problem.

Does anyone know if a diagnostics test will show this as faulty?

Also, are there any other common faults? MAP sensor etc...

Cheers

Chewy

13th April 2010, 19:30

Anyone local you can swap coil packs with? Could try removing the MAP sensor and giving it a clean I guess.

13th April 2010, 19:32

Not with a vts mate, everyone seems to have a vtr and I read somewhere that they are different, its annoying! lol

Does anyone know how much a diagnostic test from Citroen is??

Chewy

13th April 2010, 19:34

Usually £60 - £70 mate. Unless you know anyone that has an OBD cable and the right software.

Needs to be OBD though as I don't think OBD2 works with single plug ECUs.

13th April 2010, 19:39

Cheers mate, il give them a call tomorrow i think. Do you know anything else that is quite common that could cause this??

Chewy