Vw beetle 2000 2.0 running lumpy possibly misfiring too

Hi guys I recently bought a beetle for my wife,
I seen this one knowing it had issues.

If I take the car for a drive (which is quite hard to do) I can get a random misfire code and if I just run it on the drive I don't get any codes,
If I fluctuate the throttle I can get the revs up but if I depress the throttle the engine feels like it wants to die.
I plugged it in to vcds lite and the rear lambda sensorhas a lean % of -43.8% so I believe the car is running really rich.

This is what I've changed and done;

Ignition leads
Coil pack
Spark plugs
Fuel filter
Air filter
Rear lamda sensor
Cam belt and tensioner
Changed all the easy to get to vacuum pipes
Cleaned the maf
Compression test
Coolant temp sensor

I still have the same issues any ideas please?

Quote:

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Originally Posted by Dayne

Hi guys I recently bought a beetle for my wife,
I seen this one knowing it had issues.

If I take the car for a drive (which is quite hard to do) I can get a random misfire code and if I just run it on the drive I don't get any codes,
If I fluctuate the throttle I can get the revs up but if I depress the throttle the engine feels like it wants to die.
I plugged it in to vcds lite and the rear lambda sensorhas a lean % of -43.8% so I believe the car is running really rich.

This is what I've changed and done;

Ignition leads
Coil pack
Spark plugs
Fuel filter
Air filter
Rear lamda sensor
Cam belt and tensioner
Changed all the easy to get to vacuum pipes
Cleaned the maf
Compression test
Coolant temp sensor

I still have the same issues any ideas please?

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i have now changed the front lambda sensor because of the rich fuel but no joy,

There is a big discrepancy between the two lambda sensors on the vcds. Also white smoke from the exhaust
anyone help???

Quote:

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Originally Posted by Dayne

I plugged it in to vcds lite and the rear lambda sensorhas a lean % of -43.8% so I believe the car is running really rich.

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Hello and welcome to the forum. What do you mean by the above statement? Is this the fuel trim your taking about? I'm not sure how fuel trim ties in with the rear lambda (O2) sensor but maybe it's a VCDS thing. I've never used VCDS so don't know how it displays things.

Have you tried running the engine with the MAF sensor unplugged? Maybe also try running it with the front lambda sensor removed from the exhaust to see if that stops it from wanting to die. Perhaps there is a restriction in the exhaust. That's a couple of things to try that are quick and wont cost you any more money.

Jim.

Quote:

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Originally Posted by Flash2

Hello and welcome to the forum. What do you mean by the above statement? Is this the fuel trim your taking about? I'm not sure how fuel trim ties in with the rear lambda (O2) sensor but maybe it's a VCDS thing. I've never used VCDS so don't know how it displays things.

Have you tried running the engine with the MAF sensor unplugged? Maybe also try running it with the front lambda sensor removed from the exhaust to see if that stops it from wanting to die. Perhaps there is a restriction in the exhaust. That's a couple of things to try that are quick and wont cost you any more money.

Jim.

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Hi yeah I've tried pulling them out 1 at a time etc,

the -% figures means that the car is running rich but the front one says the opposite they have both been changed (lamda)

ive ran it without the maf plugged in and I can get full revs that way but still rough,
im just fed up of buying parts without being the right one, even this vw specialist garage was stumped

You don't normally (unless it's a VCDS thing, like I said) have a fuel trim value relating to the rear O2 sensor (B1S2). The front O2 (B1S1) controls the mixture, the rear is used to monitor the efficiency of the CAT.
Are you sure your not talking about long term and short term fuel trim values? What measuring blocks are you looking at? Maybe post a screen shot from your VCDS.