Over fuelling

[Mboy]

Hi, I've got a 98 Mk 3 GTI which seems to be drinking to much juice, looked into it and signs are pointing towards the lambda sensor, if anyone else has any more answers could they please let me know,   thanks

[irmscher]

Can u not run diagnostics on it from the OBD?  I did with my dad's Primera, and it reported the front o2 sensor as being at fault.. The MIL was also on.  Not sure if the MK3's have an MIL? (Malfunction Indicator Lamp - orange light with the engine symbol)..

Have you been filling up with the dodgy Tesco/Morrisons fuel?

[EvilScotsman]

if you know anyone near you with vag-com, lambda should always read 1.00 at idle and cruise - and varies between 0.90 and 1.1 during acceleration and deceleration respectively.

If the lambda readings are low (weak mixture detected) then the sensor is calling for fuel it doesnt need. You can clean them but be gentle cos theyre fragile once unscrewed from the downpipe.

On some engines the Lambda probe is heated to speed up proper operation during cold running, maybe the heater suply is open circuit at the probe, broken wire etc.

[rubjonny]

the first thing you should replace if the car is over-fueling is the ECU temp sender, then the lambda
Don't buy cheap no-name lambdas either, I got one off ebay and it lasted 2 weeks.  Then bought a bosch universal one for £50 and its been fine ever since

[Mboy]

I've ordered a vag com of ebay so hopefully that should tell me a few answers, are lambda sensors easy to replace, they look just like a spark plug ?

[EvilScotsman]

They unscrew, prob tight too. Looks like a spark plug or lightbulb but they are fragile once removed. use wd40.

[mk3-ralf]

mate ive had the same problem...but mine has been fixed after i changed the spark plugs only did it yesterday so still keeping an eye on my petrol consumption...i was only getting 80miles out of £20 of petrol..so if you havent already done so i would say try that...before you start replacing unecessary parts.

[Mboy]

Hi, recieved vag com few days ago but not sure how to work it !! whats the latest software for it ??

[EvilScotsman]

use the version for your cable or it wont work. 702 beta is the latest but it wrecks copy cables from china etc by wiping the eprom trying to update the firmware.

ver 409 or 607 probably depending on if its a hex usb or hex com.

[Mboy]

how do i i find out if its a hex usb or a hex com ? all i know is it fits onto the 16 pin port in car using pins 2,4,5,7,10,15, and 16 ? does anyone have procedure on what to follow using vag com ?