what happens when you run an abf 16v with no lambda?

[paultownsend]

i still havent sorted out welding into a bung into the exhaust into the exhaust since the abf into mk2 conversion. the garage let me down again today.
so iv got to use the car for a 250m round trip this weekend. iv left it disconnected, and the only problem im having is that the revs hold at 2k when coming to idle, and bounce around a little after that. only for 3 secs or so.
but what else is happening inside the ecu? as the car has a lambda, im assuming it needs it for something! leaning out? over fueling?

Cheers, Paul

[Wayne]

The lambda sets the fuel ratio, without it connected I believe it will overfuel.

[Mikester]

If u have a cat it will ruin it

[Wayne]

If u have a cat it will ruin it

Very good point, if it is dumping fuel it will not last long.

In stead of welding up why not screw a short bolt into it.

[paultownsend]

oh sorry. im not making myself clear. iv put the abf into my mk2. no cat.
used my dp and exhaust, so i have nowhere to put the lambda sensor. im welding a boss into the exhaust so i can mount the sensor. im not running one atm

[AudiA8Quattro]

I don't think it will make any difference to be honest. The ecu will switch to a default map.
The lambda is there to 'fine tune' the engine, so shouldn't make a huge difference.

[danny_p]

the lambda sensors poupose in life is to give feedback the ecu reagrding the exhaust,    the ABF has a narrowband lambda whitch has only one pourpose in life,  to seek out the AFR of 14.7:1  otherwise known as socheomtric    the catalytic converter requires this exact mixture to work correctly. power wise it makes no diffrence because at pritty much anything over 70% thottel the eninge is running on mixture quite a bit richer than 14.7 so the lambda just gives an output that translates to as RICH  and is promtly ignored by the ecu. 

if i disconected the lambda sensor on my motor  when ideling it would pick up a lambda hunt, there the ecu richens the mixture up then leans it out and looks for a changing lambda signal.  if it dosent get it it would just carry on till it got anoying and the lambda got pluged back in then it would promtly settel.   some seem to do it more than others  more than likely it down to the firmware in the ecu

[paultownsend]

no hunting as such. just takes a while for the revs to settle. there sticking @ 2 k for roughly 2 seconds, then resting to idle