need a few questions answered,i,ve got a 94 plate import with mods,its got a running fault which only seems to happen off boost,car seems to run with a slight miss under light throttle and pop down the down pipe,i'm thinking its the maf as i am on my second one and dont want to buy a brand new one until i'm 100% sure as the last time i brought a secondhand one,my reading on my afr gauge shows it dancing all over the place[as they do]until i throttle it then it go,s round to a constant rich reading,i have disconected the lamda in the downpipe{full decat exhaust}to see if that makes a difference but no change,i read the fault codes and it did log code 23 mass air flow sensor,did reset the ecu and now after a drive it has not logged a fault code but the fault is still there,one thing i have noticed is that sometimes when i start it from cold the afr gauge shows max richness for abit untill i give it some boost then it starts dancing all over the place as they do,any ideas or help would be much appreciated

 

Lambda sensor doesn't give any useful information until it has warmed up so that's what you are seeing starting from cold on the AFR gauge. The "dancing all over the place" under low revs/light throttle is the ECU running in closed loop mode and constantly adjusting the mixture about stoich so I wouldn't worry about it. It should show a bit rich as yours does when you are boosting or have your foot down.

Have you checked for air leaks? A small leak can often cause bad running at low revs.

Matthew

 

didnt think that it would have been the lamda sensor to be honest,yes i have checked for air leaks but have not found any,have carryed out the parallel fuel mod and vta breather mod not so long ago and the fault was there before so i no the inlet gaskets etc are ok,it had three new coil packs and i have tried a fourth one to make sure,its had new plugs etc,this is why i'm starting to think its the maf again.£211+vat any more ideas anybody,

 

Are you running a vent to air dump valve? This can sometimes give idle and low rev problems.

 

hi,yes but i have tried it with it disconected and it didnt make any differance

 

anymore ideas people