cube320

Hello i just had a second hand engine put into my 2002 wrx. I brought it with the bottom end gone. The engine has been changed but the CEL keeps comming on.

I have had the fault codes read and nothing comes up.

I have done the MAF test and when i unplug it the car just about dies but then revs back up and idles fine. Is this what is supposed to happen?

Also it has just failed an mot on high carbon monoxide at idle can the maf cause this.

The car came with a k&n typhoon kit which i have read can put oil on the maf. If there is oil on the maf is there any thing i can clean the maf with to see if this fixes the problem, because i have been getting prices for over £200for a maf

Thanks

cube320

Is the car supposed to switch of all together when the maf is disconnected? when i unplug it the car is just about to stall but then revs back up and idles fine. When i plug it back in whilst the car is started the car stalls.

C17RPA

same as mine......i was told on the S.I.D.C that my maf was ok,i thought when the maf is unpluged it should cut out but was told with the car running when you unplug if the revs go down then back up thats ok then someone said if the maf was broke the car would run like pooo

cube320

Have you changed yours since. What problems did you have if any

C17RPA

no still on the car........... the car drives sweet as a nut with no problems ........i kept reading about the maf on these cars so i thought i'd try it and did and when i unpluged it the revs when down then up but did'nt cut out and when i put it back on it went to cut out then went to what it ticks over at...........sorry not gonna worry about it i'm gonna get a one of those gauges that tell you if the car is running lean

dlatch

un plugging the maf you are trying to work out if the engine is running in (safe mode) poss reason for check engine light on.

if the maf is working correctly then the car idle should drop then recover

if the maf was not working and the car was running in safe mode (limp mode) then unpluging the maf would make no difference to idle as the engine will be running on pre mapped limp mode settings and ignoring the maf.

sounds to me like your maf is ok and you have another fault somewhere.
you don't say how the car is driving regardless of the check light being on.
high CO at idle could also be the lamda sensor so chek that out too maybe wiring has been disturbed during engine change.

cube320

Thanks for the reply, the car is driving fine. There is a slight juddering when idleing, you can feel it but revs a perfect. Would a lamda sensor have a fault code show?