Rough idle running rich cutting out

Fozzy

Fozzy

Petrolheads
So, the forester has developed an issue whereby it?s running rich (strong smell of petrol, back fires) the idle surges and occasionally when slowing down, if I depress the clutch the revs drop to zero and the engine switches off.

Codes for IACV, MAF - cleaned IACV and throttle body, swapped the MAF for one from a friends breaker forester and still the same issue. Unplugged the front O2 sensor and still the same issue. I guess both MAFs could be faulty but before I buy a new one am I missing anything else?
 
Any exhaust leaks before the 02 sensor? Also, is it Denso or Bosch? I've heard of somebody getting rough idle and poor MPG with a Bosch fitted.
 
sounds exactly like my car when MAF went
dodgy to drive em like that especially in the green maf cars i think i read before
failed maf in a breaker could be probable enough
 
Sheriff said:
Any exhaust leaks before the 02 sensor? Also, is it Denso or Bosch? I've heard of somebody getting rough idle and poor MPG with a Bosch fitted.
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O2 sensor is only 6? or so from the turbo and all seems sound so i don?t think it?s that. I?ve been driving the cooper s until I get it sorted. Both MAFs, my own and the one from the breaker are OEM
 
SCOOBYCOLM said:
sounds exactly like my car when MAF went
dodgy to drive em like that especially in the green maf cars i think i read before
failed maf in a breaker could be probable enough
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Yeah, quite possible I guess. One other possibility is that I?m still running the auto ECU so the fuelling at idle may be different due to the difference in mass between the torque converter and the flywheel. It mightn?t be activating the IACV quickly enough either - hence the stalling. I?ve a new ECU arriving this week so I?ll try that and then look at a new MAF if the issue is still there. I?ll keep it off the road in the meantime though - cheers gents
 
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SCOOBYCOLM said:
MAF be my uneducated guess even after your own specific changes,unless happened very same time.
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Certainly didn?t happen straight after the swap anyway - was driving fine for a while with the manual box so you could well be spot on - I?ll throw the ECU in and order a MAF in the meantime - wouldn?t hurt to have a spare anyway :thumbsup:
 
Fozzy said:
Certainly didn?t happen straight after the swap anyway - was driving fine for a while with the manual box so you could well be spot on - I?ll throw the ECU in and order a MAF in the meantime - wouldn?t hurt to have a spare anyway [emoji106]
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As above maf be where id be looking aa they can go anytime

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Fozzy my sf5 was doing the same not cutting out but rest sounds similar

cleaned icv no difference replaced maf and issue never reapeared all good since

Pic for attention [emoji106]

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Ciaran WRX said:
Fozzy my sf5 was doing the same not cutting out but rest sounds similar

cleaned icv no difference replaced maf and issue never reapeared all good since

Pic for attention [emoji106]

8181d1f7b9b8395751b74a0bff098676.jpg


Sent from my SM-G960F using Tapatalk
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Cheers man - ordered one now so between that and the ECU hopefully be sorted in the next ew days!!
 
So, put a new MAF in, same issue - unplugged the MAF - ran like a bag of crap. Noticed then that the metal fitting that the MAF screws into is lifted away from the intake tube - seems like the screw holding it in has stripped the threads in the plastic - gap of 3-4mm - could that be causing the issue by letting air in? Have a spare intake so will put that in and see I guess
 
Yes it?s in metered air after the Maf going into the system . Change it and see then
 
Update:

Replaced the air box housing for one in good condition - no change. Took out the old forester auto ECU and put in the manual P1 ECU - so far, no more issues. Fingers crossed !!!
 
The saga continues.... idle issue back with a vengeance bouncing from 200-1000rpm out of the blue. No codes. I?m changing the idle control valve tomorrow anyway but I?m also thinking that this could be an issue with the throttle position sensor or maybe the ground going to it as the issue is sporadic.

Anyone more knowledgeable than me have any thoughts?

3 MAFs now so don?t think that?s the issue. Manual ECU so issues there are ruled out too. Can?t find any vacuum leaks obvious, car behaves no differently with o2 sensor unplugged so unlikely to be that either. Getting fairly annoying now ...
 
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