maf sensor disconnect

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ricardo62

Active Member
Joined
Feb 22, 2013
Messages
349
Location
ipswich
Car
e320
hi my car is running badly no kickdown , and poor acceleration , only revs to 3000 rpm in neutral, when ign is switched off and restarted it revs to the max , but lots of soot out of exhaust when i floor it.
i think its never had the maf changed in its lifetime ,its on 207000 miles , car is e320 cdi , ive read up and found that this model is renowned for maf failures , my question is , according to info ive read , if i disconnect the plud that goes into the maf sensor and take it for a drive and it cures the probs then that will point to the maf being faulty , in that case if it drives better can i just leave it disconnected ? what are the pitfalls ?
 
It's more likely to be the EGR valve jammed open, but irrespective, a new Pierburg MAF is only £60.
 
If you disconnect it, you will be in limp mode all the time.

2 options - either get it on STAR to confirm what is exactly at fault or chance it with a (genuine) MAF if it has never been changed.

Genuine MAF's for these are around £55 - £60. One thing I would do once the MAF is changed is the EGR mod as this could also be a cause of your problems, which is why a STAR diag is recommeded
 
It's more likely to be the EGR valve jammed open, but irrespective, a new Pierburg MAF is only £60.
its having an mo t next week , will this pass emitions test if the egr and maf is faulty ? when it is restarted and held at a steady 3000 rpm then there is no black smoke
 
one other thing on a long run it will do 60mph and hold it on the cruise control in limp mode , takes a while to get there , but if i continue to drive in limp mode will it do any damage or is it just a case of not having the proper performance ?
 
Limp mode won't damage it, but if the EGR valve is stuck open the lack of oxygen will make it run very sooty.
 
I would go with a faulty maf being the problem, the excess soot from the exhaust when you floor it could be due to the turbo being inactive (due to the faulty maf) and unburnt diesel/ash building up in the exhaust system being ejected when floored.
 
Change the fuel filter, make that a priority, next clean the MAF, best way is with fag lighter gas, canned butane gas about a quid from anywhere, it'll degrease and blow the element clean without leaving a residue, and change the air filter, all three cause problems as the sensors start logging faults and drop the car into limp mode.
 
Change the fuel filter, make that a priority, next clean the MAF, best way is with fag lighter gas, canned butane gas about a quid from anywhere, it'll degrease and blow the element clean without leaving a residue, and change the air filter, all three cause problems as the sensors start logging faults and drop the car into limp mode.
fuel filter is new and air filter is clean i checked it
 

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