softop2011
New Member
here we go gave your suggestion a try --just went round the block --- disabled the egr took the pipe off -and plugged the maf back in---:ballchain: "stuff this" egr back in maff out :car: ...:crazy_driver:
here we go gave your suggestion a try --just went round the block --- disabled the egr took the pipe off -and plugged the maf back in---:ballchain: "stuff this" egr back in maff out :car: ...:crazy_driver:
wammers no one has disagreed that maf controls egr, but i think you were saying maf has nothing to do with fuel? which it does!
dont waste your time messing with egr valve replace maf and all will be well!!!!
here we go gave your suggestion a try --just went round the block --- disabled the egr took the pipe off -and plugged the maf back in---:ballchain: "stuff this" egr back in maff out :car: ...:crazy_driver:
i guess we will have to agree to diagree!
my biggest concern and iam sure others would agree £60 for a maf guessing its not genuine or oem just hope its not an ebay cheapo more trouble than there worth!!
All I know is that when my Omega got the MAF done it transformed the motor, I just got a new EGR on the Alfa, but for a little bit of smoke on start up and an engine managment light did not notice much difference in performance, I blanked the EGR on a Pajero I used to have and that did improve the performance a little bit. I was under the impression that the MAF was part of the engine managment system.
Davie
It is, on a turbo diesel it mainly controls the EGR. You won't see one on a none EGR engine.
EGR and MAF were introduced at the same time to reduce emissions, that does not mean the MAF mainly controls the EGR, the EDC contriols the EGR and the fueling based among other things on the air volume indicated by the MAF. You really need to read up on these systems. This is like the discussion we had over the centre diff and the VCU.![]()
Hi Dave - looked all over for one of these - oem unit £175 via bearmach - the 2218400 pierburg unit - no one can definitely say if the maf is naf ( excuse the pun) - with a fortune already spent on this car over the last month or so i'm risking £58 instead of £175 - although lots of views for and against oem or copies just crossing my fingers - fed up of throwing cash at it ... trouble is since i pulled the plug on the maf unit its flying ... if i plug the new one in when it shows up and it doesn't work - will probably go for the razor blades... or maybe have a range rover burning party - will let you know the outcome as sooooone as i plug it in .
EGR and MAF were introduced at the same time to reduce emissions, that does not mean the MAF mainly controls the EGR, the EDC contriols the EGR and the fueling based among other things on the air volume indicated by the MAF. You really need to read up on these systems. This is like the discussion we had over the centre diff and the VCU.![]()
Yeah i know Keith, but still can't get my head round how MAF can give a finer control all the way through the rev band. At low rpm maybe before turbo comes in and EGR is working. But can't see how it does it when ECU can only see temp of air coming in through MAF and does not know temp of air in manifold which is critical and will be different.![]()
The critical thing is the volume of air being drawn in whether it is helped by the turbo or not, I agree it would be even better if the manifold air temperature were monitored. The thing is that on earlier systems, if you floored the throttle, the rate of increase of fuelling depended largely on revs and a fixed fuel map so it was a little hit and miss especially as things started to wear, with the MAF the EDC knows exactly the amount of air being drawn in so can more closely control the fueling as the revs rise. The EGR is a bit of a red herring, yes it is used to reduce (allegedly) emissions under certain conditions as part of the overall fuelling strategy, but even with the EGR disabled, emissions are still reduced with the MAF due to finer control of the fuelling. The next development was common rail which gave even tighter control and direct injection leading to fuel conversion efficiencies of close to 80% on large (18,000 litre) engines.![]()
All that on board, but none EGR engines had a IAT sensor in the manifold. And because of this must have monitored fuel quantity better on turbo at least. Manifold air inlet temp is critical to fuelling. The system needs to know the density of the air which varies with temperature to inject the correct amount of fuel. It also needs to know the temp of the fuel, because this again varies in density depending on temp. Unless they have done some serious extrapolative mapping for all engine and air temps which is derived from the MAF temp sensing. Can't see how the MAF can fine control the engine on turbo. Main benifit of common rail is the injection pressure, which is much higher than conventional injection can deliver. Better atomisation is the key with that system. All diesels long ago used diirect injection (directly into cylinder), the swirl port or pre combustion chamber alla the M51 was introduced to reduce diesel knock.