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Car Forum / Volvo Cars / November 2007Failing airflow meter on V70 TDI - Symptoms ?
I have a 1997 2.5 TDi V70 (diesel), approx 168,000 miles, and wondered what the symptoms are if the mass air sensor is failing. Do they get dirty and need cleaning ? Thanks, Nick >I have a 1997 2.5 TDi V70 (diesel), approx 168,000 miles, and wondered >what the symptoms are if the mass air sensor is failing. a failed or dirty MAF usually gives the symptoms of the engine goes flat just as the turbo spools up- a lack of power over say 2500-3000rpm. If unplugging it brings back 85% of the power, then replace it. > Do they get dirty and need cleaning ? Yes, but cleaning is often short lived. Also always replace it with the genuine Bosch article. The cheaper ones are cheaper for a reason... Tim.. Hi Tim, Sounds like it may be what I have - around 2300 to 2700 rpm it is hesitating as if the "mixture is wrong" Does this sound like it could be the MAF ? Thanks, Nick > Hi Tim, > > Sounds like it may be what I have - around 2300 to 2700 rpm it is > hesitating as if the "mixture is wrong" > > Does this sound like it could be the MAF ? Nick as I said, the usual symptom is a lack of power under load when the turbo is spooled and creating extra airflow- the MAF is not signalling to the ECU that this is happening, so it underfuels. A clean exahust is also a sign - i.e. no trail of soot under hard acceloration. Tim.. OK - thanks for the reply.. I don't think I have underfuelling unless it occurs just at this rpm are.. it seems quite "pokey" at WOT and higher revs, although I don't seem to get a visible exhaust trail, just a bit hesitant around 2500 rpm and light throttle.. Thanks, Nick >> Hi Tim, >> [quoted text clipped - 9 lines] > > Tim.. > OK - thanks for the reply.. > > I don't think I have underfuelling unless it occurs just at this rpm are.. > it seems quite "pokey" at WOT and higher revs, > although I don't seem to get a visible exhaust trail, just a bit hesitant > around 2500 rpm and light throttle.. Ahh! Then check the TPS and more likely the EGR valve. (preferably blank it off alltogether) Tim.. I have heard about blanking off the EGR but also rumours that some damage might occur, so I haven't. If the only negative might be that under some conditions the emissions might be a tad worse, then I am OK about it, but I don't want to overheat or in some other way harm the lump. I guess the TPS is just a pot and a multimeter across the terminals to check for smooth / progressive operation is what needs to be seen ? Thanks, Nick >> OK - thanks for the reply.. >> [quoted text clipped - 9 lines] > > Tim.. >I have heard about blanking off the EGR but also rumours that some damage >might occur, so I haven't. If the only negative might be that under some >conditions the emissions might be a tad worse, then I am OK about it, but I >don't want to overheat or in some other way harm the lump. No harm at all, infact usually more responsiveness at smaller throttle openings, better MPG, less soot, and alot less bunging up of the intake system with soot, that you have to clean out. > I guess the TPS is just a pot and a multimeter across the terminals to > check for smooth / progressive operation is what needs to be seen ? Yes- exactly. Tim. . Great ! Thanks, I will have a go later then. Nick >>I have heard about blanking off the EGR but also rumours that some >>damage might occur, so I haven't. If the only negative might be [quoted text clipped - 14 lines] > Tim. > . >> I have heard about blanking off the EGR but also rumours that some >> damage might occur, so I haven't. If the only negative might be [quoted text clipped - 5 lines] > throttle openings, better MPG, less soot, and alot less bunging up of > the intake system with soot, that you have to clean out. Will blanking the EGR off cause the Check Engine light to come on? THNX.  SignatureHal |
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