Question about 2002 Volvo C70
The MAF code isn't really a problem, but the ETS is, because it is pointing to failure of the electronic throttle, which is a common problem, and a KNOWN problem at Volvo. The repair needs to be carried out at Volvo due to the need for a software upgrade after the repair, and it is this which is probably causing the bad idle rather than the MAF problem.
Now for the MAF problem....
Basically, the MAF is registering low air flow, and the main causes of this are:-
A dirty hotwire, which can be cleaned by removing the MAF and then spraying the hotwire with either brake cleaner or switch cleaner and then blowing it dry with your breath, but do not physically touch the wire, just blow on it gently. One good reason for a dirty MAF is the fitment of an aftermarket air filter of the type which requires spraying with oil. The oil contaminates the hotwire and causes this problem.
An intake air leak, such as a loose or split hose or vacuum line, a split diaphragm in one of the vacuum operated units such as the fuel pressure regulator, EGR valve, brake servo, etc, which could be located by sucking on the pipe connected to the unit. If you could **** air through the pipe without a vacuum build up then the unit diaphragm is split, or a leak at the intake manifold or throttle body.
If you were to spray carb spray around seams and joins in the intake system and the revs were to pick up slightly, then you would have found a leak.
If the hotwire was dirty, and becomes dirty again very quickly, then you should have the burn-off voltage checked out.
Obviously, it could be a wiring issue, but this is very rare, and 99% of the time, if a dirty hotwire or an air leak aren't the problem then a new MAF is the cure.
Very best regards
Posted on Jun 18, 2008
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