91 740 Wagon (940 body) - MAF (air flow meter) check

[MadeInJapan]

Check for large vacuum (hose) leaks too after the MAF...I had something similar happening to a S70 (although not a RWD Volvo, the concept is the same)....ended up that I had a very large leak which caused unmetered air to be caught by the 02 sensor...also made my car run terribly...actually, it wouldn't even start until I sealed the leak. You don't say if your car has a turbo or not...if it does, check the hoses to the intercooler as well as the intercooler itself...in my case, the intercooler was cracked.

[goldmember]

OK,

I sprayed carby cleaner around all the vaccum hoses and jiggled them about without any affect to the revs. I am assuming there are no vacuum leaks.

Just before I did this, I noticed that the hose from in front of the air filter (charcoal filter?) to the main air entry manifold had split and come off. I cut it clean (removed the split) and re-routed the hose and fit it back on and now its a tight fit. I doubt this was causing the intermittent problem though.

Next, I removed the relay and noticed that inside, it looked brand new. I checked under a large illuminated magnifiying glass and could not see any problems with it. I checked continuity with the multimeter successfully and also checked the diode which seemed to be ok. For good measure I re-soldered all the connections onthe litter board and added a new solder to ensure good contacts. I also sprayed the shit out of it, the terminals and the lugs on the relay board in the car with quality electronics cleaning solvent.

One word of advice which the Haynes Manual does not tell you. To pull the fuse/relay assembly into the vehicle (for removing relays) you have to also take off the lighter panel just above the ash tray.

So I have not solved the problem (well it hasn't come back yet either).

Thanks for all your help. If I ever find out what it was I'll be sure to let you know. Hey, it just may be an old MAF on its way out.

Cheers

George