Hi All
I bought a 1992 940 which badly needed a TB+IAC+EGR+Breather cleaning.
I pulled IAC, EGR TB and replaced Breather, solid days work for me. After meticulous cleaning I put it all back together(also replaced T-stat and spark plugs but I digress). Started her up, started quick and easy. But she immediately went to 2000 rpms and fluctuated in 1.5 second increments between 2000 and 1500 rpms. In very neat 1.5 second intervals like as FAQ's suggest the ECU is protecting itself from over revving. This annoyed me as I wanted her to heat up to temp so I could get out some air bubbles in the coolant system. I removed the connector to the MAS to force "limp home" mode thinking it would at least idle lower. After a brief stumble it did...1500 solid w/no hunting. I plugged it back in and the idle stayed the same, 1500rpm. First I am wondering when you force "limp home" mode by disconnecting, when you reconnect is it still in "limp home" or does it sense the MAS is back and correct itself? And secondly I am guessing I have killed my TPS, how do I confirm? I did note when I had it on the bench the two clicks when appropriate as per FAQ's so I don't think its simply misadjusted. Though I also suspect the PO's Non-volvo tech may have adjusted the set screw to compensate for the lower idle caused by the severely gunked up breather and TB...
Any suggestions appreciated.
Matt