My 2000 v70xc has been hesitating and going in to what seems to be "limp" mode. Everything I've read about the ETM failure symptoms leads me to believe that this is what I have. After reading about the extended waranty I brought it into my dealer. They downloaded the codes and found massflow sensor fault and multiple misfires but no problems with the throttle body.
Is it possible it's giving wrong codes. It seems strange to me that I have all the symptoms and it's a known problem but that they're telling me it's something different.
Any help is greatly appreciated.
This is a common complaint. The air folowing into the engine is measured two ways.
The direct measurment is by the air mass flow sensor. Two wires are heated, one shielded from the air flow and one in the air flow. An electrical current is sent through the one in the air flow until is is the same temperature as the shielded one. This is then converted to air flow.
The second is a 'table' in the computer. This table says that, for instance, when the throttle is open 30 degrees the air flow is calculated to be 20 cubic feet per minute (these are not real numbers, just play like). If this agrees with the MAF all is well. But if the throttle positition sensor potentiometer is giving the wrong reading and the throttle is not at 20 degrees open but at 25, the table look-up value is wrong and the computer says something is wrong and blames it on the MAF.
My suggestion is that let them replace the MAF, BUT tell them that you want the MAF as you have paid for it. Also tell them that if it does not fix the problem and the trouble occurs in 30 days you want your old MAF reinstalled and the ETM replaced.
A more direct test of the MAF is detailed in Volvo's Technical Net Notes 25-149A, dated 4-03-06 under procedure ECM-150A.
My web site http://vexedvolvo.org under 'ETM/ETS Troubleshooting' tells how you can download this very detailed 31 page pdf document for $6.00. The one you want is TNN25-149A-2006-04—3 Troubleshooting Electronic Throttle System (ETS).
Don Willson
[email protected]
http://VEXEDvolvo.org