Shop tells me that my recently purchased 2002 C70 had an engine changeout, and they suspect that is the source of the engine bucking while decelerating (around 1700rpm), and occasional "goofiness" at startup. We have changed battery cables, and one vacuum line, but the car acts a little drunk at deceleration. Something about the computer/engine interfacing. Does this have merit, or what else could it be?

 

Not really unless they installed a 98 motor.

 

Just a heads up...this is a double post. One is in the c70 section.

 

any ideas on what it could be then? I let off the gas, especially around 1700 rpm, and it lurches and bucks as it decelerates. Will occasionally act wacky at startup, dies quickly, then takes a little patience to get it going. ETM checks out fine at Park Place Volvo, and the software has been upgraded.

 

Turbo control valve good?
Is the ETM from your motor or the used motor?(I know you won't know but it is programmed to the car)
ETM clean?

 

don't know regarding the origin of the ETM, but that might be what the Volvo shop was alluding to. Presume they think it came with the engine replacement, and as such something is wacky. Full throttle is perfect, only idle throttle decelerating, plus an occasional goofy startup (dies, followed by no restart, wait then it starts) are the problems. Software was upgraded, ETM was cleaned, passes all test.

 

Not sure where to go from here sorry. It is really hard to say without seeing the car and having the proper equiptment to test.