1999 volvo s40 2.0 turbo, engine fault caused after hard accelera
well that can be a pain to deal with down unda!
Personally i think the traction control and the stumbles are not related. find out what the check engine light is, and go from there, could be as simple as a coil over, coil or set of plugs/wires or could be a gummed up throttle body, or vacuum leaks, check all the vaccum lines clean the throttle body test drive and , find the code and do some research and or post the code here and i will try to get back to you. a misfire code can be really helpful if it tells you which cylinder, if your over due for plugs just buckle down and replace them.i say
dont throw parts at it because it might not help and get expensive, but cleaning the throttle body and checking vacuum lines, replacing plugs should be preventative maintenance in my book.
use a throttle body cleaner can you can get a local parts store to clean out the throttle body. dont use carb cleaner as it could damage sensors,
if your mind is stuck on the traction control and or you get the stumbling fixed start on that here :
for the hard shifts check the transmission fluid for dark colors or burnt smells. then check out the motor mounts and trans mounts, but that should be done before moving onto the Traction control.
anyways if you suspect the traction control start with checking all the abs sensors. can use a good scanner with live data to save you time and check to see if they are all giving you good readings.
if no scanner is available you need to see if they can be removed from the hub, but be careful as they can break off inside. if they are removable from the hub check them for metal particles and make sure they arnt ground down on the ends, a bad hub will grind down the ends of them. if they look good then let me know
2002 Volvo S40
on Jun 03, 2017