OK, so I know this has been discussed here before, but I thought I would throw a new variable into the mix and see if anyone has had the exact trouble I have had. I have an 02 XC70 with ~70k. I have owned it for a year and my trouble started a few months ago. All service has been performed; I run 92 octane.
Trouble:
When maintaining any constant speed on a flat surface or slight incline (loading engine, not coasting), where RPM's fall between 1400 and 1800 I get an oscillation in RPM's that's seen on the tach as 100 to 300 rpms and felt as a surge. It does not happen at freeway speeds or RPM's below 1400 or above 2000; it runs smooth and strong.
Now for the twist.
If I flip the tranny to geartronic while the oscillation is happening - it goes away - when I flip it back to automatic - it returns. The trouble simply does not exist when using geartronic at any speed/RPM combination. I have duplicated this for the dealer mechanic on a 30 minute test drive and he is perplexed but doesn't think it is the transmission.
Solutions I have seen on this forum, that didn't mention the geartronic twist, were:
VADIS ECM/TCM updates
Turbo Solenoid replacement
ETM replacement (perhaps limited to 01's and prior??)
Throttle body cleaning
Tranny Solenoid replacement
Intercooler hose trouble
Turbo Boost Valve control
Tranny replacement
In addition, I have been told that there are no open VADIS campaigns against my VIN. My normal independent mechanic says he has no idea and referred me to the dealership after puzzling over it for a day (he hasn't worked on to many 02's yet). The dealership wants the car for the whole day to try and troubleshoot. I have a third party extended warranty to 100K, but they have to diagnose and call for approval before replacing anything - luckily I bought the top-o'-the-line warranty and it covers tranny replacement.
All input is greatly appreciated. Please feel free to comment on the geartronic solution - I don't mind using geartronic all the time but it gets tedious in heavy traffic.
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