Originally Posted by mt6127

the ECU upgrade kits all work pretty much the same way - they reflash the ECU to modify the boost curve (ie turbo boost level vs RPM) and the spark advance vs RPM. The gain in HP comes from increasing the boost which overcomes the pumping losses in the engine allowing for more mixture to find its way into the cylinders per RPM (same end game as bigger exhausts, free intakes, even bigger displacements). If you advance the spark as well, you are giving the engine more time to burn the mixture- which also gives you more HP, and since this happens even during off boost/highway driving, you can expect some improvements to MPGs. So if you're wondering why cars simply don't ship with more spark advance, the reason is two fold - more advanced spark means a hotter burn, which while reducing HC emissions, it creates more NOx emissions (ie too much advance can fail a smog test). Secondly too hot a burn or too early a spark can lead to pinging (knock) and engine damage (ie valves) over time. That's why when you run upgraded ECUs you MUSt run premium gas (ie 92/93 octane) - otherwise the knock sensors will work overtime trying to retard the spark your new ECU just upped. Assuming your 850T is stock, you have the 15G turbo and this product advances the spark 1 degree and bumps the maximum boost 3.3 PSI which are fairly modest changes IMHO. If you are ok sticking to premium gas, I'd say add a K+N air filter and enjoy the new ride and at least a small bump in MPGs.

Originally Posted by boldtu

I just replaced the O2 sensor on our our 97'850 R wagon, there is currently no code being thrown. We usually get around 20mpg and it has recently dropped to about 16. Do you guys have any ideas?


thanks,
Chet

Originally Posted by Benford

I have a 96 Turbo Wagon and a 97 T5 Sedan. The wagon has been getting 29 with me and one passenger on the freeway which is factory spec. The T5 gets 26 mpg hwy which is factory spec. The wagon is in the shop as I type this for a factory recall on the EVAP system. It recently started smelling like gas inside the cabin randomly and the mileage dropped a bit too. I get my best city mileage in both cars by watching lights far in advance and adjusting my speed so that I can avoid coming to a full stop. This really seems to irk a lot of folks who hurry by me and sit at the light waiting. I have about 200,000 miles on both cars, fresh air filters, regular oil changes, and Timing belts every 70 K with plugs andwiresat about the same time seem to keep my cars running good. Though the wagon did have a cam sensor go out and would not run. The T5 had the temp sensor in the thermostat housing go out, I got both parts at Pic a part and a couple of extras just in case. I think the 850 line is one of the best ever for Volvo. I also agree with using good gas, I always run premium in both cars always have.

Originally Posted by mygreent5

what does wires refer to?
any picture to show which wire need to be replaced?