gas mileage still not great
 

ok first i want to say this is a fantastic site.i recently purchased a 01 ssei with 42k and got he gm pp warranty, my wife is only getting 19mpg on the highway and ive tried premium gas and change the fuel filter just for kicks, as a car salesmen ive seen these cars gaet alot beter gas mileage, usually at the leat 22 on the highway, any ideas here.
i still fell the torque convertor is not locking up properly and killing me but any ideas would be great. the car is as straight as a arrow no signs of any misuse at all. :roll:

Well to diagnose TCC....what RPM is your engine at say 75mph? Most run around 2000. Other than that, i would do the plugs, wires, 02 sensor..both of them if you can...that kinda thing...

I had to replace my plugs/wires at 43k on my 00 SLE....increased city mpg from 21 to 24...over the road I get 31.

im running about 2000 at 60 and the slightest increase in acceleration takes my to 25-2700 rpms

Air filter
plugs
o2
tires are topped off,
junk out of the trunk

know anybody with a scan tool, they can check it for ya,to see if the TCC is working

That does sounds like your TCC is not kicking in like SSEIMatt93 is saying. I don't know if something is not telling the computer to kick in such as a bad/disconnected engine temp sensor (thinking the engine is always cold) or the plug is disconnected from the tranny. I use to know everything about the overdrive/TCC on early/mid 80's cars, but these I am foggy on. Maybe someone can chime in on some ideas..

The torque converter doesn't lock up until the engine is close to operating temperature. In fact, what is different about these converters is that they progressively engage depending on temperature. I took mine back when it was new absolutely convinced that the transmission was slipping when it fact, it really was acting normally.
I have a 44 mile commute that usually has some stop and go driving and average from 26-27 in the summer to as low as 22 in the winter but never less than that. My average this week has been just over 25.
To help decide if your transmission is acting properly, once it is warmed up, accelerate and count the gear changes. The converter should lock at 45 and you should then see 35mph/1000rpm so using your example of 60mph, you should be reading around 1700rpm. It sounds to me like you aren't getting out of 3rd. I'll try to remember to check mine on the way home to see what the rpms are in 3rd gear.

YES..... but if he has a buddy with a scan tool(with live data capabilities) you can take it for a drive and see if the ECM is commanding the TC to engage.
then you will know for shure ;)

I checked on the way home tonight and in 4th gear with the torque converter locked, the engine was at 1650rpm at 60mph. In 3rd gear it was 2350.` Keep in mind that your gear ratio is numerically a little higher than mine so factor that into your thinking. It still sounds like something isn't right with the transmission.

Most trans codes will NOT light the SES light. Your best bet is to have the car scanned for codes and proceed from there. To check your 02 sensor let the car warm up and while checking the 02b2 millivolts it should waffle low to high rapidly. If it doesnt you will want to replace the 02 sensor.