Hey guys, First post here. Well this is my issue, i just bought a 1998 gs400 yesterday, and its running at 2600rpm at 65mph, that seems a tad high for this ride, I have no lights on the dash and everything works great. Tranny shifts perfect. What could be the issue? I have done the research and it looks like the either a knock sensor or a sensor that tells the car it is warmed up. what are my options here? as i dont want to take it to a dealer and spend 500 bucks for nothing.....

 

i cant speak for the gs400s but on my gs300 that sounds about right. I believe its normal.

 

really? they run that high at 65mph? I would figure that its around 2k at 65 for a 300hp car. I could be wrong. any info of anyone else would be great!!! thanks guys.

 

Haven't drove the GS at high speed for too long that I already forgot, GS is 5 spd auto, your 400 should have M mode that allows you to partly shift gears, if you're on highway, in M mode "5", press down to 4, and you feel the shift to higher rpm, then there you go.

remember, it's a 98 car, at that time, they aren't concerned as much to fuel economy just yet.

edit see my post below,

 

yeah your car is normal. the gearing is made like that cuz they wanted you to get to max speed faster than if you were trying to get to 110 or w/e so each gear shifts a little higher than what you would expect it to be. if im wrong correct me

 

wow!! im used to around 2k in my 2002 z28, i guess that im at with 2600rpm at 70 or so. damn the gas mileage tho!!!! almost half a tank at around 100 miles, BUT i havent been nice to the gas pedal eaither.....

 

Nevermind check if you're in 4th gear... Just tried mine at 100km, it's at 2k rpm

 

Don't know if the Tranny's are configured really differently, but my 430 sits at between 2000-2100rpm at 65mph.

 

I run 2.1K @ 100km/h (60m/h) on my 2000 GS400.

 

Yeah it's probably not shifting into 5th gear. My 300 runs 75mph at 2600rpm. The 300 has a shorter final gear than the 400 (if I'm not mistaken). So your engine should be running closer to 2000rpm at 60mph.

 

All above makes sense, you should be around 2200rpm at 65mph. I am at 3000rpm at 80mph AND I have aggressive gearing (3.73 versus the stock 3.26). As mentioned earlier you are most likely not shifting into 5th gear. VERY easy checks are:

re-set the car's ecu and re-test
and
check tranny fluid levels...eventhough the car seems to be shifting good all it takes is to be 1qt too ow and strange things happen in our trannies. Also, it wouldn't be a bad idea to change the fluid AND the tranny filter; the filter could be clogged...GL!

 

How do you reset the ecu

 

And yes, the car is shifting into 5th gear, but im at 2600rpm at 65. Does the car have overdrive somewhere?

 

to reset ecu, take the positive or negative terminal out, try hazards and brake to drain power in system, leave for a few minutes should be enough. then plug things back in.

if you felt it shifted into 5th, your car may have a different diff? lol LSD maybe? hahahaha





or... your tranny might be slipping

 

It's possible that whoever owned the car before you did a gear swap. 2600 rpm should be 80 mpg if everything is stock.