what cruising rpm with auto tranny? [Merged 7-8] AT automatic speed

[91tizzy]

I was wonderin if my converter's lockup is malfuctioning or if these cars were designed to cruise at 3200-3400 at 70-75mph??? I recently drove the car 700 miles on a ten hour trip to mississippi from ohio....no problems except for my pitiful 20 mpg!!! Car has manual injectors and ecu with stock auto fpr so I know that is the major factor but just wonderin if it could be any other reason for my terrible mileage....

 

[stefanOst]

Can't say about automatic transmission, but that seems similar to what I see on mine (manual). Cruising at 100kmh (62mph?) is I believe just a hair under 3000rpm on the tach. This is kind of annoying, as it seems to be a fairly high rpm for highway cruising. The speed limits around where I am are mostly 50kmh (~30mph I guess), and I run that spot on at 2000rpm in 3rd gear, so 3000rpm to go the speed limit on the highway is a bit much, plus in Montreal pretty much no one drives under 130kmh on the autoroutes, so you get passed really close all the time by people driving like maniacs if you go the speed limit.

Seems to me that when upshifting/downshifting 1-2-3-4 there is about 1000rpm between gears, but between 4-5 there is only about 500rpm difference, which seems that the 5th gear is quite short (or tall, whatever it is).

 

[dj_remy]

i have an auto tranny 95 gsx, i'm pretty sure i'm around 3200-3500rpm at 70-75mph, but idk if thats good or bad, i've driven manuals so long i cant get used to it, or whats good or bad in an auto, but we are very close in numbers, so it must be about right.

 

[95redturboawd]

70mph is around 3k on my manual transmission.

 

[webconnect]

Cars with more power from the factory get to have taller gears. I drove a lexus IS-F (400hp) and it has 8 gears, with paddle shifters. 70 mph in 8th was at 1300rpm

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[dj_remy]

70mph is around 3k on my manual transmission.

so i guess in auto + cruise that would be about right, only 4 gears makes sense to me.

 

[xveganxcowboyx]

Meh, come drive my miata once. 4k rpm at those speeds. My Talon seems damn low every time I get in it.

 

[DSM1G90]

Did you have the selection button in "Power" or "Economy"? Economy locks the torque converter when it shifts in 4th and you should be hitting 3300rpms doing 75mph (124kmph for our folks up north).

 

[toojung2die]

I was wonderin if my converter's lockup is malfuctioning or if these cars were designed to cruise at 3200-3400 at 70-75mph??? I recently drove the car 700 miles on a ten hour trip to mississippi from ohio....no problems except for my pitiful 20 mpg!!! Car has manual injectors and ecu with stock auto fpr so I know that is the major factor but just wonderin if it could be any other reason for my terrible mileage....

The 1G A/T torque converter doesn't lock up. That helps explain the higher rpm's and low mileage.

I have an 2G A/T. I see right around 3000 rpm at 70 mph. The 2G A/T locks the torque converter. That feature helps drop the rpm and gets better gas mileage. It connects the engine directly to the wheels with no TC slip. If I accelerate slightly the TC lock disengages and I see the same rpm range you see until it locks up again. For help with A/T transmission problems and upgrades check out IPT. They know A/T DSM's. IPT Performance Transmissions

There is a difference in the 1G injector size between M/T and A/T but you solved that potential problem by putting M/T injectors in with the M/T ECU.

 

[TunaTalon]

After nine posts toojung2die has it right. The 1G DSM torque converter does not lock up. The stock torque converter on my 98 TSI locked up at about 2100 RPM when cruising straight and level.

The best all around is the IPT 2G high stall TC with multiple lock up clutches. It brings high torque at launch, Good mileage while cruising, and handles the high torque of a boosted stroker.

 

[91tizzy]

hell yeah i really appreciate the posts guys....yeah the only thing that the power/economy button does from my understanding is sets the shift points lower which actually wheres out the converter causing it to slip more so I leave it in power 95% of the time and shift it in and out of o/d as needed....once again thanks yall

 

[toojung2die]

BTW; the base fuel pressure on a 1G is 37 psi regardless of the injector size so still having the original FPR in there is fine.

 

[knochgoon24]

I run about 3k at 70mph. Only difference is I get 26mpg-28mpg highway.

 

[rEclipserGST]

I drive a stock 95 GST auto, and with the enigine warm it does 3000 rpms at 74 mph. And the gas mileage sucks!!! i feel like i get 12 city/18 highway. HORRIBLE!!

 

[91tizzy]

yeah that is about the mileage i get....honestly I fill up every 200miles just to keep it from kicking the light on....maybe 240 to the tank on a good day.....why is this thing getting such horrible gas mileage if the fpr isnt being overridden???

 

[webconnect]

My tach sits at 3000 going 70mph. (99 gsx auto). I also get about 240 miles to the tank. Sucks. GSX's are just pigs, and the drivetrain loss eats gas like a mofo.

 

[knochgoon24]

I drive a stock 95 GST auto, and with the enigine warm it does 3000 rpms at 74 mph. And the gas mileage sucks!!! i feel like i get 12 city/18 highway. HORRIBLE!!

Hard to believe that you get 18 highway and I get 26mpg with AWD. I think you have some problems that you need to address.

 

[rEclipserGST]

problems i need to address? what could i do to increase the mpg?

 

[xveganxcowboyx]

Check your O2 sensor. Check base timing. Check compression. Do a tune up.

 

[webconnect]

I have a correction to make. My car sits at exactly 2750rpms at 70mph, with the converter locked. I paid special attention to it for you guys.


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[jared]

What are you guys with automatic trannys running at around 70 mph. I am right around 3 thousand RPM's

 

[GnArKiLL70]

mine are around 3k

 

[webconnect]

2800rpm. This is in a 99 gsx

 

[EagleTalonTim]

mine is around 3200 if i am not mistaken. 1g AWD.

 

[crimsondragon]

2.5k RPMs. 3k for me is 80mph. I know because that's when the massage chair kicks in.