4Runner RPM change in mornings
#1
4Runner RPM change in mornings
I have a 95 4Runner 3.0 auto, 176k miles. Engine and heads were just rebuilt, new plugs, new coolant temp sensor, new O2 sensor, TPS was tested and works correctly, and the transmission was rebuilt last year.
I’ve noticed when I go home from work in the afternoons my RPM’s at 70mph are about 2900-3k and I get good gas mileage, however when I go to work in the mornings, my RPM’s at 70mph are roughly 3400-3600k and my gas mileage tanks. Obviously there is a temperature change between the morning and afternoon, but I live in AZ so the temps in the morning have been 50 and 70’s in the afternoon.
Does anyone have any idea why the change in RPM’s and gas mileage at different times in the day?
I’ve noticed when I go home from work in the afternoons my RPM’s at 70mph are about 2900-3k and I get good gas mileage, however when I go to work in the mornings, my RPM’s at 70mph are roughly 3400-3600k and my gas mileage tanks. Obviously there is a temperature change between the morning and afternoon, but I live in AZ so the temps in the morning have been 50 and 70’s in the afternoon.
Does anyone have any idea why the change in RPM’s and gas mileage at different times in the day?
#3
Everything is flat, on the freeway, no headwind. It’s a 40 minute drive to work so it has plenty of time to warm up. Maybe it’s not going into closed loop at freeway speeds when I start driving cold?
#5
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Anyways hook up your volt meter to the transmission diagnostic. It will output a voltage that can be compared to the shift position.
Another quick check is the vafm air temp, it will have an effect on the fuel mixture. Which was probably a red herring on my part not noting your rpm to speed correlation.
#6
I figured it might just be the cold and dense air in the mornings, I just wanted to make sure this wasn’t a common and/or fixable issue. I just picked this 4Runner up not too long ago so I’m getting used to it’s quirks.
Thanks for the input guys!
Thanks for the input guys!
#7
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But the best method, as suggested by Co_94_PU, is to just ask your transmission. You do that with a voltmeter. Either use your multimeter (you'll need long enough leads to get the meter inside the cab), or drop $5 on my patented Gear Shift Indicator. https://www.yotatech.com/forums/f116...icator-303218/
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#11
I also have a V6 Auto that doesn't go into OD - check engine light will come on then too. Still stumped. So it's in the garage just sitting around. Good luck!
#13
Scope,
it seems you are correct about OD lockup. Lockup isn’t engaging in OD. It just happened to me again driving to work, this time in the afternoon though. Lockup was engaging just fine in OD but I had to drop down a gear for a slight incline then it wouldn’t go back into lockup when it went back into OD. What could cause this?
it seems you are correct about OD lockup. Lockup isn’t engaging in OD. It just happened to me again driving to work, this time in the afternoon though. Lockup was engaging just fine in OD but I had to drop down a gear for a slight incline then it wouldn’t go back into lockup when it went back into OD. What could cause this?
#14
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The transmission won't lock up when it is "cold." Perhaps you're not warming up fast enough (thermostat?) Or perhaps the transmission temp sensor http://web.archive.org/web/201408160...34electron.pdf is dying.
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