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My 2013 4 speed auto is revving too low at 100-105kph. It’s sitting at 1800-1900 running 285/75/16 Maxxis AT tyres

The valve body has been upgraded also, unsure of brand.the engine has been tuned, piggy back ecu, Gated turbo few other bits and bobs to make 300 ponies

When I need to go on the highway it doesn’t seem to like sitting at those lower revs in 4th. EGTs start to climb to 600 +

If I increase my speed to say 115-120+ or change down to 3rd it’s happy. EGTs drop but most of the time I’m not speeding and have to put it into 3rd specially heading through mountain ranges and steep hills


What’s the best way to increase the revs a bit more in 4th sitting at 100kph.? What would the ideal revs be also .?


Is this problem caused by the tyres and valve body upgrade .?


Thanks

How long have you been running that size of tyre? I'd expect the 4 speed to struggle a bit with that size of tyre.

If you're worried about low revs at speed just click the auto into manual mode... Drops the overdrive and torque convertor lockup. My egts rise if I lug the engine at low revs too. If you're cruising low revs are fine but under load they will load up the fuel delivery and increase egt.
All of this is due to the valve body, they lockup the torque convertor and prevent the gears from changing down

hiluxxury wrote:How long have you been running that size of tyre? I'd expect the 4 speed to struggle a bit with that size of tyre.

Current tyres are maxxis AT811 I’ve been running for around 1800 kms I had muddies on before and they were the same size as what I have now.

it’s got me stumped.. the valve body has been upgraded but that wouldn’t cause low gearing

What is the ideal size AT tyres and rim to use on the hilux’s.?

Gipsy wrote:If you're worried about low revs at speed just click the auto into manual mode... Drops the overdrive and torque convertor lockup. My egts rise if I lug the engine at low revs too. If you're cruising low revs are fine but under load they will load up the fuel delivery and increase egt.
All of this is due to the valve body, they lockup the torque convertor and prevent the gears from changing down

Yes that’s how I have been driving it, trans temp and egts stay right down. Yeah if it revved around 200-300rpm more in 4th it would be sweet, just super annoying on long drives.
,

With a 33" tyre a diff ratio change will be the best option. If not id recommend dropping back to a 32" tyre.

I would take a guess and say the converter is staying locked up at that rpm due to the light throttle application, I find once they are tuned the throttle % at cruise is very low compared to standard.

32" tyres are regarded the best size for the hilux.

BigBop wrote:

hiluxxury wrote:How long have you been running that size of tyre? I'd expect the 4 speed to struggle a bit with that size of tyre.

Current tyres are maxxis AT811 I’ve been running for around 1800 kms I had muddies on before and they were the same size as what I have now.

it’s got me stumped.. the valve body has been upgraded but that wouldn’t cause low gearing

What is the ideal size AT tyres and rim to use on the hilux’s.?

The valve body doesn't change gearing, it holds the gears for longer than normal... Torque convertor lockup is not taken off as the engine comes under load, so your Hilux stays in overdrive when normally it would slip out of lockup... And it prevents the transmission from changing down under load. All this is primarily designed to reduce fuel consumption and reduces gear changes so the transmission acts more like a manual gearbox. The valve body is tuned to make gearshifts more firm and reduces the 'slip' from the torque convertor.

No worries, thanks for the info