Weird Revs

wildfaye · Post by **wildfaye** » Fri Jun 25, 2004 12:56 pm

Hiya guys,

My 98 GPX does 100kmh in 5th gear at around 2500rpm (cruising).

When I need a slight boost, I blip the throttle slightly, but not enuff to force it to downshift to 4th.
I feel a slight surge and the revs go somewhere ard 3000 in 5th, speeds pick up to around 110-115kmh.

When i feel that i have attained my desired speed, i let off the the throttle and maintain at 110kmh and the revs drop from 3000rpm to around 2700rpm(cruising).

It seems that an 'extra cam' takes over during. We all know that the mivec comes in at around 5500rpm.

This happens in other gears as well, not just 5th.

Is this normal?

I change my engine oil every 5000kms and my gearbox oil every 20000kms.

Sam

Slither · Post by **Slither** » Fri Jun 25, 2004 1:04 pm

Yeah i've got a 95 GPX and i have the same thing although only in 4th gear, my understandin was that it was just overdrive but i don't know if FTO's r equipped with it???

wildfaye · Post by **wildfaye** » Fri Jun 25, 2004 1:09 pm

I am not sure about the overdrive thing thingy, just knows that the stable cruising in 5th at 100kmh is 2500rpm.

Another thing to note is that I can feel the 'extra boost' and the exhuast sounds louder when the 'extra cam' takes over.

Err...let me reconfirm on the other gears...now that u mentioned it, I think it onli happens in 5th.

Slither · Post by **Slither** » Fri Jun 25, 2004 1:14 pm

yeah same dealy with mine, extra boost and u definately notice the exhaust sound

rxboy · Post by **rxboy** » Fri Jun 25, 2004 1:19 pm

I also have a 5spd tip, but I've never noticed what u do Wildfaye when trying to gain speed in 5th at 100km/h. Whenever I do feel that extra gain, it shows me that the transmission has dropped down a gear.

MADFTO · Post by **MADFTO** » Fri Jun 25, 2004 2:15 pm

As far as my understanding of auto's go, overdrive is just the final gear in the gear box (overdrive gear) It usually has a small ratio under 1

What you guys are experiencing I think is the lag of the torque converter.
It kinda acts like a slipping clutch in that respect.

jeremywe · Post by **jeremywe** » Fri Jun 25, 2004 4:39 pm

Yea, i get it on mine as well, and i've always though it was the overdrive. In fact, it actually feels like a subtle gear shift, but when you look at the indicators, it hasn't shifted.
On my mums older car, a toyota corona, the same kinda thing happens too.

BTW, wildfaye, are you the cousin of a guy who drives a SS2 celica? Where do you get your FTO spares from in singapore? I might need to buy some parts...

wildfaye · Post by **wildfaye** » Fri Jun 25, 2004 5:02 pm

Hmm...so it just isnt me alone who feels the extra boost w/o a corresponding gear change...

Does anyone reckon it to be a technical fault? or is it spose to be normal?

MADFTO mentioned the torque converter slipping. If so, can it be fixed?

wildfaye · Post by **wildfaye** » Fri Jun 25, 2004 5:04 pm

jeremywe wrote:Yea, i get it on mine as well, and i've always though it was the overdrive. In fact, it actually feels like a subtle gear shift, but when you look at the indicators, it hasn't shifted.
On my mums older car, a toyota corona, the same kinda thing happens too.

BTW, wildfaye, are you the cousin of a guy who drives a SS2 celica? Where do you get your FTO spares from in singapore? I might need to buy some parts...

Nope, i done have a cousin with a celica.

parts, what sort of parts are u refering to? for wear n tear spares, there are 2 shops in little india who specialises in Mit spares.

Daz_FTO · Post by **Daz_FTO** » Fri Jun 25, 2004 6:28 pm

I beleive the FTO Gearbox is fitted with a "locker" (i cant remember tech name for it) When your flywheel revs match your torque converter revs a device kinda grabs... i am assuming it is an economy thing. Nothing weird, just another feature of the INVECS.

It does the same on my 4 speed tip box.

First time i noticed it was on the highway - definite engine note change, i thought something was wrong until i spoke to a mate about it. I will find out the name of that mechanism and post it later.

Daz_FTO · Post by **Daz_FTO** » Fri Jun 25, 2004 6:34 pm

Lock-up Torque Converteri think its called.

taken from another website:

When the impeller's speed and the turbine's speed are about the same, torque can be transferred at almost 1:1. Carmakers took the torque converter one step further by adding a lock-up function beginning around 1980. Lock-up converters also contain a friction clutch that locks the converter impeller to the turbine, usually in higher gears. A solenoid-controlled oil passage, commanded by the cars powertain control module (PCM), locks and unlocks the converter based on driving conditions.

payaya · Post by **payaya** » Sat Jun 26, 2004 7:47 pm

its you overdrive.

Sometimes when your tranny get it a bit tired, you sometimes feel a sudden surge of revs, but it didnt change gears.

Its very noticable when drving up a high, engine struggles, get out of overdrive mode. If provoked more it goes down a gear.

btw the FTO doesnt have the lockup convertor feature. The falcon has it, its a very noticable feature when driving cars with this. If the FTO does i think i'll notice it, correct me if im wrong guys.

Daz_FTO · Post by **Daz_FTO** » Sat Jun 26, 2004 8:26 pm

oh... ok - i didnt know it was overdrive - does it happen in all gears?? i have felt the change in 3rd and 4th - it was just a friend of mine that suggested the lockup function as that techniologyy has been around a long time.

Overdrive makes sense.

Slither · Post by **Slither** » Sat Jun 26, 2004 9:47 pm

I've only noticed it in 4th, but if it is overdrive then u should only get it in your top gear shouldn't u??

Daz_FTO · Post by **Daz_FTO** » Sat Jun 26, 2004 11:21 pm

just 4th for me... i thinought it was happeneing in 3rd too, but it wasnt.

MADFTO · Post by **MADFTO** » Sun Jun 27, 2004 5:48 pm

Torque converters by their very nature are designed to slip.

There aren't any actually mechanical part that contact in a torque converter unless they have a locking feature.

It's perfectly normal, I'm guessing FTO torque converters are virtually the same as standard autos (vane angles and fluid used [this is your auto transmission fluid I believe] differ from car to car but the principle is the same, just some torque converters will match differences in speeds faster than others)

Anyways, it's natural in an auto. That's why I don't like them =) There's always a delay effect from accleration, unless you get a locker.

Mind you, they do have some useful aspects, especially in turbo cars =)

wildfaye · Post by **wildfaye** » Mon Jun 28, 2004 12:52 pm

Hmm...okie...i tot it was someting wrong with my gearbox...
shall let this rest for now!

Thanks guys!