[4x4zook]

hi guys. got a 92 sierra swb with 1.6 inj vitara motor and vit g/box running 31s. now my problem is it struggles really bad top end. down low in 1,2,3,4 gears it goes great but soon as i change to 5th it wont get over 80kmph. even revving 4th gear out to about 90kmph then changing to 5th it will die back to 80 again. ive read a few threads about people who are running 31s with the 1.6 and dont have gears and have no problems at all using 5th. any ideas?
cheers

[zooky08]

Tired motor maby?

[4x4zook]

it has good power in the lower gears though

[zooky08]

Oh my bad, could be the gearing needs fixing, to suit the 31's
But 80km out of a 1.6 is pretty crap.

[hooki]

yeah that seems strange. With enough road i could get my stock geared 1.3L coily sierra with 31's over 120km/h...i think that was with a tail wind though.

My leafy sierra with stock 1.3L, 6.5 gears and 31's could easily sit over 100km/h in 5th. It was reving quite high though.

With an injected 1.6L you should have no trouble sitting in 5th at 100km/h with stock gearing and 31's. Something doen't sound right with the power output of that engine...

[runtbase]

What ratio are a vitara gearbox to a sierra that might be the proplem. Don't hold me to it. Everyone seems to use the Sierra box. So it got me thinking.

[tanshi]

same ratios

[Damo]

4x4zook wrote:

hi guys. got a 92 sierra swb with 1.6 inj vitara motor and vit g/box running 31s. now my problem is it struggles really bad top end. down low in 1,2,3,4 gears it goes great but soon as i change to 5th it wont get over 80kmph. even revving 4th gear out to about 90kmph then changing to 5th it will die back to 80 again. ive read a few threads about people who are running 31s with the 1.6 and dont have gears and have no problems at all using 5th. any ideas?
cheers

Are you running the Sierra transfer?

[zuk_244]

Mine does the same thing. Is the engine out of a auto vitara? I was thinking that might be the problem with mine, im not sure if they have different tuning to the manual ones.
My gearbox is also abit sad which might be holding it back. Im going to rebuild the box in a couple of weeks and ill let you know if that helps.

[4x4zook]

yes it has the sierra transfer and the motor is out of a manual vitara.

[4x4zook]

is there some sort of limp mode that would be stopping 5th gear to get over 80kpmh?

[4x4zook]

no ideas?

[shandy92]

nah there isnt a limp mode as such, could just be that the rds are slightly inclined or the motor just needs a tune or something, even if the other gears are ok. does it cruise ok in 4th at lower revs (2500-3000rpm)?

[4x4zook]

yeh in 4th it pulls great do 100 no probs revs a bit high but ya get that in 4th =P. change to 5th and dies back to 80

[Shansh]

this may be way off or stupid as i dont really know much about engines, but when its revving hard its ok and when its not revving so hard it dies, could that maybe indicate a nearly full of shit air filter? when its sucking air really hard as its revving its enough to have some guts but when the revs back off as he goes into 5th its no longer sucking air hard enough to overcome the amount of crap in the air filter? like i said im not realy clued up on engines so im probably way off but thought i might see what people think of that theory, its how you learn i guess

[atari4x4]

while it's parked, put a brick or something heavy on the accelerator, pop the bonnet & check to see if you're getting full throttle at the throttle body

[4x4zook]

i checked the throttle body was opening fully and it wasnt. adjusted cable and the pedal stopper thing now it opens fully and still no improvement. i did this about a week ago as i thought it may be the problem also but still dies in 5th

[4x4zook]

the air filter is a new pod filter. its only temporary untill i can get a snorkel bent up

[4x4zook]

job for a mechanic i spose

[FullyZooked]

Let's say your doing 100kph in fourth, what RPM are you sitting on? Now shift to 5th and what does it drop back to?

[alien]

clutch slipping?

also, have you had your speedo calibrated or checked the speed on a GPS? (assuming your speedo is out).

[Fatzook]

A few things to check.

Is your o2 sensor plugged in and functioning?
What size and condition is your exhaust? Blocked cat?
Any blue or black smoke coming out the back when revved?
Checked the timing?

[4x4zook]

in 4th the rpm at 100kmph is about 3400. i have made the vss with the reed swich and vero board witch works fine. my speedo from 0-80 is fine above 80 it starts to go out a bit. 100kph is about 92 on gps. the exhaust is 2 inch with extractors with no cat. theres no smoke. i replaced the o2 sensor thinkin it was the problem but still no change.

[Fatzook]

So the speedo reads higher than the GPS? USually with taller tyres your speedo will read lower than actual road speed.

Do you know if there is any gear reduction fitted to the transfer or diffs?

[4x4zook]

ohh yea sorry the other way around 92 speedo 100 gps and theres no reduction gears and the diffs are standard

[Fatzook]

4x4zook wrote:

ohh yea sorry the other way around 92 speedo 100 gps and theres no reduction gears and the diffs are standard

Well regardless of any underlying power issues you may be having, you shold atleast address the gearing issues.

Have you checked for ECU fault codes?

[Brett]

Your dropping out of the peak toque band for the engine when you go into 5th but a 1.6 should do it any way

[4x4zook]

thats what i thought. a 1.6 should pull 100km in 5th =0. my 3 cyl hijet does 130 and holds it lol

[Red89]

4x4zook wrote:

thats what i thought. a 1.6 should pull 100km in 5th =0. my 3 cyl hijet does 130 and holds it lol

With 31's ?

[shep]

4x4zook wrote:

thats what i thought. a 1.6 should pull 100km in 5th =0. my 3 cyl hijet does 130 and holds it lol

stick tyres that are 5 inches bigger then standard on ya hijet and see how it goes