Why do my revs go really high then low then high

[brokeranthony]

ok, just bought a wrx sti type ra 1995.

full throttle 1st- no problem

full throttle 2nd- no problem

full throttle 3rd- turbo kick in, revs go from 3.5k to 7k then to 2k then hits limiter (foot in same postition). have to change gear to 4th as its jurking all over the place and does the same in 4th???

i spoke to the prevous owner who said its the spark plugs and its happened before (the test drive was fine)

any help would be appreciated

[Paul Drawmer]

Clutch slip.

[cheesesliceking]

brokeranthony said:

full throttle 3rd- turbo kick in, revs go from 3.5k to 7k then to 2k

That doesnt sound like spark plugs. doesnt sound like clutch slip either IMO, if it was clutch slip why the drop back down to 2k.

[ScoobieWRX]

Throttle postition sensor maybe

Could be clutch slip too. For the revs to rise so quickly, then when the clutch finally grips it pulls the revs down. It's certainly possible.

Edited by ScoobieWRX on Wednesday 15th May 14:38

[Paul Drawmer]

If the revs rise and fall out of synch with any increase or decrease in road speed, you have either got wheel spin(!) or clutch slip.

[JollyGrnMonster]

Clutch

[JollyGrnMonster]

Clutch

[brokeranthony]

Changed all four plugs and it has resolved the problem- strange but it worked, im happy again.

[ScoobieWRX]

Learn something new every day...spark plugs causing that....never in a month of Sundays would i have come up with spark plugs. If it's done it before and it's doing it again it will no doubt even after this change of plugs be doing it again and again.

I'd have said most likely was cluch or TPS maybe but not sparks pmsl