ph1 sports not revving well

[davecrook1]

i have recently bought a 172 and love it but the shift light comes on at 6k rpm and the limiter about at about 6200rpm
pullls strong up until around 5800 where the revs slow down like its struggling to rev that high....

any ideas what could be wrong.. can idle lumpy sometimes too

only mod is a small enclosed induction which i think i will change

 

[.Stevo.C.]

Could be a faulty thermostat as 6200 rpm is the cold limiter I'm sure.

 

[sbridgey]

6800 is the cold limiter, well on my ph2 it is anyway

 

[.Stevo.C.]

6800 is the cold limiter, well on my ph2 it is anyway

I stand corrected.

 

[davecrook1]

could the ph2 have a revised thermostat limiter? cause the car is always warmed up.. it wont rev to 7k

 

[davecrook1]

also car warms up fine and heaters work..so thermostat must be opening and closing.. how is the signal picked up? where is the signal for the limiter sent from

 

[sbridgey]

Well i think it is odd that the limit is below the usual cold limit something else must be up or someone has re-programmed the ECU maybe, tbh i have no idea

 

[DannyR]

Ph1 water temp and rev limits

 

[Fred@BTM]

also car warms up fine and heaters work..so thermostat must be opening and closing.. how is the signal picked up? where is the signal for the limiter sent from

the heaters will work regardless as coolant can always flow through the matrix regalrdless of what the thermostat is doing

coolant temp sensor and thermostat are common, change both anyway

does it hit the limiter hard or just stop reving??

 

[davecrook1]

its hard to say.. it gets to the limit... but kinda runs out of puff.. so at 4.5k pulls really well then at 5.8k the revs slow down like its time to change gear but doesnt readily fly around and bounce of the limiter..

where is the coolant temp sensor on the engine? i will change the thermostat too but doesnt run hot and overly cold.. it sits just under half way which i tought seemed normal, so doubt it can be the thermostat..

 

[TheEvilGiraffe]

Max power is ~6k IIRC ? I'm sure someone can confirm that..

Cam timing could be out ?

Edit: Just re-read and noticed the shift light is early... weird.

 

[Fred@BTM]

that needs a compression test

i had one similar that turned out to be a 2.0L 15v (rocker had fallen off at factory!!)