Aux belt changed, idle now VERY rough, dropping to 500rpm sometimes.

[coolspot007007]

Changed the aux belt no problem, alt is charging fine, tension is good, but now the idle is all over the place. The exhaust centre mount was shagged when I got the car and only just replaced and was sitting much lower than it should. So I'm thinking with having to raise and lower the engine so much doing the belt all the exhaust joints may need sealing again? It's definitely blowing now and the idle gets better once the car's warmed up so that's pointing me to hot exhaust = expansion, better seal, better idle. Only other thing I can think of is maybe a leak from the manifold pipe on the carbon cannister when removing and refitting it (I'm removing the whole setup to rule it out at the weekend) but can a BADLY blowing exhaust cause a REALLY rough idle. It's very jerky when setting off at low rpm. I'm sure I'm getting a buggered dephaser type sound as well now though (definitely wasn't apparent before)

 

[ben_p]

Best thing to so is to go back out, re check all sensors are connected, hoeses are clipped on, check exhaust seal and go from there.

Could be a number of things really

 

[coolspot007007]

I did double check sensors and hoses before refitting bumper but I'll try the exhaust first as that's a definite problem.

 

[coolspot007007]

Exhaust all sealed up, charcoal cannister completely removed and hoses plugged but now idle has gone up to around 1800rpm, much more stable but just high. Have checked all sensors and hoses are connected that may have been disturbed when doing the aux belt.

 

[helltone]

Did you find the reason of this?
Have the same symptoms on my 172