MIL illuminated and won't rev?

[Faxo]

This morning started it up and then got out to clear screen, but noticedit was struggling and nearly stalling - its rough most mornings but not this bad.

Set off down the road and it wont let me rev above 3k, if i keep the power on it'll drop down to about 2250 then up to 3k again. If i let off and on it'll eventually go until the next gear. The MIL was flickering this morning, took it out at lunchtime and its on all the time now. Drive it to 3k, holds you there then lets you go.

My catalst has been rattling, but i dont think its this thats blocking the exhaust. Ill put it on the scanner after work, just wondered if anyones had same problems?

Its a 2002 172 just clocked 90k

 

[Faxo]

Anyone?

 

[Faxo]

Put it on the scanner this aft, it came up with a pre cat O2 sensor fault which was abit baffling. Cleared it as it hadn't happened since monday, but on way home it did it again - i worked out if i hold the revs on when its holding me back, after maybe 3 seconds it'll just go then wont do it again. Also, MIL's back on now!

 

[Tigger]

Sorry - what's the MIL ?

 

[Jay Payne]

Malfunction Indicator Light


also know as, emission light, eobd light, etc



Faxo does your scanner have a live reading function?

If so see what that sensor is doing. when warm the sensor should produce a fluctuating signal of around 0.1v-0.9v

 

[Tigger]

Ahh - cheers mate.
I never want to see that then lol

 

[sideways danny]

well it's flagged the lambda as a fault, so that's got to be the culprit, sounds like a wiring fault more than the sensor itself though, intermitent wire break or similar. Holding back will be due to fueling being massively out (probably very lean) when in closed loop

 

[PinkoCommie]

Surely the rev limitations are due to the ECU going into "limp" mode. that limits you to about 3k revs when the MIL light comes on.

My 172 did it when i had a fault with my throttle body.

 

[sideways danny]

Surely the rev limitations are due to the ECU going into "limp" mode. that limits you to about 3k revs when the MIL light comes on.

My 172 did it when i had a fault with my throttle body.

Was my initial though, but not if it lets you rev past it

 

[Faxo]

Once it lets you rev past it it wont do it again. When it is doing it though, it white smokes loads in the cold air, a sign its over fuelling