1.9 Mi16 Emissions

[dino20vt 3]

Picture this senario.

 

1.9 Mi16 2 row develops misfire.

Change plugs, black and wet.

Weaken mixture.

Retrack AFM

Car runs spot on.

Drive 5 miles to Test staion, still runs fine.

Leave idling to get up to temperature to test fan, cuts in as it should.

Starts misfiring, cuts out, restart and idle irratic.

Diagnostic shows:

 

33 Air mass sensor circuit

55 CO potentiometer circuit.

 

I'm going to investigate what's going on in the AFM as I've been in there, buy a ECU temperature sensor as it's cheap and could be the cause of the rich running and see what state the plugs are in.

 

Any ideas on what the fault codes are referring too?

 

Cheers

Edited September 17, 2010 by jackherer
title edited

[welshpug 1,657]

yeah, the AFM

[dino20vt 3]

Thought as much but the 55 CO potentiometer circuit fault had me stumped.

[welshpug 1,657]

I believe MI16/8v motronic AFM's have a CO pot instead of an air bypass screw?

[dino20vt 3]

I believe MI16/8v motronic AFM's have a CO pot instead of an air bypass screw?

 

The screw is definitely electronic as opposed to mechanical.

[welshpug 1,657]

sounds like you need a new/working AFM, or there's a fault in the wiring to it.

Edited September 17, 2010 by welshpug

[dino20vt 3]

Retracked the afm back to it's original position, changed the ECU temperature sensor and cleaned the plugs and it ran fine, rigged it up to the emission machine and it was still rich.

 

No amount of turning the screw would change the CO or HC's so I removed the the lid on the afm and whilst turning the screw I also levered it ever so slightly to try and re engage the thread in the pot and it seemed to work ( not sure if that's how the variable resistor but it made a difference). Got the readings down to what they should be and it ran like it should.

 

Took it for a run today and it seems to have a slight hesitance and misfire when cruising.

 

Also the revs drop when wiggling the afm but the plug contacts look fine as does all the associated wiring so it looks like I'm on the hunt for a AFM!

 

It smells like it's over fueling again, will find out when there's some daylight and I check the plugs.

Edited September 19, 2010 by dino20vt

[Miles 331 1 Cars]

They all seem to do this now, I'd either get a Recon one or a new one but for the money of those it's worth upgrading to a decent ECU