[MR2] Emissions problem

[Kurt Krueger]

On 1/13/2011 11:43 PM, Joel wrote:
> zach,
>
> if i'm not mistaken, that boils down to unburnt fuel.  if it were NOx, 
> that is caused by higher than normal cylinder temperature.
>
> start off with the simplest things first.
>
-------- all very good advice (removed for brevity) ---------

Unburnt fuel can be caused to too much fuel, too little fuel (won't 
ignite), engine too cool, O2 sensor failed, EGR system issue.

Do the simple stuff first.  The two times I've had HCO issues were due 
to a bad thermostat (engine wouldn't get up to operating temp), and and 
a flaky EGR (GM truck).

In my case with the flaky EGR, they did a treadmill test and provided 
graphs.  I could see spikes in the HCO graph.  Most of the time it was 
well within the specs ... except for those huge spikes.  Disconnecting 
the EGR brought the HCO into line and boosted the NOx ... but not quite 
enough to fail.

You didn't say where you live.  Here in Oregon restests are free ... so 
you can experiment without going broke.