Comboverfish wrote:
> wrote:
> > Is there some conclusive test for an ECM failure?
> > Is there something significant in the car's behavior that I described
> > or are these units prone to failure?
> >
> > The following is originally from a vendor forum, I think.
> >
> > "...But, I have to ask, if you drove your car to the dealer with this
> > problem what part of the computer failed? My experience with bad
> > computers is really bad, as in you can hardly get anywhere with the
> > vehicle. Or you just can't get anywhere. Car computers are real tough
> > pieces of silicone. I've seen wiring harnesses melted together and
> > after the repair the computer shook itself and went back to work...."
> >
> > Are there some other steps that I can go through to test the
> > sub-components and rule out a simpler problem? What are the likely
> > sources, given the symptoms or are there no other possible
> > explanations?
> >
> > Thanks
>
> I just happened on your new posts by chance. the ECM, you
> basically have to verify that all inputs, outputs, powers and grounds
> are functioning properly before you condemn it. If your Hyundai ECM is
> the same build type and manufacture as similar year Mitsubishis, then I
> would highly suspect it as the cause of nonsensical garbage codes. You
> still need to check powers and grounds to the ECM, and ATLEAST make
> sure that the input signals are sensible.
>
> It is difficult to test an O2 sensor on a vehicle with a concurrent
> funky ECM problem. You can force it to read rich by pinching off the
> fuel pressure return hose, and you can force it to read lean by
> introducing a large vacuum leak. Those two methods will tell you if it
> is capable of reacting to known conditions by producing from 0 - 1 volt
> accordingly. Chances are that your new sensor is OK, so you can move
> on to other suspect areas for now.
>
> The possible code 25 refers to a failure in the barometric circuit
> inside the airflow meter. This could cause a large shift in fuel trim
> if it was way off calibration, or shorted/open. Similar story: I had
> a Land Cruiser in the shop that was setting a baro code. This
> particular vehicle, unlike other Toyotas, inferred calculated Baro
> readings from other sensors. IOW, it set a bizarre baro code even
> though it didn't have a real baro sensor. It turns out that the ECM
> was so far off in it's baro calculation that it ran extremely lean to
> the point of near misfire and very high NOx (failed an emissions
> inspection). A new ECM fixed the Land Cruiser.
>
> If you are still suffering black smoke out the exaust, perhaps you
> could find a junkyard airflow meter to try out. Your car uses a Karmen
> Vortex design that outputs a frequency to the ECM based on airflow,
> plus discrete air temp and baro inputs. There's plenty to go wrong
> with this design that could send a false richening command to the ECM.
> If the AFM is hard to find or too expensive to purchase as a quick
> cheap parts swap, then it's back to more diagnosis. I am having too
> difficult a time with deciphering these codes over usenet to be of much
> use. I don't feel confident that you are getting consistent results
> from the code retrieval process - and I blame Hyundai for that, not
> you. Their service info seems pretty useless.
>
> Toyota MDT in MO
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what he said.....
ditto


~:~
marsh