Rebuilding a Mass Air Flow Sensor - Page 2

On 2/10/2012 9:50 AM, Guv Bob wrote:

intelly gent, worldly types (not unlike my self... hyuk hyuk) only smarter.

an old Eclipse or shell out $400+ for a rebuilt one or donate it for next to
nothing off my taxes.

 I got no responses from the car groups, and thought maybe one of the
electronics RCM gurus here might point me in the right direction with this.

This one's DOHC non-turbo.

saw that it was OK, so that's good and bad.  Now back to square one.

and is idling rich.  First thought was to manually adjust the idle mixture.
Wrong. Can't do it on this car -- everything comes from the computer.

the wise folks here what to look at next?

does it have an iac valve? i had one go out on my vette that caused the
same symptoms.

Some (but not all) of that older stuff could display 'codes' in a
fashion. First you need your factory shop manual, then either by
shorting connector cavities, or possibly a switch on the computer, you'd
count blinks of either the 'check engine light', or an LED on the
computer proper. You'd then look up your blink code number/s in the
manual.

I still have a hunch that you may have a bad coolant temp sensor.
Usually when they go bad, they tell the computer that the engine is
really cold. The computer, dumb and dutiful as it is, believes this, and
based on the sensor data runs the engine very richŠ mimicking some or
all of the duties of the choke on older cars. The sensor check procedure
is quick, simple, and detailed in your factory shop manual.

Other trees to bark up are a possibly stuck on or leaking cold start
valve, and/or it's timer/control circuit. If so equipped, these were
just an injector spraying into the intake manifold (another choke like
enrichment device from days past). Some had various timer
circuits/devices to turn the cold start valve on when/if necessary, and
off again soon as it was not... but if they failed could leave the valve
on. These cold start valves systems were problematic with some models.
Complete info is, you guessed it, right there in your factory shop
manual.

Your manual should also have extensive troubleshooting charts and
related info.

Let us know how it comes out!

Erik

More... got me thinking, and on a whim looked up this:

<http://en.wikipedia.org/wiki/Thermotime_switch

Erik