VIN 3 msg from TBK

[Lynn R. Erickson]

Terry:

TBK wrote:
> 
> I'm glad you picked up a few things in that exchange. Troubleshooting over
> the internet is difficult though.
> 
> Some clarifications:
> 
> 1. 10" of vacuum at idle is too low. I had a VIN 3 and 15 and above it more
> like it. I replaced it with a VIN 1 3800 SC.

Picked up to 12+" with the new ECM. Since I'm at 4500', this may be
reasonable. Incidentally, since hooking up to the tranny vacuum is a
large PITA, I tried the EGR vacuum. Worked fine. The EGR vacuum is not
ported.

> 2. I've never seen a IAT heated by the ECM. If the readings are correct when
> you put it into free air, then the readings are correct. 180 degree air from
> the radiator and the wrap around exhaust sitting there will heat the air
> cleaner and intake hose. Normal. I've been through this.

My thought too, except that every ECM mode _except_ ALDL reported 82-86
F, which was ballpark correct for ambient. Your e-mail inspired me to
break out the heat gun. It appears, at least short term, that only ALDL
mode reports the actual IAT sensor reading! Curious.

> 3. Yep, the ECM will hold some things fixed when communicating, idle fixed
> at 1000, etc. It depends on the ECM. The newer P4's don't do this.

What's interesting is that the scanner has no "normal" mode.

> 4. Since the ECM was replaced, it will take a little time for it to learn.
> Don't be surprised if the problem doesn't come back. Not to be negative. The
> flicker CE lamp leans me towards the ECM or power loss to the ECM. Default
> settings from power loss can be both good and bad. Idle is usually shakey
> for awhile, but higher RPM may run better. But once it starts learning, and
> the problem was not the ECM, it could come back.
> 
> Well, glad you made some progress!
> 
> Terry

Cross my fingers. My wife's reaction on her test drive was "I can hardly
tell it's running". I get so fussily involved that I can't tell the
difference. Hope she's right. She's taking it on a 750 mile run to
California tomorrow.

Thanks for the help. I trust you don't mind me posting this to the list
also.

Lynn

PS: If you know anybody who's looking for a good real time firmware
programmer (me) who's also a registered ME, have them take a look at my
web site: http://www.xmission.com/~lre

Sorry. Can't resist a plug.

/*********************************************************/
        I may be stupid, but I ain't _that_ dumb.
        lre at xmission.com   www.xmission.com/~lre
/*********************************************************/