Re: TPS and MAP control / operation

From: Shane Moseley (smoseley@ix.netcom.com)
Date: Sat Mar 03 2001 - 13:37:09 EST


Bob Tom wrote:

> At 09:22 AM 3/1/01 -0500, you wrote:
> >How about limiting the reference voltage to the TPS? If WOT is say 5v, then
> >limit the reference to 4.5v, and the PCM never sees WOT. Jim
>
> Hi, Jim
>
> The problem that I see is that the PCM will see a signal from the TPS
> indicating "not WOT" but it will also see a signal from the MAP sensor
> indicating vacuum conditions which should only happen if the tb blades are
> at the fully open position.

Sounds like one of Bernd's little black boxes might take care of that...

> As far as I know, the PCM does a check to make
> sure that the TPS and MAP signals make sense. My guess is that, most likely,
> the PCM will do a fuel cut under this condition.

Very interesting - I had a situation at the dragstrip this past weekend that I
can't quite explain (yet). This might be something to research further - I think
I had some TCC output control happening also as the truck layed down like a $%&#*
after I hit 6000rpms when the tranny went "shift-shift" and it was all over at
that point (rpms dropped to like 1800 almost instantly....)

I've never been anywhere around 6k before but this season I've got my truck in a
pretty high state of tune and the MP computer combined w/the MPI intake is
getting me there (seems to keep wanting to pull maybe even over 6k = not me! 8)

After analyzing my scan tool results - it seems the TPS and MAP signals also
dropped to almost 0 bringing the load factor down as well and then the
"shift-shift" occurred about the same time. So far - I'm leaning towards at
least another bad MAP sensor (whats killing these things?) if not tranny temp too
high and/or some other possibilities. My autometer tranny temp gauge was around
160 degrees but I wonder where the limits of the TCC output are re: temp?

> I was thinking about the possibilites of this signal modification until I
> learned more about EFI strategies.

I agree - its all about understanding these strategies FIRST then doing the
mods...

> There is a common mod with the TPS signal that a lot of the
> owners of street cars seem to use. When the TPS reaches a certain
> part throttle opening (out of the idle mode), the mod bumps up this signal
> and sends a fully open signal.

Any idea what the the expected extremes for TPS operation are? I'm getting
around 12.5 percent fully closed and 72.x percent fully opened. Hmmm - I bet
thats in my powertrain diagnostics manual - doh! - I hate when I realize I should
be reading the friggen manual (RTFM)...

Thanks for the info!

Latr,

Shane

--
'96 IndyRam-HisIndy-MPI/TB/Pulleys/AccelCoil/MPComp/HookerSuperComps/CompTAs
'96 IndyRam-HerIndy-numbered(#142)"Track Truck"
'74 Triple-Black Dodge Challenger Rallye 360 home-brew EFI R&D vehicle
'68 Black Corvette Convertible 427 (For Sale)



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