Using TBI on moded 5.7

[Mike Vannorsdel]

The voltage going to the TPS is 4.5v.  But for some reason at WOT it only reads
3.8v.  I'm pulling 20" vacuum.  I didn't reattach the PCV, is this a problem?
I'm getting 30 counts on the IAC.  From what I can tell is the TPS is causing
the rich idle and the hesitation.  Is there a special way to "autozero" the TPS
or just reset all of the sensors?

Programmer wrote:

> Check your engine grounds, and especially those that are sensor related. The
> TPS voltage "low" at WOT is a clue.  The TPS is "autozero" type--spec should
> be closer to .45 volts. Make sure the throttle plate is at rest when you
> turn on the ignition. Like Shannon said, make sure the throttle plate is
> opening fully. The TPS ground is also shared by the MAP sensor--and don't
> overlook your EGR valve which could be leaking. If you have a scan tool note
> the IAC counts. Anything below 25 (and a higher than normal idle) with a
> fully warmed up engine "indicates" a vacuum leak or wrong PCV valve.
>
> Pay close attention to what the BL numbers are doing--they're the self
> diagnosing parameters you can use to see what the computer is commanding at
> the fuel end of things...
>
> Lyndon IPTECH
> -----Original Message-----
> From: Mike Vannorsdel <vannorsdel at rmi.net>
> To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
> Date: November 8, 1999 12:06 AM
> Subject: Re: Using TBI on moded 5.7
>
> >Well the problems I'm facing now is erratic idle and poor throttle
> response.  I
> >have tried the timing at 0 and 10 with a little added power at 10 but no
> fixes
> >to the problems.  The TBI is used and I'm not sure on the condition of
> IAC(it
> >does work but I don't know how well).  The TPS reading at idle is .78v
> which is
> >high and at WOT it's 3.8v which is low.  I replaced the TPS and now have
> added a
> >hesitation, voltage is the same.  At idle the injectors seem to be giving
> way
> >too much fuel(it almost puddles on the throttle plates).  The MAP is new
> and
> >there are no vacuum leaks.  The TPS doesn't seem adjustable.  I'm not sure
> if
> >the problem is TPS, injector, or both.  The engine cruises fine.  I'm just
> >looking for smooth running and have faced the fact that I won't be able to
> get
> >max performance from it with the stock ecm.  I have the data on the engines
> best
> >performance level but am unfamiliar with prom programming and don't have
> the
> >equipment.
> >
> >CSH-HQ wrote:
> >
> >> If you really want it right, probably will take a chip (prom).
> >> Might get by with jacking the timing via the dist/playing with fuel
> >> pressure, but those are bandaids, but will tell you how far off you are,
> to
> >> a degree.
> >> Try reading tuning.txt, tuning.doc, and programming 101, then check back,
> and
> >> you'll then have more of an understanding of where you are/what you have
> to
> >> do.  The related material is off of the home page to FTP, and projects.
> >> Grumpy
> >>
> >> >No relation.  I don't have any reprogramming eqip either.  I'm aware of
> the
> >> >needed settings for timing and fuel with the changes but really have no
> way
> >> >to change the ecm.  I was just looking to see if the TBI at stock
> settings
> >> >will be a problem or not.
> >> >
> >> >CSH-HQ wrote:
> >> >
> >> >> You any relation to Kevin?.
> >> >> Do you have a prom burner, or related equipment?.
> >> >> Have you any prom burning experience?.
> >> >>
> >> >> More fuel, timing adjustments sound likely.
> >> >> Have you read programming 101,
> >> >> do you have a 1227747 ecm?.
> >> >> Grumpy
> >> >>
> >> >> >I have a '91 K1500 with the 5.7 TBI.  I have just rebuilt the engine
> and
> >> >> >made a few changes.  I have raised the compression to 9.5 and added a
> >> >> >CompCams XE250(250/260).  What, if any, changes should be made to the
> >> >> >timing and TBI to work well with the changes?
> >> >> >
> >> >
> >