GM TBI questions - again

[Greg Woods]

original post:
> > Hey all,
> > 
> > as some of you may remember I recently completed installation of a 86 GM TBI system
> > into my 2.8l cherokee.  I drove it around 1500 miles over the 4th of july weekend
> > without any problems!  However, their are a few things puzzling me.
> > The car pops / backfires upon deceleration.  Does this mean the air/fuel is too rich
> > at that time?  How can I fix this??  

update:
Thanks to all who responded with ideas.  Basically everyone suggested that I start
at the TPS sensor.  This brings me to another clue that I forgot to mention (oops,
sorry about that!:))  When I place the computer in diagnostics mode, my computer
strobs out an error 22.  Using the haynes manual GM error code translation, it tells 
me this is a "Throttle position sensor voltage low".  So I get my DMM out and look
at the voltage on the TPS with the ignition on (engine not started).  It reads around 
390 mV.  The manual specifies < 1 volt is OK.  But I decide to rotate the TPS to raise
the voltage reading anyway.  I do this and now the voltage is around 510mV, but 
perfomance does not improve.

I must not be interpreting this error code correctly.  Can someone tell me what it 
means?  Should I just replace the TPS??  When I rebuilt the throttle body, I put
an ohm meter across the POT and looked at the resistance as I swung the wiper.  It
went from around 0 to ~2.5K smoothly  and appeared perfectly normal to me.  Thats
why I don't understand how it could be bad?

TIA!

BTW, what is a "tip" or a "tip leaker"??


Greg Woods
gwoods at symtx.com
austin, tx
86 cherokee 2.8l TBI