TOP END REFINISHING

[Schrade]

Originally Posted by mike100

Didn't you convert this car to an automatic? It is a good possibility the calibration needs more "accelerator pump shot".

Still thinking about this here Mike, as cause of hesitation...

Vacuum to tranny COULD interfere with FPR's response to vacuum - right?

BUT...

There's no vacuum connections to the tranny (that I know of) - it's got a dedicated electronic controller. Even the hammer down downshift is electronic.

Besides - the 'hesitation' was noticeable in, or OUT of gear...

Thoughts?????????????????????????????

[mike100]

Originally Posted by Schrade

Still thinking about this here Mike, as cause of hesitation...

Vacuum to tranny COULD interfere with FPR's response to vacuum - right?

BUT...

There's no vacuum connections to the tranny (that I know of) - it's got a dedicated electronic controller. Even the hammer down downshift is electronic.

Besides - the 'hesitation' was noticeable in, or OUT of gear...

Thoughts?????????????????????????????

The reason I mention it is because when I used to have an auto car and ran a double pumper holley carb, the secondary opening always introduced too much air without the fuel flow (weak vacuum signal and a large plenum). getting the accelerator pump to squirt more gas sooner covered up the hesitation.

your calibration in software assumes the stock flywheel weight and maybe less drag right off idle. basically the light load fueling table and enrichment part could use some more fuel to see if it helps. Just thinking out loud, but this happens all the time with big carbs on automatic hot rods. You converting to automatic made me think of this. Also I have a friend who put a cam etc in a TPI car (auto) and has the same problem. this is also a speed-density car so I'm guessing enrichment is needed.

[XfireZ51]

If you could add a 5V reference signal, you should measure how smoothly the TPS outputs varying voltage as you move the throttle. If you see jumps in the voltage, then the TPS has worn spots which will cause inconsistent fuel/spark.

[Franke]

Yep, I agree. It would be better to measure the TPS voltage as it is varied instead of calculating resistance. You would then get an operational view of the output of the TPS. You can use a computer power supply for a 5 volt signal voltage if you have one laying around.

[Schrade]

I did operational voltage in the TPS thread. Smooth, uninterrupted, linear voltage increase...

Not satisfied tho'...

======================================
edit:
There are NO problems with the engine, no codes, nothing.
There is only the 'off idle sag' / slow response in rpm's.
5V Voltage FROM THE TPS, back to the ECM, is LINEAR; half throttle = approximately 2.3V.
TPS resistance, in mine, is exponential / logarithmic, as snappics show here.
==========================================

But now a hardware problem...

One of the secondary butterfly screw heads sheared off of the butterfly shaft. TB inside and out is clean as a whistle, but now this...

Can low - profile nut/bolt sets be purchased for the shaft?

And, the irony / Carma of the DAG question; I've tarnished the finish in the rearward part of the P side bore. Snappics shortly here...

At worst, new (or rebuilt) TB. At best, lose a few CFM with different screws in the shaft???????????????

[Bearly Flying]

Schrade; I have the screws and secondary throttle plates I recently removed from my 91.

If you need some shoot me a PM with your address.

[Schrade]

Originally Posted by Bearly Flying

Schrade; I have the screws and secondary throttle plates I recently removed from my 91.

If you need some shoot me a PM with your address.

PM en route there BF...

[Franke]

I don't think so Schrade as I had 5 holes in mine and didn't experience hesitation. If I remember correctly that bottom hose goes to the IH to pull crankcase vapors.

[Franke]

Schrade, I have a suggestion for ya. It may be better if you had a small insert inside that rubber pipe as it tends to get soft from the oil fumes and heat in back of the plenum. That way it won't collapse. I built a new pipe from soft copper and fittings and used it before I bought an original pipe from Jerrys. IMO that GM design was cheap and dirty.

[Schrade]

So set the P side IH.

Blot the head surface with a paper towel:

clean (Jerry said DRY, no thin grease film, as I'm accustomed)



Set the gasket; make sure they're aligned with a Phillips head (WTH is Phillips anyway? )