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Old 10-30-2013   #111
Schrade
 
Join Date: Dec 2012
Location: NC
Posts: 1,783
Default Re: Throttle hesitation diagnostics?

Quote:
Originally Posted by mike100 View Post
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?????????????????????????????
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Old 10-30-2013   #112
mike100
 
Join Date: Feb 2011
Location: San Marcos CA
Posts: 1,786
Default Re: Throttle hesitation diagnostics?

Quote:
Originally Posted by Schrade View Post
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.

Last edited by mike100; 10-30-2013 at 08:35 PM.
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Old 10-31-2013   #113
XfireZ51
 
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,685
Default Re: TOP END REFINISHING

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.
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Old 10-31-2013   #114
Franke
 
Join Date: May 2013
Location: Beaver, PA
Posts: 515
Default Re: TOP END REFINISHING

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.
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Old 10-31-2013   #115
Schrade
 
Join Date: Dec 2012
Location: NC
Posts: 1,783
Default Re: TOP END REFINISHING

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

Not satisfied tho'...

Quote:

======================================
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???????????????
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Old 10-31-2013   #116
Bearly Flying
 
Join Date: Dec 2012
Location: Ponoka, Alberta, Canada
Posts: 158
Default Re: TOP END REFINISHING

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.
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Old 10-31-2013   #117
Schrade
 
Join Date: Dec 2012
Location: NC
Posts: 1,783
Default Re: TOP END REFINISHING

Quote:
Originally Posted by Bearly Flying View Post
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...
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Old 11-01-2013   #118
Franke
 
Join Date: May 2013
Location: Beaver, PA
Posts: 515
Default Re: TOP END REFINISHING

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.
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Old 11-01-2013   #119
Franke
 
Join Date: May 2013
Location: Beaver, PA
Posts: 515
Default Re: TOP END REFINISHING

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.
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Old 11-02-2013   #120
Schrade
 
Join Date: Dec 2012
Location: NC
Posts: 1,783
Default Re: TOP END REFINISHING

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? )

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