TOP END REFINISHING - Page 12 - ZR-1 Net Registry Forums

Schrade · 10-30-2013

Quote:

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 · 10-30-2013

Quote:

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 · 10-31-2013

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 · 10-31-2013

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 · 10-31-2013

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???????????????

Bearly Flying · 10-31-2013

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 · 10-31-2013

Quote:

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 · 11-01-2013

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 · 11-01-2013

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 · 11-02-2013

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? )

10-31-2013	#113
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	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. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

10-31-2013	#114
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	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.

10-31-2013	#116
Bearly Flying Join Date: Dec 2012 Location: Ponoka, Alberta, Canada Posts: 158	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. __________________ 91 ZR-1 Arctic White/Gray 01 C-5 Magnetic Red/Black 85 FJ 1100 (Big Bore kit, Hooligan Bike) 05 FJR 1300 Yamaha (Long Distance, Sport Touring) And a whole whack of RC Planes

11-01-2013	#118
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	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.

11-01-2013	#119
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	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.

11-02-2013	#120
Schrade Join Date: Dec 2012 Location: NC Posts: 1,786	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? ) __________________ I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads... ( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b] Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc... 1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3" [IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]