1990 Throttle hesistation - Page 6 - ZR-1 Net Registry Forums

GOLDCYLON · 10-11-2013

swap the fuel pumps. Make the secondary the primary and the Primary the secondary. See if the swap changes the stumble.

just an idea

XfireZ51 · 10-11-2013

Does the stumble continue if you keep the pedal at a steady 1.6% TPS? Or does it stumble on the initial tip in?

Blue Flame Restorations · 10-11-2013

I just put pumps in the 95 a week ago. Easy peasy.

Schrade · 10-11-2013

Quote:

Originally Posted by Blue Flame Restorations

I just put pumps in the 95 a week ago. Easy peasy.

No 'cautions', or 'gotcha's' on it there Brett???

Quote:

Originally Posted by XfireZ51

Does the stumble continue if you keep the pedal at a steady 1.6% TPS? Or does it stumble on the initial tip in?

YES - although it's a lope, no 'stumble'.

I'm gonna' do another vid here momentarily, with engine running to show DM readouts in sync with engine lope...

Blue Flame Restorations · 10-11-2013

Nope. Real straight forward. Checkout Dynomite's Solutions. Takes about an hr first time through.

Franke · 10-11-2013

Since the fuel pressure increases to maintain regulated pressure when the vacuum drops (opening throttle) then removing the hose should tell the FPR to increase fuel pressure. The FSM does talk about that in Emissions and drivability. I wouldn't do this for long periods of time with the FPR to prevent problems in case of injector malfunction. Follow chart A7 to check FPR on page 6e3-A-29&31. Maybe that will help.
Scottfab once said in another post that fuel pressure as low as your was (44psi) is too low. According to FSM I would have to agree. Performance issues could crop up but I'm not sure it would cause your hesitation at just off idle.

Dynomite · 10-15-2013

Quote:

Originally Posted by Schrade

Should I pull the IH's next? Or DIS?

Pull the His....the DIS is under the Plenum with four bolts. That is already pulled with the Plenum.

And are you removing the starter and AC compressor?
If so on the AC compressor....you just set that aside but be very very careful you do not put a bending load on the AC lines going into the evaporator.

I assume you are pulling the starter and cleaning out the Valley Drain also.......and maybe pulling the crankcase breather cover and installing new gasket.

And since you have starter removed....take the Solenoid apart and clean up the contacts when you are at it.

Schrade · 10-15-2013

Quote:

Originally Posted by Dynomite

Pull the His....the DIS is under the Plenum with four bolts. That is already pulled with the Plenum.

And are you removing the starter and AC compressor?
If so on the AC compressor....you just set that aside but be very very careful you do not put a bending load on the AC lines going into the evaporator.

I assume you are pulling the starter and cleaning out the Valley Drain also.......and maybe pulling the crankcase breather cover and installing new gasket.

And since you have starter removed....take the Solenoid apart and clean up the contacts when you are at it.

Yep - got to roll the AC comp aside - dropped a bolt for mounting one of the 4 the ?'s (distributors) (above the starter), at the PS pump. Another hunting setback.

Di-electric grease after cleaning, on the contact prongs at re-assembly???

Breaktime on breakdown; cleaning parts ahead...

GOLDCYLON · 10-17-2013

http://www.youtube.com/watch?v=FsqJFIJ5lLs

GOLDCYLON · 10-18-2013

By request. I split the threads. GC

10-11-2013	#51
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Throttle hesitation diagnostics? swap the fuel pumps. Make the secondary the primary and the Primary the secondary. See if the swap changes the stumble. just an idea __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

10-11-2013	#52
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,669	Re: Throttle hesitation diagnostics? Does the stumble continue if you keep the pedal at a steady 1.6% TPS? Or does it stumble on the initial tip in? __________________ [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

10-11-2013	#53
Blue Flame Restorations Join Date: Feb 2010 Location: Pendleton, IN Posts: 3,904	Re: Throttle hesitation diagnostics? I just put pumps in the 95 a week ago. Easy peasy. __________________ 1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project

10-11-2013	#55
Blue Flame Restorations Join Date: Feb 2010 Location: Pendleton, IN Posts: 3,904	Re: Throttle hesitation diagnostics? Nope. Real straight forward. Checkout Dynomite's Solutions. Takes about an hr first time through. __________________ 1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project

10-11-2013	#56
Franke Join Date: May 2013 Location: Beaver, PA Posts: 516	Re: Throttle hesitation diagnostics? Since the fuel pressure increases to maintain regulated pressure when the vacuum drops (opening throttle) then removing the hose should tell the FPR to increase fuel pressure. The FSM does talk about that in Emissions and drivability. I wouldn't do this for long periods of time with the FPR to prevent problems in case of injector malfunction. Follow chart A7 to check FPR on page 6e3-A-29&31. Maybe that will help. Scottfab once said in another post that fuel pressure as low as your was (44psi) is too low. According to FSM I would have to agree. Performance issues could crop up but I'm not sure it would cause your hesitation at just off idle. Last edited by Franke; 10-11-2013 at 10:14 PM.

10-17-2013	#59
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: 1990 top end restoration http://www.youtube.com/watch?v=FsqJFIJ5lLs __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V

10-18-2013	#60
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: 1990 Throttle hesistation By request. I split the threads. GC __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V