New here, have a question - ZR-1 Net Registry Forums

93ZR-1 · 06-17-2020

Hello everyone, I just became a member here and wanted to say Hi and possibly pick your brains on an issue that has me stumped.

If you are already on the corvette forums this may sound familiar... and sorry this has turned into a book but I thought all the information would be pertinent.

I have a 1993 ZR-1 with 80,000mi. The car sticks at wide open throttle. Not specific to a gear or the high or normal power setting. It was intermittent at first but now is happening more often. I took off the intake today and cleaned the throttle bodies and butterfly valves, they were seriously dirty and I suspected this was the culprit however after getting it all back together it is still happening. I have checked and lubed the throttle cable, checked the gas pedal and neither seem to be sticking.

Take two; I checked out the connection and surrounding wiring to the TPS and everything looks good, no rough or high or low idle when the car is running. Took it for a drive today and the same thing happened only worse. It was driving normally until I depressed the gas pedal past halfway and the car got stuck at an open throttle position to the point I could not get it out. I had to shift to neutral after slowing down with the brakes and shut the car off. I drove it home gently with light throttle and it drove normally. When it did get stuck, even when I went to neutral it did not run up to redline, it was stuck at around 5000 rpm. Any ideas? Think I might have not gotten all the junk out when I cleaned the throttle bodies and maybe loosened up something that got stuck afterword?

Take three; I took everything apart again. Used an entire can of intake cleaner, and lubed the crap out of all the throttle linkage parts, springs, and cables. Checked the ASR cables and movement, found a rotten vacuum hose and replaced that. Replaced both fresh air hoses because they were worn and cracked.

Took it out for a test drive and it drove wonderfully. Better than it ever has before. Smooth crisp and instant throttle response and return, no hint of hanging up anywhere through the rpm range or the throttle range. The car drove like I imagine it did when it was new.

The latest... so I drove the car again today, everything is normal in the low power setting, however when I set it to high power and floored it, it stuck again between 4500-5000 rpm, a quick kick of the gas pedal got it out and it was more controllable this time but something still isn't right. Any ideas where to go from here?

Ccmano · 06-17-2020

Welcome to the Registry! You found the right place for all things ZR-1. I saw your post on CF. I recommend you call Mark Haibeck www.zr1specialist.com My guess is your throttle shaft is worn causing the binding. Mark can rebuild the throttle body.
H

A26B · 06-17-2020

I agree with Ccmano, probably worn shaft(s)/blades.

lfalzarano · 06-18-2020

I had mine rebuilt by Marc and it has been flawless. Mine wouldn?t idle below 1500. He found some crap on the back side of the blades. You may have a similar problem binding the blades from opening all the way.

Sent from my iPhone using ZR-1 Net Registry

We Gone · 06-18-2020

Welcome.

EvanZR1 · 06-19-2020

Had similar issues to you, had Steve @ Crossed Flags rebuild the throttle body and have not had the issue since.

jss06c6 · 06-19-2020

Agree with all that have commented. The throttle shaft gets worn and it hangs up. It doesn't take much (throttle blade open) to cause high hanging throttle. It's a combination if wear on the rod as well as the throttle body itself.

Depending on how severe the wear is, you can polish it (shaft) up a bit and then increase the spring return tension, lubricate (graphite) and buy some time. At one time there was someone that could "sleeve" the bore in the throttle body (where the shaft goes). This helps, but the shaft also has to be replaced to get like new performance..

Sent from my SM-G950U using ZR-1 Net Registry mobile app

06-17-2020	#1
93ZR-1 Join Date: Jun 2020 Location: Colorado Posts: 4	New here, have a question Hello everyone, I just became a member here and wanted to say Hi and possibly pick your brains on an issue that has me stumped. If you are already on the corvette forums this may sound familiar... and sorry this has turned into a book but I thought all the information would be pertinent. I have a 1993 ZR-1 with 80,000mi. The car sticks at wide open throttle. Not specific to a gear or the high or normal power setting. It was intermittent at first but now is happening more often. I took off the intake today and cleaned the throttle bodies and butterfly valves, they were seriously dirty and I suspected this was the culprit however after getting it all back together it is still happening. I have checked and lubed the throttle cable, checked the gas pedal and neither seem to be sticking. Take two; I checked out the connection and surrounding wiring to the TPS and everything looks good, no rough or high or low idle when the car is running. Took it for a drive today and the same thing happened only worse. It was driving normally until I depressed the gas pedal past halfway and the car got stuck at an open throttle position to the point I could not get it out. I had to shift to neutral after slowing down with the brakes and shut the car off. I drove it home gently with light throttle and it drove normally. When it did get stuck, even when I went to neutral it did not run up to redline, it was stuck at around 5000 rpm. Any ideas? Think I might have not gotten all the junk out when I cleaned the throttle bodies and maybe loosened up something that got stuck afterword? Take three; I took everything apart again. Used an entire can of intake cleaner, and lubed the crap out of all the throttle linkage parts, springs, and cables. Checked the ASR cables and movement, found a rotten vacuum hose and replaced that. Replaced both fresh air hoses because they were worn and cracked. Took it out for a test drive and it drove wonderfully. Better than it ever has before. Smooth crisp and instant throttle response and return, no hint of hanging up anywhere through the rpm range or the throttle range. The car drove like I imagine it did when it was new. The latest... so I drove the car again today, everything is normal in the low power setting, however when I set it to high power and floored it, it stuck again between 4500-5000 rpm, a quick kick of the gas pedal got it out and it was more controllable this time but something still isn't right. Any ideas where to go from here?

06-17-2020	#2
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: New here, have a question Welcome to the Registry! You found the right place for all things ZR-1. I saw your post on CF. I recommend you call Mark Haibeck www.zr1specialist.com My guess is your throttle shaft is worn causing the binding. Mark can rebuild the throttle body. H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.

06-17-2020	#3
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,376	Re: New here, have a question I agree with Ccmano, probably worn shaft(s)/blades. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

06-18-2020	#4
lfalzarano Join Date: Feb 2011 Location: Clayton, North Carolina Posts: 1,133	Re: New here, have a question I had mine rebuilt by Marc and it has been flawless. Mine wouldn?t idle below 1500. He found some crap on the back side of the blades. You may have a similar problem binding the blades from opening all the way. Sent from my iPhone using ZR-1 Net Registry __________________ Lou[COLOR="Red"][B][SIZE="4"][/SIZE][/B][/COLOR]

06-18-2020	#5
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,163	Re: New here, have a question Welcome. __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

06-19-2020	#6
EvanZR1 Join Date: Nov 2010 Location: Omaha Posts: 402	Re: New here, have a question Had similar issues to you, had Steve @ Crossed Flags rebuild the throttle body and have not had the issue since. __________________ Evan 2023 70th C8 HTC, 94 Admiral Blue ZR-1 SOLD - 2012 Carlisle Blue Metallic ZR1 - 800HP SOLD - Steel Blue 91 391cid ZR-1 #391 SOLD - Black 91 ZR-1

06-19-2020	#7
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: New here, have a question Agree with all that have commented. The throttle shaft gets worn and it hangs up. It doesn't take much (throttle blade open) to cause high hanging throttle. It's a combination if wear on the rod as well as the throttle body itself. Depending on how severe the wear is, you can polish it (shaft) up a bit and then increase the spring return tension, lubricate (graphite) and buy some time. At one time there was someone that could "sleeve" the bore in the throttle body (where the shaft goes). This helps, but the shaft also has to be replaced to get like new performance.. Sent from my SM-G950U using ZR-1 Net Registry mobile app