Deaded Idle Surge? - ZR-1 Net Registry Forums

vettn71 · 02-22-2009

This evening I was driving my 90 Z back from the Dallas Auto Show. Everything was golden until I pulled off the highway and up to a stop light. The idle stayed at about 2000 RPM for 20 seconds or so, then, in steps, dropped to 1200, then 750, then 600 or so where it remained for the rest of the drive home (all on secondary streets). It hasn't done this before, but I really haven't driven it enough to know what is normal. Any comments/suggestions?

Jim

carter200 · 02-22-2009

Check your vacuum hoses. Usually they are the culprits. One is probably cracked or hanging on by a thread. Good luck and let us know what you find.

XfireZ51 · 02-22-2009

Quote:

Originally Posted by vettn71

This evening I was driving my 90 Z back from the Dallas Auto Show. Everything was golden until I pulled off the highway and up to a stop light. The idle stayed at about 2000 RPM for 20 seconds or so, then, in steps, dropped to 1200, then 750, then 600 or so where it remained for the rest of the drive home (all on secondary streets). It hasn't done this before, but I really haven't driven it enough to know what is normal. Any comments/suggestions?

Jim

Check the PCV "F".

GOLDCYLON · 02-23-2009

Aslo are you running the original PROM? Gm released an update to the prom due to this surging problem but the previous owner may or may not have gotten it fixed. If this is the first time you have experienced this then as the other members have already stated the PCV hose and even a dirty IAC can cause this as well. If you had poped a hose under the TB the idle would never fall.

tomtom72 · 02-23-2009

Just in case you may want to see the TSB on the PROM update it's over at the netreg site.

http://www.zr1netregistry.com/bulletins/476503-1.jpg

The only issue now is this replacement PROM seems to be NLA. I'm not 100% positive on the NLA, but when I run the P/N nothing comes back. I get the "no such part number" message.

I'd check for vacuum leaks first and you can tell if the PROM was done by hooking up a scanner as it will give the PROM ID# after you verify the VIN #.

Tom

Jarek5_7 · 03-02-2009

maybe someone could copy that updated prom and post a file so everyone could burn it because I also know that its no longer availabkle from gm

XfireZ51 · 03-02-2009

Here it is. I found a BRXB which looks to be a 91 ZR-1 cal as well. Don't know much about it but maybe some of the ZR-1 gods can chime in.

Note: I make no guarantees for the bin. Use at your own discretion. If somebody tries it out, let us know if it works.

Sgreg · 03-02-2009

Quote:

Originally Posted by Jarek5_7

maybe someone could copy that updated prom and post a file so everyone could burn it because I also know that its no longer availabkle from gm

This should have been a recall and not just a Service Bulletin ! Hard to find an owner of a 90 or 91 Z with the original Memcal that hasn't had high idle problems and hard hot cranking.

vettn71 · 03-03-2009

I've got a Haibeck (sp) prom in the car. Still have the original in a bag. I haven't had a chance to look at the vacuum hoses and just bought a set of manuals off ebay. I haven't driven the car since bringing it home from the Dallas Auto Show.

Jim

GOLDCYLON · 03-03-2009

Ok that answers that Jim your prom is ruled out as the culprit. So a dirty IAC or a vac hose maybe the issue. Did the car backfire upon a startup recently? Normally that event occurs before the PVC hose blows off behind the plenum next to the firewall. As will cause the idle symptoms

02-22-2009	#1
vettn71 Join Date: Oct 2008 Location: Colleyville, TX Posts: 274	Deaded Idle Surge? This evening I was driving my 90 Z back from the Dallas Auto Show. Everything was golden until I pulled off the highway and up to a stop light. The idle stayed at about 2000 RPM for 20 seconds or so, then, in steps, dropped to 1200, then 750, then 600 or so where it remained for the rest of the drive home (all on secondary streets). It hasn't done this before, but I really haven't driven it enough to know what is normal. Any comments/suggestions? Jim

02-22-2009	#2
carter200 Join Date: Jun 2004 Location: Texas Posts: 2,431	Re: Deaded Idle Surge? Check your vacuum hoses. Usually they are the culprits. One is probably cracked or hanging on by a thread. Good luck and let us know what you find. __________________ 95 ZR-1 BLK/Gry #392 LT5 Reg# 868 RIP ZR1NET Founding Mem #155

02-23-2009	#4
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Deaded Idle Surge? Aslo are you running the original PROM? Gm released an update to the prom due to this surging problem but the previous owner may or may not have gotten it fixed. If this is the first time you have experienced this then as the other members have already stated the PCV hose and even a dirty IAC can cause this as well. If you had poped a hose under the TB the idle would never fall. __________________ 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

02-23-2009	#5
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Deaded Idle Surge? Just in case you may want to see the TSB on the PROM update it's over at the netreg site. http://www.zr1netregistry.com/bulletins/476503-1.jpg The only issue now is this replacement PROM seems to be NLA. I'm not 100% positive on the NLA, but when I run the P/N nothing comes back. I get the "no such part number" message. I'd check for vacuum leaks first and you can tell if the PROM was done by hooking up a scanner as it will give the PROM ID# after you verify the VIN #. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

03-02-2009	#6
Jarek5_7 Join Date: Aug 2008 Location: Radom, Poland Posts: 38	Re: Deaded Idle Surge? maybe someone could copy that updated prom and post a file so everyone could burn it because I also know that its no longer availabkle from gm __________________ 1991 zr1 convertible ;)

03-02-2009	#7
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,669	Re: Deaded Idle Surge? Here it is. I found a BRXB which looks to be a 91 ZR-1 cal as well. Don't know much about it but maybe some of the ZR-1 gods can chime in. Note: I make no guarantees for the bin. Use at your own discretion. If somebody tries it out, let us know if it works. Last edited by XfireZ51; 03-08-2024 at 02:10 PM.

03-03-2009	#9
vettn71 Join Date: Oct 2008 Location: Colleyville, TX Posts: 274	Re: Deaded Idle Surge? I've got a Haibeck (sp) prom in the car. Still have the original in a bag. I haven't had a chance to look at the vacuum hoses and just bought a set of manuals off ebay. I haven't driven the car since bringing it home from the Dallas Auto Show. Jim

03-03-2009	#10
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Deaded Idle Surge? Ok that answers that Jim your prom is ruled out as the culprit. So a dirty IAC or a vac hose maybe the issue. Did the car backfire upon a startup recently? Normally that event occurs before the PVC hose blows off behind the plenum next to the firewall. As will cause the idle symptoms __________________ 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