Short idle/engine Issue - ZR-1 Net Registry Forums

TealZR1 · 04-26-2018

My 91 on cold start is perfect. Idles down to 650 but always when reaching about 110 degrees it bogs down (runs rough) for about 20-30 seconds with rpm's decreasing some. After 20 seconds or so is comes back up to normal and drives perfect through normal operating temps. But again does this about every time. Had on scanner (ok) and no warning lights come up.
Thanks in advance of any help.

Ccmano · 04-27-2018

I would check the fuel pumps and fuel filter first. Sounds like your primary pump is on its way out. There are some excellent threads on the subject if you care to search.

Post 7 in the following thread is excellent.
http://www.zr1.net/forum/showthread.php?p=136108

H

XfireZ51 · 04-27-2018

Quote:

Originally Posted by TealZR1

My 91 on cold start is perfect. Idles down to 650 but always when reaching about 110 degrees it bogs down (runs rough) for about 20-30 seconds with rpm's decreasing some. After 20 seconds or so is comes back up to normal and drives perfect through normal operating temps. But again does this about every time. Had on scanner (ok) and no warning lights come up.
Thanks in advance of any help.

110F is 43C which is about where the fueling transitions from Open Loop to Closed Loop. That transition may be a bit lean before it continues to warm up and the ECM adjusts fueling accordingly.

GOLDCYLON · 04-27-2018

Actually this is somewhat normal and consistent with both my cars. Yeah it does that as Dom states. Never throws a code but its like the idle is adjusting. Any way to video this stumble ?

XfireZ51 · 04-27-2018

Quote:

Originally Posted by GOLDCYLON

Actually this is somewhat normal and consistent with both my cars. Yeah it does that as Dom states. Never throws a code but its like the idle is adjusting. Any way to video this stumble ?

Altho that can be addressed w tuning so the transition is nearly seamless.

TealZR1 · 04-27-2018

Thanks all for responding to my idle issue. Per Goldcylon's suggestion here is a video. About 15 seconds in it starts to stumble but about 32 seconds it goes back to normal.
Thanks!

https://www.youtube.com/watch?v=SNqW...ature=youtu.be

GOLDCYLON · 04-27-2018

Quote:

Originally Posted by XfireZ51

Altho that can be addressed w tuning so the transition is nearly seamless.

Correct

GOLDCYLON · 04-27-2018

Quote:

Originally Posted by TealZR1

Thanks all for responding to my idle issue. Per Goldcylon's suggestion here is a video. About 15 seconds in it starts to stumble but about 32 seconds it goes back to normal.
Thanks!

https://www.youtube.com/watch?v=SNqW...ature=youtu.be

Yeah needs some fine tuning there. Lots of input from close loop to open loop. Condition of o2 sensors, TB, IAC all play into this

jss06c6 · 04-27-2018

Agree with Dominic that's it's likely an open to closed loop issue, but have a question... Is this a relatively recent development, or has it always done this? Have you checked and cleaned your O2 sensors? Was the tune changed and it subsequently started doing this?

Sent from my QTAIR7 using ZR-1 Net Registry mobile app

TealZR1 · 04-27-2018

thanks JSS and Gold - yes fairly recent since I had an antifreeze leak at the TB. I had Haibeck service the TB and reinstalled but I am wondering if the antifreeze possibly started another issue like contaminating one or both 02 sensors.
If I get it on a scanner next week what should I look for?

04-26-2018	#1
TealZR1 Join Date: Oct 2016 Location: Atlanta GA Posts: 51	Short idle/engine Issue My 91 on cold start is perfect. Idles down to 650 but always when reaching about 110 degrees it bogs down (runs rough) for about 20-30 seconds with rpm's decreasing some. After 20 seconds or so is comes back up to normal and drives perfect through normal operating temps. But again does this about every time. Had on scanner (ok) and no warning lights come up. Thanks in advance of any help.

04-27-2018	#2
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: Short idle/engine Issue I would check the fuel pumps and fuel filter first. Sounds like your primary pump is on its way out. There are some excellent threads on the subject if you care to search. Post 7 in the following thread is excellent. http://www.zr1.net/forum/showthread.php?p=136108 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. Last edited by Ccmano; 04-27-2018 at 02:13 AM.

04-27-2018	#4
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,155	Re: Short idle/engine Issue Actually this is somewhat normal and consistent with both my cars. Yeah it does that as Dom states. Never throws a code but its like the idle is adjusting. Any way to video this stumble ? __________________ 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 Last edited by GOLDCYLON; 04-27-2018 at 10:35 AM.

04-27-2018	#6
TealZR1 Join Date: Oct 2016 Location: Atlanta GA Posts: 51	Re: Short idle/engine Issue Thanks all for responding to my idle issue. Per Goldcylon's suggestion here is a video. About 15 seconds in it starts to stumble but about 32 seconds it goes back to normal. Thanks! https://www.youtube.com/watch?v=SNqW...ature=youtu.be

04-27-2018	#9
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: Short idle/engine Issue Agree with Dominic that's it's likely an open to closed loop issue, but have a question... Is this a relatively recent development, or has it always done this? Have you checked and cleaned your O2 sensors? Was the tune changed and it subsequently started doing this? Sent from my QTAIR7 using ZR-1 Net Registry mobile app