Weird thing happened last weekend. - ZR-1 Net Registry Forums

cadillac531 · 03-26-2014

Had the car out last weekend, and was running nice and strong.

On the way home, I did a 25-35ft burnout and it sounded like a champ! All of a sudden, the SES light popped on. All the gauges looked good, nothing sounded out of the ordinary, and no unusual smells. Got the car home, shut it down, fired it back up, the light stayed on for about 2 seconds...and went out.

I've had the car out a couple of times since that and the light hasn't come back on. I haven't had a chance to pull any codes (current or historic), but all seems good.

Anyone have any ideas? Glitch in a sensor or in the ECU?

Not too worried about it, since it seems to have fixed itself. Just thought it was strange.

QB93Z · 03-26-2014

I have had that happen in the past. For me it occurs rarely, and follows a short, full throttle excursion.

The source has never been identified. I suspect that it stems from an intermittent lazy O2 sensor, but I don't have any evidence to prove that.

I guess that if the Lotus/GM engineers wanted a record of the transient, they would have made it a hard fault code.

Jim

GOLDCYLON · 03-26-2014

Pull the codes anyway. You had an error condition that did not set a hard code. It Happens. If I was a betting man it was a secondary issue like a seconary vacuum actuator leak based upon hammerng the car. The rest is specualtion. From o2 sensors to cam sensor fault/

scottfab · 03-26-2014

Quote:

Originally Posted by cadillac531

....snip....
I've had the car out a couple of times since that and the light hasn't come back on. I haven't had a chance to pull any codes (current or historic), but all seems good.

Anyone have any ideas? Glitch in a sensor or in the ECU?

Not too worried about it, since it seems to have fixed itself. Just thought it was strange.

See if it is setting a lean code (left or right).
Could be a fuel pump starting to act up. The bad news is that if it is
you could get stranded (happened to me). I put in an emergency switch that turns on and leaves on pump #2. That is just a guess based on my car.
The key would be to get a scanner on it to record data the walk through the data (assuming you can make it happen again) and see what the O2 sensors are doing and how the fuel trim and throttle position are behaving. Very not likely the secondary actuators since you'd have gotten the symptom during WOT not after.

cadillac531 · 03-26-2014

Thanks for the replies. I'll put my scanner on it and see what's happening.

Great idea on the switch for the second pump! I'll have to look into doing that as a safety precaution.

This car's never kicked a code before, so needless to say I was a little concerned when it came on, then a little confused when it went out.

XfireZ51 · 03-26-2014

My guess is lean O2.

Paul Workman · 03-27-2014

I too had an O2 issue. Mine was on my 95 LT1, and it was easily spotted with my scanner.

Note: I thought I would force a little RTV into the hole where the wires to the O2 element ran to seal it up. Big mistake! Not only does the element need contact with the atmosphere to work, they're very sensitive (read: can be easily destroyed) in the presence of silicon which was introduced by the RTV. (I think I was on my 3rd replacement O2 in as many months before suspicion took over and I figured out what the problem was. Left them alone and no problems for the 4 years I had it before trading it for the Z)

03-26-2014	#1
cadillac531 Join Date: Jul 2005 Posts: 243	Weird thing happened last weekend. Had the car out last weekend, and was running nice and strong. On the way home, I did a 25-35ft burnout and it sounded like a champ! All of a sudden, the SES light popped on. All the gauges looked good, nothing sounded out of the ordinary, and no unusual smells. Got the car home, shut it down, fired it back up, the light stayed on for about 2 seconds...and went out. I've had the car out a couple of times since that and the light hasn't come back on. I haven't had a chance to pull any codes (current or historic), but all seems good. Anyone have any ideas? Glitch in a sensor or in the ECU? Not too worried about it, since it seems to have fixed itself. Just thought it was strange. __________________ Constantine Registry Founding Member #0235 1991 Corvette ZR-1 -- Stock, 94 ZR-1 exhaust system, muffler delete. 1956 Chevrolet Belair -- Pro Street, 531ci Cadillac, 8-71 Blower, 8pt roll bar, built TH-400, 9" rear, 1,100 HP -- Street Car. https://www.youtube.com/watch?v=z8y4cwcvK0s 1968 Mustang "Pegasus" -- Zeeker Chassis, 584ci Dart Block, Brodix Big Brodies, 2-1150 Dominators, FTI 'Glide, 1168 hp, best ET & Trap(holding back) 8.57@159 -- 7.9X -- 1/4 mile car. 1970 Chevelle -- 468ci, TKO600, shaved and smoothed everything.

03-26-2014	#3
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Weird thing happened last weekend. Pull the codes anyway. You had an error condition that did not set a hard code. It Happens. If I was a betting man it was a secondary issue like a seconary vacuum actuator leak based upon hammerng the car. The rest is specualtion. From o2 sensors to cam sensor fault/ __________________ 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

03-26-2014	#5
cadillac531 Join Date: Jul 2005 Posts: 243	Re: Weird thing happened last weekend. Thanks for the replies. I'll put my scanner on it and see what's happening. Great idea on the switch for the second pump! I'll have to look into doing that as a safety precaution. This car's never kicked a code before, so needless to say I was a little concerned when it came on, then a little confused when it went out. __________________ Constantine Registry Founding Member #0235 1991 Corvette ZR-1 -- Stock, 94 ZR-1 exhaust system, muffler delete. 1956 Chevrolet Belair -- Pro Street, 531ci Cadillac, 8-71 Blower, 8pt roll bar, built TH-400, 9" rear, 1,100 HP -- Street Car. https://www.youtube.com/watch?v=z8y4cwcvK0s 1968 Mustang "Pegasus" -- Zeeker Chassis, 584ci Dart Block, Brodix Big Brodies, 2-1150 Dominators, FTI 'Glide, 1168 hp, best ET & Trap(holding back) 8.57@159 -- 7.9X -- 1/4 mile car. 1970 Chevelle -- 468ci, TKO600, shaved and smoothed everything.

03-26-2014	#6
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,678	Re: Weird thing happened last weekend. My guess is lean O2. __________________ [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

03-27-2014	#7
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,493	Re: Weird thing happened last weekend. I too had an O2 issue. Mine was on my 95 LT1, and it was easily spotted with my scanner. Note: I thought I would force a little RTV into the hole where the wires to the O2 element ran to seal it up. Big mistake! Not only does the element need contact with the atmosphere to work, they're very sensitive (read: can be easily destroyed) in the presence of silicon which was introduced by the RTV. (I think I was on my 3rd replacement O2 in as many months before suspicion took over and I figured out what the problem was. Left them alone and no problems for the 4 years I had it before trading it for the Z) __________________ Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry

03-26-2014	#2
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,687	Re: Weird thing happened last weekend. I have had that happen in the past. For me it occurs rarely, and follows a short, full throttle excursion. The source has never been identified. I suspect that it stems from an intermittent lazy O2 sensor, but I don't have any evidence to prove that. I guess that if the Lotus/GM engineers wanted a record of the transient, they would have made it a hard fault code. Jim __________________ If it isn't fun, you aren't doing it right! 1990 Black ZR-1 - sold 1993 Quasar Blue ZR-1 1994 Competition Yellow ZR-1 1995 Dark Purple ZR-1 Maryland State Coordinator WAZOO Member