Welcome to the Corvette Forums at the Corvette Action Center!

Pinging and Hesitation

S

secondchance

Guest
Hi, all,

I currently have a 94 ZR-1. Car started to ping right around 2200 to 2800 rpm at moderate acceleration when in closed loop mode about a year ago. Then I noticed a vacuum leak, you guessed it, under the plenuem. All vacuum hoses were replaced and problem went away. Then, about three months ago, she started to ping again around 2200 to 2800 under moderate acceleration, never under wide open throttle, and only in closed loop mode. When hooked up to a scanner, driverside O2 sensor was fluctuating between 40 to 190. So, I replaced the O2 sensor. This did not cure the problem. Furthermore, she started to hesitate under moderate acceleration, again in closed loop mode, and this hesitation seems to be getting worse. I have talked to Mr. Gordon Killbrew and he seems to think the knock sensor have gone bad. I have a knock sensor on order and will be replacing it shortly. Any thoughts?

p.s. I always use 93 octane, either Amoco or Mobile.:confused
 

90 Corvette ZR-1

Well-known member
Joined
Jan 11, 2001
Messages
561
Location
Pittsburgh
Corvette
90 Red ZR-1
if you do need the parts call tom henry chevy. It may be a tad far outa your way, but he is the only one I let touch my car
 

Rob

Site Administrator
Staff member
Administrator
Joined
Sep 16, 2000
Messages
13,763
Location
New Hampshire
Corvette
1990 Corvette ZR-1
Actually, Pohanka Chevrolet in Chantilly is fantastic. They have a ZR-1 certified mechanic there who has worked on my own ZR-1. I normally get most of my parts from them as well.

Tony's Corvette Shop up in Gaithersburg, MD is also excellent. They too have a ZR-1 certified mechanic who is also a ZR-1 owner.

As for the pinging, welcome to the club....mine pings all the time right in the same rpm range that you mentioned....a little lower. I've done everything including the replacement of the secondary port vacuum system to no avail. I had the car checked back up in NH when I lived there and they couldn't find anything wrong with it. I haven't taken it in down here for the same problem. I'm curious if the knock sensor will cure it.

I too run either 93 or 94 octane. In fact, I normally go to the Sunoco station in downtown McLean to get the 94 octane as there isn't another Sunoco close by here.

The fuel ping gets even worse when the engine gets really hot. Where did you order the knock sensor and how much was it?

-Rob
 
S

secondchance

Guest
Hi, Rob,

Thanks for the info. I had no idea that the Sunoco off of Chainbrige rd. had 94 octane. I use to run sunoco back in the late 70s when they offered 96. I got the knock sensor from White Racing out of Tampa at $39.60. Also bought a pair of gaskets for the intake plenum and vacuum lines. Mr. White is very helpfull and prices are reasonable. Hope to see you on the road sometime.

yun
 

Rob

Site Administrator
Staff member
Administrator
Joined
Sep 16, 2000
Messages
13,763
Location
New Hampshire
Corvette
1990 Corvette ZR-1
vettaholic said:
Hi, Rob,

Thanks for the info. I had no idea that the Sunoco off of Chainbrige rd. had 94 octane. I use to run sunoco back in the late 70s when they offered 96. I got the knock sensor from White Racing out of Tampa at $39.60. Also bought a pair of gaskets for the intake plenum and vacuum lines. Mr. White is very helpfull and prices are reasonable. Hope to see you on the road sometime.

yun

Yup, I was there last night about 7:00 getting a fresh tank-full. :D

-Rob
 
S

secondchance

Guest
By the way. I also had a 91 ZR-1 and never had a problem with pinging. Has changes made in 93 ( from 375 to 405) has anything to do with this?
 
S

secondchance

Guest
Corvette Action Center Knowledgebase v1.0
Introduction :: Search ::Topics

> Click here to send these Q&As to your friends

> Top > 1990 - 1995 ZR-1s > Engine Mechanical

[ Click here for a printable version ]
::: Questions & Answers
Q: Service Bulletin: 1993-1994: Sag or Surge on a Light Throttle Acceleration
Corvette Action Center, 2002-05-31 14:23:11
A: Subject: Sag or Surge on a Light Throttle Acceleration Below 2500 RPM

Model and Year: 1993-94 CHEVROLET CORVETTE WITH 5.7L ENGINE (VIN J-RPO LT5) AND MANUAL 6-SPEED TRANSMISSION

TO: ALL CHEVROLET DEALERS

CONDITION:

SOME OWNERS MAY COMMENT OF A SAG, SURGE, OR A CHUGGLE ON A LIGHT THROTTLE ACCELERATION BELOW 2500 RPM.

CORRECTION:

INSTALL E-PROM KIT #12528772. THIS KIT CONTAINS THE FOLLOWING ITEMS.

1 - E-PROM 1 - PREMIUM LABEL 1 - LABEL INSTALLATION INSTRUCTIONS


General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information


I wonder if this has anything to do with it.
 

Rob

Site Administrator
Staff member
Administrator
Joined
Sep 16, 2000
Messages
13,763
Location
New Hampshire
Corvette
1990 Corvette ZR-1
It's possible, although I'm not sure how to check if your ZR-1 has the updated EProm or not.

I'm curious though....did Gordon happen to say why he felt like the knock sensor might be the culprit?
 
S

secondchance

Guest
When I mentioned hesitation he thought that the timing advance was incorrect and this was possibly due to knock sensor sending a wrong info.
 

rkreigh

Well-known member
Joined
Dec 27, 2000
Messages
216
Location
Alexandria VA
check a few other things too.

plugs, coil packs. a misfire causes the hesitation too. lt5s are known to sometime crack the plug insulator (can hear the plug rattle) not sure why.

with these driveability problems, I always change the plugs as it's ez and sometimes something a small as a misgapped or bad plug is all it takes.

two words JOE MALO!!!

I'm Alex VA, give me a shout and we can see if we can fix it!!

if not, Joe sure can.
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom