85' Vette Pinging Problem

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Jan 13, 2005 | 02:09 PM

#21

VetNutJim

Safety Car

Joined: May 1999

Posts: 3,651

Likes: 5

From: Atlantis

Cruise-In I Veteran

FIRST thing to do is find what the BASE TIMING is set to and go from there.

There's a little connector back with brown wires on the drivers side of the distributor that you need to unplug before you check the base timing.
Factory base timing is 6* but you REALLY need to verify that's where it's set first before you try anything else.

Try a tankfull of that 110 octane.
If the knock goes away you may need to RETARD the timing a couple of degrees to kill off the ping.

Jan 13, 2005 | 04:28 PM

#22

lensvet

Instructor

Joined: Jul 2004

Posts: 248

Likes: 0

From: HERNANDO FLORIDA

St. Jude Donor '05-'07-'08

Check the knock sensor wire. Make sure it's connected
and that it's making good contact.

Jan 14, 2005 | 09:46 AM

#23

HeeHaw89

Drifting

Joined: Jan 2002

Posts: 1,261

Likes: 4

From: Middle River MD

I'm having a similar problem. I replaced the ESC with no appreciable improvement. Checked the knock sensor and it appears to be fine, wire hooked up not broken,etc. I even backed off timing to 4 deg and still pings.

Jan 15, 2005 | 04:33 AM

#24

olman

Racer

Joined: Mar 2004

Posts: 311

Likes: 0

From: Oakley Ca

Quote:

Originally Posted by Jim Martley2

One more possiabulity is a plugged EGR passage in the manifold or a non functioning EGR valve itself.

Check the EGR to see if it is working. Should set a code if it isn't. Reach under it and lift the diaphram with the engine running and listen for a change in RPM. If no change it is probably plugged.

Jan 15, 2005 | 10:49 AM

#25

Toymans85

Instructor

Joined: Apr 2004

Posts: 100

Likes: 0

From: Barrie Ontario

My 85 had ping too!

What I had found was the octane in the gas is the best possible deterent for this condition providing your knock sensor and timing are correct first. Use the 94 stuff or close whatever you can get easily at the pump and use for at least a week. I found this seemed to solve my issue as my timing was set to 6 degrees and I had replaced the knock sensor and neither of those things fixed the issue untill I went to high test gas.

My 2 cents hope it helps.

Jan 15, 2005 | 01:41 PM

#26

Chewch87

Burning Brakes

Joined: May 2004

Posts: 1,182

Likes: 14

From: POINT PLEASANT NEW JERSEY

What brand gas do you use??? Sound crazy...But EXXON gas is notorious for causing engine Ping in some engines . I know it does on my car. Try a different brand.....BP/Amoco or Mobil or i like Sunoco. Ultra 94 for my 87. Hey can't hurt.

Jan 15, 2005 | 05:10 PM

#27

kcpaz

Instructor

Joined: Dec 2004

Posts: 136

Likes: 0

I found a plug that isn't plugged into anything. It's been sitting on the passanger side header/exhaust manifold melting. It has a single wire going to it, and the plug itself is black. I am going to put on my new tires and wheels this weekend so I will get under the car on Monday and look for the other half. Oh yeah, I have been using Chevron 91 octane. It's the nicest stuff you can get from the pump in AZ...other than the 110 race gas stuff from Mobile....at a mere $5 per gallon.

Jan 15, 2005 | 07:06 PM

#28

Muffin

Race Director

Joined: Jun 1999

Posts: 14,924

Likes: 9

From: Merritt Ils Fl

I suspect you are on the right track. Off hand I can think of only two single wire devices on the passanger side, temp switch ( between number 6 and 8 spark plugs behind the oil dipstick tube and the knock sensor in front of and below the starter. Knock sensor has a somewhat odd shaped shield over it. Good hunting.