Mechanics

4.2 PINGING

1987 Jeep Wrangler • 87,000 miles

Hello I have this jeep that is driving me crazy. It pings on light acceleration when engine is at operating temp. It has had a new carburator, egr (operational), distributor, ignition coil, and map sensor installed, all vac lines have been gone over several times and ignition timing has been set to under hood instructions to a "t". It runs and drives great, no misfires just pinging. Harmonic balancer doesnt seem to have slipped and champion spark plugs have been installed. It does have a knock sensor on the intake just forward of the carburator ( can verify operation by tapping on intake and watching timing marks move) Maybe its not sensitive enough but I cannot locate one, part stores show one for 88 and up.
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Mikeyreyna1
February 4, 2012.




I would also like to add that I have tried adjusting timing up or down even to extreme's but didnt help


Tiny
Mikeyreyna1
Feb 4, 2012.
You may have excessive carbon build up which will cause the ping. It may be an octane ping as well. Try using some premium fuel to see if it goes away.
By the way, the kncok sensor is on the block. The sensor you are referring to is intake air temp sensor.

Roy


Re set ignition timing to correct settings and try the premium fule as mentioned in last post.
AD


Mhpautos
Feb 5, 2012.
I thought aabout the carbon build up too ran a tank of chevron super and 2 bottles of chevron injector cleaner didnt help seemed to have happened all at once. Just went out to see if I could find knock sensor on block couldnt find it but I did see that one bolt on the starter is loose and starter isnt sitting straight maybe im hearing that rattle. I was about to pull timing cover to see if jumped time but with wrench on crank pulley only has about 3 degrees slack in chain dont think it would be that (runs too good anyway to be that) thanks for making me look for knock sensor even though I didnt find it (maybe thats why parts stores dont list one for that year it dont have one) maybe timing didnt move after all when I tapped on intake I will put fan back on and tighten starter and go for test drive hope thats the problem already sank a lot of $$$ into this thing figures it would be something simple. It does crank fine though but at times you could hear something rattle underneath. I will let you know. Mike


Tiny
Mikeyreyna1
Feb 5, 2012.
The kind of cleaning you need cannot be done by additives. It has to be done at a shop by a pro. It is a great service.

Roy


I WAS NOT SURE WHAT YOU HAD FOR A DISTRIBUTOR

I LOOKED HERE

http://www.autozone.com/autozone/parts/Cardone-Reman-Distributor/1987-Jeep-Wrangler-4WD/_/N-iibqeZ93xku?itemIdentifier=768895_0_0_

YOU HAVE, WHAT I "NOW" HAVE IN MY '77

MAYBE YOUR DISTRIBUTOR IS SCREWING UP

MAYBE THE MECHANICAL ADVANCE IS NOT WORKING, POSSIBLE BROKEN SPRING

IT COULD ALSO BE THAT THE VACUUM ADVANCE AIN'T-A-WORKIN'

BOTH OF THESE CAN EZily CHECKED W/ A TIMING LIGHT (NEVER EVEN LOOKING INTO THE BOTTOM OF THE DISTRIBUTOR...LESS YOU JUST WANT TO)

DO YOU KNOW HOW TO USE THE LIGHT TO TEST 'EM, OR DO YOU NEED SOME GUIDANCE?

THE MEDIC



CJ MEDEVAC
Feb 5, 2012.
Ok im back sorry been at work. Found a loose starter didnt help, found a vac diagram in chilton manual showed ported vac to vac switches hooked up in a different spot from hood sticker again didnt help actually worse. This being carbureted any cleaners would hit everything from carb, intake, valves, combustion chamber etc. The knock sensor is on the intake though it shows it the chilton man. I have to tap pretty hard on the intake right beside it to make it change timing maybe it is bad cant find one though. I will look some more today. Mike


Tiny
Mikeyreyna1
Feb 7, 2012.
INFO ON THE VEHICLE SUPER-SECEDES ANY OTHER INFO YOU FIND

IS THIS ACTUAL "PINGING" YOU ARE HEARING, OR IS IT ROCKER ARM/ PUSH ROD RATTLE OR TAPPING YOU ARE EXPERIENCING?

THE MEDIC


CJ MEDEVAC
Feb 7, 2012.
It sure sounds like pinging you can deliberately make it make the noise by accelerating let off (or cruise) and it goes away sounds like a bag of marbles, im getting my hands on a lab scope this week and im going to check the signal coming from the knock sensor gonna take the hood off and leave scope hooked up and see if knock sensor hears anything while engine is pinging


Tiny
Mikeyreyna1
Feb 8, 2012.
DO YOU KNOW HOW TO CHECK YOUR 2 ADVANCES WITH A TIMING LIGHT---TO SEE IF THEY WORK AS THEY SHOULD?

IF NO, I CAN TALK YOU THRU IT, YOU NEED A DWELL/ TACH METER AND TIMING LIGHT....I SORTA GO OUT OF MY WAY TO TRY TO HELP ANOTHER JEEP....1 EXAMPLE BELOW OF HOW FAR (THIS IS NOT YOUR FIX)

http://www.2carpros.com/questions/1980-jeep-cj7-timingtuning-problem-with-a

THE MEDIC


CJ MEDEVAC
Feb 8, 2012.

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