1987 4.2 Jeep pinging

Tiny
MIKEYREYNA1
  • 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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Saturday, February 4th, 2012 AT 11:43 PM

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Tiny
MIKEYREYNA1
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I would also like to add that I have tried adjusting timing up or down even to extreme's but didnt help

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Saturday, February 4th, 2012 AT 11:46 PM
Tiny
ASEMASTER6371
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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

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Sunday, February 5th, 2012 AT 12:15 AM
Tiny
MHPAUTOS
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Re set ignition timing to correct settings and try the premium fule as mentioned in last post.

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Sunday, February 5th, 2012 AT 12:37 AM
Tiny
MIKEYREYNA1
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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

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Sunday, February 5th, 2012 AT 12:42 AM
Tiny
ASEMASTER6371
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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

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Sunday, February 5th, 2012 AT 12:47 AM
Tiny
CJ MEDEVAC
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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

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Sunday, February 5th, 2012 AT 2:01 AM
Tiny
MIKEYREYNA1
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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

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Tuesday, February 7th, 2012 AT 4:46 PM
Tiny
CJ MEDEVAC
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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

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Tuesday, February 7th, 2012 AT 6:06 PM
Tiny
MIKEYREYNA1
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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

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Wednesday, February 8th, 2012 AT 3:26 AM
Tiny
CJ MEDEVAC
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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

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Wednesday, February 8th, 2012 AT 3:43 AM
Tiny
MIKEYREYNA1
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I have checked both advances checked good I have a good adjustable inductive timing light and a matco mulitmeter that has dwell and tach timing light has a tach too. I dont remember if I checked dwell I put this on the back burner for a couple of months (not a daily driver)

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Wednesday, February 8th, 2012 AT 5:21 AM
Tiny
MIKEYREYNA1
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Thanks mr ranger I will keep you posted what I find. Mike usn 88-95

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Wednesday, February 8th, 2012 AT 5:33 AM
Tiny
CJ MEDEVAC
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DWELL IS SORTA "A GIVEN" ON ELECTRONIC IGNITION, NO NEED TO TEST

I DO NOT KNOW IF YOU HAVE A MANUAL OR AUTO TRANNY--SO I CANNOT GIVE YOU YOUR IDLE OR TIMING SPECS

WHAT I MEAN AS FAR AS TESTING IS TO DISCONNECT AND PLUG VACUUM ADVANCE HOSE TO DISTRIBUTOR. PIC 1 (DISREGARD THE WRENCH AND TAPE MEASURE)

SET TIMING LIGHT ON ZERO--LEAVE IT THERE FOREVER---NOW IT IS NOT CONFUSING TO USE--IT'S JUST LIKE A REG TIMING LIGHT

JUST SHOWING YOU "0" ON MY SCALE (NOT MY TIMING) MY TIMING IS ABOUT "9 DEGREES" IN 2nd PIC. JUST SO HAPPENS PIC 2 IS COMPRESSION STROKE, AND #1 IS AT TDC (1 MORE 360 REVOLUTION, IT WOULD BE ON ZERO AGAIN, BUT ON THE EXHAUST STROKE, THAT WOULD NOT BE TDC)

I KEEP MY IDLE SET AT 700 RPM. IF IT CHANGES WHEN MOVING THE DISTRIBUTOR--I GET IT BACK TO 700 RPM W/ THE IDLE SPEED SCREW

WATCH TIMING MARKS---THIS SHOULD BE PERFECTLY SET WHERE I WANT MINE SET TOTHAT IS, EVERY TIME MY TIMING LIGHT FLASHES I SEE "PIC 3", 9 DEGREES BTDC.

YOURS WOULD BE WHATEVER IT IS SUPPOSED TO BE. IF NOT TURN DISTRIBUTOR TO GET IT THERE.I HAVE SPECS, JUST NOT ENOUGH OF YOUR INFO. HOOD STICKERS TAKE DOMINANCE OVER BOOKS

NOW THAT'S HOW TO TIME IT

TO TEST MECHANICAL ADVANCE, WATCH TIMING LIGHT, AND THROTTLE ENGINE UP SLOW---THE TIMING MARKS SHOULD ADVANCE FURTHER BACK FROM YOUR MARKS. IF SO, IT DOES WORK. IF NOT A SPRING ON THE WEIGHTS MAY BE BROKE, OR SOMETHING IS PREVENTING THE MOVEMENT, LIKE DIRT

THERE'S SEVERAL WAYS TO TEST THE VACUUM ADVANCE, I LIKE HOOKING THE HOSE BACK ON THE DISTRIBUTOR, THEN TAKE THE OTHER END OF THE HOSE AND SORTA TEMPORARILY HOOK IT TO A MANIFOLD VACUUM PORT---THIS WILL IMMEDIATELY ADVANCE THE DISTRIBUTOR MAYBE 10 DEGREES--- YOU CAN SEE THIS ALSO WILL MOVE THE TIMING MARKS BACK FROM WHERE YOU HAVE THE TIMING SET, IF YOU WATCH THEM IN THE LIGHT (A BUDDY PLUGGING AND UNPLUGGING THE LINE MIGHT LET YOU SEE IT BETTER. IF IT MOVES THE VACUUM ADVANCE WORKS. HOOK EVERYTHING BACK AS IT GOES

IS THE ARM IN PIC 4 (RED ARROW) IS MOVING, WHEN THROTTLED, MOST LIKELY VACUUM ADVANCE IS WORKING RIGHT. WITHOUT USING A TIMING LIGHT. IF IT DOES NOT MOVE, THE DIAPHRAGM THAT MOVES THE ARM MAY BE BAD, OR DEBRIS, ETC, WILL NOT ALLOW IT TO MOVE

THE REASON I THREW THIS IN, I HAVE SEEN TOO MANY PEOPLE USE AN ADJUSTABLE TIMING LIGHT INCORRECTLY (IT DOES HAVE ADVANTAGES, ONCE YOU DO KNOW HOW TO USE IT) ZERO IS BEST FOR TEACHING, OR USE A REGULAR LIGHT.

MAYBE IT'S THAT SIMPLE THAT YOU JUST SET THE MARKS WRONG.

SORRY I'M NOT THE BEST 'SPLAINER!

THE MEDIC

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Wednesday, February 8th, 2012 AT 6:36 AM

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