What else could it be?

[chevychic]

My truck is progressively running worse each day.
It started out as pinging under load as I'm going up hills or passing someone. This is after the truck had sat for about a year.

So I did a tune up. New fuel filter, cap, rotor, plugs, plug wires. Adjusted float level, idle mix, rechecked and set distributor timing. Replaced all exhaust gaskets to eliminate exhaust leaks. Checked for vacuum leaks. Removed and cleaned EGR valve...getting ready to get a EGR blank out plate so I can get rid of it since all the other emissions stuff is gone. I've plugged the vac advance line and took it out for a drive to eliminate a bad pickup coil but I still had the pinging.

Through all the adjustments, I've checked the plugs a couple times and all look just fine.

After all this, I still have the pinging and now when idling at a light, it idles so low, if feels like it's going to die. But I've set my distributor timing and idle mix and all is set good so I have no idea what's going on. Vacuum advance appears to be working fine.
I've retarded the timing, advanced it, and all it does is affect how soon the engine starts to ping. It'll either start under medium load, or it will start under medium to heavy load. It's set to where it was running good before all this started.
Also, my gas mileage sucks right now. I'm spending $10 a day to get to work and back...I'm about ready to get my bike out.

When my car gets out of the shop so my truck can be parked for awhile, I'm going to remove the valve covers and see if anything looks like it's not moving right.

Next I'm ruling it down to carb, fuel pump or distributor. Distributor has less than maybe 2000 miles on it, carb was rebuilt 3 years ago so I would hope it would be less likely to be carb or distributor....but with my luck...who knows

In the meantime, am I missing something? What else could be going on?

[Slonaker]

Are you sure it is pinging and not an exhaust leak? I have had exhaust leaks, that sound a lot like pinging when accellerating.

Slonaker

[Prerunner1982]

heather, did you change the collector gaskets too? if not you might and while you are down there check for holes in the exhaust pipe itself.. could be towards the inside of the veh and hard to see. Just another idea.. good luck hun.

[chevychic]

Thanks guys,

I left out in my original post that this was my first thought. I've replaced the collector gaskets and header gaskets, plugged the exhaust pipes with a handful of rags one at a time to see if I could hear or see anything but found nothing. Although if it wasn't visible, I wouldn't see it. I might take it to a shop and have them check for exhaust leaks.

This sure is frustrating. At lunch today I sat in it and revved it up real good while in park. The first time it accelerated it popped real good but stopped as I revved past into WOT. The second time it didn't pop at all. I was trying to listen to determine whether it's coming from the carb or somewhere in the exhaust but it's very hard to tell. I don't smell any gas like I would if it were coming from the carb but it's not obvious that it's coming from the exhaust either. Where's the bang head against the wall emoticon when I need it???

On top of that, I don't know if I should be calling this a "pop", "ping" or "backfire". It sounds like popcorn or marbles in a jar, which I THINK is most commonly called a ping. So in trying to explain this, I hope I'm explaining it properly.

So does anyone want to volunteer to make a visit to Oregon and listen to my truck to tell me what it is I'm hearing???

[79BIG10]

I wish I could head up there and help you out but it's a little far.

Are you getting gas at the same place everytime? I'm wondering if you're getting a lower grade than they're advertising. When I get some bad gas the engine will ping like you're talking about. Try a different station and maybe grade. Also look to see if it's the Ethanol and not regular gas at the station. If it is the new stuff this could be your problem.

[jimfulco]

Does it have a centrifugal advance mechanism under the distributor rotor? If so, it might be sticking or sloppy from age.

Also, does it have a knock sensor? A friend of mine had an '81 (or thereabouts) with "ESC" (electronic spark control, I think) that wouldn't run worth squat and after several mechanics failed to fix it, it turned out the knock sensor had gone bad.

[Slonaker]

Originally Posted by jimfulco

Does it have a centrifugal advance mechanism under the distributor rotor? If so, it might be sticking or sloppy from age.

Also, does it have a knock sensor? A friend of mine had an '81 (or thereabouts) with "ESC" (electronic spark control, I think) that wouldn't run worth squat and after several mechanics failed to fix it, it turned out the knock sensor had gone bad.

If it has an ESC distributor (the one with the giant flat plug coming out the passenger side) like mine, you might consider disabling it. As I just posted in another thread, I have referred a couple of people to it who made all of their problems go away.

Look at the bottom of the page:

http://www.73-87.com/7387garage/drivetrain/escrepl.htm

Slonaker

[chevychic]

I don't believe I have an ESC distributor. What is the best way to tell?
Also, since this distributor is just over 2 years old, what are the chances it could be bad?

About the centrifugal advance mechanism....this I checked also. It moves as if it's brand new. No sticking or binding.

I'm not sure if they're putting ethanol in our gas yet or not, but that is a possibility. Although I haven't gotten gas at the same place twice in a row. I wish it were that easy.

And Brandon, Anytime you get to Oregon....we have some great rivers and lakes here if you like to fish at all

[79BIG10]

Heather I love to fish and would love to get up there

If you have replaced the distributor with one that was aftermarket I can almost bet it was not a ESC but if it was made for your specific year model etc. then it could have that on there. Follow the link Slonaker posted to Jeff's site and see if it's what you have.

[chevychic]

I followed the link but there's only one picture
I have a plug like that from my firewall of course, but I'm not sure if the receptacle on the distributor takes signal from each of the wires.

It is aftermarket but I can't for the life of me remember if I got one specific for the year or not. It's a summit. I know, not the best, but what I could afford at the time.

[rage'nrat638]

yep..if your dizzy is this type the wire from the firewall has to plug into it.

other wise the regular dizzy just has 12 volts run to it..and maybe a tach wire..

[SSC's76]

What is the engine temp when it starts to ping? Hot cold, dosent matter?
What did you gap the plugs to? If your getting a healthy mix of ethanol in your gas now and the plugs are gap'd at .45 re gap them to .35. Just out of curiosity what heat range are your plugs? High Ethanol fuel likes a hot engine and a short gap but we would need to verify that is the case, it may not be.

[79BIG10]

But wouldn't a .035 be a cooler running engine since it has less spark?

[swervin ervin]

Heather,

try moving your vacuum advance hose over to a ported source if it's now on a manifold vacuum source. This will cut down on the amount of and when the vacuum advance works. I don't like to run ported vacuum but if it's all you can get away with until it's fixed properly, so be it.

A ported source will have little or no vacuum at idle to where a manifold source will have full vacuum at idle. If the above works, it's time to dial in the distributor and vacuum advance.

Edit:
I just went back and reread your post at top. I seen (this time) where you said you unhooked the vacuum advance and took it for a test drive. That blows my suggestion out of the water.

[Sgt.Booya]

Not sure if its the same thing but a had a similar symptoms on my 74 Nova 350. Took it to my friend's Dad, after looking under the hood for few minutes and taking it for a test drive he diagnosed it as the "350 death rattle". We tore the engine down and it was a spun bearing on the crank. Not to scare you, but if all the other suggestions fail, I'd take it into a good shop (or a friend's Dad) for a closer look. Hope it's something simple cheychic.

[MidnightBlues]

I'm having the same problem with my old Peugeot right now. At first I thought it was pinging too, but according to my mechanic it's either a main bearing or a gudgeon pin.
How old is your engine, how many miles?

[220mph]

If you want to test if it's faulty fuel, add a can of MOROSO 108 octane booster (or STP octane booster) to a half tank of gas. Drive around like you normally would for 10 minutes then jump on it. Does it still ping? If you still have the noise, add a bottle of LUCAS oil to the crankcase. If the noise subsides, it could be a bearing or a collapsed lifter. The LUCAS will thicken the oil, fill in some bearing gaps and help raise the oil pressure for a collapsed lifter.

[SSC's76]

Originally Posted by 79BIG10

But wouldn't a .035 be a cooler running engine since it has less spark?

The smaller gap creates a stronger more intense spark but it cools quicker. When you open the gap it reduces the intensity but increases the burn time increasing overall cylinder temperature and increases the possibility of pre-detonation. So yes it reduces the cylinder temperature except durring ignition. You want coolant temp hot as possible to prevent pooling in the intake since ethanol absorbs moisture. If you could add somthing to the chemical structure of ethanol that prevents it from absorbing the moisture or redcues the amount of moisture it would react more like gasoline. It's wierd stuff it even has a lower boiling point then gasoline and a higher resistance to detonation (octaine) but it dosent act like it.




If it was a bearing failure here there is quite a difference in the sound of a rod knock and detonation. If you cant tell the difference I suggest you do a quick cylinder cancel test and see if the noise goes away. If it goes away completly durring the test you have a bearing failure if you still notice the noise you have a detonation issues.

[ElGracho]

Another thing to check is your battery, alternator, and alternator belt. If you are running low voltage into the HEI, it will cause missing which could also show up as backfiring and pinging.

[chevychic]

Thanks guys. These are great suggestions which I'll try out next week.

To answer some of the questions:

Yep that's the same connector I have. I read the site for the mod. I'm going to read through it again before I decide whether to disable the ESC.

The coolant temp doesn't seem to matter if it's hot or cold. My truck runs at just about 180° and has since before this started.

The plugs are gapped to factory at .045. However, the previous plugs had been in there at the same gap for some time before it started acting this way. Kinda makes troubleshooting hard.

There is only Ethanol in the gas here during the winter months (Nov - Feb) so Ethanol shouldn't be a cause in this.
I'd still like to try the octane boost and Lucas additive to see how it responds.

The alternator check is something that has me curious. When I revved it up real good on Friday, it popped for a bit but as I went through the rpms and pass the popping, the belts started squealing. Later that day I did it again but didn't get any popping and the only noise I heard was the belts squealing again. I'll have to grab my multimeter and do some initial testing to it or take it in to someone and have them tested. The belts are all like new.

At this point, I'm not ruling anything out and I certainly hope it's not a bearing. My car is having the engine pulled out at a shop this week to replace the thrust bearing, my boyfriend's truck's engine seized so we're tearing it down this week, and I really don't want to tear into mine.

The cylinder canceling procedure...do I just need to pull a plug wire so the cylinder doesn't fire? Could you explain the steps to take so I don't do something wrong and make more problems for myself?

[jimfulco]

With HEI, you don't want to just pull a plug wire & see if RPM drops. An open circuit can cause the module to fail, not to mention sending a high-energy jolt through you. It's not like a point-type shock where you jerk your hand away and bash your elbow on the hood hinge, it's more like your whole body just goes rigid, no movement involved, and you just stand there and wonder what the h*** just happened. Get an old spark plug and clamp it to a good ground, and pull a wire from a plug and hook it to the old one, THEN start the engine & check RPM. If you test a cylinder and the RPM doesn't drop, then that cylinder is not doing its job.

[81shavedtrk]

could also be a misadjusted valve. Might want to check all your rockers and make sure non are loose.

[chevychic]

Originally Posted by jimfulco

With HEI, you don't want to just pull a plug wire & see if RPM drops. An open circuit can cause the module to fail, not to mention sending a high-energy jolt through you. It's not like a point-type shock where you jerk your hand away and bash your elbow on the hood hinge, it's more like your whole body just goes rigid, no movement involved, and you just stand there and wonder what the h*** just happened. Get an old spark plug and clamp it to a good ground, and pull a wire from a plug and hook it to the old one, THEN start the engine & check RPM. If you test a cylinder and the RPM doesn't drop, then that cylinder is not doing its job.

Doh, I knew this...it's getting obvious that I haven't been spending much time on my truck.

On the ls1tech forums for my firebird, I was reading where people were just pulling their plugs to test for firing. Seemed weird to me at the time but it apparently stuck with me.

[ElGracho]

Any luck with this?

[chevychic]

Well I replaced my EGR valve with a known good one but that didn't clear up the problem.

I've lost some steam on this since I dedicated last week to helping my bf take his possibly seized engine out of his F*rd.

Although, I did confirm that I'm definitely backfiring out the carb. This noise has been weird because it sounds like it moves around...Sometimes it sounds like its in the exhuast, but other times it sounds like it's in the carb....but finally I took it up some hills and got it doing it really good, then got out and checked the underside of my air cleaner and sure enough, there was gas dripping off of it and some sitting on the edge of the carb air horn.

So at least I have a little more to go off of now.