Pinging under partial throttle

[Vanilla Sky]

Alright, this one is stumping me. I have replaced the following within the past 3,000 miles: fuel pump, fuel tank sock, fuel filter, spark plugs. Within the past 2 weeks, I've replaced the spark plug wires (ripped an end off), changed to a colder spark plug and tried with both a larger and smaller gap, change the fuel filter again, and flushed my cooling system. I haven't checked my tank sock since I put it back in, but crud is getting through it. I think I need to either seal or replace my tank. In the short term, I'd like to get this fixed.

What other things can you guys think of that I'm not checking? TPS, o2 sensors? Temp sensors? I've always had carbed cars and I just ripped the emissions junk off and never had an issue. I'm not to the point I can megasquirt this one yet.

[Keachman1]

Check your ignition timing and vacuum advance to make sure it is not sticking. Too lean of an air-fuel ratio will cause pinging also so check for issues that cause a lean mixture like plugged injectors, vacuum leak, low fuel pressure, O2 sensor, etc. Carbon buildup in the combustion chambers can also a cause it along with too high coolant temp.

[2oodoor]

Good suggestions. The distributor advance plate rests on a ball bearing set that covers the circumference of the dist body, which is the coolest design but it can get gummy and stick after 25 years.

[Legend_master]

I'm not sure about obd0, but on obd1 an improper coolant temp signal can cause a lean issue.

[Vanilla Sky]

Ignition is as far retarded as possible. Vacuum advance works when I cap off the port on the vacuum manifold and pull vac with a mityvac. I'm inclined to install a different distributor since I have one laying around.

[Stealth]

.

[Dr_Snooz]

How many miles on the engine?

[Vanilla Sky]

215,000 on the odometer, looks original to me. I'm not above pulling the head because I have a half built ported head I can finish up and bolt on if it turns out that mine needs to come off for any reason.

Spark plug color reads normal. No oil leakdown, no signs of more carbon ash than to be expected, and they're completely dry. Of course I'm not doing a hot pull here, but that sounds like what I should expect from my spark plugs.

[Vanilla Sky]

So, it pings less in the cold. Seems temperature sensor related somewhere maybe. Has anyone ever have an intake air temp sensor go bad?

[2oodoor]

Sometimes what pinging is tellng you there is something in the compression chamber at a time when there isn't supposed to be. Carbon, coolant, exhaust charge or intake charge, water in fuel, something like that.
That is why the ign timing relates to ping, timed explosion not clear of charges, solids etc.

[cygnus x-1]

These engines are fairly knock resistant so something is definitely wrong. What is your ignition timing advance at idle? Shouldn't be anymore than about 20 degrees. If you have a dial back timing light you can also check it at say 2500RPM and see if it's advancing too much (no more than 35 degrees). If the mechanical advance mechanism is sloppy it could be advancing too much as the RPMs climb. Sticky vacuum advance is another possibility.

And then you could possibly have gotten a bad batch of fuel as well.

C|

[Dr_Snooz]

You sure your timing belt didn't jump time?

[Vanilla Sky]

Tomorrow, I'm going to recheck the timing belt and recheck the timing. The ignition timing is set as far retarded as it can go, so if that's my cause, it's because it's worn out. My next step is pulling the fuel pump and checking that sock. I can see into the tank then, so if it's nasty, it might come out for cleaning and possibly sealing if I find rust in there. The fuel filter was gunked up pretty bad, so I was sure that would at least tell me that a fuel system cleaning would solve the issue.

Would the valves needing adjustment cause ping? I adjusted them a while back, but I'm not terribly sure I got all of the retainers tight again.

[Dr_Snooz]

Usually you'll just get a lot of noise. I've had them pretty loose and didn't get any pinging.

[88Accord-DX]

I'd hook up a timing light pointed at the mark on the flexplate/flywheel & see if your timing is good.

[Vanilla Sky]

I need to find some time to work on the thing.

[Vanilla Sky]

Threw a code today, but turned the car off and cleared it. I've gotten one before under similar conditions (same bit of road, even) that was for the EGR lift sensor. I haven't had any codes for weeks, so I didn't mention it in this thread.

Somehow I think this could be something other than pinging. I haven't had it on a lift to check for anything loose, but it is a thought.

[Legend_master]

Have you checked the condition of the EGR? Technically it could cause some pinging?

[Vanilla Sky]

I have not. The guys that have theirs blocked off seem to have no issues, but I remember it being a huge deal with small block Chevies from the emissions era. Time to pull and check it out. I've been meaning to check it out anyway. So little time, so much to do.

[Keachman1]

The EGR valve sticking open will cause your air-fuel mix to lean out and could cause pinging. Try a block off plate and see if it helps. You will probably get a code but you can always re-install it if it cures the pinging and your location requires smog. Cleaning the EGR valve with carb cleaner works sometimes.

[Vanilla Sky]

Nah, no smog here. If I weren't having running issues right now, I'd likely be working on installing a megasquirt system so I can tune the thing right. I want to put an OEM air box and piping back on and possibly a stock muffler (my only 2 real mods) and dyno tune it compared to the same car on the stock EFI. They probably left a lot of the table with these engines because the tech wasn't available then like it is now. The more sensors and monitors you have on an engine, the closer you can run it at the edge of blowing up, or the longer you can make it last. Since I'm not in this to be a number matching, show-quality car (it already has a transmission from another car), I plan on playing with it, perhaps coming up with some fixes that Honda should have implemented from the beginning.

[w261w261]

Try filling up with 93 octance and see if it helps. Also, you can get one of those video inspection tools and stick it into the combustion chamber and see if there are deposits.

[Vanilla Sky]

Last fill was with 93. No change there.

My EGR valve does leak down after a few seconds, but I haven't had a chance to replace it. I think I'm introducing unmetered air somewhere. I'm thinking it might possibly be my fast idle valve, because it tends to car the bouncing rev (blocking the port in the TB with my finger levels off the idle to 800RPM, so that's an air leak, and at partial throttle, there might be enough air passing through there that i'm running lean. This also explains why I don't hear it pinging at full throttle, because it's just dumping fuel at that point, and the throttle is full open, keeping air from passing through fast idle valve.

I think I might go take a video real quick and post it up for you guys. Maybe you'll hear something I won't.

[Dr_Snooz]

The O2 sensor should be richening it up so you don't ping. That's its job. Unless you have something else going on, a vacuum leak shouldn't give you pinging.

[Legend_master]

Just a quick thought, what about the fuel pressure regulator? If its not working properly your fuel may be leaning out.