I'm not much of a mechanic but I think if you recently replaced your head, depending on how much it was milled and depending on the thickness of the head gasket used, you could be running at higher compression. did your problem start in the winter? I don't know where you are, but we use oxygenated gas in the winter in CA for smog purposes. trying some higher octane gas would be a cheap test. It doesn't explain your fouled plug though -- did you check the gap and replace your distributor cap?

 

combatcarl: The other three plugs look much cleaner than the one in your pic. No fouling whatsoever with a nice tan insulator. Even after running them 10,000 miles. But that one cylinder(#4) just gets worse and worse.


HappyCamper: I do live in CA but premium gas gives me little to no improvement. The head isn't milled, it's a new head, or at least that's what I paid for. 180 psi in all 4 cylinders. Runs much better since I had that done.

Thanks!!

 

That one plug does look like some oil fouling, but it's hard to tell from the photo, or could be too rich on that one cylinder. Any smoke out the tailpipe or having to add oil? Try putting new plugs in if you have 10k miles on them, then check it again.

 

Here's a related thread:

https://www.yotatech.com/forums/f116...cement-230564/

 

You said you checked the modulator. How??

Were you able to confirm that there actually is substantial vacuum being delivered to the EGR valve at cruising speed?

 

No smoke, needs about a quart at oil change after 4-5000 miles. Plugs have been replaced. Problem plug after about a tank of gas worth of driving looks burnt, not oily, while the other 3 still look new.

 

That's way too much oil consumption, and probably why it pings. It's probably also creating deposits in the combustion chamber which makes it ping even more. There's a few chemical treatments you could use to de-carbon the combustion chamber, but it's just going to return burning that much oil.

 

Checked it by doing the blow test on port Q with P and R plugged and seeing a change in flow restriction with engine running and not. And put vacuum on the bottom port, held just fine. And tested vacuum on the line to the EGR valve while driving. On the freeway vacuum to the valve stayed around 5 in. more or less depending on load. I think it read as high as 7 while cruising. I also checked the whole EGR circuit and made sure the hoses and ports were connected right, had no blockage. Tested the VSV with leads to the battery. I'm pretty sure EGR is working right. Ya beats me.

 

So that's a lot? Before the new head it would burn twice as much. I had to add a quart every 2000 miles or so, and it NEVER had a ping. Mechanic said not to worry unless it burned a quart in 1000 miles. Thanks

 

Your vacuum to the EGR looks about normal. Since it's burning oil the EGR passages might be getting restricted with crud build up, just like whats on that one spark plug.

 

Well, if you want the quick fix, retard the timing a couple degrees and use premium gas. Burning a quart of oil in 4k miles doesn't make the 22RE happy, that oil is coating the plug, O2 sensor, and catalytic converter. Older carbed engines wouldn't matter as much, but the EFI is more sensitive.

 

I did just that and it made the ping less intense but it still did it. That and it ran sluggish. Had to take the timing back to about 1 or 2 degrees btdc to make a difference. With premium gas. My dream is to get it back to running on regular with no ping at stock timing!

So how does oil consumption make it ping? I've read that carbon build up raises compression to cause it. Maybe that ring is blown. Don't know what else it could be with a pretty new (even at this point) head. I pulled the EGR valve and checked/cleaned all the passages, looked sooty but clear. Also, I did have the mechanic run some stuff through the intake to clean it and the injectors out. It stopped the pinging for about two freeway trips.

 

Oil does not burn the same as gas, that will cause a ping. Oil in the cylinder seals the rings more, raising compression slightly, that will cause a ping. Oil burning coats the combustion chamber with carbon, again raising compression, more ping. Like I said, there's chemical treatments to remove the carbon buildup in the combustion chamber, which will prevent the pinging until it starts building up again.
One thing you could try is increasing the gap slightly on that one plug, or going to the next hotter plug, that might help keep the combustion chamber clean, but it's hard on the pistons.
We had an old 60s V8 dodge come in pinging its brains out, all cylinders pegged the compression tester. We did the de-carbon trick and it cured it for a while, but eventually came back because it was burning oil.
Edit: Maybe also try going up to a thicker motor oil.

 

1qt in 4-5 thousand miles ain't bad at all. You may see if somehow your injectors are clogged, under fueling leading to a lean condition... But I think you'd see other performance issues then. I don't have my EGR system operating, and I don't have detonation problems. So EGR isn't that big of an issue. What does your timing run at idle, without the check jumper? As it revs up, no load, what's the advance climb to? As a "see if there's a difference" trial, have you tried seafoam? I don't swear by it, but some people do.

 

Oil will raise compression to some extent, and it will lean out fuel if it's enough, or mixed right, but I've seen engines that burn a quart in 1k miles that didn't ping. That's partly why I say that oil consumption isn't a big issue here.

 

Only one out of four plugs shows signs of fouling. If you call only one cylinder burning a quart of oil every 4k miles normal, then OK. I call that a problem. Most likely a bad oil control ring or valve guide on that cylinder.

 

Makes sense. I wonder if it's time to just get the old guy rebuilt. I guess it's better to do it before damaging anything. I've suspected that cylinder since I noticed the fouled plug as being the source of pinging, it just runs fine other than under load at high speed but it's gone on for a long time. At least a year. I just worry that it will still ping even if I rebuild it! Like the problem lies elsewhere, distributor, ECU etc. That's why I'm ultimately trying to get to the root of this.

 

Timing without the jumper is about 10-12 degrees at idle, mark moves a bit. It advances quickly when the throttle is opened some and tops out somewhere in the 30-40 degree range. I don't know where it ends up because it's off the mark but it looks like about 3 times the distance of the 12 mark.


Haven't tried any seafoam. Like I said the mechanic ran some stuff through the fuel injection and it stopped pinging for a day, with premium gas.

 

The only other thing I can think of is a lean condition (or overly rich) or overheating, but you haven't said if it was surging (lean) or overheating. 300k miles on the bottom end is great, that's why I bought my Toyota, they last a long time.

 

No hot running or surging. Doesn't even misfire. Yea I've had it for 9 years! This truck is my money maker!


I will add that there's NO knock sensor. Not even a wire for one that I can see and check engine light stays off. I guess some of these trucks didn't come with one but that's just what people say. Seems weird and I feel like that would help to have one.


I did have to repair some melted wires going to the o2 sensor behind the cat converter (dummy who put the new converter in broke the wire clip and they melted to the pipe) that was giving me a check engine light around the time it started to ping. Light went out but I don't know if that sensor is ruined? Strange coincidence? The exhaust is pretty smelly now too. I wonder if that sensor could have anything to do with this?