99 OBW suddenly pinging

[NOMAD327]

The wife’s 99 OBW 2.5 DOHC recently started pinging under load. It never happened before and mid grade gas fixes it, and it works perfectly otherwise. No CEL And No Error Codes, but that’s after running on midgrade for a few days. 155,000 miles, It had headgaskets, thermostat, belts and idlers and spark plugs about 15,000 miles ago, plug wires andO2 sensors about 50,000 miles ago. The original knock sensor cracked and was replaced about 60,000 miles ago. The knock sensor looks OK, but I'll probably have to pull it to make sure, last time it set a code when it failed. All parts are genuine Subaru. I will run it on regular gas and check for codes again, but am thinking ahead to what else it could be? Is there anything else I should be checking or replacing?

[davebugs]

Probably the crappy Ethanol gas and nothing more. Like here the gas gets worse in the summer trying to improve the ozone or something. Result is the gas is crap. Really kills small engine stuff (chain saws, weed eaters, somewhat lawn mowers).

 

Not only is Ethanol crap, and "corn based Ethanol" specifically pandered to last election instead of Ethanol made from biomass waste but it ruins the pumps at the gas station and they don't care much about our cars because they have deemed it "good for us".

 

I laughed when they were saying it took 8k to retrofit pumps at the gas station because Ethanol eats them up internally. The interviewer asked what it did to our cars then. The fella being interviewed said the new cars can handle it. The interviewer asked how many people drive new cars? The question was never really answered.

 

Ethanol draws WATER. Water in all phases of a fuel system does bad things. Heck - Ethanol can't even be put through a pipeline because it eats up the pipes!

 

The current pres PANDERED to Iowa with the "corn based Ethanol" rather than jsut Ethanol. A coincidence they are early in the primary process I'm sure.

 

So the do gooders are screwing us again.

 

Try different fuel. In the fall the blend gets a little better.

 

They want to INCREASE the Ethanol blends in our gasoline - the Ethannol producers are heavy political contributors.

 

You can research on your own why we're forced into Ethanol. A product that takes more energy to produce than it generates and isn't profitable on it's own.

 

The important thing is it's screwing up OUR stuff. Virtually anything with a gasoline engine. I have antique cars - carbed and fuel injected. Ethanol is evil - although good intentioned I'm sure. Like a lot of gov't mandates.

 

Not a chemist, not a corn farmer, didn't vote fo rthe Bozo's currently running the country.

 

I do however have a dozen cars of my own, work on other cars, and have a small army of small, 2 and 4 cycle powered things. BTW 2 cycle is evil and they are phasing them out as well.

 

Bottom line is probably crappy gas due to politics more than science.

[porcupine73]

Good talk about the ethanol. Interesting how things play out like that time and time again.

 

Your soob might benefit from a good thorough induction system cleaning. You may have carbon buildup and such in the engine at this point, and that can result in pinging.

[Rooster2]

If it were me, I would add a bottle of Seafoam to the gas tank. That product does a remarkable job of removing carbon build up inside the engine. The carbon build up is most likely the source of your ping.

[Subruise]

also, since you just did tbelts make sure one wasnt loose and slipped a tooth. happened to my ea82. dunno if this helps but nobody said it

 

 

 

RV

[davebugs]

I have success with Seafoam for O2 sensors and cats.

 

Usually Lucas Fuel Injection cleaner does well for me in the fuel. I buy it by the gallon and run it in all my gas vehicles.

 

Definately try a different station for fuel though -a different brand.

[OB99W]

Hot weather in combination with high enough engine load can lead to pinging even if the fuel octane rating would otherwise be sufficient. It would be nice if knock sensor data would just cause the timing to be retarded, but sometimes that's not the answer. Especially if the cooling system isn't quite up to par (but not bad enough to cause overheating), that can be the tipping point.

 

Since there's apparently a "Danville" in several states, I couldn't check to see whether particularly high temps are a recent situation. Is the temp gauge reading where it usually does? Have you checked for any obstruction of airflow through the radiator? (A bunch of dead insects can make a difference.)

[Fairtax4me]

Might be a plugged/restricted EGR valve.

[NOMAD327]

It's Danville, PA, and it's been a very hot summer with no problems, and a bit cooler the last couple weeks. I have a lot of ideas to check out here and appreciate the input. The heads were off about a year ago, and there wasn't any carbon to speak of then and they were cleaned up before going back on. We will be trying fuel from different stations and continuing to check for codes. I will post back in a few weeks if I find anything definitive.

[davebugs]

Please update your profile to say Danville, PA so we can tell in the future. Members have been known to stop in to be a second set of eyes and offer a second opinion to other members.

 

In my experience a Knock sensor causes performance to suck but not pinging - perhaps I've just been lucky. And it causes a CEL.

 

My daily driver is a diesel and when I'm driving something gas I'm towing something so it's hard for me to tell when our gas hits the official "crappy" stage. I didn't even get any antiques out this year to see how it's effecting they but I run a cocktail or lead substitute(which is a salt I believe) and Sta-bil.

 

Please report back with a solution. I think the gas may get a little "better/less crappy" about the end of this month IIR.

[NOMAD327]

I got a chance to put regular in it, and it started pinging again and no codes now that it's been pinging. It seems to ping more as gas tank level gets lower, but still a few gallons left. It had a new fuel filter recently, and no problem going up hills, so I don't think it's really a fuel delivery problem, but will continue to check things out.

[porcupine73]

You could still have carbon buildup even if the heads were off and cleaned 15,000 miles ago. It doesn't necessarily take all that long for it to happen. There was an article on endwrench about this happening with some gasolines iirc.

[mikec03]

Recently my '95 started pinging on regular gas with no CEL and someone suggested a restricted EGR valve as a possible cause [as was suggested here]. I took apart the EGR and there was about a 1/16" even carbon coating on it. The orifice of the valve is not very large-about 1/4-3/8" dia. and the 1/16" coating could substantially restrict it. So I scraped out the coating with a screwdriver and the pinging has been eliminated.