22R Pings in hot weather?

[GTO52]

My 1995 Toyota pickup(22R engine) pings on hot days under load(mostly on the highway).I have to drop a gear so the engine revs stay higher which reduces the pinging.
I have checked the timing,I also had mechanics check it out throughly and say everything is okay.
As soon as we have a cooler day or in winter there is no pinging?
I reckon it is carbon deposits raising the compression ratio and thus the octane requirement goes up?
I run it on 95 Octane Lead replacement fuel, in 1995 when it was built we used 97 Octane Leaded fuel here in South Africa.(There is a sticker on the vehicle showing 97 for the coast)

I have tried octane boosters and combustion chamber cleaners but they do not seem to make much difference?

The engine has 138500 miles on it and has never been opened.
I do drive half a mile to work and back each day but I do use the vehicle during the day as well on longer trips (50miles).
Can these short trips cause the carbon deposits?
Also it doesn't use much oil between oil changes.

How serious is this pinging?(will it eventually destroy my engine)

 

[MrBeachcomber]

"Hot days" and "cooler day" are subjective so I don't know what the exact temperature range causes the problem. However, short stop and go trips can cause an engine to build up excess carbon in the combustion chamber since the engine doesn't reach operating temperature for any sustained period of time.

Pinging can and does pit aluminum piston tops over a period of time if not corrected. Heavy detonation will break rings and hole the piston in short order under heavy load.

I would try two fixes to see which works best. The first would be a fuel system cleaner such as RedLine SI-1 every fill up to remove/prevent carbon buildup. The second would be retarding the initial ignition setting by two degrees in incremental steps until the pinging goes away during the hotter days of the year.

Rather that use octane boosters, I would switch to a higher octane fuel (if available). (The link provides info on "homebrew" boosters as well as what's used in the commercial products.)

 

[fsskier]

Did your mechanic check the knock sensor, including the connections, etc??? Checking the timing is only half the battle, the knock sensor should set the timing back as soon as ping is detected.

If you mechanic does not know what a knock sensor is...... its time to find a better mechanic!

 

[Quest]

LOL fsskier!

The OP is from South Africa and the vehicle was running leaded gas before so the likeliness of it being a computer controlled EFI vehicle is low (for you cannot run leaded gas through one of those mission-critical emissions feedback device called "O2 sensor").

The venerable 22R engine is on timing chain and most likely carb'ed in this case so the problem most likely due to timing issues, carboned up combustion chamber or fuel mixture issues on the carb side (lean during acceleration/partial throttle opening mode).

Quest

 

[The_Jeff]

Five second test to see if you have a knock sensor: Idle the motor, rap on an engine lifting hook/ accessory bracket with a big wrench or hammer. If the idle changes, you have one!

 

[fsskier]

Yeah, I wondered the same thing, except......

Even a non EFI vehicle can have a knock sensor, since this is part of the electronic ignition system.... not really related to the EFI at all.

Hopefully his South African mechanic can determine if it has one or not!

Of course the EGR system.... if it has one.... when it fails you often get part throttle pinging. The EGR actually increases effective octane, and timing curves were advanced to take advantage of it. Good idea until the EGR fails, then..... woodpeckers move into your motor!

Agreed again, it depends on what Toyota sells in that area!

 

[crazyoildude]

egr valve not opening ?

 

[lexus114]

Carbon build up?

 

[mechanicx]

Yeah I agree. I'm not a Toyota expert but 22R means not electronic and probably carbed as opposed to 22RE with fuel injection. I'm going to guess since the timing is correct the pinging is caused by the fuel mixture being off due to a dirty/misadjusted carb. Cleaning the carb and readjusting the idle mixture might help. Even at cruise speed a lot of the fuel mixture is supplied by the idle circuit. But who knows, maybe the truck is running hot in hot weather and the cooling system needs checked out.

 

[mechtech2]

Octane boosters are misleading. They claim increases in 'points', but those are TENTHS of a point in octane, not whole numbers!
You'd have to use a load of it in the tank to do any good.
Use a higher octane, in the meantime - it is best overall.

HOt engines can knock. Whether from high coolant temps or hot intake air.
Make sure your intake air is getting cold [external ambient]air - that there is not heat to it - some systems still use heat or have bad routing.
An air temp sensor or coolant sensor may be faulty, but still not throw a code. A thermostat that is too high will also be a problem [even though the rating is OK] - 5-10 more than normal will have an bad effect.
An EGR system that is stuck will also cause part throttle knocking [not opening].

You don't want to rely on the knock sensor to retard the ignition timing. You are killing performance and possible gas mileage. Higher octane until you get it fixed, or used a a fix, is really a good idea.

 

[Scott_Tucker]

That engine does not have a knock sensor. I would check that the EGR system is working and the ports are completely clear as this will definitely cause knock. It may also be that it has carbon build up from being so old. Our work truck is a 91 toyota with a 22R-E and it has nearly 300k mi. and it pings like crazy. I keep trying to beat on that thing so it will blow up and we can get something newer but it will just not die.

 

[Quest]

Originally Posted By: fsskier
Yeah, I wondered the same thing, except......

Even a non EFI vehicle can have a knock sensor, since this is part of the electronic ignition system.... not really related to the EFI at all.

Hopefully his South African mechanic can determine if it has one or not!

Of course the EGR system.... if it has one.... when it fails you often get part throttle pinging. The EGR actually increases effective octane, and timing curves were advanced to take advantage of it. Good idea until the EGR fails, then..... woodpeckers move into your motor!

Agreed again, it depends on what Toyota sells in that area!


Sorry bud but you have it wrong, for a knock sensor only exists in an EFI (electronic fuel injection systems) for it's an electrical device (more like a piezo sensor that picks up knocks and translate that into electrical signal, period) and only electronic fuel injection systems come with that. Carb'ed engine even with electronic ignitions, do not come with such device (too sophisticated for it's time).

EGR, carbon build up or mixture problem during part-throttle would be a cause. 1 thing I wouldn't dismiss would be some vacuum leaks from cracked/aged vacuum rubber hoses.

Q.

 

[GTO52]

Engine has a carb and no knock sensors and no EGR.
Toyota South Africa kept this engine in the production until 1998, we never got the RE here.
The mechanics checked the mixture and found it was actually rich!
We do not get Redline Seafoam etc here.
What about carb cleaner I fed some the other day through the intake on my lawnmower(2 cycle) the spark plug was clean afterwards?
How does one tell if the engine is running to hot?(Water temp is always just below half)
Must I fit an oil temp gauge(I do not like the idea of drilling a hole in my sump plug)
95 Octane is the only octane available here.

 

[Scott_Tucker]

That's a different octane rating than is used in the states. I believe that is the research octane number (RON)? In the US we use the average of the research and the motor method (RON + MON/2 = AKI (Anti-Knock Index). I think 95 octane research method would equal like 89 octane AKI here?

 

[GTO52]

Hot weather I mean temps higher than 25C(77F)
Winter temps in Cape Town do not get much lower than 40F
I have changed the termostat with an OEM one.

 

[MrBeachcomber]

If Chevron Techron Fuel System Cleaner is available, I'd use that every fill up to clean out the combustion chambers. Otherwise, periodically spraying carb cleaner down the throat of the carb while the engine is running should work too. (Just make sure you don't stall the engine doing this else you'll contaminate your oil with solvents.)

Other than a localized hot spot within the engine's cooling jacket (I don't know the 22R that well), your water temp is the best sensor to gauge whether or not the engine is running "hot". Oil temp gauges are really engine savers for street vehicles - don't run high RPM's until the oil's up to temperature, and shut off the engine if the oil temp get's too high (~250F for dino and 350F for synthetic).

Going back to your original post, with all the miles on the engine, it might be time for a cylinder head rebuild. Oil passing down the valve guides could be the source of deposits inside the combustion chamber causing pre-ignition during your "hot" weather.

Hope this helps!

 

[GTO52]

Originally Posted By: MrBeachcomber
If Chevron Techron Fuel System Cleaner is available, I'd use that every fill up to clean out the combustion chambers. Otherwise, periodically spraying carb cleaner down the throat of the carb while the engine is running should work too. (Just make sure you don't stall the engine doing this else you'll contaminate your oil with solvents.)

Other than a localized hot spot within the engine's cooling jacket (I don't know the 22R that well), your water temp is the best sensor to gauge whether or not the engine is running "hot". Oil temp gauges are really engine savers for street vehicles - don't run high RPM's until the oil's up to temperature, and shut off the engine if the oil temp get's too high (~250F for dino and 350F for synthetic).

Going back to your original post, with all the miles on the engine, it might be time for a cylinder head rebuild. Oil passing down the valve guides could be the source of deposits inside the combustion chamber causing pre-ignition during your "hot" weather.



We have Caltex(Chevron) fuel with Techron in it but not the Techron additve unfortunatley, here.
I usually either fill up with Caltex with Techron or Shell V-Power.


She doesn't really use much oil between changes.
But what I have noticed after washing the pickup I drive it down my driveway and leave it in the sun.When I return +/- 1 hour later there is a small puff of smoke on start up.
What is weird is there is no smoke on cold starts or hot starts?
I actually had the exact same problem with a car my wife had a few years ago which had only done 20000 miles and when I would take it to the agents(it was under warranty) they could find anything wrong with it?

 

[The_Jeff]

Originally Posted By: Quest

Sorry bud but you have it wrong, for a knock sensor only exists in an EFI (electronic fuel injection systems) for it's an electrical device (more like a piezo sensor that picks up knocks and translate that into electrical signal, period) and only electronic fuel injection systems come with that. Carb'ed engine even with electronic ignitions, do not come with such device (too sophisticated for it's time).


Carb'd buick turbos (predecessors to the grand nationals) had ESC with knock sensors in 1978!!

http://home.flash.net/~rjgeorge/knock.htm

The only coincidence with EFI was the cheap computing horsepower that came out in the 80s.

 

[mechtech2]

There are umpteen jillions of knock sensors on carbureted vehicles.
Gm had them for years and years.
I don't know if this particular car has one, but for sure many carb cars had them.

 

[fsskier]

Yeah, lots of knock sensors were sold without injection. By the mid 80's it was hard to find a car without them. Thats why I would suspect that this engine could have it, unless a COMPETENT mechanic/ tech manual/ what ever determined that it did not.