Pinging when warm

[Silent Bob]

Here's the problem: 91 Loyale, 2wd 3at spfi 160k Runs fine on cool days, but when the air temperature gets much above 70 deg., it has a terrible pinging problem. So far I've: replaced o2 sensor, checked timing (actually dialed it back to 15* btdc), checked coolant temp sensor, tps, &maf- all seem to be within spec. tried disabling EGR temporarily, didn't make a difference. Did the Seafoam thing several times. Replaced PCV valve, haven't found any vacuum leaks so far. There does seem to be what I would consider a lot of oil in the PCV hose, so a catch can/oil separator may be the next step. Any suggestions?

 

I searched through the archives and found a couple of people who reported exactly the same symptom, but none of the threads had an "I found the solution" post. So if anyone has figured it out, lay it on me.

 

thanks all

[GeneralDisorder]

Sounds like your cooling system needs an overhaul. I see a new radiator in your future....

 

GD

[bgd73]

At the miles you mentioned my old sube absolutely had to have more air. No more excuses. I changed a few things and it doesn't even matter the gas station I go to anymore, there are no pings. (being sure all else was good, like your car seems to be)

this is site with an idea of what it took to stop it .Pictures easily say it all:

http://93loyale.50megs.com/ntakt.html

[bgd73]

hey a follow up to my ping cure:

I am back to pinging again, have no clue other than drop thermostat way down.Does it the same as yours Silent Bob. Any ideas? higher grade fuel is absurd for the compression ratio, the problem is elsewhere. My last resort is no thermostat at all for the summer like some of my old v8's that did it(it fixed them- as well as 165 degrees too). I even spent 10 bucks on a miracle fuel injector cleaner/stabilizer and it didn't work also.

[Petersubaru]

you could try with the thermostate change...I know it worked for me along with changing the regular plugs for colder ones..I am sure in your manual or at least in my 1990 manual there are 3 different heat ranges for the subaru ...and it would be a good idea to check the rad and if the fans and the thermostates are coming on when they are suppose too

hey a follow up to my ping cure:

I am back to pinging again, have no clue other than drop thermostat way down.Does it the same as yours Silent Bob. Any ideas? higher grade fuel is absurd for the compression ratio, the problem is elsewhere. My last resort is no thermostat at all for the summer like some of my old v8's that did it(it fixed them- as well as 165 degrees too). I even spent 10 bucks on a miracle fuel injector cleaner/stabilizer and it didn't work also.

[bgd73]

hey thanks

I have some hot bosch platinum in now, would like to work with them rather than take them out. benefits are good. Never flushed the radiator, just added to it after an overheat a year ago.maybe turn air box and intake boot 90 degrees towards the back, and set it up where spare tire is, and put a small scoop on hood (?). no doubt air again, cool thermostat should help. Everything is spotless clean as well :-\ .with airbox where it is, I bet the rotor and tire heat even affects air flow....

[DerFahrer]

The words 'Bosch', 'spark', 'plug', and 'Subaru' should never be used in the same sentence.

[thepenguin]

sir bosch plugs belong in european cars and nothing else please for the sake of your vechile remove them and install the same ones that came in the vechile when it came of the showroom floor that could be causing part of your problem.

[thepenguin]

ok found that bit of info for you take that bosch crap out and put in NGK please man please

[mikeshoup]

Try switching to a colder range spark plug. That will carry the heat out through the spark plug if it is the spark plug causing the pinging.

 

And as everyone else suggests, NGK spark plugs usually run the best in Subarus. But hey, if Bosch platinums run fine, then use them.

[Loony]

Well pingin happens when your combustion chamber is getting too hot, and one of the best cooling devices for your combustion chamber is your egr valve, i know you say the egr recirrculates exhaust gas which is hot.. but it is alot cooler then your combustion chamber.. i would suggest rather then diabling your egr, which will cause gasses to not recirculate.. You should get your hands on a vacuum pump and run a line to your egr from your drivers seat, when it starts to ping pump up the egr if it will even hold pressure(if it doesn't replace it), if the pinging goes away your not getting vaccum to your egr under load if it does not and holds pressure you will more then likely have carbon built up in the passage blocking a way to cool your motor... In that case pull intake and get it heat treated or find a shop to do a motovac

 

hope this helps if ya lived closer i'd tell ya to run it by and i'd help ya test it all but your like on the other end of the planet

 

Oh and one more thig platinum plugs burn alot hotter the regular plugs causing more heat in the combustion chamber, and all japanese cars run great on NGK's first and if you can't get them Nippon denso's

[Silent Bob]

Thanks for all the ideas, here's an update: I switched the plugs, took out the Champions that were in it and replaced with NGK BPR7ES (1 step cooler than spec). The idle had been a little rough, so I pulled the hose off the IAC, filled it with carb cleaner (engine off) and let it soak for a while. Ran quite a bit better after that. Truth is, I'm not sure exactly sure what I did to correct the problem, but it is not pinging nearly as badly now. Maybe just a result of everything done so far (makes a bit of a case for regular maintainance eh?).

 

Summary:

 

O2 sensor

cooler plugs

set timing to 15* (didn't help, set back to 20*)

disconnect EGR (once again, no help-hooked it back up)

Seafoam

cleaned IAC (idle is smoother if nothing else)

replace PCV valve

replaced radiator hoses/flushed rad./changed coolant(doesn't seem to run any cooler, still 1/4-1/3 on gauge, but certainly didn't hurt)

blocked off coolant passage to throttle body(seemed to have a good bit better throttle response after that, didn't seem to make it run hotter or make the original problem worse)

 

 

I think I'm leaning toward the actual problem being a localized "hot spot" in one or more cylinders, whether that's from carbon buildup or a coolant restriction, I don't know. Sure would be nice to have a borescope about now...

 

Anyway, whatever I did it has improved. Mybe it was the incense and voodoo spells;)

 

 

 

Here's the problem: 91 Loyale, 2wd 3at spfi 160k Runs fine on cool days, but when the air temperature gets much above 70 deg., it has a terrible pinging problem. So far I've: replaced o2 sensor, checked timing (actually dialed it back to 15* btdc), checked coolant temp sensor, tps, &maf- all seem to be within spec. tried disabling EGR temporarily, didn't make a difference. Did the Seafoam thing several times. Replaced PCV valve, haven't found any vacuum leaks so far. There does seem to be what I would consider a lot of oil in the PCV hose, so a catch can/oil separator may be the next step. Any suggestions?

 

I searched through the archives and found a couple of people who reported exactly the same symptom, but none of the threads had an "I found the solution" post. So if anyone has figured it out, lay it on me.

 

thanks all

[Petersubaru]

always like to here from a mechanic...just seeking to understand..when you say that the "bosch plat. plugs burn hotter", do you mean that the "spark" is hotter then the standard plug or that the so called "same" heat range between the NGK's and Bosch are in fact different and not really the same heat range, and in this case bosch burns hotter(cylinder temp)..I hope I am making myself clear here...thanks

Well pingin happens when your combustion chamber is getting too hot, and one of the best cooling devices for your combustion chamber is your egr valve, i know you say the egr recirrculates exhaust gas which is hot.. but it is alot cooler then your combustion chamber.. i would suggest rather then diabling your egr, which will cause gasses to not recirculate.. You should get your hands on a vacuum pump and run a line to your egr from your drivers seat, when it starts to ping pump up the egr if it will even hold pressure(if it doesn't replace it), if the pinging goes away your not getting vaccum to your egr under load if it does not and holds pressure you will more then likely have carbon built up in the passage blocking a way to cool your motor... In that case pull intake and get it heat treated or find a shop to do a motovac

 

hope this helps if ya lived closer i'd tell ya to run it by and i'd help ya test it all but your like on the other end of the planet

 

Oh and one more thig platinum plugs burn alot hotter the regular plugs causing more heat in the combustion chamber, and all japanese cars run great on NGK's first and if you can't get them Nippon denso's

[Loony]

i mean it will increase the combustion heat

[Loony]

i mean it will increase the combustion heat and just because one type of plug specify's heat range there not exact to the actuall o/e range

[bgd73]

I have figured the bosch not to be the problem. Figuring the energies results, hot plug, burns fast, more heat to dissipate in less amount of time versus less time to dissipate more heat on a so called cooler plug. <-(does this make sense?)

I though it was something slow in ECU until I remembered the DL with hitachi carb I had did the same thing.

The real low thermostat (160-180) fixed it forever. I have yet to get this chore done on the spfi. The stuff silent bob did with cleaning is a huge helper too, inside and out.it hit near 85 today and didn't do it all day among my travels- I wonder if it is a sticky thermostat through the 70 degree days :-\ bouncing perfectly open/shut to less flow than on a hot day or cold day.I have gone thru every piece and even doubted the fuel pump, dirty gas, etc, etc.

[Petersubaru]

When my 86 subaru was only a few yrs old with 30k miles, it would always ping going up hills even with high octane gas..I ran a 170F thermo. and it did fix the problem..what ever the problem was with those low miles, I still have not figured it out..now with rebuilt heads and 200k miles, no more pinging even with the stock thermo....the machine shop said the compression was slightly lowered due to the valves sitting lower on the seats(regrinding)

I have figured the bosch not to be the problem. Figuring the energies results, hot plug, burns fast, more heat to dissipate in less amount of time versus less time to dissipate more heat on a so called cooler plug. <-(does this make sense?)

I though it was something slow in ECU until I remembered the DL with hitachi carb I had did the same thing.

The real low thermostat (160-180) fixed it forever. I have yet to get this chore done on the spfi. The stuff silent bob did with cleaning is a huge helper too, inside and out.it hit near 85 today and didn't do it all day among my travels- I wonder if it is a sticky thermostat through the 70 degree days :-\ bouncing perfectly open/shut to less flow than on a hot day or cold day.I have gone thru every piece and even doubted the fuel pump, dirty gas, etc, etc.