pinging SOLVED timing off from factory

[brus brother]

From day one, my 2000GT pings with the approved 87 octane. It does this under mild acceleration. The tech tried hard acceleration without pinging. Now they want to pull the covers and check timing. The latest computer flash has been applied without any remedy. It doesn't seem to misbehave when very cold outside but with warming here in the northeast, it is coming back. It's still under warranty. Plugs and filter are new. Any ideas?

[blitz]

IMO, the first thing to try would be some Techron or Regane for an extended period to clear the injectors, intake valves and intake ports of deposits. It'll take a while if there's a heavy buildup. Use it regularly thereafter to keep buildup from recurring.

 

Second thing would be to clean the combustion chamber of deposits. I use the water-blast method every summer. Some folks don't agree with using water, but I've never encountered any problems with it.

 

If the knock persists, bite the bullet and step up to a higher octane.

[frag]

Second thing would be to clean the combustion chamber of deposits. I use the water-blast method every summer. Some folks don't agree with using water, but I've never encountered any problems with it.

.

 

Could you give me (us) a description of the exact procedure you use for doing this?

[Al_SemC]

You gradually feed water into the combustion chamber at a high engine speed, usually by sucking it from a bottle in thorugh a vacuum line. This is an age-old method that originally involved pouring it down the carbeurator. The idea is to steam clean it. I'm not at all comfortable with the process. If you stall it, you hydrolock it and then you're screwed. I don't personally know anyone who's willing to do it and I've never talked to a mechanic whose eyes didn't bug out when it was suggested within their earshot.

[brus brother]

I think I made it clear that the car has behaved this way from day one, so the various treatments meant to eliminate carbon etc. wouldn't have come to play with a brand new engine.

The car has new plugs and the recommended gas line additive/cleaner BG44K.

It behaves well when it is very cold outside.

It is noticeably worse with warmer weather and high humidity(low air pressure?).

Tech feels it is something mechanical. All guesses accepted and I will report back with any findings.

PS I had originally been running 91 octane but ran into other owners who had no problem with 87 octane and since I'm still under warranty, I figured that I'd let them try and figure why the runt of the litter is in my driveway.

[blitz]

I think I made it clear that the car has behaved this way from day one

Well, actually you made it clear that it BEHAVES this way from day one rather than it HAS BEHAVED this way from day one. So with all due respect, if you'd like folks to not mis-read your post, please use correct syntax. :-\

 

so the various treatments meant to eliminate carbon etc. wouldn't have come to play with a brand new engine.

The car has new plugs and the recommended gas line additive/cleaner BG44K.

It behaves well when it is very cold outside.

It is noticeably worse with warmer weather and high humidity(low air pressure?).

Tech feels it is something mechanical. All guesses accepted and I will report back with any findings.

PS I had originally been running 91 octane but ran into other owners who had no problem with 87 octane and since I'm still under warranty, I figured that I'd let them try and figure why the runt of the litter is in my driveway.

Check the resistance curve of the IAT sensor. It tells the 'puter to both lean the fuel (WOT) and pull back the timing as air temp rises.

 

I meaured mine once:

-------------------------------------

In the freezer (approx. 26*F), it measured 8k ohms.

 

At 70*F ambient, it measured around 2k ohms.

 

At approx. 140*F it measured about 1k ohms.

 

You can substitute the sensor with a cockpit-adjustable resistance and dial the timing where you want it. I've had a 6-position selectable one on my car for the last 30k miles. I throw 93 octane in the tank and crank the timing all the way up. It really fattens up the midrange torque. If I'm in a situation where I'm forced to use a lesser octane, I dial it back.

[blitz]

Could you give me (us) a description of the exact procedure you use for doing this?

Like Al_Smokemcrack said, you control the throttle with one hand and meter a LIGHT stream of water into the throttle body vaccum line with the other. DON'T STICK THE HOSE IN THE WATER, rather suction it off the top like slurping hot soup from a spoon. If you give the engine a big gulp of water, you stand a chance of bending a rod. The engine needs to be fully hot (fans cycle at least once). Afterwards, drive the vehicle moderately hard to chase all the moisture completely out of the tailpipe.

 

To expand further on the cautions regarding this proceedure:

 

Don't stall or hydrolock the engine. Also be careful not to bang your head on the hood or inadvertently get your finger in the accessory belt. Lastly, when driving the water out of the tailpipe afterwards, be careful not to crash the car.

 

If you play sports, can apply spray paint competently, or play at least one musical instrument, you can master the water-blast technique.

[Chef]

Perhaps a faulty knock sensor is at play. Wasn't there a recall regarding the knock sensor and subies from that period? If so, it might be adjusting the timing such that it knocks. Probably not liekly, but a thought.

 

 

 

Well, actually you made it clear that it BEHAVES this way from day one rather than it HAS BEHAVED this way from day one. So with all due respect, if you'd like folks to not mis-read your post, please use correct syntax. :-\

 

 

Check the resistance curve of the IAT sensor. It tells the 'puter to both lean the fuel (WOT) and pull back the timing as air temp rises.

 

I meaured mine once:

-------------------------------------

In the freezer (approx. 26*F), it measured 8k ohms.

 

At 70*F ambient, it measured around 2k ohms.

 

At approx. 140*F it measured about 1k ohms.

 

You can substitute the sensor with a cockpit-adjustable resistance and dial the timing where you want it. I've had a 6-position selectable one on my car for the last 30k miles. I throw 93 octane in the tank and crank the timing all the way up. It really fattens up the midrange torque. If I'm in a situation where I'm forced to use a lesser octane, I dial it back.

[brus brother]

Thanks for the responses.

If my reading is correct, the problem is related to either a bad knock sensor, a faulty or out of range IAT sensor or bad grammar.

[charlierh2]

is your grammer still under warranty too?

[blitz]

Thanks for the responses.

bad grammar.

LOL .

 

If your air-temp sensor is the type mounted in the front of the airbox, it's a snap to pull it out and measure it's resistance at various temperatures. Unfortunately I don't have any specs. In my experience, during the summer months (80 - 90*F), 3k worth of resistance in that circuit is enough to induce spark knock in my 2.5 using 87 octane.

 

The knock sensor doesn't influence timing in any way other than to tell the ECU to apply temporary "corrective bulk retard" in the event of spark knock. The single centrally-mounted sensor doesn't work well on the boxer and it never will. It's a flawed application by nature of it's design. It's either too sensitve for certain specific engines, or not sensitive enough for others. Then as a lot of the 2.5's develop piston slap over time, the sensor picks that noise up and interprets it as knock.

 

Subaru has a knack for hardware but they have a difficult time with software.

[brus brother]

They changed the knock sensor today... no change. I showed the tech Blitz's IAT sensor option and while it is a different variety, it apparently chacked out. As far as my grammer, she and my grampa have been out of warranty for many years.

Tomorrow they'll pull off the timing covers and check the cam timing.

[brus brother]

And the answer is....Today, after 51/2 years of complaining, a clever tech pulled the covers off and checked the cam timing. It was off by one tooth. The pinging is much reduced but not completely gone. I had them change the timing belt early at 72K since they were in there and it only cost me $40 for the belt.

Dealer suggests injector cleaning. Is there a DIY version or is the $129 dealer service worth the bucks? I have used BG44K every 30K but will this clean the injectors as well as the other service?