Heres a question..... I have a 90 subaru legacy and now that the air is warming up outside it has started pinging under acceleration, since the timming is not adjustable, what could be causing this?

Usually ist the spark plugs. Try a cooler heat range.

 

nipper

As mentioned pllugs are a good thing to check. Does it still do it on a tankfull of premium fuel? Maybe your combustion chambers are all coked up and could use a couple stiff does of techron, redline si-1, or other quality cleaner.

well I will try the premium gas as soon as I need to get more gas-- at about $3.15 - $3.20 a gallon it kinda sucks to run premium! What heat range of plugs would you reccomend? At the parts store I always just ask for the plugs that are supposed to be for my car... I usually buy NGK, Denso, or Bosch...

If your 1990 car ran well in previous summers and now it's not, likely carbon buildup is culprit, unless you got a bad batch of gas. Obviously new plugs is a good place to start but then conisder top engine cleaner.

I just bought the car about a month ago... so I don't know about past summers... I will try some of that redline additive and see what happens! However, I am still interested in the different heat range of plugs... any suggestions?

I just bought the car about a month ago... so I don't know about past summers... I will try some of that redline additive and see what happens! However, I am still interested in the different heat range of plugs... any suggestions?

 

Its been covered here and if you do a google search on it you will find lots of info.

 

A cooler plug just means that the plug has less metal on it so it wont retain heat. If the plug retains too much heat it can cause ping. This ping is annoying, as opposed to compression ping (hot spots on the piston or cylinder head) which can cause damage.

 

A hotter plug is used for short distance driving, as it retains more heat and wont foun as easily. Usualkly you dont move more then one heat range in either direction.

 

nipper

Well, if you just bought the car you have a lot of unknown parts to deal with. You most likely don't know when the plugs were last changed, nevermind other things like filters.

I usually throw new plugs, filters, and disty cap/rotor (I know you don't have them) in every car I buy. The exception would be the last Loyale I bought, which had all of that done right before I got it.

You can probably just put in a set of new NGK plugs in the standard heat range for the engine. Run some fuel system cleaner as suggested (something else I like to do) and see how it does after that. A lot of Legacys (especially auto's) don't get driven hard enough to burn the crap out of the combustion chambers. After putting a good dose of fuel system cleaner in the tank, run it hard up a long hill or something to get some heat into it!