I have had an intermittent problem where my car starts pinging(crackling), most prominantly during light acceleration and going uphill. Although lately is has gotten worse and has started to do it at other times as well, but almost always around third gear speeds. I took it to the dealer and they said it is "normal" pre-detonation although we both know it is not. They claim it can do that sometimes and the knock sensor detects it and retards the timing. They recommended changing fuel grade, but I almost always use premium and they said to downgrade. I believe that it is in fact...Pre-detonation, but I do not think it is normal. It has gotten so bad it sounds like my car is going to blow up and I am affraid it will cause permanent damage. The dealer seems gun shy to investigate because they do not want to eat any costs. Has anybody out there had similar experiences or have any further avenues to which I can investigate the problem. I will deal with Mitsu Corporate if I have to. Thanks to all who have taken the time to read this.

2004 Galant LS 3.8L V6
32,300 mi., Dealer Serviced

What grade of fuel does the mitsu tell you to run, because if it tells you to run premium then you should, if it doesn't tell you to then run 89, the problem with running premium in a car that doesn't require premium gas is the fact that premium has a higher flash point and a longer burn time, burning cleaner then lower grades, but causing knock in a motor that does not require it, due to the fact that the stoke has to be higher in the cylinder to help with detontionation. The best things you could do right nowis try 1 tank of 89 and maybe some fuel system cleaner and see if it gets better, 1 tank of a lesser grade of gas son't hurt the engine, just don't make a habit of it, if the car requires premium, but the gas lid or gas door cover should tell you if you need premium or not. If it doesn't get better after that then take it back to the dealer and demand them to fix it.

light "surge" pinging is indeed normal, but should only last a second or two.
always run the top of the line fuel, and buy it from a name brand station.

there is a software update to quell pinging on the 4 cylinder, but not the 6.

I have tried all three types of fuel grades and several cleaners as over a 6 month period. I almost always buy from the big stations. The sticker on the door says premium is recommended and that is what I normally use. The problem started intermittently around 6 months ago(owned 2.5 years) and would rarely happen then. This is how I know it is a malfunction an not something the car has done from when it was new. It has however started doing it at almost every hill and going up some long hills can last 10-20 seconds until I crest the hill. I am taking the car back to the dealer this week for a different repair and I am going to demand they do something or let me talk to a regional mitsu rep. I just wanted to know if anyone else has heard of similar problems and what they did to fix it.

if its been building up over time, chances are you have combustion chamber deposits, which may or may not be a warrantable item.
do you drive slowly? An easy way to get rid of those deposits is to push the car hard for a while... W.O.T, high rpms. That will raise the combustion temps enough to burn a lot of it off.

Man, I think you are right about the deposits. I drove it really hard for a few days(didn't know how fast it really was) and the pre-detonation has not happened since. Who would have thought your car could mess up from treating it to good and fixing it would be so fun. I don't want to stop flooring it now, but the gas is killing me! I will post another update if the detonation comes back, but I hope it doesn't.

its a common problem for a LOT of cars, regardless of manufacturer. especially today with high HP cars.. most people rarely need to push a car like the 3.8 galant very hard to achieve excellent acceleration and high speeds, so the combustion chamber gets deposits prematurely from lower average combustion temps.

What do you guys use to clean out your intake and combustion chamber as maintenance at work? We use Valvoline intake cleaner with a fogger.

nothing. We usually tell the customer to drive it a little harder, or do it for them for 20-30 minutes.

Ok, well it is August now and the pinging/detonation has come back full force. I talked to the Mitsubishi Rep in May and they changed the knock sensor and did a complete fuel system treatment to no avail. They then told me it was just a characteristic of the engine and everything is fine. I am just upset because a characteristic of something means it should have been there from day one and this hasn't. I am not sure what I am going to do but it is driving me nuts. I have been driving it hard still as stated above and that is not working anymore. In addition, it is a black car and the paint is starting to get the notorious "white cancer" that was supposed to have been fixed in 2004. I just had it in for a week and they repainted the roof, trunk deck, and hood. Well, now a couple weeks later it has started on the sides. Maybe I just have a bad apple but I don't think after this experience I would buy a Mitsubishi again. If anybody has any new ideas about the detonation problem please let me know. Just to elaborate a little more on when it exactly does it.

Always during lower RPM's from 1200-2000 usually after shifting to lock-up(overdrive). It has started doing after shifting to third as well, low RPM'S. It will do it ever time I am going up a hill and those shift points are introduced with light or no acceleration. The pinging will sustain as long as those conditions are maintained in lock-up. The Mitsu Rep said "well you should just give it more gas when it does it to bring the RPM's up" but he is not paying for the gas and anyone who drives in the city knows you can't just drive through other vehicles if front of you!!! Any help in this matter would be greatly appreciated.

Thanks, Justin

What kind of spark plugs have you put in it?

Perhaps the plugs are too cold/too hot?