Detonation at low RPM in high gear

auu

New member
Hello, I understand that this a total noob question (hence the section), but I come from a diesel car for the last five years and this is the first week in MY06 so, please, bear with me. I have noticed that when I do a daily commute to work (drive responsibly) there is a heavy detonation, if accelerating from the 3rd or even 2nd gear at around 2K RPM, I fully understand that this is a petrol and the gear probably is too high and that's why the detonation is present, but is it really the case? I just don't feel like switching to 1st gear all the time, is there something to be worried about or I should adjust my driving?

For the info, engine (EJ257) and the car is completely stock USDM with 75K miles on clock, only premium 98 octane has been poured in. Currently Castrol Magnatec 5w40 is inside which has been changed 2K miles ago, this is the other concern of my, I'm not sure the oil is appropriate (semi-syntetic?) for this engine. Did a hell of a read for the last two nights and didn't come to any plausible resolution, currently thinking about going the 5w30 route as the climate over here is quite chill at times and that's the viscosity rate suggested by Subaru and at least in my head I think that 5w30 will be more thick for engine of this milage and will lubricate/protect better than the thinner 5W40, am I wrong?

Thanks and first post for me.
 

War_Panda04

STill Plays With Toys!
welcome to the site! i probably wont be the best to answer a question like this maybe [MENTION=9]HolyCrapItsFast[/MENTION] or [MENTION=652]Grinder34[/MENTION] could assist. you should make a thread in introductions and show us some pics of the car. i also own a hawkeye MY07.
 

IGOTASTi

System Operator
Staff member
When was the spark plugs changed last?
 

HolyCrapItsFast

Drinks beer!
How are you determining knock? Are you actually hearing it or are you logging it?

Ideally you should never have any significant knock during normal driving and you should never be able to hear it. If you do then you have mechanical issues that need to be addressed and no kind of driving behavior will fix it.

Hello, I understand that this a total noob question (hence the section), but I come from a diesel car for the last five years and this is the first week in MY06 so, please, bear with me. I have noticed that when I do a daily commute to work (drive responsibly) there is a heavy detonation, if accelerating from the 3rd or even 2nd gear at around 2K RPM, I fully understand that this is a petrol and the gear probably is too high and that's why the detonation is present, but is it really the case? I just don't feel like switching to 1st gear all the time, is there something to be worried about or I should adjust my driving?

For the info, engine (EJ257) and the car is completely stock UDM with 75K miles on clock, only premium 98 octane has been poured in. Currently Castrol Magnatec 5w40 is inside which has been changed 2K miles ago, this is the other concern of my, I'm not sure the oil is appropriate (semi-syntetic?) for this engine. Did a hell of a read for the last two nights and didn't come to any plausible resolution, currently thinking about going the 5w30 route as the climate over here is quite chill at times and that's the viscosity rate suggested by Subaru and at least in my head I think that 5w30 will be more thick for engine of this milage and will lubricate/protect better than the thinner 5W40, am I wrong?

Thanks and first post for me.
 

auu

New member
welcome to the site! i probably wont be the best to answer a question like this maybe @HolyCrapItsFast or @Grinder34 could assist. you should make a thread in introductions and show us some pics of the car. i also own a hawkeye MY07.
Thank you! Haven't got around to do any proper photos of the car yet, will try to do so on the next weekend and then will introduce MY06 :)

When was the spark plugs changed last?
A very good question, I have no idea, as far as I know it hasn't been done for at least 40K miles. I would even say 50K miles and if I have 75K miles on the clock then, probably, never. Regards the service intervals there is mixed information, one say 30K miles, others 60K miles, either way I guess it should be done, but to be honest I don't think that this could be in any way related. Am I wrong?

98 octane? Where are you from? I can pull from 2500 rpm in 3rd and 4th no issues so something sounds wrong
Latvia / Baltic states / Eastern Europe, regards the gasoline 95 octane and 98 octane are the only ones we actually do have over here. Might be that in States notation is different than in EU?

How are you determining knock? Are you actually hearing it or are you logging it?
Ideally you should never have any significant knock during normal driving and you should never be able to hear it. If you do then you have mechanical issues that need to be addressed and no kind of driving behavior will fix it.
It's not really a knock and I never said it was a knock :) It's more like a detonation or even vibration sound of the whole chassis. I'm hearing/feeling it. It might be that I am a little bit paranoid at this point and accelerating from 5 miles/hour in 3rd gear isn't what this car is meant to be.

Could it be that I'm just driving a little bit too softly and I should rev my engine a little bit more or switch to the lower gear or are you guys able to accelerate smoothly in 3rd gear from the mentioned speed?

Thanks everyone for the replies! Any thoughts on the oil question? (No need to start the "oil war", I only want to hear your subjective opinion and what oil do you prefer, thanks.)
 

IGOTASTi

System Operator
Staff member
We would suggest doing some maintenance asap!!!
 

HolyCrapItsFast

Drinks beer!
Thank you! Haven't got around to do any proper photos of the car yet, will try to do so on the next weekend and then will introduce MY06 :)


A very good question, I have no idea, as far as I know it hasn't been done for at least 40K miles. I would even say 50K miles and if I have 75K miles on the clock then, probably, never. Regards the service intervals there is mixed information, one say 30K miles, others 60K miles, either way I guess it should be done, but to be honest I don't think that this could be in any way related. Am I wrong?


Latvia / Baltic states / Eastern Europe, regards the gasoline 95 octane and 98 octane are the only ones we actually do have over here. Might be that in States notation is different than in EU?


It's not really a knock and I never said it was a knock :) It's more like a detonation or even vibration sound of the whole chassis. I'm hearing/feeling it. It might be that I am a little bit paranoid at this point and accelerating from 5 miles/hour in 3rd gear isn't what this car is meant to be.

Could it be that I'm just driving a little bit too softly and I should rev my engine a little bit more or switch to the lower gear or are you guys able to accelerate smoothly in 3rd gear from the mentioned speed?

Thanks everyone for the replies! Any thoughts on the oil question? (No need to start the "oil war", I only want to hear your subjective opinion and what oil do you prefer, thanks.)

5 mile per hour is definitely to low a speed for 3rd gear. My personal shift points during normal driving are between 3000 and 4000 rmp depending on the requirements.
 

auu

New member
Some time has passed... sorry for resurrecting an old thread, but for the sake of complete info - problem turned out to be a rattle of loose downpipe heat shield.
 

IGOTASTi

System Operator
Staff member
Some time has passed... sorry for resurrecting an old thread, but for the sake of complete info - problem turned out to be a rattle of loose downpipe heat shield.
No worries.

Thanks for the update.

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