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knock retard

M

mx3matt

New member
so I just picked up a 2002 gtp and finally got a scanner on it and went for a spin, on the highway at wot i'd start out at 1.6*kr then if I kept my foot in it over 120km/h I noticed it slowly rise up to 7.5* and that worries the **** out of me. saw three different momentary spikes of 12*-13.7* at its worst.

guy that owned it before me did some hack mods, was running no mufflers( currently still no muffs) and a gutted airbox. so i'm in the process of rebuilding a decent exhaust. on Friday i'll be running 2.5 from the ubend delete back and zzp 3inch dp.

currently only thing I've done is install 0 gauge power wire upgrade, short ram 45degree with a 9 inch aem dryflow.


any ideas where I can start looking? really can't afford a motor right now lol.
 


These engines had some KR from the factory. Make sure you run at least 91 octane through it (I preferred 93), check the state of the spark plugs and fuel filter, and see how it goes from there.
 
Swap the open cone air filter back to the stocker, that'll drop some KR until you have better flowing exhaust to get all that extra air back out.

Removing that U-bend will definitely help it breathe a little better.

I, along with quite a few other people, would recommend getting a set of headers, or a PLOG and downpipe combo. It's the cheapest/easiest way to drop off a lot of KR.

Of course, make sure your plugs are in good shape.
 
Intake won't matter, the car can't suck anymore air in than it could with a regular intake. You are just allowing it easier access to the air. The size of the pulley never changed so it can't use more air.
 
on a ramp accelerating it doesnt hit more the .7kr until i'm up over 4500 then it hit 5kr and peaks out at 13.7kr at just over 5000rpm. i throttle off at that point to try not to hurt anything. i've only used premium and the last couple tanks have been ultra94. i've got a appt at the exhaust shop on friday morning for a 2.5 catback with 40 series muffs and ubend delete.

i've got a po420 code so i'm starting to wonder if maybe my cats clogged and causing a jump in kr...... the guy selling me the zzp downpipe isnt responding anymore so i'll be holding off temporarily on the dp.
 
the suggestion about the air filter is correct. if not doing a cold air, you are allowing more heat to enter the engine. hot air only gets exponentially hotter when going thru the SC. stock air box will pull cooler air.

I also agree headers are a better option then buying a DP now and then later wanting a PLOG and then be out the same amount of money as a set of speed daddy's. just invest now and have no regrets later.

KR of 7* is normal on a stock motor. if you are worried swap to 605 plugs, do fuel filter, and injector flush, headers, and your current plan for exhaust. a good coolant flush will help pull heat out of the engine too.
 


Same issue happen to me one time ago before on my stock motor chamge the plugs along with wires how are your dogbones? Motor mounts? willing to bet that It could giving you false knock.. and have you given the car a oil change since you have had it ?

Sent from my SAMSUNG-SGH-I747 using Tapatalk
 
as far as I know its the stock pulley. oil changed twice since I owned it(1800km's) with royal purple 5w30, as for the dogbones the passenger side dogbone looks like its a little bit crooked and i'll be flipping the rubbers tonight to stiff it up a bit.
spark plugs i'm going to be changing in the next week or so and will be going one step colder wires look to be in good shape. it looks to have been a bit abused by the previous owner so i'm just catching up on maintainance.

Friday morning i'll be flushing the rad out as its got some decent sludge buildup as well as doing a transmission flush then its off to the exhaust shop for some much needed upgraded piping. my zzp downpipe fell thru so for now i'll be having the delete the ubend and then figure out what i'm doing in regards to headers. I also have been discussing many of my options with will at overkill as to how far I should really go with as this car was purchased with the strong intentions of being a daily driver. my mx3 is supposed to be the track mule lol.
 
Just order speed daddy headers for your first mod and worry about mufflers later. Stock Rez back is fine. Something like 300 whp I read on here
 
i will be ordering header, but i'm running open pipes and need some mufflers, been pulled over twice the only thing that saved tickets was that all the exhaust is sitting in the back and i tell the cop it fell off and i'll be heading to the exhaust shop in the morning lol.
 


Z34Phoenix said:
the suggestion about the air filter is correct. if not doing a cold air, you are allowing more heat to enter the engine. hot air only gets exponentially hotter when going thru the SC. stock air box will pull cooler air.
Click to expand...

Completely false.. Dyno runs have proven that an open cone intake will make more power (at least no less) then a cold air intake system, which shows the air does not get exponentially hotter.
 
Iceman6669 said:
Completely false.. Dyno runs have proven that an open cone intake will make more power (at least no less) then a cold air intake system, which shows the air does not get exponentially hotter.
Click to expand...

They weren't talking about making power with a different intake. KR alone should be tested really
 
I understand what he was talking about... But if the air is exponentially hotter as he claimed the Dyno car would have seen more knock.
 
He should have gotten rid of the exponentially really lol. I'd say if the IAT with a cold air intake like the stock setup was 80° on a 75° day, instead of 110° on the same day (HAI), that 30° difference of temperature should be pretty close to the same difference past the supercharger. (maybe with a 15% increase) So it's the same reason you get a lot more power in the winter than the summer. Just not quite as large of a difference, but still there. I don't know how accurate a dyno test is vs on the highway with airflow involved, but we know a large difference in temp makes a decent difference. A small difference in air temp should make a tiny difference.
 


As far as power is concerned, a big ass air filter that isn't a restriction is what's needed. Be it a "cold air intake" or just slapped on the TB.

As far as KR is concerned, read this little story.

Bought my car bone stock, except for a K&N drop in filter in the stock airbox. Had 3-4* of knock at the top of 1st, and had 2-4* throughout 2nd at WOT.

Put my 9" filter on, connected with about a foot of tubing (a hot air intake if you will) and did a run. Butt dyno said it was better, and you could hear the blower whine more loudly.
Scanner said otherwise. 1st was now peaking around 7* and 2nd had a constant 4-5* through the rpms. Switched back to the stock airbox with the K&N drop in, and was back to 2-4* of knock.

Installed headers, no more knock. Put my 9" filter/intake back on, and would see a blip from time to time, but wasn't enough to worry about, so it stayed on.

Reasoning behind the knock?? Unsure. Possibly more heatsoak of the incoming air, possibly the stock airbox/ducting is restrictive enough to choke the S/C some? All I know is real world results said it gave me more knock.
 
mx3matt said:
as far as I know its the stock pulley. oil changed twice since I owned it(1800km's) with royal purple 5w30, as for the dogbones the passenger side dogbone looks like its a little bit crooked and i'll be flipping the rubbers tonight to stiff it up a bit.
spark plugs i'm going to be changing in the next week or so and will be going one step colder wires look to be in good shape. it looks to have been a bit abused by the previous owner so i'm just catching up on maintainance.

Friday morning i'll be flushing the rad out as its got some decent sludge buildup as well as doing a transmission flush then its off to the exhaust shop for some much needed upgraded piping. my zzp downpipe fell thru so for now i'll be having the delete the ubend and then figure out what i'm doing in regards to headers. I also have been discussing many of my options with will at overkill as to how far I should really go with as this car was purchased with the strong intentions of being a daily driver. my mx3 is supposed to be the track mule lol.
Click to expand...

I highlighted a few things and I'll go in order for you.

1: If you are running the stock pulley (3.8"), there is no need for a colder plug. Replace the plugs with AL606 Copper Core Plugs. These L67 motors like the copper plugs, but are only good for 15k~ miles.

2: Giving a coolant flush is a good idea. Don't forget to also flush out the LIM as well. Just stick a hose in the Rad/LIM and let clean water push out the gunk.

3: Do not do a transmission flush. I'll repeat myself... DONT FLUSH THE TRANSMISSION. If it has not been regularly done, you'll kill your transmission by doing this. (Ask me how I know). Just drop the Pan, replace the filter, and refill with 7~ quarts of trans fluid, or however much it needs.

4: Pay the money and get headers. It will kill a lot of KR. Speed Daddy Headers are the cheapest and they work just fine. You can find those on eBay. Also, browse forums for used headers for cheap.

My own two cents here: Intake shouldn't matter at all. Just make your own with a filter and PVC piping. (Look at my signature). Replace the fuel filter/plugs/wires.
 
02NavyBlue said:
He should have gotten rid of the exponentially really lol. I'd say if the IAT with a cold air intake like the stock setup was 80° on a 75° day, instead of 110° on the same day (HAI), that 30° difference of temperature should be pretty close to the same difference past the supercharger. (maybe with a 15% increase) So it's the same reason you get a lot more power in the winter than the summer. Just not quite as large of a difference, but still there. I don't know how accurate a dyno test is vs on the highway with airflow involved, but we know a large difference in temp makes a decent difference. A small difference in air temp should make a tiny difference.
Click to expand...

Well my IATs with my open cone are almost ambient once I get over like 10 mph.
 
02NavyBlue said:
He should have gotten rid of the exponentially really lol. I'd say if the IAT with a cold air intake like the stock setup was 80° on a 75° day, instead of 110° on the same day (HAI), that 30° difference of temperature should be pretty close to the same difference past the supercharger. (maybe with a 15% increase) So it's the same reason you get a lot more power in the winter than the summer. Just not quite as large of a difference, but still there. I don't know how accurate a dyno test is vs on the highway with airflow involved, but we know a large difference in temp makes a decent difference. A small difference in air temp should make a tiny difference.
Click to expand...
Temps past the sc can be over 300* from what i hear.
 
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