Hey guys, I went and did some 2nd to 3rd gear pulls, and I'm getting a lot of knock in 2nd gear. I know most people pull in 3rd and 4th but I don't have a lot of road around here. Anyways here are my plots... mods are only a DP and Catback on a 06 IX MR. I'm thinking 2nd gear might have something to do with all the knock???

**************Update********************

Alright, so I went ahead and filled it up with the finest of 76 gas (well not really its still 91oct LOL), and did another 2-3 gear pull. The temps were about the same as last time and I'm still getting LOTS and LOTS of knock in 2nd gear. I can also see that ~2 degrees of timing is pulled at the end of 2nd. Good news is there's not much knock in 3rd...

SOOO even if there is no detonation in 2nd, the knock sensor is still picking up knock freq. and pulling timing. This will still effect my performance yes? Is there anything else I can do other than hook up a wideband at this point? Any input would be appreciated

***********Newest Update 12-26-06****

OK, so I decided to throw in some 100oct from a local 76 pump. I had about 1/3 tank of 91oct and I mixed it with ~1.8 gal of 100oct so I was somewhere within 95-96 octane at least after mixing. Anyways, I'm happy to say that the 2nd to 3rd gear pulls were pretty much knock free which means the culprit is the crappy 91 octane gas we get. The timing was not pulled during the runs. This to me is very alarming since my car is pretty much stock AND I'm on the stock ECU tune. That means cars that run on 91 octane could be knocking like crazy especially in 2nd gear.

My IX has the first ECU version so maybe if I flashed it to the newest revision it may help with the knock... I might try that next. See the attached files for the graphs/log.

 

Wow !

Once you get that knock spike your timing plumettes.

The question is ... What is causing the knock ?

Is the new downpipe or catback hitting anywhere ?

Is it the California 91 Octane ?
If you have a gas station with 100 octane ... why not mix a few gallons
to make it to the equivilent to 93 ?

Getting a wideband and logging your a/f ratios is not a bad idea either.

 

Thanks... I have a 2.75 inch DP and it clears everything real well, I guess I'll have to go check on it. I've never heard it hit or rub anything. Yes I'm running 91oct from Chevron and I quite a few miles away from 100. I'm going to try running 76 after this tank to see if it helps. Also the temps are in the 40s-50s right now with high humidity.... I just wasn't expecting to see this much knock on a pretty much stock Evo!

 

With the 2.75 ... it's not likely that your exhaust is hitting anything.
( Still doesn't hurt to double check ).

Another thing to look out for is any small exhaust leaks.
( double check the tightness of all your exhaust bolts. )

The thing about the Evo ... ( according to the owners manual.)
Mitsubishi recommends 93 octane.

After you put some 76 in there ... Why not try a 3rd gear pull ?

 

That plummeting is when he shifts, I think. Notice how the rpm drops and the timing goes to 35 when he shifts and then goes back down again when he gets on the gas.

The timing pull happens before he shifts. He is getting about 7-9 (could not clearly tell). His car is pulling about 2-3 degrees.

 

Switch to 76 as you indicated. Get a wideband unit and read your AFR as Spec'd said. Your knock is not that bad, but you should try and fix it. I logged a stock 9 and it had 4-3-2 counts of knock from 6400 rpm to cutoff. It happens on our crappy gas.

The best way to fix this is to mix gasoline to get the desired 93 octane gas. As Spec's told you the car is supposed to run on 93 octane gas.

Also please post your Evoscan log. Just zip it and upload it to the forum. It will be helpfull if we can read the actual log.

 

Yes I think you are partially right.

1.) On the trailing edge of the big knock spike...when the big knock spike drops...The timing climbs.

2.) When shifting the timing plummettes...while simulaneously there is a smaller
knock spike.

 

Yes timing is getting pulled and that timing spike is from shifting.... Here is the worst knock portion from the log

 

Honestly ... That's a little bit to much knock for my comfort level.

I think it's mainly the wonder 91 Pisstane we get here in California.

 

bump for update

 

Well, at least you're not getting knock around peak torque! I was also getting a ton of knock around 6.5k-7k rpms on my 05. I adjust my timing map and reduced the timing in the regions where I was getting knock.

Whenever the car sees knock, it'll pull timing, which will reduce performance. That, and knock isn't good for the longevity of things like piston rings, pistons, connecting rods, and bearings.

 

bump for update

 

What update are you looking for?

Have you retarded timing yet?

 

I updated my first post in the thread...

 

I don't see how that will solve your problem.
You have knock because of 91 octane. Retard timing.