Hello Everyone,

Happy new year's eve to all!


I have my personal evo x with an fp green. I had a stock engine and everything was fine. Recently I switched to a 2.2L setup, about 10:1 CR on 93 oct (98 RON)

While tuning the car I found it was VERY know prone, IE had to decrease timing
At 4000RPM 23psi boot to 4*, before it was at 4000RPM 29psi 11*!
At 7000RPM 22psi had to go from 16* to 7*!

The car is very knock prone and I have no idea why.
The car has s2 cams

Your help is much appreciated

 

well honestly I am not sure why you did 10:1 compression on pump gas, that was a no no. My tuner was hesitant to bump compression on E85 even.

I am guessing you are seeing a lot more knock because of the compression. Throw in some race gas and I bet it goes away

Not trying to sound like a jerk, sorry if I am, but that would be my first guess as to why.

 

new years eve were the hell are you??

but 93 oct with that compression probley isnt going to cut it. also are you using a knock box or something similar to help with knock or are you relying strictly on your factory knock sensor there known to fail ..


edit: maybe try a thicker headgasket as a cheap alternative to lower the compression a bit hard to say anything without knowing your full setup

 

There have been a lot of discussions on phantom knock issues. The compression isnt the problem---too many other strokers out there running 10:1 without a problem. If you were trying to run 89/91 I could see it to a degree.. The earlier post had a good idea, run some race gas to see if the knock goes away, guesssing it won't, but will lead you to look for something else... search this sight for more, i know I have read a few postings on this in the past--but since its something I haven't had to deal with I dont have a link to post--

 

The Evo X knock algorithm is different from the 8/9's and its a lot more sensitive and harder to tune. My tuner had all sorts of problems with the knock system on my X vs. other 8/9's he has done.

Also you are referring to 8/9's with higher compression being fine. That doesn't apply to the X at all really as its a totally different motor. Higher compression is almost untested at this point on pump gas on the X's so I would still say that its a strong possibility its the problem.

But like I said, throw some 110 octane or race gas in there and see if it changes anything. If not you will have to adjust your knock sensitivity tables.

I actually had problems on my 2.2L and had to replace my knock sensor because I was getting codes from it. Random knock counts seemed to go away too because of the change so maybe start there too.

 

^^ this!

 

r u losing fuel pressure

 

I have a very similar motor...2.2L, 10.1(Je Assym), S2, Cosy springs, etc

Send me you map and I can help you get started on a proper timing curve. There are a few things you can do to help this. First, make sure you properly torqued the knock sensor. If it is over torqued, it can cause false knock issues.

Running a fuel, non leaded, that is at or above 100Oct would be an easy way to see where your timing curve should start. You could find where MBT is and see if the sensor is freaking out. This is not the only way though, as you should be able to run 93OCT on moderate boost. Keep in mind, the change in displacement and compression will allow you to run less boost and achieve similar power goals.

Hope I can help, feel free to send the map to my email.... john@akumamotorsports.com

Regards,

John

 

Thank you everyone, I see some interesting points, most of which occurred to my mind but ruled them out for reason or another:

1- High CR causing knock: I would agree if knock was occurring at high rpms only, but why would it knock at 4000rpm? S2 cams are very aggressive and even with a lot of overlap the car keeps knocking.

2- Knock sensors: that was my 1st thought, but if that was the case shouldn't the car keep knocking irrelevantly of the timing? when I lowered the timing about 7-8* across the car wasn't knocking anymore.

3- Losing fuel pressure: as long as the afr is right, I don't see why I should worry about that.

AkumaMotorsport: Thank you for the offer, I will send you my 2.0L map which I used to run with no knock at all, and the 2.2L map along with evoscan 3rd gear pull logs. Afr doesn't show on the logs, but it's 11.2-11.3 across (I read it on the afr gauge)

I currently have two things that I suspect to be the problem and will check them on Tuesday;

1- Fuel pump relay: I'm still on the factory one (1st generation), and if it's cutting and engaging very fast it's very possible that it won't show on the afr gauge.
2- One of the fuel injectors (DW 1100cc) is not flowing properly which is causing one of the cylinders to run lean.

 

in Belgium you should have a Shell V-power , or something higher oct. then 98oct . In Hungary and Germany the V-power is a 100oct(ron) Also we have special cases to get even higher oct gas at gas stations.
I would only run those if i were you, specially with a have a build engine.

I hope you will solve your problem soon.

 

I had the same issue with a 2.2 on 93 (98 here in Australia) , mine is 9.5CR
for less boost and same AFRs as with my stock 2.0 , i could only run 4-5* at 4000-4500 where i used to run ~10*. any more and it will knock. Same at about 6000, lots of knock even at 20psi and timing of 9-10* where i used to run 14-15* on the 2litre

I know i will need to modify knock tables but you need a knock box etc to do it safely. it shouldn't be detonating at those levels i don't think.

So, you are not alone!
My plan is - dyno time, knock box/det cans, and tune the knock tables accordingly. the built motor is obviously more "noisy" than stock, we just need to figure out where.

 

I will keep a look out for the map. Remember guys, we use RON/MON so 98 RON is closer to 93 USA Octane rating.

John

 

yep i think our 98 is like 92.5 in your scale. And that's our super expensive stuff!
Our cheap pisstane is 87 for you guys from memory

 

yes something like that in Europe too.

98 = 93
95 = 89
93 =87

Also the V power and some "higher end " fuel is actually a 100 or higher in my country.
Not like the V-power 93 in USA, if i am right.

 

our cheap fuel is 91RON. Yikes so maybe 85MON!!

We used to have V Power Racing = 100RON (94MON?) - but it was taken off the market a few years ago.
Our normal V Power is 98RON = 92.5/93MON