Could carbon build up be causing knock?

[Road-Rocket]

I just installed dsmlink about a month ago. I logged a run for the first time with 15psi and got about 9 counts of knock at about 5500rpms. Lowered boost to 13psi, got 6 counts of knock at same rpm range. Lowered to 10psi and still got knock above 5krpms, 5 counts. I added fuel where I was getting knock and same thing. Of course, my timing is being pulled and my car is running like shit. The administrator at the dsmlink forums looked at the log and everything like a/f ratio and fuel trims were correct. He suggested that there might be a lot of carbon build up on the pistons. How can I check to see if there is any? And how can I fix it, or how much do you think a shop would charge to clean them if indeed there is carbon build up? Mods are in profile.

I do have a boost leak somewhere in there. I get full boost on my evo3 at about 3800, so I know I need to get that leak fixed. Could this also be causing my knock problem?

I will be getting the car back to stock status in a couple of months, sell all the aftermarket parts, sell the car, pay off my debts, save enough money for a 2g manual gsx (current one is gst auto), get a built 2.4 strocker engine, and work my way to a 400whp goal. But before I start putting the car back to stock condition, I wanted to see if I could get the car to run decently and enjoy it while I can.

Any suggestions on how to get this fixed, will be greatly appreciated. Thanks.

Miguel

 

[ECLIPSE4x4]

Yes it can cause knock by pre ignition.

Here is how to take care of it "IF" you have carbon crowns.

http://www.vfaq.com/mods/MCCC.html

 

[Road-Rocket]

Thanks for the info. I'll give that a try.

 

[Bohrn]

I speak from first hand experience when I say YES!

MCCC won't always get rid of it completely as it's not just on the piston tops but on the valves, the head etc.

Do a complete MCCC, let it sit overnite.

Then in the morning, disconnect your MAF(electrically) and take off your intercooler hose at the throttle body elbow.

Start the car and then mist a couple of liters of water thru the throttle. This takes time but will clean out the carbon very well. get a plant mister or better a pump up sprayer so you can just spray. Set it to a nice fine mist.

It will set a cel due to the maf being unplugged, but you can clear it afterwards.

We do this all the time at work for emissions failures etc. The water actually does more than the cleaner. it hits the hot carbon deposits and makes em flake off. Out the pipe they go.

Also, unless you fix your rich condition it will come back.

I find that water injection takes care of this as it steam cleans the cylinders every time it comes on.

 

[Road-Rocket]

Thanks for all the info. Is this something any shop should be able to perform? My schedule at work in the next couple of weeks won't allow me to take the time to give this a shot and try to fix the problem. Also, I've been working on my car fixing things here and there quite often in the last couple of months and honestly, I'm kind of sick and tired of running with my tools up and down the stairs (I live in an apartment) and having to clean up afterwards. If this is something a shop would be able to do, I'd rather pay to get it done unless it's ridiculously expensive. Any idea on average how much a shop would charge for something like this? If it's too much, then I'll just find the time to do it my self sometime by the end of this month. Thanks again for your help.

Miguel

 

[Bohrn]

yea I getcha on the time and pain in the ass part.

If you have a shop that you can for sure trust and that you have a good relationship with, yes they can for sure do it. Should really only run you an hour, maybe 1.5. You will have to let it sit there overnite.

If its a well equipped shop they can use thier fuel injection flush machine for the water mist part. we just put water in the canister and put a nozzle on the output end. then place the nozzle in the throttle body. Pressure it up and leave it till the thing runs out of water.

It has to be a trusted shop and one that is not under too much time pressure. If not, they could just say they did it or do a poor job and skip alot of steps and you would never know, unless you pulled your head. They could just say that you have other problems and thats what the knock issue is. It could very well be as well, but this is something to do first.