Here is a question for all the gurus and experts. My car has had several different people try their skill at tuning it. Starting with the stock ECU and a custom reflash to the AEM EMS with major mods. In all cases, the engine just does not take timing advance very well. It is very prone to knocking so I can not run the advanced timing required for higher power output.

My question is what can be the cause for this situation? Is there some obvious thing that everyone has overlooked so far? I'm thinkng there must be something out of adjustment or out of spec that is causing to engine knock when the timing is advanced.

So far all I've heard is "I don't know why" or "some EVOs are like that". The first answer is OK, but the ignorance could be cured and in my case, should be cured. The second answer is a cop-out.... There has to be a cause for this. Perhaps the cam timing, perhaps some anomaly in the head or valves, or something else entirely.

I know that some of the experts in these forums have had a lot of experience with these engines. I'm sure enough of these engines have been torn down and re-built as well. I wonder if somebody has run into these kinds of problems and has found answers or solutions. Please share them with me and other ppl in the forums. I'm sure this problem is not unique, and it sure would be nice to solve it.

Thanks

 

I would only guess that either your knock sensor is bad or is hearing something that isn't knock... Last answer would be combustion chamber... if it has any nasty peaks in it anywhere which would cause knock...

bryan

 

I remember somebody that had a cam gear that was one tooth off from the factory which was causing it to knock.

Try checking that

 

Piston/Combustion chamber!

 

yep, I'd pull the head and have a look. usually this is a sign of something melted at least a little bit...

 

How loud is your tranny/drivetrain? That can interfere with the knock sensor and pull timing.

 

Post your timing map!!!

Some cars just don't like timing and it some times has nothing to do with knock sensor just a hardware issues or your not getting the gas you think you are. I see it all the time in NYC.

 

Can't really say anything until we see what sort of timing you are trying to run.

Also, are you certain that the EMS is set up correctly? You can have set-up issues regarding the cam/crank position sensors that will show low timing advance in your datalogs, and in your maps, but the actual timing advance at the engine will be sky high.

 

That is not good Glad I'm a xede user just pull timing when ping

 

AEM has been beta testing their hardware, firmware and software on end users for years, unfortunately.

The EMS is a standalone, and has to be set up correctly for it to work properly. The flexibility of such a system is amazing, though, compared to a piggyback. So some of the ease of use has to be given up for flexibility. You can't get something for nothing.

 

Lets face facts the only reason stand alones make more power is because they do not have the stock ECU pulling timing based on the knock sensor. by the by

 

Not true. The AEM EMS definitely pulls timing based on knock or knock prediction based on sensor voltage. Actually, I think ShapeGSX has some very good points. I suspect this might be a very likely cause of the problem. I also thought that something in the head or pistons might be glowing and causing detonation, but I guess there is no way to tell without pulling the head off the car and inspecting it carefully.
So far I hear some interesting theories, has anybody actually experienced these phenomena and found an answer and solution for it? If so, please post to this thread. I would like to find a shop that's got the expertise motivation to find and correct the problem or situation.

 

Actually, that was me. Back in Feb or March, George at Boost Solutions told me that my car was one tooth off the cam timing from the factory and he corrected it and the car now loved timing.... I guess something happened because within days, George found himself unable to deal with the same problem when he tried to tune my car...... Wasn't this the case George? Anyway, the whole cam timing issue is my mind still undecided and controversial. I wish I could get this and other issues finally put to rest. Too bad I cannot do it myself

 

Well, there is a lot more flexibility in a standalone. You could just put the knock sensor on the firewall if you wanted to duplicate a knock-senor-less setup with the stock ECU.

I think that the knock sensor is useful, though, and I don't feel it has held me back at all.

Even the EMS can utilize a knock sensor to change timing or fuel or boost on the fly. That is a good idea on the street, when your fuel is a big unknown.

 

This is a good question. I'm wondering about this possibility as well.... There is something to remember though, way back last year, big Al came to Atlanta and he ran into the same problem when he tried to custom tune a Dynoflash in my car. IIRC, he said his knock sensor (Link knock sensor) was definitely seeing knock just like the stock knock sensor.... BTW, I still have that reflashed ECU in my closet, heck, I might end up putting back in the car one of these days.