Hi guys,

A few weeks ago there was a topic up here about "Anyone blew up with their EMS?"

The topic was actually pretty good even with the fighting a lot of important things were in there if you read it.

One of the subjects were on knock control and everyone's theories of if it works, if it will save you etc.

A bunch of people seem to think it is useless to use it. I didn't agree with it but left the subject alone after speaking my peace on it.

Well I am hear to speak about it again after a tune I did left here heading for disaster.

Car left here last week that all we did was install parts on. Parts from everywhere. Big turbo, injectors, AEM EMS, exhaust etc. I tuned the car with both pump gas (94) and race gas. The boost controller on the car did not work, I found this out the hard way trying to tune the car and seeing the boost going WAY to high on the datalogs. The car didn't have and still doesn't have a boost gauge in it. (As I said, parts from everywhere, no real guidance given though, just vendors making money)
Anyway, before I start a tune I work on idle and such and set up all the timing, fuel and knock control, before it ever hits the road. I also believe in tuning with the knock control turned on, stupid not to. Yes, it can make corrections to what you think you are adjusting but if you log it you can see if it is doing it, so there is no reason not to use it.
Again, anyway, these WAY to high boost numbers were well into the 30 psi range, this was on 94 octane! NO damage was done from this. After fighting the electronic boost controller that was in the car I came to the shop and installed one of our manual controllers. Instantly the problem was fixed, the pump gas and race gas tunes were finished and the customer was called. He didn't want our controller or a boost gauge and he was warned that running the 28+ psi boost that his electronic controller was giving him would blow the engine. It left and hit those boost levels a few more times, by this time I am sure it had seen in excess of 28 psi over a dozen times.

Week later, car comes back to be have the idle looked at and to have the Japanese instructions read to us on how to hook up the boost controller/wastegate. Customer and myself go out on the road and first hit on the new proper installation netted us 32 psi of boost (still on 94 octane). Customer re-adjusts the electronic controller and we hit it again, 32 psi. He gets out and looks under the hood, says we have the boost lines backwards and reverses them, try it again 31 psi of boost. Now all of these, since he has no boost gauge, I am running to 7500 rpm, so it is in boost a long time. After a few more failed attempts at getting it to work we put in another manufactures manual boost controller, bam, another 32 psi boost hit. Then a re-adjustment and 28 psi, lowest it would go was 27 psi. I am fed up at this point and return to the shop to get one of our controllers. Put it in, first hit is 23 psi, turn it down 16 psi, one more adjustment and it is dead steady 20 psi through all 4 gears.

Moral of the story. 32 psi of boost will blow melt the engine in an EVO down in seconds on 94 octane. IF the maps are set up correctly and the knock control is also set up correctly I say it is just about impossible to blow one up. Here is proof of 20+ pulls done up to 7500 rpm (1st gear) at over 30 psi of boost and NO damage done at all to the car.

I say bull**** to anyone that tells me the knock control won't save an engine.

David Buschur
www.buschurracing.com

 

Very nice! I'm glad his motor didn't get cooked too!!

This is a great write up and I would hope any logical person can see your side of the story.. I hope.

 

David,

Are you using knock control to only retard timing or are you using it to control additional fuel as well? I'm just wondering if the car ran out of fuel as well with such high boost levels (not knowing what pump and injectors he has).

 

I concur with the godfather 100% as usual

 

i must say well put.. people only hear what they want to hear.

i think the ems is great im learning how to tune my self with a little help from the guys at AEM

 

I am right there with you, you would be crazy and asking for trouble not to use it. If you don't use it then don't get pissed off because you tore somthing up and didn't use all the resources possible to do it the right way the first time. I use it everyday and I enjoy the security.

 

well said..I will be ordering one.

 

I use timing and fuel for controlling knock when it happens.

David Buschur
www.buschurracing.com

 

This happened to me. The tuner never setup the knock control and first time taking it out it shattered 1 piston and cracked another in half. The problem was i knew how to the the AEM but still thought it would be a good idea to get it on the dyno and have the "certified guys" do it for me. Long story short after rebuilding the engine from the ground up i feel it is pretty much bullet proof now yet i still run knock control just for added security. Anybody that says it doesnt work has no clue about tuning and what knock will do to your engine. I guess people have to learn the heard way!

Chris

 

I have an evo and I took the exhaust off for the night and on the way down the road the engine detonated and cracked the #3 piston and shattered the spark plug (no boost was even applied). Is this a tuning issue or is the lack of pressure in the exhaust that important to the aem???? Want to know for next time...thanks!

 

You should heed this advice people!!!!

I have helped tune several evo's from 290HP to over 500HP and endless your on a dyno under very strick conditions you should always use the knock controll. If your car is tunes in say 70 degree weather and you punch it on a 85 or 90 degree day you might get some knock and save your engine.

 

The exhaust didn't blow up the car, the tune did from the sounds of things.

Had a car on the dyno last week. Dialed in at 26-27 psi of boost on alcohol and 93 octane. Using the knock control, of course. The first two pulls I made on the car the 2nd day it was on the dyno the alky never came on. The car made two full pulls at 26-27 psi on straight 93, no damage was done, knock control saved it.

David Buschur
www.buschurracing.com

 

I completely agree with you. My friend hit 38 or 39 psi on 91 octane **** gas because his manual boost controller came apart and his engine stayed in one piece. Knock control is good stuff. You obviously tune so it doesn't kick in, but it is for the just in case.

As far as the AVCR that you were trying to use (I am assuming it was an AVCR by the sound of it), it was most likely not connected properly. It is very complicated to hook up and I have to say manuals are more stable at high boost anyway. I will probably be selling mine (AVCR), as my Hallman is working very well even at high boost levels. The AVCRs are tricky to hook up and you need to use a compressor nipple for them to function correctly (meaning do not use the manifold or the blow off valve line like you might on a manual).

 

What Knock Voltage Is Too High

 

Every car is different. You run your car under ideal conditions (low boost and timing) without knock control on and see how the voltage reads to see what your engine's normal noise looks like at any given rpm. This is how you know what is too high. Just go like .3-.5 volts above your "normal" noise everywhere and set that as your threshold. If it varies too much then adjust your threshold appropriately. You will know what real knock looks like because it will be like 1 volt or even more higher than everything else and it will be multiple spikes or a thick line. Just one single thin line as a spike usually isn't real knock. Of course then after you set your calibration turn on knock control and start turning up boost and timing. If your engine pulls timing and you notice what looks like real knock back off in that area of your rpm band.