CPA5

iTrader: (1)

My recommendation for everyone running the AP is to leave the AP in the car set to the Knock Count live data feed.....I use this every day when driving and always view it when in WOT or 1/2 - 3/4 throttle as well.

Generally I see no knocks at all during WOT....maybe a 1 count......only during part or 3/4 throttle do I every see 3-4counts.......regardless of weather (cold)....I use the same fuel religiously so there is no difference there...except now our AZ fuel is even more garbage for the winter.

Maybe this fuel cut/bog issue is the car knocking past a 4 count.....I was told anything at around 5-7, especially in higher rpm is lethal

anyways just my cheap-O $0.02

mrfred

iTrader: (50)

Stock tune with stock motor will have knock sums up to 10 on a regular basis. A knocksum of 25 won't hurt the motor if its an isolated or infrequent occurence. There's not much point in letting the car reach more than 3 knock counts though because the ECU starts pulling lots of timing which pretty much kills off power.

Boost cut is a feature built into the ROM code that will cause fuel cut anytime the load exceeds a user specified load for a user specified number of seconds. Here is the table with the stock values as viewed in ECUFlash.

CPA5

iTrader: (1)

mrfred--

your knowledge of this stuff is waaaayyyy beyond anything I know....I don't understand that chart unfortunately.

But...so what you're saying is that the fuel cut issue, in this instance has nothing to do with 7600 rpm but it can happen anytime. Like maybe the boost hits higher than expected and there isn't enough fuel to account for it at that moment....so then the WALL hits.

Am I understanding that right?

Lets say this happens....I would imagine this is really bad and can cause damage either instantly or over time?


SO far I have not had this happen running the AP stage 2 91oct map...but today in third gear at around 2800rpm I pulled to about 4000rpm (3rd gear) and my boost gauge lit up for my warning point and the peak hit 23.3/4psi.....WELL ABOVE THE 21.5psi THIS MAP CALLS FOR

mrfred

iTrader: (50)

The table shows rpm in the left column and max permissible load in the right column. If the engine load exceeds the value in the right column for more than a specified amount of time, then the ECU will cut fuel just like what happens at the rev limit. Hitting the load limit is no worse for the motor than bouncing off the rev limit if the tune is good in that operating range.

My point was that if the ECU is hitting this load limit, then the engine is obviously running out of the intended operating range where the tuners may or may not have done any testing. Anytime that happens, its wise to check the knock sum to make sure that no damage is being done.

CPA5

iTrader: (1)

mrfred---1st off thanks for taking your time to answer these ???

okay...so from you just stated...the example of "maybe" this is going bad...downhill would be:

(example) 5000rpm, spike of boost higher than map intends...say 23psi...more load at that moment than can be handled...fuel cut...and we notice say a knock of 3-5

I gather that the above situation would be okay if say there was no knock at all at that moment vs. a knock of 4 or above......once again I was told that registered knocks of 1-4 are relatively "normal" or okay and anything above that point 5-6 is time for concern and 7 is blow up time.

THis was how the knock count feature of the AP was explained to me....I assumed there was only one way to read this knock sum thing...so to hear you say knock counts of 10.....from how it was explained to me....the engine would be a gonner

mrfred

iTrader: (50)

A knock sum of 10 is definitely not an engine killer. The mail-in tune that I purchased from a very well known vendor was causing occasional knock sums of 20-25, and my motor is still working perfectly. I'm no longer using that tune though because the motor was never intended to run with those kinds of knock sums.

The bottom line for safety in a tune is the knock sum. No one knows for sure what knock sum is needed to be in danger of causing engine damage, but its easy to see from the ROM code what the Mitsubishi engineers thought was acceptable. Its clear from that ROM code that a knock sum of 1-3 perfectly acceptable under any conditions. A knock sum of 4-6 is fine too (but is handled a little differently than 1-3). The engineers did not want the knock sum to go higher than 7 for any length of time though, and there is an extra algorithm to help prevent this from happening.

So, if the knock sum is 6 or below when you hit 23 psi, no problem at all. If its 6-10, then still no problem as far as engine safety goes, but its a sub-optimal tune. If you're seeing > 10, then who knows whether there is a possibility for damage, and the best I can say is that I'd suggest staying off full boost until the tune can be fixed up.

TheEvolutioner

iTrader: (12)

Thanks guys, I'm understanding this more and more. Today my friend was driving my car and he got the CEL again for the overboost condition. Of course i did not have the AP connected so I am not sure what the knock count was but after i cleared the code I took it for a spin. While viewing the knock screen I notice maybe 1 knock out of my entire run. The code did not come back.

My dumb a** keeps forgetting to view the knock sum at WOT, . I just get so excited

CPA5

iTrader: (1)

I generally don't see anything past a 1 maybe a 2 knock sum at WOT regardless of rpm.....it is at 3/4 or 1/2 throttle in 3rd-5th gear from around 2800 - 4500rpm where i see registered 4 counts.

I have talked to Christian about this already....basically there was no need for concern on that issue. The way I understood it was that if at WOT in higher rpms the sum was greater than a 4 then we would need to figure something out.

BUT....I also have not had this FUEL CUT/BOG/CODE issue either.....My main concern Jason would be what if your car is hitting higher sums of knock when the WALL hits. That I would think would not be good. and now you've had this happen a number of times....just be careful....I would just tone everything down until you have Christian on the phone or something.

Other than your code problem though it seems that you and I are hitting well above the boost targets that the maps are set for. Yesterday I hit 23.3/4 psi in third gear at around 3500rpm....I didn't look for knocks....so I can't say I had any....Most times when I look at WOT the car has been fine....but the main concern for me is the boost is rising and not leveling off at the 21.5psi the stage1 91oct map calls for.

TheEvolutioner

iTrader: (12)

I've been on the Cobbforum and Christian is actually on vacation. He should be back soon. I rearly push the car, some people say I'm a ***** for never opening her up , but whatever, when your paying 600+ per month you want to be careful. I can not afford things to break.

My boost peaks around 22 just fine then tapers down to 20.5, I have never notice it go past 22.

CPA5

iTrader: (1)

I guess I misunderstood I thought you had some boost spikes above intended levels...oops

you sound like me then also...I don't go WOT a whole lot either....maybe 1 time a day....and I only drive the car 3days a week......I'm like if a grandpa owned an evo....which is funny cause where I live I've seen an old A%* man easily 65 with his crusty wife in the recaro looking like she's pissed he's still alive cruising an silver MR IX

anyways I can't wait for these guys to get back to find out what we should do.

hang in there East Coast Friend!!

CPA5

iTrader: (1)

for bump

Christian.

I have been at PRI taking classes. I am back and will be able to assist you. Those boost targets are correct for 93 octane, is that the fuel you are running? What intake system are you running on the car?

Christian.

CPA5

iTrader: (1)

He is using the COBB (aka your intake )

Christian, why do you think he is getting the Fuel Cut/COde problem recently?

also...PRI classes...don't you get vacation....they got you working your fingers to the bone

denny424

iTrader: (2)

Get some GSC s1 cams to maximize your pro tune cpa

TheEvolutioner

iTrader: (12)

Christian, CPA5 is correct, I am running the Cobb intake including the Cobb TBE with test pipe and a megan O2 housing and that is it. Boost has been on target for me. I havent notice any dramatic spike even when the hesitation occurs and the CEL comes on (overboost condition). I havent had the time nor space to really open her up to log it. New York traffic sucks. But i've seen maybe 2 knocks the most.