I was just wondering, does anybody else get way more knock in the lower gears (1,2) then the higher gears (3,4,5) I did some pulls in every gear, and i picked up counts as high as 7-8 in 1st and 2nd but 3rd 4th and 5th i didnt see anything higher then 2-3. Does this happen to anybody else, im not sure why, my IDC seem to be higher in 1st and 2nd too yet for some reason, 1st and 2nd gear dont hit load% as high as the top gears do.

 

Do you have too much timing / too lean fuel at lower loads?

 

well my timing and fuel tables are stock. So this isnt something that happens to other people, im getting my wideband next week so ill check out my AFR. I know i live in the 91 pistane state, but the thing thats killing me is that i might have to retard timing further then stock. My car already feels super slow as it is, cause im use to the power (had a thred about that).

 

Don't tune in first and second gear. Your going to get false knock in those gears. Sometimes it has to do with the engine sweeping through the RPM's too fast (just stab the gas in neutral sometimes you can get knock this way). Sometimes it has to do with the engine/tranny torquing and slamming against metal ****. Third and 4th are good gears to tune in. If you roadrace run out 5th to ensure you don't have any knock and/or leaning out issues in that gear as well.

 

thats exactly what i was assuming, since 1st and 2nd seem to be the most ferocious felt pulls, i would think there would be some sort of added possibility of knock due to the engine leaning back further then it would based on the acceleration.

It sucks i wish there was a sure way to figure out whats real knock and what isnt. Besides setting up the maps and having to fill 100 octane to cancel out the possibility of un real knock every time.

 

While I do think that vibration causing false knock is certainly possible, my opinion is that you contact higher load cells in lower gears punching the throttle than higher gears that have slower spoolup. I believe the problem is ignition timing and/or over run load ranges on the map during these occurances.

 

I typically see lower load columns in lower gears, which make the car run more timing and leaner AFRs depending on the tune.

 

Depends on how the car is set up and also depends on what type of intake filter is influencing the karman signal of the MAF.

With the stock turbo's taper, to get it to hold 20psi @ 7000rpms, many tuners use boost spikes all the way to 25-26psi on pump. EVO IX responds better to this type of tune than the Evo VIII.

With the boost spike you EASILY can see the KPA load jump down low and move lower in the load colums in the higher rpms with boost dropoff.

I agree that you will see lower BOOST in lower gears and lower physical load on the motor using typical MBC's, however this lower boost will raise high rpm timing numbers as the kpa load drops in upper rpms with boost falloff.

 

Even with my car @ 26psi I see lower load in lower gears, but like you said, it depends on the cars setup and how the maps are tuned.

You're right you will see higher timing because of it being in lower load columns like I said above.

I am basically agreeing with you that the knock can be caused by higher timing and leaner AFRs in lower gears. This can be changed by reducing the timing and changing the fueling in those lower load columns.

 

I think scott is talking about higher momentary load in lower gears, in other words if you romp on the gas at 2500 in 2nd you may hit a higher peak load and lower final load than if you did a 3rd gear run. I have seen this myself for sure.