ans2k

not sure if this belongs in the "under the hood" forum or here. but is it possible to have knocking in 4th gear but not third. i did street e-tuning using third gear and never had knocking issues. i got gas at the same place as usual and when i went to the dyno and did the runs in 4h gear. i had knocking either in cylinder 1, or cylinder 2 and 3, or just in cylinder 3. i think on flash pro you can tune by the gear, but is it possible to knock in one gear but not another?

xredjar

You can find out with FP which cyl is knocking. I'd do that first. You need to find out how many knocks you have, if they are in specific rpm/load ranges, and what cylinder they are in.

Knock should not be a product of what gear your in.

sohc_mshue

Pulling in a longer gear = more heat build up = easier to detonate

Gernby

Does your calibration already have anything setup for ignition by gear? If so, those settings would all be incorrect for a dyno, due to the rate of accelleration being different from the street. Rate of accelleration does change the effective ignition timing due to the latency of the ECU.

EDIT: I removed part of the post above, since I was thinking backwards. Lower engine accelleration effectively advances timing, so unless you have some correction by gear, you are more likely to get knock in 4th than in 3rd. I would do some datalogging on the street in 4th and 5th gear to see if you are getting any knock counts, or even 3rd gear up a significant hill. If you don't get any knock counts, then I would suspect bad gas or poor IAT / ECT compensations.

ans2k

the knocking is kinda random. the knocking could be in cylinder 1, cylinder 3 or cylinder 2&3. but mostly in cylinder 3. and the knock count could be 6, 16 or even a 100. the IAT is 80.6 degrees F. ECT doesn't even go over 180. the bad gas could be a possibility but i have always gotten gas at a particular place and i have tuned on that gas.

phantom_

knock phenomena (anybody here knows the funk phenomena of armand van helden ?) is quite complex and has several causes;

• auto-ignition: uncontrolled burn of the mixture due to hot & under pressure combustion chamber. mixture self-ignites, without a spark.
• pre-ignition: carbon buildup points in combustion chamber starts to ignite the mixture, i.e. acts as a saboteur spark plug. naturally, engines with much mileage may have more carbon buildup.
• low octane fuel: mixture self-ignites easier with low octane fuel.

please correct the above/make additions, if necessary.
solutions to pre-ignition & low octane fuel are already there. however, solving auto-ignition is not straightforward.
now my questions about knocking;

1. due to F20C/F22C's quite high compression ratio, can we say that S2000 is more prone to knock?

2. in-cylinder temperature changes according to weather conditions (day/night, summer/winter). does driving on hot summer days increase the knock probability?

3. can we monitor in-cylinder temperature by EGT probes? and have an idea about knock probability due to combustion chamber temperature?

4. what can we do to decrease in-cylinder temperature so that we protect the engine against knocking?

s2konroids

Different gears have different loads.

You can reduce knock by obviously pulling timing, using different RON/MON rated fuels, using colder rated spark plugs but careful not too cold so they don't self clean, run a richer mixture (AFR) to reduce temps, do changes in an acceleration map (ECU dependent), there are several adjustments to be made on an aftermarket ECU, lastly Ingest colder air with a CAI, of course weather plays a part in knocking issues (due to colder air being denser and vice versa).

Cheers

phantom_

i note your summary of ways to eliminate knock...

what about applying a water injection system to the intake manifold?

i am reading very positive comments about the water injection solution, that it cools down the induced air and EGT to quite low temperature levels...

next, do you think that heat soak is an issue for increasing the probability of knock? if so, what can be done against heat soak?

murderedrsx

Cold air intake and hondata intake manifold gasket. I dont have flashpro or even kpro but i did have a kproed rsx-s down here and the south and knock was a huge enemy. Best way to elimnate it aside from pulling timing is to cool the air. Check afr for lean conditions as well. Thatll do it as well.

ans2k

i will look at the tune later. i dont have one step colder plug and i also have a cai. the weather was about 70 degree at night with two big blower fans.