chipped p28

[whatever210]

hey guys i come to you agian with a question. im gunna get a chipped p28 for my h22. the h22 came out of a bb4 and came with the jdm p13 ecu. the ecu is total shit. i want to get a chipped p28 but my question is: should i get the knock sensor disabled when i get the ecu chipped or leave the knock sensor enabled. ive heard of people disabeling it but does vtec still work if i dont have a knock sensor? if they disable it will it matter. let me know asap thanks guys.

[MR.PHIL]

VTEC Will still work .
OH..... I LOOOOOVE VTEC

[dbsharp]

stock honda knock sensors are a p.o.s., by what I hear. you probably wont miss it.

[GhostAccord]

P28 ECU doesn't look for a knock. It won't matter if you disable it in your .bin file or not. Don't actually wire it up......and bob's your uncle!

[nolehorridus]

it won't look for the KS or the EGR so connected or hooked up or not, they do nothing either way. you can just sell the KS to anyone who has a motor w/ KS. they're the same on the vtec b18's, b16's, and any other honda with a knock sensor from 2001 and older (they changed the design around 2001, but depending on the model, it may not be exactly 2001, kinda like the OBD swaps.

[whatever210]

Just some very intresting info i found.


Limp mode is VERY uncommon and i have only seen it about 2 times in god knows how many years. There are in fact many redundant systems in honda ecu's that provide safety nets in case of misc sensor failures. In all honesty its redundancy is one of the beauties of the honda ecu and why many people choose to use rom editing software over true stand alones. What happens inside your ecu all boils down to which specific sensors are affected.

examples

engine coolant temp sensor - fails your car will run slightly richer and you will not have vtec, why? because the ECT sensor is used in determining fuel trims thus the reason you would be running slightly richer. its a safety protocol built in to the ecu in the case of an ECT failure. and obviously vtec will not work since you must have a certain operating temp established in order for the system to be live. oh and a constant cold rev limit in some cases

knock sensor - a damaged knock sensor will not put you in limp mode. it will in fact retard your timing as a safety protocol and check back every couple revolutions to see if the problem has been corrected. same holds true if a correctly functioning knock sensor is detecting knock

o2 sensor (primary)- will not put you in limp mode. when the primary o2 fails your ecu is forced into open loop mode and will rely on the ecu's default maps that came from the factory or what would be the equal of a reset. during this time no long term or short term fuel trims will be done as there is nothing providing input to alter the trims, thus you will just run overly rich like you would on a fresh reset.

o2 sensor (secondary)- no limp mode here either, hell this one cause next to no side effect. its basically an expensive way to make sure your CAT is functioning withing federal specs.

iat sensor - will not cause limp mode, it will just ever so slightly alter your fuel trims towards the richer side to compensate for its failure

iacv (idle air control valve)- limp mode = the negatory on this one. you will just have a shitty idle

what does cause limp mode? like the real one true limp mode.... core sensor failure...distributor failures like the cyp taking a shit or loosing the rpm signal, map failure, catastrophic ecu circuitry failures that are internal. even this has a wide margin of outcomes. a map failure will cause the car to run like absolute shit but still somewhat ok. on the other hand a primary injector circuit failure will cause the worst limp mode of them all in which you will find getting up to 20mph if as difficult as gary coleman trying to slam dunk without a trampoline.

now this isnt the most technical thing ever but hopefully it helps clear up some peoples misconceptions about what limp mode is and when it comes into play and also about hondas redundant systems and failsafes for non critical sensor failures.

[smokeeey420]

what your thinking/talking about is open loop/closed loop

You have two ways the ecu works; closed loop (ecu reads from o2 sensor) and open loop (No o2 feedback).

When in closed loop your ecu takes readings from your o2 sensor to adjust for better mpg and daily driving.

When in Open Loop your ecu reads straight from the map sensor and uses pre-programmed maps/chips to run the car.



am i getting it right???

yeah limp mode sucks. not very common??? ive seen it like 3 differnet times/cars in 1 year.lol