jameswwt

Hi,
do anyone have a clue on why my car suddenly "Knock" seriously?
Im running PFC ecu, Walbro 255 & Fpr.

Things ive checked :
1) Wire harness to A/F sensor = OK
2) A/F sensor = How to check?
3) Fuel pump condition = How to check?
4) Wire harness to ECU
5) Boost or Vacumn leak?

Please advise what should i check?

Knocking shown on commonder 60~90 when WOT on gear 4 and 5.

When i boost the car from 1st gear ~ 4th gear no serious knocking but when i crusing on 5th gear and full throttle it will knock seriously most of the time.
Just wonder why this suddenly happen!

RSMike

iTrader: (1)

do you know how to tune the PFC?
if so, try taking 2 deg of ignition timing out of the whole map and see if the knock goes away.

why would it suddenly start to knock? how do you know it wasn't knocking before... ?

jameswwt

Hi RS Mike,
ever since after my engine rebuild, im quite religiously checking on my PFC commander whenever im driving hard...Usually, the recorded knock level while WOT and boosting on 1.4 bars is averagely 20~40 but after that day when after my i re-tighten all the silicons hose clamp on the IC and TB the problem started.
At the same time i notice my ECU also dangling below the drawer side after the cable tye gave way...

Will it be the A/F sensor problem? But idling very smooth
Will it be weak fuel pump? But when WOT with full boost on 1st~4th gear knock level on 20~35

Any other idea?

Thanks

Laxman

iTrader: (5)

My engine was knocking pretty bad, turned out to be a bad injector. Figured it out after a lot of trial and error, with the last straw being swapping out injectors to just run E85

jameswwt

Guys, today ive tested my car again and its confirmed the high knock level only happen when im on gear 4 & 5th gear.

The knocks only happen whenever i throttle on 4 & 5 gears while cruising...

The knocks rocket sky high (55~88) with obvious sound from the engine bay but ive tried few hard launching from 1st to 3rd gear with high boost (1.4bar) but the knock level only register not more than 18

Am i encountering engine hardware failure (rod knock, piston slap, crankwalk, etc)???
I just rebuilt the engine 7 months ago and the my engine power output still great.

What happening????

What i did after my tune previously is just fine tune my profec b II controller, tighten silicon hoses and what happen is my ecu drop hanging below my drawer.

That's all!!!!!

Again, am i facing engine failure again????

sloAZevo

Don't know if this helps, but my evo was doing something pretty similar. I'm not a tuner and I don't have anything to monitor everything that goes on, but in 4th gear the car felt obviously low on power, and only in the mid-upper RPMs. This came up after a tune. I had the shop that tuned the car retune it to a "safer" tune, I'm assuming thats less timing/more fuel. On the dyno it lost some HP, but i was able to pull all the way through the gears, took a couple tenths off my 1/4 mile too (due to not falling on its face on that last 1/4 of the run) . So maybe you're tune is off?

RJSP

Hi Jameswwt, the safest thing to do right now is to follow RSMike´s advice and lower your timing, and see if knock goes down or dissapears.

You mentioned tightening the silicone hoses, well if you did have a boost leak before and now it is reduced or gone because of the tightening then it is very posible to get knock, specialy in the higher gears because of the added efficiency that your current map doesn´t account for.

Good luck resolving the issue,

Ricardo

jameswwt

Omg! Exactly what happen on me! Thanks Man

jameswwt

Thanks Ricardo will be seeing my tuner later this afternoon.

jameswwt

Hi RS Mike or Friends,
just curious will it be a failing engine hardware (crankwalk, piston slap, rod slap, bearings toast)???

Any similar sympton failure listed above?

RSMike

iTrader: (1)

anything causing vibration will be picked up with a knock sensor.
even an externally venting wastegate can cause the knock sensor to react.
something like your exhaust vibrating on your sump could cause it.
you best bet is to try lowering your ign timing and rechecking

jameswwt

Thanks A Million RS Mike...

Eblue_ix

iTrader: (1)

yes just get a re-tune! more likely your timing is set a little high, if your running more boost then factory levels that will happen a full woot through 4, and 5th when you get on it in 5th thats where you would get the most knock. this happened to my evo the best thing would be to get a re-tune and run that "safer" tune and the knock/worries will go away.

jameswwt

Thanks Man...

jameswwt

Hi Guys,
just to update on my thread, Problem Solved after a fine tune by my tuner...
No longer knocking on whatever gears...

Thanks for kind sharing...