neil_jdmr

Ok getting a bit worried now,

cat heat light is flashing regular now pretty much anything above 4k rpm and the knock is reading between 80-115 also above 4k

at idle the knock value is a perfectly normal 1-3 but upon any throttle it leaps up, and normal sub 4k rpm driving its anywhere up to 80.

today i found a bolt from the uim had worked loose, dropped and wedged itself next to the knock sensor so i removed it and fitted it back into the uim. I though woohoo that will sure have fixed it but i just come back from a test run and its still the same.

seeing as my pfc was mapped by one of the uk top tuners (pip) i gather it should be fine and at full boost(0.8bar) and wot im usually sub 100 knock reading, but im fairly sure this has only just started happening .

i know for sure the heat light is only flashing because the knock reading goes to max (over 100) but anyone, please any more ideas what to check before i spend £££ trailing my *** all the way down the country to see pip.

Would my motor be dead already if these readings were true? only thing is the idle reading seems fine.

mucho thankio

RotaryBuddha

iTrader: (4)

At .8 boost, you should not see anything more than 50 knock. Even that for some is pushing it. Check to make sure your sensor is within spec. If I were you I would not drive the car in any sort of boost till you find what is wrong.

neil_jdmr

Just heard on one of the uk rotary forums that the stock knock sensor is useless with even just an aftermarket exhaust and de-cat test pipe.

For reference mods are:

dp
decat
nurspec
arc smic
hks shrooms
pfc fully mapped

also i've never seen more than 92% injector duty at wot, full boost and 8k rpm

neil_jdmr

Talked to pip this afternoon and thought i would post what he said just to close this out incase anyone else ever has the same issue.

he is 99% sure that knock is certainly not the case and is confident that a loose engine mount/exhaust mount or similar is the offender so im gonna get underneath and have a good search around. Since the high knock reading/flashing light is only happening on part throttle i.e less than 50% then it could not be true knock especially when at wot and full boost im getting much lower figures.

Apparently between 3-4.5k rpm is where any vibration is most noticable so if something is not as tight/solid as it should be this is where i would see it, Which i am.

Thanks for everyone's input and another thumbs-up for pip for being a helpful friendly chap.

Macen

The PFC is set to flash the heat light when knock is above 60. My light flashes when rpm is between 2500 and 3500, and throttle at <50%. This is also where I have the most resonance from the exhaust system, so I guess that the knock sensor is picking up that noise.

You can disable the knock warning flash in the Commander under Etc -> Function Select -> 3. Knock Warning.

RX7_FD3S_JDM

hey man im getting the heat light flashing on my fd3s. i too am using the power fc. its scaring the **** out of me and i dont want to dive it.

my water temp is only hitting 45 degrees so i dont know why its flashing heat?

what should i be checking? oil level is fine.

as if i didnt have enough problems with the secondary turbo not kicking in, now i have a flashing heat light in my face

RX7_FD3S_JDM

may sound stupid but this happened after my battery went completly dead, would this cause it? maybe ecu resetting?

Ceylon

iTrader: (3)

45 degrees???

When does it flash? At WOT/deacceleration etc? Where abouts in the rev range?

The PFC should not reset when it loses power.

The heat lights original function (Only with the standard ECU) was to warn you when the cat was getting hot - The FPC uses it as a warning light - Depending on how many times it flashes it can mean different things - For a knock >60 warning it will flash 3 times.

RX7_FD3S_JDM

between 3-4k mate. I will start it up again now and count the flashes.

ill also check the knock on th commander

RX7_FD3S_JDM

hm thats weird, i went for an hour long drive and no flashes.

KenSpeC

iTrader: (16)

In jdm cars the pfc uses the cat overheat light as a knock sensor but most of the time its more of chassis noise. I find that unless you get a dedicated knock sensor like the JACOBS knock sensor, the pfc and warning light is merely a reference, but inaccurate

arghx

iTrader: (3)

The knock sensor reading on the PFC isn't necessarily completely useless, but you really need to analyze datalogs for patterns. Here is a log of a dyno pull on an engine that doesn't have much noise:



purple is knock pattern. Under heavy load you would be concerned about a spike beyond this type of baseline signal pattern. Now here is a log on an engine that has much noisier readings:



You can see how much noisier this engine is. This is actually an early FC engine with the knock sensor located in the middle iron instead of on the rotor housing. Actual knock on this engine usually reads over 90-100.

Neither engine was actually detonating in the two logs above.

digger02

I need some help with my "cat heat light" too, now when I start the car the warning light doesn't go away. Where is the sensor for this? I have an aftermarket system.