Jump to content
SAU Community

Recommended Posts

No it's not the title to a chinese who done it.

I have a strange little problem with a mystery 'knock'.

I can give it a full throttle take off from standing and 1st gear all the way to 7000rpm is without a rattle. Into second and third there is just a brief knock at 5000rpm each gear.

I was wondering if this is the sign of a dicky fuel pump or perhaps something else?

Link to comment
https://www.sau.com.au/forums/topic/13289-knock-and-ping-mystery/
Share on other sites

You probably know this, but remember that the higher the gear the more load is on the engine and therefore more likely to ping.

You might have to pull 1 or 2 degrees of timing off of her.

Or doesn't it happen in 4th and 5th??

I suppose to find out if it does ping in 4th or 5th you'd have to be doing mach 3 or something :rolleyes:

thanks for the ideas so far.

No it's not a timing issue, the knock is 'before' full power and timing can be pulled back 10 degrees and it will still occur at the same magnitude. Obviously I take off timing if I can 'hear' a ping at any time but, quite often this is just a very strong 'knock'

I had a feeling it might be a fuel supply issue.

This might be a long shot - but it could be the harmonic's of the motor at those RPM/Load. Sort of extra 'noise' that the knock sensors think it's knock...

Any idea when your peak torque is?? Could be doing it on your peak torque too??

Strange stuff though - like said before, might be time for a test and tune on a dyno..

Originally posted by Jay95R33

You probably know this, but remember that the higher the gear the more load is on the engine and therefore more likely to ping.

You might have to pull 1 or 2 degrees of timing off of her.

Or doesn't it happen in 4th and 5th??

I suppose to find out if it does ping in 4th or 5th you'd have to be doing mach 3 or something :P

Yeah i agree whack some timing out to be sure...do your octane.....do it on a cold night...only one at a time and u should figure it out easy enough.

Dont forget rb25s are prone to pinging with their high comp ratio...

If the fuel pump was dying u would ping all the way and your engine would last 2 minutes.

ur saying its only faint? turn your stereo up :D

rev,

I have the exact same problem, i only have an exhaust, filter and BOV.

I put on a atomic bleed valve to upped the boost to find that it got worse (obveously), then wound it down to find that it was still there. i have have plugs changed, platniums make no diff, and changed the gaps with no luck. my only options left are the Air flow meter (could be that) or the fuel system (like a coil pack or the like). waiting until i get motec before i look further into it. its just too much hassle looking for this thing blind.

Although run BP ultimate, this made it less.

Good luck and let me know what you find out.

never flashes.... i dont think that its a pinging however, it sounds more like a popping from the exhaust with a engine retard at the same time. the car exhaust rumbles off load and backfires between low speed up changes.

havent checked timing though. ive had it a slakos whoes done a full check on the thing and sees nothing wrong with what could be obveous, went to cred and they just changed to platnuims, worked fine until i got home... then you guessed it... back again.

pinging will usually happen under full load, full throttle

if u back throttle off...its not ping....

maybe your too far retarded.(timing :P)

usually advancing to 15 deg and over makes the pop pop go away unless u have a straight thru with only one muffler so the engine doesnt have alot of backpressure

anyway.....

thanks macka,

the sad thing is that i cant even get the thing up to full boost at the moment as the clutch is on the way out, it will slip shortly after 5krpm.

geting it replaced next week, and i will get the guys to have a look at the timing at the same time.

i do have a 90mm straight through exhaust to a tip muff. i also have a rx7 racing cat on the thing... it sounds blooody mean i tell you. would think that it would be a issue though...

I have run octane shmooster and it persists. Backed the timing off.

I've got some BCPR7ES plugs in now and still it persists (better power delivery up top tho' with a nice 1.0mm gap.

I'm thinking its a fuel thing, might have to try a big wack of extra fuel just before 5000rpm. The other thing it could be is cooling system (say it aint so!).

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...