RB20DET Pinging Issue @ Lighter Throttle

[yogi000]

Hey Guys,

I have an issue with my rb20det which has me annoyed.

The problem is.

The car is tuned to run a max of 1.35bar on request. I have 5 different boost settings From 0.8 bar to 1.35. No matter what boost setting i have i wont get knock over ~35 on the hand controller for Wide Open Throttle. At this level i'm using LOAD point 15-16 on the maps.

But lets say i hesitate at about 4300rpm and ease off the throttle to about 2/3 or even 1/3 throttle, so i'm still accellerating and on boost. Knock will jump to rediculous number like 75, 93, 98 ....and so one......

I've done a map trace on the hand controller and found it happens around LOAD point 11 to 14 and between revs 4400 and 6000 (points N11 -N16).

So what i did was put it on the dyno to try find if it knocks at all. NO PROBLEM, ADDED more timing, got up ~60, added more and got my puff of smoke from the exhaust. So i have still abit up my sleeve.

Then on the freeway in 3rd was able to replicate the problem. So i pull out 3 degrees out of the entire map. Still get the same problem. I pull out another 3 and still getting the same thing. So i've pulled out 6 degree and i'm getting the same thing. At wide open throttle i was only getting a reading of 19 at WOT with 6 degrees less timing.

Anyone who can help me out.?? Offer any ideas????? Over sensitive knock sensors???

I remember reading Chris32 having a similar problem on his car, any progress?

Thanks

George

The mods are :

HKS 2530

GTR injectors

gtr pump

fuel reg

stock BOV

exhaust

cooler

[Menthu_Rae]

Is anything happening in regard to the actual car/power? Or is it just the knock reading? You got a Power FC? AFAIK the knock reading is a bit sensitive on these - it's just a unitless measurement... and AFAIK knock can be falsely read from things like resonance/other engine noises...

Someone who actually knows stuff might be able to respond better But if it doesn't repeat it on the dyno - and if you've tuned it a bit rich - and so long as the car doesnt actually behave any different/cant hear anything - then I would say it's just the sensor/reading being silly.

[Roy]

Id be inclined to think its engien noise...though its getting pretty damn high. With a spun bottom end it was getting around the 120. The mech noise i get on light throttle highway driving or on decceleration is usually no higher then high 50-55

[yogi000]

power of the car feels good. making ~207 rwkw on ~1.2 bar. I've never had much wheel spin problems, except first.....when i pull 6 degrees out.....i got no wheel spin anywhere. Its using an ap engineering power fc and blitz boost controller.

The tune is fairly rich to be able to run 1.35 bar as safe as possible so i'm inclined to guess engine noise too because at .8 bar it cant be not getting enough fuel.

[Chris32]

Mine still the same, apart from swapping knock sensors I have given up!

I did some on road testing, adding fuel and pulling timing and it didn't really change one bit, so I put it down to some other noise going on in the engine bay. My exhaust sits really close to my cars floor, and has no flex joint, so I am guessing it could be picking up that?

Its safe to assume, if its not knocking on the dyno, and you can throw more timing at it before it starts to audibly detonate or you see unburnt fuel puffs out the exhaust, that its just a funny sensor, much like mine!

I will keep persisting though, it mus tbe something silly! I thought about it the other day, I remember giving my knock sensor wires a fair old strech when my spanner became caught when I was putting in my oil cooler adapter on the block?

At the moment my commander has Water Temp, Boost, Speed and Revs on it, the knock readout is in my bad books and will remain hidden until I find a fix

[Chris32]

Bit of a update

Played around with mine on the weekend, it was shitting me bad!

Had some joy - looks like maybe my injectors where not flowing evenly? I added 1% more fuel in the injector scaling to cyl. 1 and 6, and knock went from 60ish to 35.........

My car also idles way smoother, I can get it to idle at 600rpm, before it wouldn't idle smoothly unless it was at around 8-900rpm

Will keep you guys posted

Chris

[yogi000]

my scaling goes

1. 90%

2. 90%

3. 90%

4. 90%

5. 91%

6. 92%

I've tried playing with lag settings but to no success, still using 0.00ms lag adjustments.

So i might try your theory tommorow night after i install my gearbox and clutch.

[Chris32]

Bit more of a play last night showed that it has made some differance.

I bumped up the boost to 1.4bar, and gave it a run in 3rd gear to about 7000rpm, and the worst knock it had was about 65, down a heap from previous. Car feels allot smoother too

Maybe add a little correction to cylinder 1, or play with each cylinder until you can see a change

[yogi000]

hey,

has the knock returned to its high numbers???

cheers

[Cubes]

I am now had issues with this.

I noticed a few changes to the way the car started first thing in the morning.

First thing in the morning when cold she would start, stumble then want to stall, most of the time it would stall. Especially if I touched the accelerator to try and bring rev's up.

Start her again and it would idle fine, HOWEVER if I were to touch the accelerator to try and give her a little free rev she would stumble and try to stall.

Knock levels have also gone up, it never used to knock now it tends to knock when coming off the throttle (looking at the pfc h/c graph) and changing gears after wot half way through the rev range. It doesn't so much hold a knock it only spikes a knock.

Edited September 29, 2005 by Cubes

[Chris32]

Funny, I had a play on the way home last night and added a few degrees timing through the middle and a degree up top just to see if it would knock anymore...

It knocked LESS!!!! WTF!! I seriously think my sensor is screwed, as it wasn't pinging at all

Either that or the RB20 PFC's are a tad dodgy when it come to the knock sensors?

Yogi - mine did seem to go back to what it was after playing around with the injector correction, has yours?

Mines still a spike here and there, it will be at 30-40 then hit 80 then back down, then I drive through the same section of the map, same load etc, and it doesn't do it!

Giving me the shits!

[Chris32]

Would a lifter make enough noise to register as knock?

I have a ticking/puffing noise coming from the exhaust side of my motor, I think I have dropped a few studs of the exhaust manifold, as when it boosts up it makes strange noises and you can smell exhaust in the cabin

[degeko]

my old rb30et used to stall every morning if i touched the accelerator until it was warmed up, found ou the injectors were stuffed and not able to be cleaned or fixed, new ones made it run so much smoother and eliminated most det problems even at 20 degrees timing and 12psi. uneven injector flow will unbalence the motor aswell.

maybe something to think about

[yogi000]

i'm using r33 gtr injectors which were cleaned and flowed before install.

I'm still having the spiking knock reading with lighter throttle and and when coming off boost sometimes....not as much...

What kind of BOV are you guys using.......plumb back or atmo venting. I'm using a stock BOV so could it be the extra air venting back making a difference??

I've got lifter noise on the exhaust side too, i've replaced all my exhaust manifold studs too about a year ago. I've found one is missing again.

i've got some new tomei cams sitting here waiting to go in but i want to fix this problem before i start the next mod.

I cant be bothered going back to a workshop since the last two i've seen have wasted my time and money.

[Chris32]

I'm using the stock BOV, with the mod to prevent it leaking

Something on my exhaust side is making a little bit of noise, not much though, I think the manifold is missing a few studs

[yogi000]

hey chris,

how do you prevent it from leaking?? Wouldnt mind trying that

[Chris32]

Its piss easy

Take the BOV off, you see a little hole next to the main vent

take about a 10mm drill, and lightly drill the small hole so you can counter-sink a screw in there

find a suitable screw, and plug that hole up!

Its bleeds of excesive boost pressure, a mate of mine picked up 8rwkw from doing this, didn't do a before and after with mine, but it felt better

[yogi000]

thanks, will try it over the weekend.

did you need to thead it or just use a self tapping screw?

[Chris32]

Just used a self tapper, you'll see once you get it off, once a screw is in there, it ain't going anywhere once you plug it up!

just make sure its nice and snug around the countersunk part you have to drill

[Chris32]

What lag times are you running on your injectors?

Mine where set at -0.14, setting them to zero reduced knock quite a bit