Hello everyone...

I got a car that's giving me some trouble to tune without detuning the knock sensors to the point where I don't even believe they're even working much anymore (30% increase at low rpm).

I'll post up the map and logs when I get to my laptop but I'm setting up this thread to see if anyone has had similar issues before. (Just to get a ballpark, it's a smooth timing map, peak TQ timing at 2 degrees, load goes up to ~330-340 stock maf, stock injectors, upgraded fuel pump)
Tephra mod V7

The spec of the car is well - noisy:
4G64 block, Evo 8 head, 2,4L
CP X-Forged pistons 9:1 CR (clearanced to accomodate 600-650hp) Noisemaker #1
Oliver I-Beam rods
GT Racing Cams - seem to be a replica of BC racing biggest version cam (biggest version of the cam) Noisemaker #2
Balance shaft delete Noisemaker #3
Carbonetics twin carbon clutch Noisemaker #4
Supertech valve springs and retainers Noisemaker #5

Specific stupidity on the car: only 1 adjustable cam gear - exh camshaft, centered correctly for 4g64, but the intake isn't.

Car is running an Evo 9 turbo, AMS Fmic, Walbro, 3" exhaust etc... Full bolt on built car with a small turbo. The previous owner said he'll go up in turbo size hence the built, but it never happened so now we got a torque parade going on at low RPM. Running pump gas.

Now on to the "problems".

Running 1,7-1,8 bar peak (25-26psi) ign. timing 2 degrees at peak tq.
4th gear pull, starting 2000 RPM
Pulls nicely, spools up fast, by 3000RPM knock counts go 0 0 0 0 5 7 10 15 (lift) - knock voltages 1-1,7v mostly, rarely rarely a single value over 2v
Tried detuning the knock sensor (low rpm from 13 to 18), knock values get under control - still picks up some at times - 1-3s. Voltages the same.

I tried reducing timing at peak tq even to 0 - it did reduce the "knocksum" values to an extent, but on stock knock sensor settings, was still picking up significant amounts.
AFR's at 11.5ish every time in all scenarios.


Overal drivability of the car is brilliant, spools fast, drives great at lower boost levels, but simply trying to push it, goes to hell.

I don't have access to any way of det.cans at the moment - but I will have to fix something up. It's quite hard to use det cans on the road anyway.

Has anyone had similar issues? I know it's really not a common setup at all to run a funny sized turbo on a motor like this, but the previous owner had been runing the car for long enough for me to believe that if the knock values were real, the motor would have been LONG gone as he did push it quite a bit.

I know it'll need an injector upgrade to run in the upper RPMs but right now we're not even there.

I'm a bit stuck with the way I should even approach the problem really, so any ideas are welcome.

 

How certain are you that it's not the knock sensor itself that's the problem? Are you sure it wasn't over-tourqed? I did something similar on mine, replaced it, and had no more random knock. I was otherwise registering knock all over the place.

I'm running a 2.4, no balance shafts, quartermaster twin disk clutch, and ams CNC head with upgraded valvetrain. My pistons are also clearanced for high horsepower.

 

We will change knock sensor next week with brand new one.......and hope for the best

 

sounds good. Don't over-torque it or else you'll have the same damned problems.

 

Yeah 20Nm.

We installed it yesterday and i am waiting for mapper to check it.....untill then ill drive off boost

Fingers crossed

 

So we did few runs with new knock sensor and things are better........knock count is still there (up to two counts) but not on every run. Some times it runs spot on and the next one we got some counts.............knock magnifiers were set 5% higher than OEM.

My mapper suggested that i need after market ECU or tune down on current unit

 

what other than knock sum and knock voltage is he using to verify knock before you spend stupid money on something you dont need and that prob has no knock control anyway,
what do you mean by cp-x pistons clearanced for 600 ponies ??

 

Hi.

Piston rings were gapped for 600 bhp in mind ,i guess.

He is using knock sum and voltage as you mentioned......i think hes about to buy one gadget for knock monitoring just to solve my issues.

I also think that it is pointless throwing $$$ for new ECU for this kind of power level.

 

worth their weight in gold

https://www.google.ie/search?q=det+c...8dz2qGFsVJQ%3D

 

Most storkered engines without balance shafts cause noise at low RPM, I'd increase knock filtering (low) to around 20-21
But make sure it's a phantom first by either the use of det cans or decreasing timing in knock area.

 

My 4g64 was making phantom knock picking up the bad input shaft bearing.

 

Been having similar issues on one of my project cars for about four years now. Just recently decided to try and figure it out again. I've got about 40miles on the motor now and its a 2.4L, 10:1 with the same type of "noisemakers" you have. Been running a 9.8 stock turbo until I could get it sorted. Gonna start tuning the knock sensor its self tomorrow, if i make any head way I'll let ya know but your not alone.

 

My motor was a loose build... it knocks like a pig when cool but after a couple wot runs it's dead silent and knock goes away. Basically have eliminated knock detection at this point and drive it without concern.

 

I'm also on the stock ecu and am not having these problems. Re-look your knocksum values.