Forum » General Tuning Discussion » 2JZ Piston Pitting Or (Knocked Issue)

2JZ Piston Pitting Or (Knocked Issue)

General Tuning Discussion

Discuss all things tuning in this section. News, products, problems and results. 


Page 1
Author
419 Views

Hello everyone,

Below are the specs of the engine

2JZ GTE VVTI Stock Long block with some upgrades

CAMS : 264

Turbo: AR70 Journal bearing

Boost Pressure: 1.5 Bar

Spark Plugs : NGK BKR7E

Fuel : RON 97

Piston: Thailand Made Stock 2JZ Pistons

ECU : LINK Storm G4+

Timing Table :[img="blob:https://www.hpacademy.com/36c2d18f-94c7-4c7a-a3d7-96966361981d" alt=""]

TPS vs RPM

The Max RPM limit is set to 7.5K

After A little three months of engine running

We open engine a apart for some upgrades we notice that there is pitting on the pistons on the exhaust side.

Wondering is it piston is not genuine or there is a problem with my timing table, do think that the numbers in the table are very very minimum?

Did check for Knocked with Links knock equipment, no sign's of knock.

Wondering which part went wrong that cause the issue.

For fueling AFR is around 10.5 at WOT, engine make 354 WHP

Already did check for timing drift there are no signs of it drift from 1.5K RPM to 4K.

This have been hunting me for the past week, hope that you guys can shine a light on me.

G'day Chyuan. Can you post the picture of your timing table as an attachment, I can't get your link to open. If you could pop up a picture of the pistons too that'd be ace :-).

Is the fuel in Malaysia pretty good quality? What I mean, is if you purchase 97 RON, is it pretty consistent?

Hi Zac,

Attached files for you to study.

As of fuel they claim that its pretty good, but i do notice it varies among the few company.

The engine is facing quite a number problems when we get on top. I think the timing at the top is pretty pretty low. Did not even get to push it, getting miss firing from coils. when the car is back on the ground one of the ignition coil is dead.

The piston with pitting on the intake and exhaust side, are due to serious knocking. After we pull the engine apart and send the injectors for testing found out that the no6 injector are flowing way lesser than the others.

Our concern is on the other cylinder where we started to see signs of pitting on the piston but not on the head.

Attached Files

I don't know man, a 7 heat range plug is barely going to cut it. You should at least run an 8. You could have preigniton. AFR and timing are more than safe.

What coils are you using? You should really not use stock. Get the General motors LQ9 coils.

Running on Stock coils and they fail, now we have taken the motor apart.

We are planing on up grading it to Toyota Yaris COP. In our part of the world, GM stuff are hard to come by, if we get it ship from US or NZ the tax and shipping will be more expensive than the coils.

That why it makes me think what actually did happen with such low on timing it still have knock.

Ouh Another important question, should I use the Timing Table with TPS vs RPM.

Or it is more appropriate to set the Table up with MAP vs RPM ?

As Explain in the Tuning Video, Timing is not as sensitive as fuel that is why I set it up to TPS vs RPM.

You're getting misfires with stock 2JZ coils at that power levels?? If it's really coil related I'd replace them with genuine coils, because in my opinion it's very unlikely that they're too weak at that power / boost level.

Have you set your dwell times accordingly? Also, you might want to you run one heat range colder, as Raymond pointed out.

Timing Table is to be expected to be set up as MAP vs RPM in a boosted application.

Also, 12-11 degrees of ignition advance at 1.5bar of boost with that power level isn't aggressive on stock compression ratio. Are you sure about the compression ratio?

Hi Andy,

After much investigation, the pitting issue is only on the last piston.Which its a knocking issue. From the photo its seems like all of them have pitting issues, but after they totally pull out all the piston its only one that is doing it.

The culprit is a bad injector, we send it in for volume flow check, the last Unit is lack of fuel if compare to the others.

We are pretty sure about the compression ratio, as the head is dead stock. No skimming have been done to it.

The stock coils are not going to cut, after last Dyno session one of them are pretty dead.

We are upgrading to Yaris Smart coils.

I have cross check the dwell time and it seems where it should be.

Have also change the timing table Axis to MAP VS RPM.

May I know how much ignition advance at 1.5bar of boost is consider aggressive. I do understand it comes down to fuel quality, compression ration and other factors. Do you have a ball park number that at least could give me an idea to judge ?

I am also finding ways to detect knock and respond to it in a more sensitive way. I does not detect or notice any knocked during the Dyno run. Do you any suggestion ? I am using Link knockblock.