Jump to content

Gav's 200sx RPS13 1JZGTE of race car.


~Slideways~
 Share

Recommended Posts

I'd get the forged pistons ceramic coated to help prevent hotspots 

Looks like it's gradually happened right, so could have been an existing issue and already had a small deformation causing a hotspot that's slowly gotten worse. Could look at adding egt sensors per cylinder as I'm tipping your overall AFR is fine? 

You've ruled out injection and ignition, timing was correct. How's the cooling around that cylinder looking, nothing blocked?

Do you know the history of the motor, had you had the head of previously? 

  • Like 1
Link to comment
Share on other sites

  • Replies 360
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Possible has had some previous damage.  and has been your misfire issue all along.   if that hole was burning a bit of oil. which looks like it has been, would be more prone to knock.    Which will have been what ended it for good, you'll probably find the ringlands just floating around in there when pull the pistons. 

 you can get all fancy and egt every cylinder.    but making sure isn't set on the edge of knock when tuned is the main thing.  checking the plugs after few pulls is good idea also.    

Not saying it was a tuning issue.  but also make sure you tuner is using knock detection and not just using ign map numbers that worked on another engine the same.

 

  • Like 3
Link to comment
Share on other sites

On 24/07/2022 at 08:25, shrike said:

I'd get the forged pistons ceramic coated to help prevent hotspots 

Looks like it's gradually happened right, so could have been an existing issue and already had a small deformation causing a hotspot that's slowly gotten worse. Could look at adding egt sensors per cylinder as I'm tipping your overall AFR is fine? 

You've ruled out injection and ignition, timing was correct. How's the cooling around that cylinder looking, nothing blocked?

Do you know the history of the motor, had you had the head of previously? 

It does seem like it was gradual yeah. And it makes some sense that it just got to the point where it let go.

Cooling looks ok but haven't had a good look yet, the thin black layer of the metal headgasket has stuck to the head and makes it look like the cooling passages are partially blocked but its just that thin later left behind. Will have a better look though.

I imported the engine in a car from japan (jzx100 earlier in this thread), drove it around the block and compression tested ok. It had the stock turbo and ecu but it was a basic amature drift car type thing so more than likely had the boost increased. So maybe it had a cracked ring land all along but was able to hold compression most of the time?

Never had the head off no, didn't have a reason to. Would have been interesting to see if there was any damage that slowly killed it though.

  • Like 1
Link to comment
Share on other sites

13 hours ago, kpr said:

Possible has had some previous damage.  and has been your misfire issue all along.   if that hole was burning a bit of oil. which looks like it has been, would be more prone to knock.    Which will have been what ended it for good, you'll probably find the ringlands just floating around in there when pull the pistons. 

 you can get all fancy and egt every cylinder.    but making sure isn't set on the edge of knock when tuned is the main thing.  checking the plugs after few pulls is good idea also.    

Not saying it was a tuning issue.  but also make sure you tuner is using knock detection and not just using ign map numbers that worked on another engine the same.

 

This would be a silver lining really, finally having an answer for the the intermittent misfire. So much so I feel like a broken record writing the words 'intermittent misfire' so many times.

I don't think it was a tuning issue, it has been on the same dyno 4 or 5 times now using knock headphones and the fact that it was only one piston while the others don't appear to have any signs of damage. Right now the most likely theory is that it already had piston damage from it's previous life, maybe ring lands from too much boost on stock ecu back in Japan?

Thanks for throwing some of your experience at this, really helps getting my head around what could have happened etc.

 

 

 

  • Like 2
Link to comment
Share on other sites

39 minutes ago, ~Slideways~ said:

It does seem like it was gradual yeah. And it makes some sense that it just got to the point where it let go.

Cooling looks ok but haven't had a good look yet, the thin black layer of the metal headgasket has stuck to the head and makes it look like the cooling passages are partially blocked but its just that thin later left behind. Will have a better look though.

I imported the engine in a car from japan (jzx100 earlier in this thread), drove it around the block and compression tested ok. It had the stock turbo and ecu but it was a basic amature drift car type thing so more than likely had the boost increased. So maybe it had a cracked ring land all along but was able to hold compression most of the time?

Never had the head off no, didn't have a reason to. Would have been interesting to see if there was any damage that slowly killed it though.

I think the joint diagnosis is that that piston may have had existing issues, its all subjective however if you hadn't had the head off to confirm the pistons looked good then I would lean that way.

Cooling blockage would have been more if you knew the engine was good/head had been off and pistons looked good previously etc, as if that cylinder wasn't cooling as well it could lead to issues (would expect the knock sensor to pick up any detonation however)

I wouldn't bother with EGT sensors for the new setup as I think you have diagnosed the issue now and I doubt it will repeat with new pistons etc

Sucks but at least with the new build you'll know what will be in it, any plans to balance the rotating assembly?

  • Like 1
Link to comment
Share on other sites

I'd check the fuel rail for internal corrosion, if the car has a stock fuel rail which isn't anodised inside and has been run on ethanol it can cause pretty nasty corrosion and a partial blockage. I have seen a single piston meltdown in an evo caused by this. 

The piston has been torched somehow, and the edge of the valve recess is most prone due to material thickness, as mentioned before the head was pulled. So at some stage in its life that cylinder has seen more air (or more likely less fuel) than its other 5 Brothers. 

What you don't know is when this was..

First up is get yourself 6 milk bottles and take a leaf out of @Roman 's fuel injector science (cool idea) to rule out fuel delivery in its current condition. 

Does the car run ballast resistor for injectors? As dodgy impedance across one of those would affect duty cycle. 

  • Like 3
Link to comment
Share on other sites

1 hour ago, mjrstar said:

I'd check the fuel rail for internal corrosion, if the car has a stock fuel rail which isn't anodised inside and has been run on ethanol it can cause pretty nasty corrosion and a partial blockage. I have seen a single piston meltdown in an evo caused by this.

I see you mentioned xspurt injectors. They have no filters in them. Could easily get shit in them?

Link to comment
Share on other sites

6 minutes ago, fletch said:

I see you mentioned xspurt injectors. They have no filters in them. Could easily get shit in them?

I ran the Xspurt ones for a while but changed to st215 injectors about 1-2years ago as the spray pattern was better. The Xspurt ones appear to spray directly at the wide port divider on these heads so lose atomization. 

 

Link to comment
Share on other sites

2 hours ago, mjrstar said:

I'd check the fuel rail for internal corrosion, if the car has a stock fuel rail which isn't anodised inside and has been run on ethanol it can cause pretty nasty corrosion and a partial blockage. I have seen a single piston meltdown in an evo caused by this. 

The piston has been torched somehow, and the edge of the valve recess is most prone due to material thickness, as mentioned before the head was pulled. So at some stage in its life that cylinder has seen more air (or more likely less fuel) than its other 5 Brothers. 

What you don't know is when this was..

First up is get yourself 6 milk bottles and take a leaf out of @Roman 's fuel injector science (cool idea) to rule out fuel delivery in its current condition. 

Does the car run ballast resistor for injectors? As dodgy impedance across one of those would affect duty cycle. 

While I did build it with Ethanol in mind, E85 was gone by the time it was ready for it so it never actually ran Ethanol, not even E10. Only ever BP98.

Good thought though as I changed everything to ethanol safe but didn't think of the fuel rail.

The injectors are powered with their own dedicated relay and fuse but no ballast resistor no.

 

EDIT: will be getting the injectors tested again.

 

 

Link to comment
Share on other sites

2 hours ago, shrike said:

I think the joint diagnosis is that that piston may have had existing issues, its all subjective however if you hadn't had the head off to confirm the pistons looked good then I would lean that way.

Cooling blockage would have been more if you knew the engine was good/head had been off and pistons looked good previously etc, as if that cylinder wasn't cooling as well it could lead to issues (would expect the knock sensor to pick up any detonation however)

I wouldn't bother with EGT sensors for the new setup as I think you have diagnosed the issue now and I doubt it will repeat with new pistons etc

Sucks but at least with the new build you'll know what will be in it, any plans to balance the rotating assembly?

Will still see if the injector is the culprit but it doesn't seem likely as it is all filtered properly and they were cleaned and tested when trying to find the misfire cause.

Haven't made much plan for the rebuild yet except looking at piston prices and deciding I don't really need to replace the rods since they are more than enough.

Link to comment
Share on other sites

16 hours ago, Roman said:

ahh man this sucks to see. 

Fingers crossed for you that the block is okay and everything is easily fixable. 

I reckon the block needs machining so probably 0.5mm oversize since that is a commonly available OS forged piston.

I didn't do a 1NZ double windowed job at least, right?

  • Like 1
  • Haha 2
Link to comment
Share on other sites

  • 2 weeks later...

Automotive sadness ensues:

image.thumb.jpeg.c8ec178dc5ca0c6d2aa90784e99413a9.jpeg

 

 

The piston looks far worse than I expected. The ring lands look intact too.

20220806_152813.thumb.jpg.e6cf183ac4ddc3ac5b03d51f52fd520f.jpg20220806_152804.thumb.jpg.b57cb2d80e25ec3648c3326d46ac269d.jpg20220806_152752.thumb.jpg.de245723a260ea7d718327929c7bc74d.jpg20220806_152744.thumb.jpg.b5bed4553e6668764c3e0f1ccf73ccfb.jpg

 

Another unexpected thing is number 2 had what looks like corrosion on the bearing?

image.thumb.jpeg.b8af10753a8ae983b476f85a900efdac.jpeg

 

And some of the others have scoring which is maybe piston material going through the system since I can now see that the piston particles/melted bits worked their way below the rings.

20220807_171128.thumb.jpg.c327f9d611598f98fe5281c98b631369.jpg20220807_171117.thumb.jpg.c52208f92b05825c819d4f076f1564dd.jpg20220807_170753.thumb.jpg.5f98b50047d5e9c533c30bf30d1961b4.jpg20220806_155901.thumb.jpg.07b7d3adc1363d22ee478519b5de140e.jpg20220806_155647.thumb.jpg.7f4e632024516863feeb140d89859898.jpg20220807_171216.thumb.jpg.c5b59cea9c53e4d0c757e3c92a5be5e4.jpg

 

Everything went pretty smoothly with the disassembly except this one bastard allen bolt on one oil squirter. It was so tight that it rounded the inside of the allen head. I ended up having to chisel a groove into it to use an impact driver. No other damage though so just need a replacement bolt.

image.thumb.jpeg.33d42ec1e82e931c305634838279d6e2.jpeg

 

Going to send the ECU off to Link to see if they can test the injector driver on number 4. Will contact to find out what can be done, even just paying to have it replaced just incase.

Dropped the injectors themselves to be tested late last week.

 

  • Like 2
  • Sad 11
Link to comment
Share on other sites

That piston's had a big old lean moment eh. It reminds me of the time my Beams leaned out due to low battery voltage and had a big moment at 8000rpm. My issue was caused by an issue with my alternator wiring causing a lack of voltage, which combined with batch injection, caused bad things to happen. 

I'm going to throw in my theory that your fuel pump supply might still be a problem? Either a bad connection or undersized wire, which would also explain the melted fuse - I've had fuel pump fuses melt exactly the same way because of undersized wiring. 

1.jpg

 

  • Like 7
Link to comment
Share on other sites

On 08/08/2022 at 20:51, kpr said:

weird texture on the bearings can be signs of knock.  i assume number 4 big end bearing is a pretty beaten up?  what do all the others look like?

Yeah this is interesting because the big end on number 4 is actually pretty 'good', some scoring but nothing like number 2 with the pitting/corrosion. Out of all of the mains and big ends, it is only number 2 that had the weird pitting. The others are either good or light scoring.

This is number 4:

20220809_210022.thumb.jpg.158560fc875d99167e72c01c4bb91b55.jpg20220809_210031.thumb.jpg.319fdd8271773871ebc32f9149efe37f.jpg

Link to comment
Share on other sites

44 minutes ago, Truenotch said:

That piston's had a big old lean moment eh. It reminds me of the time my Beams leaned out due to low battery voltage and had a big moment at 8000rpm. My issue was caused by an issue with my alternator wiring causing a lack of voltage, which combined with batch injection, caused bad things to happen. 

I'm going to throw in my theory that your fuel pump supply might still be a problem? Either a bad connection or undersized wire, which would also explain the melted fuse - I've had fuel pump fuses melt exactly the same way because of undersized wiring. 

1.jpg

 

That does look very familiar!

But on the fuel pump, it has a big dedicated power wire directly from the battery through a relay. Way bigger than the factory wiring etc. I checked the fuse a few times after that happened and it showed no signs of burning again, although I had crimped it down so the connection definitely has good contact. I'm pretty sure now that it was caused by a bad contact.

The thing that gets me is that there doesn't look to be any damage to the other pistons, just number 4 and it is serious damage. Possibly long term, is its is likely a long term problem there.

It has been suggested that it may be an injector driver fault with the Link g4+. I've been told of a similar story where an RB filled a cylinder with fuel after having similar misfire problems.

Right now I'm working on getting the block ready to be measured and see if it needs over sized pistons or not. Then make a list of everything I need and figure out the best place to source them. There look to be supply delays on bearings etc. Will go with genuine Toyota headgasket etc though.

 

  • Like 3
Link to comment
Share on other sites

I had an injector driver fail on my ECU - the mosfets fail "on" so its easy to test if its happening. 
Because it will just hose out fuel constantly. 
If you plug in an injector while the ECU is on, without engine running.
If it makes a click noise on number 4 then the injector driver is chooched. 

If you have been having issues with low voltage, and your injector deadtime table isnt compensating then it could definitely cause issues. 
From 14v to 10v your injector deadtime could be 30-50% larger.
This makes the most difference at low load, but could definitely make it run a bit lean at full blast too. 

Even if your deadtime table was correct, if you had low voltage issues causing your fuel pump to be less... pumpy. then you could be running lean as well if fuel pressure was dropping momentarily. 

 

Link to comment
Share on other sites

2 hours ago, Roman said:

I had an injector driver fail on my ECU - the mosfets fail "on" so its easy to test if its happening. 
Because it will just hose out fuel constantly. 
If you plug in an injector while the ECU is on, without engine running.
If it makes a click noise on number 4 then the injector driver is chooched. 

If you have been having issues with low voltage, and your injector deadtime table isnt compensating then it could definitely cause issues. 
From 14v to 10v your injector deadtime could be 30-50% larger.
This makes the most difference at low load, but could definitely make it run a bit lean at full blast too. 

Even if your deadtime table was correct, if you had low voltage issues causing your fuel pump to be less... pumpy. then you could be running lean as well if fuel pressure was dropping momentarily. 

 

Definitely worth testing, I'll wait till they are back from testing etc.

That description does kind of match the intermittent misfire problem where it would happen at low load then go away it you let it drop down to idle, but I am sure I've been over logs and the voltage was fine. It's all in pieces now though so will press on with at least making a rebuild plan as well as trying to test all possibilities for the failure.

  • Like 2
Link to comment
Share on other sites

 Was more meaning like in this picture rather than number 2.      not the scratches  but the textured look.      should be able to look up and compare to some pictures what it means. 
this is one of the mains i assume?    number 2 looks like something else again

20220807_170753.thumb.jpg.5f98b50047d5e9c533c30bf30d1961b4.jpg

 

Either way it looks like it was knocking right up until failure, the way the piston is so clean in damaged areas.   weather that was due to some previous damage. causing oil contamination in that cylinder.  or a fuel/ignition advance issue is the question

I'd do a roman  dave milk bottle injector test.    That will test the ecu, injectors, wiring at the same time.    give the loom a good jiggle around in the process, see if any injectors play up.
would work just as well / better than sending everything away to be tested

Any  chance we can get a screen cap of the ignition map?

 


 

 

  • Like 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...