Jump to content
SAU Community

Recommended Posts

Ok, im pretty sick of this shit, i've been dealing with this loss of power for a while, the cars a track car, drift specifically.

Engine:

RB20DET

RB25 Turbo

Pnumatic Boost Controller

Pod Filter

Front-Mounted Intercooler

3" Split dump pipe with screamer

Bosch 040

Nistune Remapped ECU

Power when it was first remapped (probably 3 years ago) was 180rwkw, hasn't been dyno'd since, but there is a noticeable loss of power, bogs down a lot easier, it's laggier, and generally slower on the straights. it cuts out around corners when i go in hard some times, i think this is fuel surge from the fuel slushing around, and probably completely unrelated.

Symptoms:

- White smoke, smells like burning oil but not overly blue, could be burning water as well. Has been smoking for a while on start up, but went after some driving, now smokes all the time, although seems to reduce after it's been on the track for a bit

- Low power, no missing or anything, runs smooth, just lacks power

- Laggy

Extra details:

- Still seems to hold boost ok, possibly spools a bit late

- The screamer which is pretty good (split dump on internal wastegate), known for how good they seal, and definitely sealed back when i had it on the street, now has exhaust coming out on idle and under light load, well before the wastegate should be opening. unsure whether the screamer just isnt sealing properly anymore, or whether the wastegate is opening early

- I just replaced the exhaust manifold gasket + faced the manifold + replaced studs (they were f**ked, 2 were missing), also the turbo/manifold gasket was replaced.

- Actuator has been adjusted to make sure the gate arm is as far back as it goes at rest

- Runs smooth, no missing, sounds great

- Quite loud tappets, been loud for a while, haven't bothered with them

- Looks like it's gone through a little bit of coolant (radiator was low when i just checked it), but can't be 100%

- Small amount of bubbles in radiator

Compression test:

120 - 135 - 120 - 130 - 120 - 120 (Cold Dry)

170 - 150 - 150 - 150 - 150 - 170 (Cold Wet)

140 - 140 - 145 - 145 - 140 - 140 (Hot Dry)

170 - 165 - 170 - 170 - 170 - 180 (Hot Wet)

at this stage, im thinking the turbo is going, but i'd just expect to see it struggling to hold the 12psi it's set to.

that's it off the top of my head, but as i remember more i'll add details.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/
Share on other sites

do a leak down test... that will tell you more then anything.

to be honest it sounds like from what you are saying that the motor is just tired..

+1

Sounds alot like my old RB20.

Was tired, just turfed it out.

I had a slight oil slick in the radiator and reserve bottle aswell.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5668539
Share on other sites

do a leak down test... that will tell you more then anything.

to be honest it sounds like from what you are saying that the motor is just tired..

pretty much my thinking after last night, but the compression test was slightly promising as after a quick search it didnt look like that was a too bad result, maybe im wrong?

and the bubbles in the rad are pretty slight, headgasket could be buggered.

just not sure what to check to confirm it, to give you an idea simon, this is the difference between me making winton or not, so if i just write off the engine as old and f**ked, then im out, but if i can find an issue and fix it, then im there.

leak down is next on the list, unfortunately dont have one myself, only comp tester.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5668703
Share on other sites

ive seen engines with major internal damage comp test ok... i remember trent saying on here he comp tested a car that had a chunk missing from the crown of the piston comp test ok.. the point is its not the most accurate indication of posblems. leak down test is however.

if its HG. i'd say rip the head off... ddo a quick head shave. check the manifold gaskets while your at it. check the turbo and wastegate. and put another OEM gasket on and put it back together

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5668750
Share on other sites

Try re torqueing the head down to help the head gasket. Put in some chemi weld or similar,

Make sure u run enough fuel so it doesnt surge around corners.

Go to winton with a little bit more boost and enjoy the day and get a new motor after u finish.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5668980
Share on other sites

ok, thanks to simon, was leak tested yesterday, got between 5-20% across all 6cyls.

pulled off the dump, still burning oil, but i noticed it did take a few minutes before it really started to smoke, which really made me think it was a leak that was burning from touching a hot surface in the exhaust at some stage once it heated up from running for a few minutes.

anyway looked at the exhaust housing, not much shaft play, blades look alright, wastegate seems to be sealing.

took the turbo off the manifold and ran it straight out the manifold for a bit, couldnt see any white smoke anymore.

so i can only conclude the oil is coming from the turbo.

the question is, if it's spooling up and building full boost still, can it still be affecting power? i didnt think so. even if it is leaking oil, does that mean that it's definitely the source of the low power?

im thinking of grabbing another turbo, putting it on, then taking it for a power run on monday, check the tune etc etc.

one thing i did do at the same time was disconnect the rocker cover breathers so that they didnt go back to the intake and just vented to the atmosphere, there was quite a decent amount of pressure built up after blocking the breathers off with my thumb for about 15 seconds. not sure if that's an issue though.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5676071
Share on other sites

lol i know it's blow by, i just wasnt sure how much is considered normal. there is a lot of oil pooling in the in take and i want to get an idea if it's just bad blowby or whether it's oil getting into the compressor housing via f**ked seals.

stock Rb20 turbo going back on, currently running rb25 turbo.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5676465
Share on other sites

I always assumed that fuel surge would probably damage a motor - with lean outs and power cutting in and out... a quick search turned up these threads below that seem to support that idea. Might be worth doing something about it before the next motor goes in. At the very least it will mean you always have power in corners.

http://www.skylinesaustralia.com/forums/topic/188138-fuel-surge/page__p__3394937

http://www.skylinesaustralia.com/forums/topic/316605-help-please-no-1-cylinder-low-compression-and-turbo-failure/page__view__findpost__p__5181420

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5677486
Share on other sites

yeh it's definitely not a good thing, but it's an RB20 so it's not top priority atm, but it's the kind of thing i should be able to fix by running a full tank of fuel. it's the constant power loss while the engines running smooth that's getting me.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5677675
Share on other sites

lol i know it's blow by, i just wasnt sure how much is considered normal. there is a lot of oil pooling in the in take and i want to get an idea if it's just bad blowby or whether it's oil getting into the compressor housing via f**ked seals.

stock Rb20 turbo going back on, currently running rb25 turbo.

Keep in mind: Excessive blow-by can cause a positive pressure in the crankcase which can, in turn, lead to seals leaking due to the excessive pressure felt at the seal. This doesn't necessarily mean perished seals.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5678656
Share on other sites

Keep in mind: Excessive blow-by can cause a positive pressure in the crankcase which can, in turn, lead to seals leaking due to the excessive pressure felt at the seal. This doesn't necessarily mean perished seals.

yeh that was my main concern with the amount of blow by i was feeling, i have had the dipstick blow out once or twice, but certainly not a regular occurrence.

as mentioned the leak down test has shown pretty positive results. so at this point im really not sure.

going to chuck a oil cooler on, thinking the oil overheating could be causing some of the results ive been getting, as a minimum it's needed anyway.

Link to comment
https://www.sau.com.au/forums/topic/353799-diagnosis-help/#findComment-5680703
Share on other sites

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

    • The car/ECU will have all the sensor that it needs and expect to have. I think i do not have to explain to you how the Link is way better specialy if you have swapped engine   I just do not want to deal with any "problems" cuz i have only Nistune which i learned is not that great and in my case cant even deal with that speed problem (Link can) And of course it will be way more easier to tune and diagnose and safe. And for the ECU/speed problem...i dont know.
    • Per Mark Roberts of Sonictune: Mark Robert Author At this time, no. No ETA either 2016-17 models. You will be able to purchase and install a 2018.5+ TCU though   TCU purchasing and pricing info! As we near the release of TCU tuning, I am going to answer some questions I get asked often.   What do I need for TCU tuning? At this time, you will need a 2018.5+ TCU to be able to tune. If you have a 2016-to early 2018, you will need to replace your TCU with the newer version. One good way to know if your TCU is good is if you have auto upshift in manual mode in 1st gear around 6500 rpms. If your manual 1st gear goes to 7k rpm and will hit the rev limiter unless you shift, you have the older TCU.   Why do I need to buy another ecu license/phone flash if I already have it on my ECU tune? The TCU is its own computer module. It is completely separate from the ECU. Because of this, you will be required to purchase a TCU license and, if your tuner has it, the phone flash license required to tune it via phone/bluetooth.   Do I need TCU tuning? TCU tuning is NOT required. However, the faster your setup, the more it will assist in track and dragy time consistency.   If I’m ECU tuned by (tuner A) can I get my TCU tuned by (Tuner ? Yes, since it’s a different module and a completely separate flash, you can have two different tuners. However, it is highly recommend that you have both tuned by the same tuner. For me, my TCU tuning will directly complement my ECU tuning style and features and running my ECU and another TCU or vice versa MIGHT cause some issues. At this time and for the foreseeable future, I will only be tuning my current ECU tuned customers TCUs.     I have a SYVECS AWD controller. Do I still need it? Yes! The AWD controllers main job is to control your AWD system. However, with TCU tuning, you will no longer need the auto-shift function as that will be done through the TCU. The AWD controller will still be very beneficial for racers looking to maximize traction on the launch.     Shift schedule changes: holding gears longer at lower pedal input as well as max shift rpm changes. Please note, the new ECU race rom coming out will address 90% of the shitty drivability issues these cars have through custom maps from myself and Racebox—as well as others I am sure.   Increase shift speeds: as seen in the videos I’ve been posting, the TCU shifts much faster once tuned.   Increased shift pressures: as also seen in the videos, much firmer full throttle shifts.      
    • Per Mark Roberts of Sonictune:     Mark Robert Author At this time, no. No ETA either 2016-17 models. You will be able to purchase and install a 2018.5+ TCU though   TCU purchasing and pricing info! As we near the release of TCU tuning, I am going to answer some questions I get asked often.   What do I need for TCU tuning? At this time, you will need a 2018.5+ TCU to be able to tune. If you have a 2016-to early 2018, you will need to replace your TCU with the newer version. One good way to know if your TCU is good is if you have auto upshift in manual mode in 1st gear around 6500 rpms. If your manual 1st gear goes to 7k rpm and will hit the rev limiter unless you shift, you have the older TCU.   Why do I need to buy another ecu license/phone flash if I already have it on my ECU tune? The TCU is its own computer module. It is completely separate from the ECU. Because of this, you will be required to purchase a TCU license and, if your tuner has it, the phone flash license required to tune it via phone/bluetooth.   Do I need TCU tuning? TCU tuning is NOT required. However, the faster your setup, the more it will assist in track and dragy time consistency.   If I’m ECU tuned by (tuner A) can I get my TCU tuned by (Tuner ? Yes, since it’s a different module and a completely separate flash, you can have two different tuners. However, it is highly recommend that you have both tuned by the same tuner. For me, my TCU tuning will directly complement my ECU tuning style and features and running my ECU and another TCU or vice versa MIGHT cause some issues. At this time and for the foreseeable future, I will only be tuning my current ECU tuned customers TCUs.     I have a SYVECS AWD controller. Do I still need it? Yes! The AWD controllers main job is to control your AWD system. However, with TCU tuning, you will no longer need the auto-shift function as that will be done through the TCU. The AWD controller will still be very beneficial for racers looking to maximize traction on the launch.     Shift schedule changes: holding gears longer at lower pedal input as well as max shift rpm changes. Please note, the new ECU race rom coming out will address 90% of the shitty drivability issues these cars have through custom maps from myself and Racebox—as well as others I am sure.   Increase shift speeds: as seen in the videos I’ve been posting, the TCU shifts much faster once tuned.   Increased shift pressures: as also seen in the videos, much firmer full throttle shifts.      
    • The fancy pants red shock tower brace is finally incoming from MX5 Mania, getting it shipped from 'Merica has been a long and problematic process, and GWR, the 'Merican supplier will not ship directly to consumers outside of the US, Mania basically had to order a heap of them, the colour choice was silver, or red, and we all know anything red adds 5 killerwasps of dynotorques..... Whilst it does fit over a 2.5, and I've seen a few photos and videos of it being installed and fitting, google also says it might get real close to the FAB9 intake front runner, people in the US says it does fit with the FAB9 intake, except for one person who said it slightly touched.......so there is that.....LOL..... As it seems that I am the first in AU to have this combination of parts there's no local knowledge about fitment, so I'm just a willing guinea pig in this endeavour, I'll cross my fingers and toes and hope for the best In other news, I ordered stuff from China  on the same day I ordered the 23° silicone bend from Victoria, the stuff from China arrived a day ago, the 23° silicone bend is still travelling around Australia thanks to Australia Post, and "may" be here next week
    • Very good news...I contacted Racebox about it last night. My car is a 2016 so remains to be seen if it is compatible, requires a TCU swap, or is impossible.
×
×
  • Create New...