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Rb25 Engine Troubles

sd9k

By sd9k,
in Engines & Forced Induction

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sd9k Apprentice

sd9k

Posted
Posted (edited)

hi i drive this

skyline-1.jpg

so i got my car tuned last week and have been having nothing but problems

and the dyno is whacked looking

dyno2.jpg

current mods are: safc neo, custom t3 (stock compressor housing bored out with a bigger wheel, t3 exhuast housing), sard fpr, greddy fmic, 3inch straight pipe

can anyone tell me why there is a huge "dip" in the powerband?

Edited by sd9k
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https://www.sau.com.au/forums/topic/236635-rb25-engine-troubles/
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sd9k Apprentice

sd9k

Posted
  • Author
Posted
need ecu

meh alot of money went out this past month so it will have to wait

which baffles me is that my car has run perfectly fine in the past with about the same amount of hp

any other ideas?

PM-R33 Grand Master

PM-R33

Posted
Posted (edited)

AFM maxing out by the looks of it and hitting airflow cut. How you managed even that power on the stock AFM is interesting....

Also, you aren't running the standard injectors and fuel pump are you?

Edited by PM-R33
sd9k Apprentice

sd9k

Posted
  • Author
Posted

ya stock injectors and fuel pump

prolly back the hp down to around 230-250 or so

i've ran that power before with nps

but i think it's just way too lean

takin git back to the dyno friday

so hopefully everything will be sorted by then

or it rather be

ha

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Yep AFRs are horrible, knock sensor is probably going nutso

huh?

AFR's look fine to me, sitting on 12:8 - 13:1 quite consitently. Dosn't seem anything wrong there

Gets a slight leanout as the RPM goes up, but that looks to be totally controlled by the tune as its not sharp, its slight, even and linear.

270rwhp is 200rwkw, which is what is probably the limit of the stock turbo.

And as your the aftermarket turbo, its likely reaching the AFM limit as stated. Every car is different with the AFM. Some are fine, some dont like it. Just how each seem to be really.

I'd be looking to

1. Change the fuel pump (do it regardless)

2. Upgrading the AFM

In the short term to get it driving nice, smooth and so on. Retune required there.

3. As i'd roughly say the turbo should make 340rwhp or so (hard to tell but thats what id be expecting), injectors might not be a bad investment at some point depending on how 1 & 2 go.

Cheers

Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

remember ppl US power is about 20 to 40 % more then Aussie power. We work on true HP figures not the fairy HP that gets quoted on the other side of the globe.

that AFR is too lean. i would not let any car off the dyno with a AFR like that unless the owner knows it needs to be fixed. IMHO

Lithium Grand Master

Lithium

Posted
Posted
remember ppl US power is about 20 to 40 % more then Aussie power. We work on true HP figures not the fairy HP that gets quoted on the other side of the globe.

Couldn't disagree with this more - so bored of hearing Aussies say that. If any dynos could be said to read "untrue", its Aussie dynos. Low reading doesn't mean more true.

that AFR is too lean. i would not let any car off the dyno with a AFR like that unless the owner knows it needs to be fixed. IMHO

Very much agreeing with that - not sure why sd9k is asking for advice and then basically ignoring it. Sd9k - you are LUCKY that you haven't blown your engine up running that kind of setup, the ECU is obviously trying to save it and with no help from the S-AFC.

A Neo by no stretch of the imagination gives you a decent proper tune, and you shouldn't be running a bigger turbo like that with stock AFM/injectors/pump. I am pretty damn sure anything else you try at this stage will not work, a proper ECU and associated fuelling changes are the first things you should be considering. Really - you should have done that before changing the turbo if limited funds are an issue.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
remember ppl US power is about 20 to 40 % more then Aussie power. We work on true HP figures not the fairy HP that gets quoted on the other side of the globe.

that AFR is too lean. i would not let any car off the dyno with a AFR like that unless the owner knows it needs to be fixed. IMHO

Haven't people been tuning around that a lot lately?

More higher end tuners etc.

I cant remember exactly ;)

Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

Okay so your saying aussie dyno's read low compared to the ones used in the US ? that would explain a few things.

and yes that car needs some serious attention. if you drive it hard like that it will blow in a matter of time. Take the advice given by these guys, computer, injectors and fuel pump is a MUST for this car or you will destroy the engine, have to buy a replacement and then still be where you started from.

Lithium Grand Master

Lithium

Posted
Posted
Okay so your saying aussie dyno's read low compared to the ones used in the US ? that would explain a few things.

Dyno Dynamics are pretty much the lowest reading dynos used anywhere. Again, that doesn't mean they are more or less accurate - they just put smaller numbers out.

  • 2 weeks later...
sd9k Apprentice

sd9k

Posted
  • Author
Posted
Couldn't disagree with this more - so bored of hearing Aussies say that. If any dynos could be said to read "untrue", its Aussie dynos. Low reading doesn't mean more true.

Very much agreeing with that - not sure why sd9k is asking for advice and then basically ignoring it. Sd9k - you are LUCKY that you haven't blown your engine up running that kind of setup, the ECU is obviously trying to save it and with no help from the S-AFC.

A Neo by no stretch of the imagination gives you a decent proper tune, and you shouldn't be running a bigger turbo like that with stock AFM/injectors/pump. I am pretty damn sure anything else you try at this stage will not work, a proper ECU and associated fuelling changes are the first things you should be considering. Really - you should have done that before changing the turbo if limited funds are an issue.

i'm not ignoring advice at all man

i just don't come on here that much

but as far as the car is concerned right now

the guy who was supposed to retune the car never returned my calls

so i said f**k it and returned the boost back down to stock

and all of the corrections on the safc back down to 0 and the car runs fine like it did

and as far as the turbo on the car, it came like that when i bought it so i didn't really have a choice in the matter

but thankfully i'm coming into some moeny here next week like 1k bucks

so i'm pretty hyped

going to buy 550cc injectors, GTR fuel pump, and a z32 maf

is an ecu reflash a good idea or should i just wait to get a PFC

i've heard nothing but good things about PFC so i'm assuming that's the standard esp for RB's

but i'm open to other options as well

thank you all for the support and advice :cool:

Cheers.

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