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Rb25det Runs Like Shit

STIVS6

By STIVS6,
in Engines & Forced Induction

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STIVS6 Contributor

STIVS6

Posted
Posted

Hi Guys,

I have just transplanted the 25 into my VS commodore and got her driving yesterday.

And it has no balls at all... I think a Starfire may be able to take me off the line.

I have not done my diff yet, so it is still 3.08 which I know is very low, but the 4.11s will be in soon, but I think it should still have a bit more guts than what it has at he moment.

It is running very smoothly on all 6 cylinders, the fuel may be a little stale (4 months). It idles nicely. It isn't in Limp mode and will rev all day.

I have a FMIC, GReddy Intake plenum, 044 and adjustable Fuel Reg and T3/T4 Hybrid (POS, but no leaks), while these may attribute to the cause of problems, I would not have thought it be as bad as is.

I have turned my fuel reg down to a point where is seems to be between running rich or lean. I have my Z32 MAF removed and a stanard AFM plugged in. I would have though the computer would have compensated and adjusted for the new AIR and FUEL????

I had an eManage Ultimate, but have that off, as I want the thing running normally first before I get into the computer side of things.

What else could I look at?? Plugs? Injectors? Any sugestions.

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Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

you have a skyline engine in a commodore .. thats your problem.

:) I would change the diff ratio to 4.39:1 before you start complaining about power. 3 is just wayyy too tall and it will feel like a megga dog regardless of power.

STIVS6 Contributor

STIVS6

Posted
  • Author
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you have a skyline engine in a commodore .. thats your problem.

LOL, so do VLs... seems to work for them. Don't be rude. :) Its a match made in heaven.

Yeah, I had given some thought to the Diff, but I am not the first to venture the way of the 25 in a VS and the last guy I knew to do it, tested the car at first with the 3.08 and it pulled alright once it got going.

4.11 is standard for R33 yeah? If I can get 4.39.1 for a commodore the shorter gearing the better right?

cactus Collaborator

cactus

Posted
Posted

I have had an RB25 running in my HQ for past two years, and an RB20 in it before that, like you said match made in heaven haha!

Did you change timing belt? When I first put a rb30e in my HQ it was a tooth out, ran awesome but was a slug. But the fact you said it revs well is probably suggesting it aint that. 4.39 is pretty high, I have 4.11's with auto and it revs like mad.

Good luck with it though.

STIVS6 Contributor

STIVS6

Posted
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I have had an RB25 running in my HQ for past two years, and an RB20 in it before that, like you said match made in heaven haha!

Did you change timing belt? When I first put a rb30e in my HQ it was a tooth out, ran awesome but was a slug. But the fact you said it revs well is probably suggesting it aint that. 4.39 is pretty high, I have 4.11's with auto and it revs like mad.

Good luck with it though.

Yes, I have a gates timing belt, brand spanker.

I may go with the 4.11s then. Cheaper too :)

joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
Posted

you need more guages steve :)

glad my afm worked out for ya, just keep it in there until you get hold of one...

whats the kerb weight of a VS? only like 100kg's more then a 33 yeah?

STIVS6 Contributor

STIVS6

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Nah, I havent reset the ECU yet... how do you do that? That may be a half smart thing to do as it came off a halfcut... never now what the original owner was running... I have a couple of things to adjust around the place.

Thanks for the AFM. I may have also found another AFM (r33 1) cheap, so if I can grab that, that would be good.

Yeah, the VS is only like 100kg heavier, but the RB engine is lighter, so the car should be fairly balanced out with a 33 now.

joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
Posted

the ecu should would have been reset when it came out of the halfcut... but since you have had it running with differing afm's etc...

just disconnect the battery and then hit the brake pedal until all residual charge is gone.... reconnect and let idle... it shoud relearn over a short period of time.... 20 mins or so i beleive

STIVS6 Contributor

STIVS6

Posted
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the ecu should would have been reset when it came out of the halfcut... but since you have had it running with differing afm's etc...

just disconnect the battery and then hit the brake pedal until all residual charge is gone.... reconnect and let idle... it shoud relearn over a short period of time.... 20 mins or so i beleive

Excellent, will do. It did take a small amount of time to find idle when I first had it running. So, it may have adjusted a small amount, but not a full reset.

blind_elk Grand Master

blind_elk

Posted
Posted

I may have overlooked something in your original post, but what are the symptoms of "runs like shit"? You've said it runs smoothly, idles ok and will rev all day. What bit "runs like shit"?

You have an adjustable fuel reg - 1:1 or rising rate? If you don't have a pressure gauge on the fuel line, don't go playing with the fuel pressure - you risk leaning the mixture too far at the top end of the rev range.

You are running a stock RB25DET ECU? I don't think they work with Z32 AFMs (which I note you have replaced with a stock unit). And the stock ECU probably won't run too well with a rising rate FPR (top end will be far too rich).

You've checked the timing @ idle? The injectors are firing in the correct order? The sparkies are firing in the correct order?

grigor Rising Star

grigor

Posted
Posted

I doubt you'll do much good here. Conversions need that "hands on" perspective.

Are you sure about the cam timing and IGN timing? Check it again.

Is your VVT actually working?

What actuator is on that turbo and what boost does it make?

Are your knock sensors/harness etc plugged in and working properly?

Did you give the ecu a speed signal?

Neutral switch connection to ecu open?

Use your stock AFM. The ecu has no capability to "learn" that you have fitted a Z32.

I find it odd with that turbo, FMIC and stock ecu you haven't had the R/R jerks.

Even with tall diff gearing, an Rb25 should get up and go in your lower gears once you make some boost.

STIVS6 Contributor

STIVS6

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I will check all these things after work guys and let ya know, thanks

I dont have the z32 AFM plugged in, I removed it once i pulled out my emanage.

I have a fuel gauge on the fuel line too.

Here is a photo of my reg for ref:

http://c1.ac-images.myspacecdn.com/images0...d29b4ad66a0.jpg

STIVS6 Contributor

STIVS6

Posted
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how much boost are you actually running? and also how old is the t3/t4 these things dont make much power with low boost and if the bearings are on their way out it wont make much power either

I recon the turbo is stuffed lol... not making boost. Could be the(internal) wastegate.

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