Slow Rb25. Need Help Please

[RB30 Ceffy]

Thanks for all your ideas guys. Much appreciated!!!!

The engine in the car is a bone stock standard S2 RB25DET. I have a K&N air pod and a Blitz cat back exhaust on it with a test pipe. The ECU is factory, boost is at factory level too.

The air filter is fine. She runs the same with the filter and without the filter.

I do not have a boost controller. The waste gate actuator is working properly too. I don’t spike anything over 1 or 2 psi above standard boost levels. So boost is currently at .5-.6 bar.

As for the VTC not switching properly and giving me a retarded ignition timing, this could be a problem. The pins to the VTC are fine with the ECU and I never got a code when I plug in the Nissan consult. This made me think that it was working properly. If someone could explain how the VTC works I can try to diagnose this further than I already have.

As for the R&R I would hope to assume that since everything is standard I should be able to fix this problem without using an AFC. I do have one and could use it but for now I would like to keep the factory management and fix the problem if I can.

I am trying to book some dyno time in the next couple days. So if everything goes well I should be able to get a dyno graph posted before the weekend. That should help me in the right direction and rule out a lot of possibilities.

Thanks again for all your help, keep the ideas flowing

[NUTSGTR]

Hey Dude, I know this is p**s weak but I just couldn't help myself; have you taken the handbrake off? :laughing-smiley-014: Sometimes the obvious is the answer... sometimes its just stupid.

[munro'sgts-t]

if u dont have anything useful to contribute dnt bother saying anything mate where all hear to help each other not take the piss outta people

[NUTSGTR]

if u dont have anything useful to contribute dnt bother saying anything mate where all hear to help each other not take the piss outta people

In all seriousness i was trying to make a bit of a valid point. RB30 Ceffy said he had this problem with a previous engine in the car. Every1 seems to wanna find faults with his current engine setup when perhaps its a problem with the driveline/chassis. Maybe his brake system isn't up to scratch. He's ruled out just bout everything else and he wanted ideas! Probly wrong but whats the harm. Geez settle on the tude dude.

[RB30 Ceffy]

No worries on the question. I had a feeling that somoene would post that. haha

But ya, brakes are just fine. I can push the car around the yard on my own and the e-brake is working like a pimp does his ho's.

Doesnt look like I am going to get dyno time this week I am running out of time and need to run to the states to import a trailer this weekend. Hopefully early next week I can have something up.

The more I think about this problem the more it seems to be the R&R. I just wouldnt know why it would be doing it or why im not getting any codes for this.

[Johanz]

if you find any solutions, do let us know.

its the same problem with my car. boost buildup is fine. after around 3500rpm, it feels "empty". then between 6000-7000rpm, it feels ok(can feel the g force). no boostcut on my car, no airfilter installed (not running airflow), VCT running ok. car is bone stock except for walbro 255, megasquirt EMS. its not about tuning. feels like no boost. boost leak check OK.

[RB30 Ceffy]

if you find any solutions, do let us know.

its the same problem with my car. boost buildup is fine. after around 3500rpm, it feels "empty". then between 6000-7000rpm, it feels ok(can feel the g force). no boostcut on my car, no airfilter installed (not running airflow), VCT running ok. car is bone stock except for walbro 255, megasquirt EMS. its not about tuning. feels like no boost. boost leak check OK.

My car is slow right to redline. If you loose power in your mid range and get it back I would assume you either need new plugs or the tune in your ems is a bit wonkey. I would check these first. Don’t think our problem is the same but could be related maybe :S

I will be all over this thread till I get it done. I can normally figure this stuff out but I am just stuck at the moment on my car

Edited September 13, 2007 by RB30 Ceffy

[Johanz]

PLUGS!!! totally forgot about that! i think i'm still running the same plugs that came with the engine from japan! will change soon and let you know if the problem is solved. dang! how could i forget that!

[NUTSGTR]

Im wondering about ur ecu. I'm assuming the ecu is factory but is it from an auto or a manual? As the car is about to change gears in an auto, it needs to reduce torque from the engine for a nice smooth gear change and it does this by pulling timing. Perhaps your ecu thinks its hooked up to an auto and thinks that 4-5000rpm is when it should be shifting? Any chance of this? Can you find an ecu you know is from a manual and swap em over?

[RB30 Ceffy]

the one in it is a 5 speed ecu. But I thaught why not try another one so I swaped it with one I had kicking around the shop and it ran just the same. That one was from a 5 speed as well and is now running in my friends Silvia just fine.

[Nick033]

any updates on this as my car is doing the same sort of thing

cheers nick

[s13_Skyline_inside]

not gunna solve the problem but just thought id add this in for the future, you can run a manual with an auto ecu with no problems, but you cant run an auto with a manual ecu.

the vct is oil activated to do with oil pressure i think, i dont know enough about it to give advice though.

Edited November 15, 2007 by s13_Skyline_inside

[Tangles]

what type of fuel you running ?

have you had a compression test done on the engine lately ?

Id suggest wiring up the safc and trying it on the dyno. just to see if aftermarket air:fuel mangement helps or not

[sh@un]

what power has it made on the dyno and what 1/4 mile times does it do?

[RB30 Ceffy]

Hey guy's. I havnt had it on the dyno yet. I've been very busy and now moving to a new career. Might move to Aus actually

I havnt touched the car since I was tweeking with it. Last thing I wanted to do was drop in the Nissan consult and go take it for a spin to see what timing does. I am sure its geting pulled big time. Havnt had it on the 1/4 mile yet either but if I had to guess it would be about a 18 second pass haha so I save the embaresment and keep the car at home.

The fuel in Canada is total crap. 92 oct is the best I have avalable, tho thats not enough to slow this puppy down. I run many many Nissan's on this crap fuel just fine. I just normally pull a deg or 2 on the GTR's to keep em safe.

I have not run a compression test at all but the engine and the way it drives tells me that everything is okay. I can check but its not on the top of my things to do. I've built many RB's for many reasons and this one seems like compression and leak are fine. But never know I guess. I'll give it a go when I get the chance to.

Any more ideas are very welcome. Thanks guys!

[benl1981]

If it is the same RON rating as our fuel then 92 oct will need more than 1-2 deg timing taken out.

If I run the standard fuel you may need to pull up to 9 deg timing out so you dont see knock on the hand controller!

[black_gtst]

had simular prob with my 25, ended up bein coil packs. would run fine on low boost but anythung over 10 it would do exactly same thing. if not coil packs could be fuel pump. dyno will tell if so (lean)

brett

[copycutter]

I think faulty knock sensor/s could be your problem also.

I had problems with the ECU winding out timing of both my ca18 and my rb25 in my 180sx. The sensor winds the timing out of the engine, making it feel gutless right through the meat of the powerband. Since you've diagnosed about every sensor and replaced your ECU, i'd say you've done about everything you can do without hitting the dyno and watching what's happening with the engine real time.

[RB30 Ceffy]

im in the moddle of moving to my home town and my buddy's got a new dyno. Once I finish up the move I will get it on and see what goes.

I will prob check those knock sensors tho. They are easy enough to change out. I remember checking the resistance on them and being alright but might not have. I might even just toss in a PFC and see what knock I am getting as well. Easier than wireing in a AFC anyways

Everything on the fuel side is good. Normal pressure and even tossed in a new tomei pump for shits.

I dont think a GTR would enjoy a 9 deg retard. They wont run a crap if I were to do that. Knock is safe on a 18-20 deg timing on factory boost. Maybe my oct and your ron may be a different rating??? It's still not near as great the japs have for fuel, but aslong as its safe i'm happy.

[race_snooze]

Have you done a compression test?????