Low Rev Problems

[Krille]

Ive mounted a rb25det neo into my r32gts, also done a top mount conversion along with a bit inlet manifold and 90mm throttle body, and new 630cc injectors, also mounted new splitfire packs and iridium plugs. also mounted a greddy Emu, also walbro fuel pump and removed the control unit for standard fuel pump and replaced it with a relay.

the car runs fine except most times, happens alot then the car is warm, when im stopping and lights and such the car dies, sometimes the rev goes down to 1k idle then drops down and engine stalls, it can go into idle if i help with the pedal a bit, but then the idle is around 600rpm, and then when im give it a small gas it dies, but if i give more gas it coughs and then goes up and runs fine. if im looking at the log in the Emu, when i get the car idling the ignition jumps around a lot, could this be just the TPS thats in wrong place, tried to adjust it but not sure where it should, at one part i didnt get any idle at all, at another part i got very weird rev, jumped from like 1200 and 800 up and down, apart from this the car runs fine when im driving, only doing like 1bar atm, but nothing seems unstable with boost and vacums and such

also have Hks Ssqv and ive tighted the spring a bit.

ive also mounted the R34GTT instument cluster to get the speedo working, and ive checked for codes using the engine check light, but ive connected different parts to get all codes away

[aphid]

Are you sure it's not the Blow off valve?

When you're on the gas heading to a set of lights, and the light goes red, you push the clutch in and get off the gas onto the brake. The blow off valve opens up and lets out air that the AFM has already measured as being in the system, so the ECU is still injecting gas into the engine, making it run extremely rich and causing the stalling issues as you've said.

AFM reversion can also cause similar symptoms. The flutter you may hear when the BOV sounds is actually air flowing back out through the compressor, flowing the wrong way through the AFM. This upsets the AFM readings and can lead to the same stalling issue.

My 2cents anyway, best of luck with it!

[Krille]

tried tighted the blow of valve spring more but no difference i only hear the flutter if i rev the engine pretty high, forgot to mention that also when its warm the car is often very slow to start

[Benzino33]

AFM or IAC valve. get them cleaned or replaced, im sure that will fix ur problem

[Krille]

just had everything apart and checked and fixed before i put all together, the IAC valve is now located under the inlet så cant be taken out without removing the engine...

is there a posibility that you have to adjust the idle screw when you change manifold?

[chinii]

i hav the same problem s1 r33... i changed spark plugs and coil packs are fine, cleaned IAC valve and AFM and ran injector cleaner but still keeps stalling when the car is warm n comes to a stop i dunno wat to do. would it be o2 sensor or ecu (i think its been remapped or sumting rev limiter kicks in only at 8500rpm) or anything else :S

[Benzino33]

the IAC valve is now located under the inlet så cant be taken out without removing the engine...

What? I took mine out without having to remove my engine, i just unbolted the intake pipe where the throttlebody it to get easier access. unplug a few pipes and its real easy to change

[Krille]

just but as i said ive changed intake manifold for an aftermarket one so i can have a topmount turbo, this new large intake doesnt have have the intake part for the idle valve in the back cause there is no space, so its fitted on the underside pointing down

[Krille]

checked timing now, somethings messed up there, unplugged the TPS and checked, i couldnt see the timing marks then, pulled the cas max to retard, then i got the marks to 25degrees, what more controls the timing?

[aphid]

Not really across what kind of tuning ability the Greddy EMU gives you, can you run a map trace on it?

If so, replicate the conditions it'll stall under watching the map trace and note the cells it'll hover around when it stumbles and stalls (Should be the very left column) and then lean the shit out of them..

To stop the stalling on my engine (T04Z rb26 with a power fc) I have to run these so the ecu thinks it's running an AFR of around 25:1

I dare say that'll fix your problem..

EDIT: The stock ecu runs +15deg ignition at 650 - 900rpm, so as long as your ecu is still stock and the Greddy EMU isn't set to intercept the ignition if you're seeing +15deg ignition at idle your timing will be correct

Edited June 24, 2009 by aphid

[Krille]

Hmm okay heres a weird one for you all.

Ive checked and double checked most things now, till i tried stopping the vacum pipes to different sensors, and when i stopped the vacum to the standard mapsensor the car suddenly gets good idling?

what i know the standard Map sensor only have mission to check for over boost?

next question, can i just plug the hose going to the map sensor and run like that? im using both Emu and Apexi AVC to control everything, or will the standard ECU go into fail safe if it doesnt get readin from the standard map sensor in some time?