rb25det idles perfect, horrible throttle response

[squigy]

So my 92 hatch is giving me problems. I've never had this motor running in this shell so let me explain the situation.

Mods:
50trim turbo, 63 housing
stock ecu no emanage or anything
greddy bov and waste gate
greddy intake
air intake
n62 maf
stock full rail+injectors
aeromotive FPR
full bolts on pretty much.


I got the idle perfect, i fixed all of the vacuum leaks, and stuff like coils, igniter, CAS, tps all work , because the car idles fine, when i go to give it gas, 1/8th throttle, 1/4th throttle or anything more then a tap, it sounds like it bogs down and it will just have horrible break up. the turbo housing is being rebuilt right now because it was leaking oil in the exhaust. also i had backfire because of that leak and some gas was getting in the exhaust mani. new walboro pump, new FPR at 40 PSI, one thing i do notice if i feather it into high rpms it still breaks up but it will manage to get there and also vacuum is at -18 to -20 , but when i get it to high rpms and let off the vacuum dips down to -30+. any ideas or anything i should try? ive also put new spark plugs in, and my intercooler piping is on nice and good. one thing im thinking is maybe it needs a tune? an emanage or power FC or something because it might be running to rich. any help or advice is much appreciated!

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[beems240sx]

yes get a tuning system. the stock rb ecu is horrible and cant handle anything honestly. dont even mess with the emanage, its just a giant piggyback. go with something like AEM EMS V2 or Vipec. you and your tuner will thank me later. also get yourself some id1000's. also do a boost leak test and see if it leaks under boost at all.

also what spark plugs and gap are you running?

[Croustibat]

You changed the MAF without getting a tune and wonder where your problem is ?

Get a tune. Your car wont drive with a different MAF if the ECU does not know the MAF has changed. If you need to move, unplug the MAF, the ECU will go on limp mode but you should be able to move the car (not fast). As far as ECU tuning goes, nistune is cheap and easy to use on SR & CAs, i am quite sure it also works on RBs.

[beems240sx]

You changed the MAF without getting a tune and wonder where your problem is ?

Get a tune. Your car wont drive with a different MAF if the ECU does not know the MAF has changed. If you need to move, unplug the MAF, the ECU will go on limp mode but you should be able to move the car (not fast). As far as ECU tuning goes, nistune is cheap and easy to use on SR & CAs, i am quite sure it also works on RBs.

not entirely true. the car im sure will drive alright. every MAF just puts out a value to the ECU. all the ecu cares is that it sees the right values, which right now it is not. nistune will work with the z32 ecu, but at that point might as well go full standalone..

[squigy]

yes get a tuning system. the stock rb ecu is horrible and cant handle anything honestly. dont even mess with the emanage, its just a giant piggyback. go with something like AEM EMS V2 or Vipec. you and your tuner will thank me later. also get yourself some id1000's. also do a boost leak test and see if it leaks under boost at all.

also what spark plugs and gap are you running?

bcpr7e-11 gapped .8 , NGK plugs, my ' Tuner ' keeps trying to throw me at an emanage for 350$ with a new harness. also since i have the turbo off i just connected the maf and plugged up the oil line and had it with open headers, i gave it gas and it just died down.

[squigy]

You changed the MAF without getting a tune and wonder where your problem is ?

Get a tune. Your car wont drive with a different MAF if the ECU does not know the MAF has changed. If you need to move, unplug the MAF, the ECU will go on limp mode but you should be able to move the car (not fast). As far as ECU tuning goes, nistune is cheap and easy to use on SR & CAs, i am quite sure it also works on RBs.

i unplug the maf and it dies down completely.

[smoked240]

i unplug the maf and it dies down completely.


That's good. Means it's working. You need to get it tuned.
The larger turbo and different maf are causing readings the ECU cannot handle. I would go AEM, PFC, Haltech or Nistune.

[Croustibat]

not entirely true. the car im sure will drive alright. every MAF just puts out a value to the ECU. all the ecu cares is that it sees the right values, which right now it is not. nistune will work with the z32 ecu, but at that point might as well go full standalone..

Every MAF outputs a 0-5V signal (at least on cars of that era). It is the image of the flow, which depends on the VE map contained in your ECU. using a MAF that flows 10grams/min for a 2V input when the VE map says 5grams/min for 2V means your ECU cant manage. (totally arbitrary figures, i dont have nistune installed on this computer so cant see nor post the VE maps)

Basically, the scale changes. And it is not linear at all.


The reason why it idles is because the MAFs send a similar, very low voltage at that kind of flow. but once you get more flow, then the values change completely, and your ECU is lost.

If you just changed turbo/maf /injectors, no need for a full standalone really... unless you want the latest refinements like builtin boost control, launch control, flatshifting and so on. But emanage? I cant see the point. I have seen 500+HP setups on a CA18DET, controled by a nistune... really, no point in getting a "real" EMS at that point, unless you want to show off and spend more money than needed. I think i'll get an OMEX some day, these have a very impressive feature list (way better than any expensive JDM tyte yo EMS)

smoked240> the larger turbo has nothing to do with it. He could even run with no turbo, as long as it does not leak, or a big gt42, that would not change (although that MAF will be sending a 5V signal quite often with that one :D ) The MAF change is the problem.

That and as usual there could be some boost leaks here and there. But yeah, i am even surprised the car starts with a bad VE map. Mine did not when i went from a CA18DET one to a SR20DET one (cheap and is still not giving 5V, although very near now, so no need for a big Z32 one that does not see enough flow at idle on these small engines)

Basically, your ECU needs new fueling and timing maps because of the turbo, and it needs a new VE map (sometimes called VQ map) because of the new MAF. Changing just the VE/VQ map is a matter of seconds, you may be able to do it yourself for cheap provided that ECU is not locked and if you know your way in electronics. I can do it on a CA18DET, cant comment on yours though... if it is similar (it should) then you dont need much.

[squigy]

Hmm, sounds like a stand alone will cost a lil more but in the end i will save money
On tuning simplicty.i have few friends with all out race cars with HALTECH but big$$$...
They are full on race cars but get tuned in seconds at the track. One has run 6.70s in the 1/4.
So which is recommended for street on the fly tuning?
Thank u guys so much learning alot on these motors..
Have had ka,sr, and managed to work my way up to an RB.

[Croustibat]

Hmm, sounds like a stand alone will cost a lil more but in the end i will save money
On tuning simplicty.i have few friends with all out race cars with HALTECH but big$$$...
They are full on race cars but get tuned in seconds at the track. One has run 6.70s in the 1/4.
So which is recommended for street on the fly tuning?
Thank u guys so much learning alot on these motors..
Have had ka,sr, and managed to work my way up to an RB.

The EMS you get should depend on this:
1/the features you want
2/the price you are prepared to pay
3/the time you are prepared to spend

Every EMS allows for fast tuning; the difference is what other things they do.

For ease of use, ease of installation and price, considering a "relatively low power" (up to 500-600HP), i like to use a nistune. It is not a true new EMS, as it plugs in your oem ECU, but it offers what you need to tune in seconds (on some engines with a slow bus it takes more than that to transfer files though :D ). Downside : basically every ECU needs a different board. If you change your RB and go SR, you need a different nistune board (the software licence is still valid though) . Features and tuning is limited to what your ECU can do - which satisfies a lot of people actually.

If your only need is fast tuning and you dont plan to change any sensor, i really think it is the best way to go. The hardware/software cost is around 300$ i believe.

Now i nearly bought an omex some time ago. The reason ?It has all the features you want from an EMS for a road car AND for a race car. And it was somewhat cheap at that time. I guess haltech, vipec and other offer a similar feature list, so i'd recommend using what the people you know already use; tuning these is a whole different story than using a nistune (or a PFC if that matters)

Anyway, omex 710 series feature list (standard ECU features removed from the list):

Up to 12 cylinder ‘coil on plug’ ignition using external amplifiers
Sequential fuel injection for up to 12 cylinder engines -> i can manage 2 injectors per cylinders with that
Inner and outer injectors mapped on both speed and load
Programmable load and speed sites
TPS or MAP can be used for main load sensing
Wide range of crank trigger patterns are suitable (user programmable) -> this allows to use any crank angle sensor. Want to keep the current CAS ? i can !
Turbo wastegate control -> i am running a boost controler. That is a 300$ feature by itself
Turbo anti-lag system -> Because lag is bad. Another 200$ feature
Constantly variable cam control -> dont want to lose your VCT ?
Launch control -> because anti lag is not enough
Inbuilt 1/2MB data logging
Narrow and wide band lambda support -> no need for an external wideband controler, another 150$ economy.
Twin lambda sensors -> useful for V engines.
Individual cylinder trims for fuelling -> 1 AFR sensor per cylinder anyone ?
Push/pull, and single line idle controls in addition to scattered spark control
Knock sensing capability -> no need for a phormula knock device.
Security protected calibrations -> no more fried injectors / drivers
Full throttle gearchange ->flatless shifting !
Intercooler water spray control -> another 200$ goodie
Water injection control -> if e85 is not available
Nitrous ignition retard ->oh yes, it can run nitrous.
Cooling fan control -> another 50$ economy, no need for a fan controler
Internal 1 bar MAP sensor for barometric correction -> no bogging down when on mountains
Uses the latest version of the superb MAP3000 Windows programming software -> i dont know about that. Sounds good :o
Inbuilt independent fuel and ignition rev limiters -> programmable soft and hard cut
Tachometer, Shift Light and Fuel Pump outputs (and other programmable outputs) -> no need for a stack dash
Magnetic or Hall Effect crank and cam sensors ->if i ever use another engine, i can keep that EMS
Automatic interpolation between mapped sites ->any ECU does that, marketing BS
Sophisticated acceleration fuelling setup ->any ECU does that, marketing BS
Battery voltage compensation table for fuel injectors (not just a simple number)->any modern ECU does that - our S/Z ECU dont ... but they dont really need that.
Battery compensation and engine speed compensation for coil charge time ->now THAT is great.
Mappable coolant temperature compensation for engine warm-up -> standard on oem ECUs
Air & coolant temperature compensation for fuel injection pulse width -> neat. Now standard, but was not on S/Z engines
Separate cold cranking and decay tables in addition to warm-up fuelling-> not every race EMS has that, and you want it !
User settable ignition trim based on air temperature, coolant temperature, and barometric pressure -> neat.
Separate start advance for cranking provides easy starting for high compression engines -> nice for NA
Deceleration fuel cutoff feature for road engines -> standard
Maximum recommended engine speed 12,750 RPM ->that, i love.


It really IS nice. But the price reflects that. Bare EMS: 1000£ . Add a 3bar MAP sensor, temp sensor, half harness, communication devices and so on and that is another 500£ on top of it.

[greenwood]

please please dont be running stock injectors on that setup.

[squigy]

please please dont be running stock injectors on that setup.

stock injectors stock rail =( i have a aftermarket rail and no injectors yet.