Explain Me This....

[Ryanrb25]

why is it when i squeeze the throttle to build boost (only a little) then flatten it it seems to go so much better than when i flatten it straight away...???

is it because it may be pumpin mega fuel too quickly and boggin it down than when i let it breath a bit before gunnin it? it tends to pull so much harder when i let it build pressure first especially in the mid to top end rev range.

also....

sometimes the boost can climb all the way to 1 bar....i am using a bleeder valve and am full away of spiking etc..this aint spiking..this goes straight to 14 pounds which is straight past the 10 pounds its set at. This is at random intervals in random gears....its doesnt flat spot either...like most rb25's do. it actually goes quite well.

[R31Nismoid]

Search with

+Rich +retard

that will answer all your questions

[T04GTR]

again with rich and retard.0 grrrrrrr no!!

much like your dyno graph is the best way to explain it.

instead of your engine making say 50rwkw at like 2k and slowly coming up on boost and making your power what ever it is..

your not letting the engine "start" to make power instead your skipping the frst half of the dyno graph and going from say 50 instantly to 200 say..

as well as you efectivly giving it anitlag by throttling it then flooring it lol.

[mad082]

gotta love this forum. the moment there is a hesitation problem everyone say rich and retard. if it was R&R he would have it in both situations. he is stomping the gas in both situations, just in one he gives it light throttle for a few hundred rpm then stomping it.

where do you have the bleeder valve getting its reading from? is it a hose that gets vacuum as well as pressure (such as the bov hose) or if it just off the cooler piping. i was getting spiking after my intercooler instal as i had the booct controller getting its reading from the bov hose. i put a nipple into the hot cooler pipe (from turbo to cooler) and this solved my problem.

[Ryanrb25]

thanks mad082

ive had 2 rb25dets and the first had that R and R problem. This one doesn't NO FLAT SPOT, just pulls much much harder when i let it get 0 VAC before flattening rather than having it flat straight up... pull much harder through rev range...

[RANDY]

I used to do something similar with my V8. If I eased the pedal with the revs, it would speed up much more quickly rather than if I just planted my foot down.

I'm still testing with the Skyline, and I think I feel what you are feeling... but not as obviously.

Two thoughts...

1) Perhaps it just feels better because you're already moving some speed before you hit the pedal, and the sudden burst feels stronger?

2) Possibly this could have something to do with the maps in the ECU? You'd be on wide open throttle (TPS sensor), but at a low rev-range, and the AFM would be reporting whatever air it is currently building up. So at a guess there... perhaps your low-rev, high TPS areas of the ECU are rather rich and/or timing is quite retarded at that point?

Dunno... i'm still trying to work out in my head whether this is myth or fact... whether it's a perceived feeling, or an actual difference.

[Ryanrb25]

yea thats what im still figuring out....i had this problem with my last rb25det....

im just putting it down to when i stab the throttle straight up its pumpin the juce in richening it up more than it has to and boggin it down a tiny bit. where as if i let it kinda free rev with 0 VAC its cleared all the 'dead' fuel and its ready to GO....because i feel a NOTICABLE difference.

[T04GTR]

its all an alusion people.

and can someone please explain to me wtf this rich an retard retared explination means?

is the a diagnostic flowchart for this strange problem. or did someone just give up on a issue and come up with this stupid explination.

seriously. take your car to a workshop and tell them "oh can you fix my r and r problem " theyle shut the door and laugh a you lol.

do we have a timing light and air fuel meter hooked up to confirm this issue?

were all aware that if the engine knocks/pings it pulls the tiing back?

aaaaanyway. the only true way to tell is a back to back test on a dyno and plot the two graphs

bottom line is theres nothing wrong with your car.

[paulr33]

the stock ecu has excess airflow protection, that is, it will protect itself if too much air is coming in via the airflow meter. this is usally assocaited with someone fitting a boost controller & a bigger exhaust or a combination of either.

the stock ecu has a ramp for what it considers is too much airflow for a given RPM range and if it (afm voltage) exceed's this value it kicks the timing out the window and runs mega rich. the ecu assumes something is wrong and backs off timing/afr to protect itself, hence the name "excess airflow protection". its other names in "boost cut" or "rich and retard" as simply thats what it is.

[bazr33]

Sorry to interrupt

but im havin similar issues, with slightly putting my foot down at 100

comin under load, and jsut creepin into positive boost

that my car starts hesitating, and feels like compressed air build up and then unloads the air back through the propellers through the turbo.

and jerks.

its comin down that i f@#kin hate drivin my car,

other then that ya flatten ya foot and it pulls hard as.

I have noticed it in 4th and 5th.

And have only noticed it since i had a tune with my pod air filter install, 550cc inj, fuel reg, and upped boost to 18psi.

Anyone have similar problems, im goin to get my car tuned soon. see whats happenin

[bazr33]

and please dont say anything about the turbo

as its not stock, its hiflowed and had been runnin at that pressure for couple of months and is awesome, have checked the play in the wheels recently and is the same as when i got it rebalanced and cleaned.

currently running 320rwhp but have restriction on standard actuator and only goes to 15psi

[T04GTR]

basr33 your getting compressor surge. quite common on highflows still using a smalish exhaust housing.

its heaps anoying.

fitting a factory tension blow off valve and plumbing it back should fix it.

although my gtr when it was stock used to do that heaps hard on the freeway. peoply crusing past me looking at me as my car sounds like zoidburge. heaps funny but

[bazr33]

i have a turbosmart type 3 blow off valve

would you be able to explain what a factory tension blow off valve is

cause from lookin at it, it sounds like it nothing to do with the turbosmart one.

is it one thats on the turbo itself??

Any help is much appreciated

[bazr33]

and i'll just add in that my turbosmart bov is plumbed back in if it makes any difference.

thanks

[paulr33]

compressor surge actually occurs when the pressure past the compressor outlet is greater than what the compressor can actually supply. that is, for example if the compressor map dictates that in the best possible turbine speed it can flow say 12psi of pressure and you are actually getting say 14psi. the compressor is forced to a speed beyond what it can supply in a stable state, so the compressor wheel surge's.

it usually sounds like turbine or compressor wheel flutter as its coming on boost (vl turbo zzztttt ttt tttt tttt noises). you should discuss this with the place that supplied the turbocharger hiflow and do a few simple checks on your car setup. look for leaks, fouled intake tubes/pipes/clamps. check the bov setup.

[Ryanrb25]

way to hijack....

MY CAR ISNT DOING THE RETARD TIMING- RICHEN UP SAFETY SHIT!!!!

do you NEED me to repeat that..i know what that is and its not that.

I will repeat what i am DISCUSSING! not complaining about!

I PULLS HARDER FROM 2000 RPM to 6800RPM when i feather throttle to 0VAC to 1-2psi and squeeze throttle. RATHER THAN having it on 15VAC and STAB the throttle!!!! pull so much harder its noticable. all the way to redline WITHOUT any flat spots.

[chiksluvit]

i'll give this a go...

to put things simple

at lower revs when engine doesnt require that much intake air, with throttle fully open, airflow will be slower than throttle partially opened

so thats why, say for arguments sake, on 3000 rpm, full throttle will be slower than 50% throttle

at higher revs, the throttle will need to be fully opened so that the air flow can catch up to the engine speed

so progressive throttle will always be faster than flooring it when accelerating from lower rpm, this gets more apparent in a taller gear

but yeah, not good flooring the car in lower rpm, it just stresses the engine

ecu will dump more fuel and add timing -- doesnt promote torque either

Edited January 7, 2007 by chiksluvit

[Ryanrb25]

thanks for that, thats' all i needed...