Turbo to big for standard ECU??

[blackrb20silvia]

hey people as some of you know i have finally got the car running after 12 months of build time

Now that it is running im having big problems with the car on full boost

it kinda splutters and stalls and is real ruff but only at ariund full boost

now here are the mods

can some one siffer through and try and help me narrow the problem

dont know what size the turbo is but have been told it slightly larger than T4

Externall wastegate with 10psi spring

custom manifold (high mount)

3" dump high flow 3" cat and Exhaust

large front mount

malpassi rising rate fuel pressure reg

GTR fuel pump

i think thats bout it for the mods to the engine

what im thinking is becuase i have a standard computer and air flow meter and injectors some thing is not keepimg up and i dont know what it is

what Kw rating do the injectors computer and AFM have

like when do they max out or what causes them to max out

i dont think injectors are my prob as they have the malpassi keeping them going

but i could be wrong

maybe the AFM and the computer as they are controlling the show

is it possible that the turbo that i have on the car is to big and flowing to much air and not able to read it all??

as i have no clue what to do

i do plan to upgrade to a Wolf 3d which will do away with the AFM anyway

but for now i just want to know what the prob is

mind you the engine is a RB20det with a big turbo and only 10psi

what is the problem have others had this problem???

matt

here is pic of turbo

[dangerous_daveo]

Silver or black top malpassi???

[Al]

The ecu is definately a major problem. Without tuning the ecu you are risking blowing you 12 months worth of work. Have you had it dynoed yet? What is the air/fuel ratio? what is the inj duty cycle?

With any turbo upgrade you need to first change ecu, inj, and pump. If you want to take full advantage of the turbo.

[Cubes]

I got 176rwkw at 4400rpm with 92% duty cycle. 12.0:1 afr's, The stock AFM was getting 4.98v so very close to its limit.

The Z32 AFM dropped afm voltages by almost 1v. Highest I get now is a shade .002 or something 4v.

Dyno figures vary so really all you can go by is the afr's, duty cycle and AFM voltage readings. Chris32 made 190rwkw or so but the afr's were a little lean getting very close to 13:1. A dirty fuel filter would cause his to lean out and ping, it was that close to the edge.

I'm thinking my Bosch 910 fuel pump that is 3years old may be getting a little long in the tooth, either that or I need to supply the fuel pump via a replay direct battery voltage.

I've known a Bosch 910 to make 260rwkw and only start having issues supplying fuel after that.

[fresh]

u can't change AFM on a standard ecu.........i'm 99% sure of this, by changing to a bigger AFM your car will run leaner cause ur AFM will send in a lower voltage despite more air flwoing in and the computer will correct accordingly, hence u leaning out, buy an ecu, for god sakes, all that work and u stinge on the computer, shoulda been the first thing u bought

[dangerous_daveo]

Id say its the fuel pressure reg. Change it to the one you dont have and see what happens. IE, black top, go for silver top, silver go for black. Also what fuel pressure are you running thru it?

[BHDave]

Id say its the fuel pressure reg.  Change it to the one you dont have and see what happens.  IE, black top, go for silver top, silver go for black.  Also what fuel pressure are you running thru it?

I agree. If it's a rising rate reg then you will find there is more fuel being put into the engine than the ecu realises and as a result you will have very rich mixtures and associated misfires when the ecu switches to open loop.

If you remove the reg and run the turbo at 10psi then you will be reaching the limits of the stock injectors and AFM too as some of the other guys have mentioned, but in all honesty you can get about 180rwkw fairly safely with the stock ecu/injector/afm combo.

If in doubt, put it on a dyno and see what the top end mixtures are like.

[blackrb20silvia]

1 i know a computer had to be the first thing i had to change but im not rich and every thing i got i got after shopping round but any way i am getting a wolf 3d but i was just concerned as everything and i mean everything on this car has been changed like i mean every nut and bolt i have had so much bad luck and i knew i had to change it but i wanted to make sure the car would be ok

aalso i have to drive 4 hours to syd then get the computer and a tune in one go as it would be realy stupid as to fit the computer then drive a farked and retarded piece of shit just to get a tune you know what i mean

2 its not the reg as the car runs the same weather its on or off the car when we set the base fuel pressure we noticed a imediate gain turned it half turn more (its adjustable fuel pres reg) it became absolute shit splutters all through the rev so wound it all the way back so its running off the standard reg at the moment till i get the computer

dont get me wrong the car pulls really hard its only round bout 6000 rpm it fells like its leaning out so ill assume that its only the computer that is causing this???

sorry no dyno still have engineering and blue slip and rego to go

engineer will come round on sunday so all will be legal on monday tuesday and ill see how much i have left over

how much for a tune approx anyway like from scratch does anyone know i just need like expeiriance from what people have payed for first tune i need to know how much to budget??

matt

[dangerous_daveo]

Dude, is it a black or silver top malpassi. Mine was crap on a black top as they are run off a different rising ratio. Put a silver one on and awesome. Also whats the base fuel pressure set at. Mine was orginally at 40psi, its now down to 31psi and its a LOT better. Obviously different car etc. But if it splutters with it on, and leans out when its off, I think it might be a reg problem. Theres a few people that have had no problems with their cars running similar set ups while saving for the ECU.

Just my thoughts anyway.

[blackrb20silvia]

silver top cant remember it was in kpa we measured in

dont quote me but i think base was 240kpa?? i think that is bout 34psi

wound out to bout 300kpa went great

[Cubes]

Clutch fluid level looks low.

[Jolinator]

Cas looks quite advanced, how much timing?

[blackrb20silvia]

clutch fluid is perfect its a nissan patrol master cylinder had to find a new master as i have installed ABS and finding a ABS master cylinder for a silvia is like finding rocking horse shit so i bought a new patroll one from nissan

CAS is set at 15 degrees BTDC as per nissan specs

is this correct where do you think it should be????

any one with a rough price on a first tune for any aftermarket computer ???

[Cubes]

Must be the different master cyl.

Mine looks like the fluid is almost at the top when its filled to max.

With regards to the cas postion, it looks ok. Mine leans slightly towards clockwise of center and its set to 15degree's. 15degree's is spot on for the RB DET's.

20degree's for the Rb26 from memory. Larger overlap requires a little more timing for it to idle nicely.

[blackrb20silvia]

sorry my mistake what you can see in the pic is a brake master cyl sorry its a nissan patrol and clutch master is a brand new gen nissan

[Cubes]

lol no its my mistake.

I said clutch when in fact it is a brake. lol

[Jolinator]

15 is fine, :kick: i just realised i have an adjustable exhuast cam gear, hence it being retarded more

[blackrb20silvia]

ok all i have maybe solved the problems concerning the turbo and computer

previusly i would only be able to run 7psi on a 10 psi external gate spring

now i thought this was wierd but was assuming that this was cuz of the cooler and the pressure drop

i was wrong i had a slight miss at idle and all through the rev range so i changed over the plugs all brand new with less gap then before (was 1.1 now .8) and changed all the coil packs to new ones

and now all solved

boost now hits 10 psi hard and pulls all the way to limiter with out a splutter or shutter at all and no miss

i cant believe how much a diff it made im in love again have not taken for a full hard drive but seems 100% better than before

ill keep you all posted have to go for a long trip tomorrow so ill see how it goes

but yeh maybe the turbo is perfect

i know might even wind the fuel pressure up as well we will see how she goes

thanks all who helped out with advice any more is also much appreciated

cheers

matt