BuckyFD3

Tryign to sort my car out today so took it for a drive to get some miles on it to run it in. (only has about 90miles on it since rebuild)

The car runs mega rich and when cruising runs at high 12's AFR, if I turn the injector duty down it just starts to stutter and back fire and the AFR doesn't change.

At cruise the injector duty is in the 40% range and I am pulling slight vacuum, if i put the throttle down and produce boost (around 5psi) the injector duty doesn't change but the car smoothes out and is alot better to drive (AFR's still in the 12's)

But later on once I hit 5000rpm the car started to stutter alot and the wide band was going from lean to rich very quickly.

I have also had to turn the primary injector duty down to 80% to stop it running in the 10's, as I said before if i go any lower the car just stutters and backfires.

To me it sounds like dodgy injectors or wiring, but I dont think I should have 40% duty at cruise either.

It running the base map on the PFC.

Any ideas??

sdminus

What are the current injector settings ?

Is the wide band calibrated correctly

Scott

BuckyFD3

running standard injectors 550 and 850's, the wideband should be ok. It is running stupid rich since I was only getting 5mpg when i had the primary injector setting at 100%.

BuckyFD3

Put some 850's in the primary the other week and it ran like a bag of ****, just wouldn't rev. I changed the injector settings on the commander aswell.

sdminus

Is the car flooding. There is a posibility that you have a leaking o ring on an injector.

Scott

edit--- did you have the fuel rail machined to fit the 850cc's in ?

BuckyFD3

Yea I machined the fuel rail. I'll check the orings 2morrow but i'm sure they are OK.

Runs at 20% duty at tick over at 3000rpm, that still seems to high for tick over (runnign the car in so thats why tick over is at 3k btw)

sdminus

Yeah that duty is way high for idle..I presume you have a large port then hense the high idle.

you are sure the injector settings are 100%.

Scott

BuckyFD3

Large half bridge port. it does idle at 2000rpm or lower it just set it at that so it doesn't stall.

Primary injector settings are at 80% atm to bring the fuel down.

I'll try the standard ecu and see what happens then, thats if it doesnt take a fit with all the solenoids removed

sdminus

The correct settings for the 850cc's used as primaries are 64.7 % and 0.04

Scott

BuckyFD3

I now have the 550's back in. Just tried to start the car on the standard ecu and it didn't work. (might not be enough compression yet with running it in)

sdminus

Im not sure if the stock ecu will like a half bridge. THe new port wont help the engine produce much vacum. Stick the power fc back in and reset the injector settings. It looks to me like you had the incorect values in for the primaries.

Scott

BuckyFD3

I have had the primarys set to 100% and it was running 10.8AFR at idle, so reduced it to 80% and it now runs mid 12's at idle and cruise.

To me it seems like the injectors are dodgy.

sdminus

ok.... Well the settings i gave you are from my own car. I idle at 12.5:1 and cruise at 16.5:1

Scott

BuckyFD3

I couldn't get the cruise above 13.8 without it stuttering and backfiring. like it had ran out of fuel.

EDIT:

What injectors you running??

sdminus

denso 850cc primaries and the same in the secondaries.

Scott

BuckyFD3

I'll try my 850's in the primary again and see what happens.

sdminus

For added piece of mind why not pull all 4 injectors and send them off to be cleaned and flow checked.

Scott

BuckyFD3

Thats what I will do

JhnRx7

iTrader: (12)

I have 850's all around, my injector settings are 64.7 and 0.04. no matter how much fuel i take out i am still extremely rich at idle and crusing. are there any other settings i can play with that will fix this and allow me to tune my idle and crusing?

cewrx7r1

iTrader: (2)

The running rich at idle with large primary injectors has been discussed many times here on this forum and is mention in my tuning notes. Doing a search on 850 will most likely result in your answer.

Here is a hint: you have to use primary injector lag to lean out the idle. Once this is done, then you tune your boost AFRs as they will have gone leaner.

Ledfoot

iTrader: (1)

...if your primary rail is machined to accept the shorter 850cc...

You might want to try this.

The Commander does not allow you to change "INJ Pr Lag (ms) vs BatV"
This is the reason for the making the calcs for "Injector size and lag difference".
These are Commander specific calcs and settings.

The Datalogit however allows you to change values for "INJ Pr Lag (ms) vs BatV"
For 850cc primaries
Copy the values from "INJ Sc Lag (ms) vs BatV" to "INJ Pr Lag (ms) vs BatV"
Set "Q Primary" to 850
but leave Injector size and lag difference alone i.e. 100.0 / 0.00

....I've been wanting to try this myself, but currently I'm back trying to install a GT35R on my GSXR ....you can never have too much power...just projects...lol