lsjon

f20b dohc vtec engine
chipped ecu with f20b basemap by j-k-tuning.

Full throttle im getting engine bucking. Feels like fuel is cutting in and out during acceleration.
More common when trying to give full throttle at 3k-4k.
Light throttle doesnt cause the same effect.
also running into issues with choppyness when letting rpms fall during breaking.
Throttle engagement isnt very smooth either.
No CEL on.

Recently replaced.
fuel filter
cap
rotor
chipped ecu(was runnign p13)
coil
plugs
New 02 sensor
No egr(chipped ecu has egr turned off)


Next step is wires. ( any recommendations beforedoing this)

snobordboy

How did it run on the old ecu? My first thought is to get rid of the crap web tune and get tuned on a dyno.

lsjon

Had same issue with old ecu. The tune should be fine, since the tune is the same as many other similar setups.

snobordboy

What injectors are you running, and do they require the resistor box, and is the resistor box plugged in? How is the cat, if you have one?

lsjon

Pretty sure their obd1 h22a injectors. And yes a resistor box is plugged in. Car has no converter.

Gonna test another coil today, and a set of wires.

Should also point out the car seems to run into more choppyness the longer it runs. It's not overheating though.

snobordboy

Hmm, maybe fuel pump? It could be going out, and as it heats up while running it pushs less and less fuel.

lsjon

At lunch i hooked up fuel pressure gauge to the service port, and pressure stayed consistant between 30-40psi, which is where its supposed to be. Gauge stayed on point during the surging as well at full throttle. So that ideally means the pump is working.

1GPlusSH

have you tested your injectors? pull some spark plugs and see how lean that thing is.

lsjon

Havent pulled injectors yet. It smells like its running fairly rich though.

1GPlusSH

is there a setting in your tune for launch control that has a mph on it? if so, that needs to be set at zero. i'm all out for other possibilities that you haven't checked.

lsjon

Does not have a launch control that im aware of. Yes im running out of ideas as well, so im just gonna throw a coil and wires at it.

Sebastian26

I'm having that same problem with my F20 in my DX . Idles rough , chokes and cuts back when accelerating . I have changed wires , plugs, injectors . And it runs really rich . Haven't considered the fuel pump though .

Ariddle25

did you figure out the problem im havving the same problem with my gsr

Ariddle25

although i am not running a resistor box. but i didnt run one at all with my old setups any ideas should i put a resister box in?

Turbo3GLude

I know I'm new here at H-T so take the following as you want.

As far as I understand without a resistor box 3 ohm injectors are prone to pulse errors, with a 12 ohm you would remove the resistor. Could be part of the problem...

Zak Ketts

I am also having issues with my f20b in my eg hatch. bucks like crazy in 1st taking off and feels like fuel cut if i go wot it cuts out and bucks seems to only go to 3-4k...has anybody figured it out...im on a p72 ecu chipped with f20b basemap...replace rotor, cap and blocked the egr but still runs rich...please help about to tear apart wiring to check it over.

holmesnmanny

Just like they were saying, check the resistance of all the injectors. If they are 3 ohms or less you should be running a resistor box.