Gtr Low Rpm Richness And Hesitant

[andre_gtr]

HI Guys

some help here please

so I have rebuilt my rb26 from scratch, flowed and ported head with Tomei poncam type-b

so first install with rc750cc injectors and Mine's mafs brings no joy, idle is rough afr erratic, i can lean the afr out completly and it would still run rich

replaced the mafs with old mafs and old injectors still the same problem

the car came with bov's that vent to atmosphere I have disconnected them they are not leaking at all when disconnected

when driving the car it hesitates alot but when turbo's start making neutral pressure 0bar the AFR starts to lean out then when on boost its start riching up like You would expect and it feels pretty solid on boost with no issues

any suggestions

could the cams perhaps be out to overlap and cause an issue like this?

Thanks hope somebody can shed some light

[Ben C34]

What ecu?

Definitely check the cams if you have doubts.

[andre_gtr]

Thanks Apexi PFC L-jetro with Mine's AFM's

[Badgaz]

are you using the same map loaded on your powerfc as before? i recommend, if you can...to do a data initialise (wipe) of your power fc and then reload your maps...then run through the startup procedure for the powerfc again. if you can't do this...i'd recommend taking it to a tuner that can.

[andre_gtr]

are you using the same map loaded on your powerfc as before? i recommend, if you can...to do a data initialise (wipe) of your power fc and then reload your maps...then run through the startup procedure for the powerfc again. if you can't do this...i'd recommend taking it to a tuner that can.

I have initialized the apexi so with stock injectors and mafs you would expect it to idle like normal but no luck, its just beyond rich and adjusting the correction does not lean it out

I am thinking that the ovelap of the cams 35degrees is maybe losing some of the air in the chamber and causing the richness

but driving at low RPM is also horrid so much hesitation

[Blackkers]

if it's a fresh build perhaps cam timing is out? how big are the type b's? I thought they were pretty streetable AFAIK.

Also, not that it would matter in idle but you can't tell if the Bov's are leaking without pressure testing

[andre_gtr]

I sparyed some quick start in the bovs while idling with no change in idle

paid so much attention to the timing when assembling the motor but will chack again

does anybody know what would be safe degrees to start off with when degreeing these cams could maybe close some of the overlap

cam specs below

B

260°

260°

9.15mm

9.15mm

110°

115°

0.45mm

0.38mm

You can calculate overlap here https://www.rbracing-rsr.com/camshaft.html

with these settings

Tomei Poncam B

Intake 260 degrees 20 BTDC 60 ABDC 110 degrees
Exhaust 260 degrees 65 BBDC 15 ATDC 115 degrees

[Badgaz]

I have initialized the apexi so with stock injectors and mafs you would expect it to idle like normal but no luck, its just beyond rich and adjusting the correction does not lean it out

I am thinking that the ovelap of the cams 35degrees is maybe losing some of the air in the chamber and causing the richness

but driving at low RPM is also horrid so much hesitation

check your o2 sensors.... They could be poked. unless you have o2 feedback turned off. either way if you are not able to tune it.. try getting it Tuned.

[Ben C34]

The cams wont cause the issues you are having, unless installed incorrectly.

I only recently installed type B's into my neo and it has been running fine with no change to the tune (havent had a chance to get on the dyno yet)

[andre_gtr]

ok so Update

I checked cam timing according to true TDC everything is spot on

I did a compression test on the fresh motor couple of km's on it and it was super low 6bar 87psi cold, could be due to cams and not run in yet

I am at a loss here and I feel I want to burn this fekker

so when on idle now it would be on 12 afr but very rough as soon as i want to rev it up slowly it starts leaning out up to the point that it wants to die

when I leave the throttle it wants to die aswell then i need to sort of keep it alive, I am now getting a set of standard recirc bovs in hope that that can help but wont bet my life on it

[Dose Pipe Sutututu]

You've got bigger injectors however have you scaled your injectors on the ECU?

I didn't see any mention of that.

[andre_gtr]

Yes I do have bigger injectors

I have RC pl4-750d 750cc injectors, played alot with the settings and ended up on 59.2% and +0.24 lag time

this seems to work best, if anyone has used these injectors with apexi would you mind sharing your experience and settings please

[Dose Pipe Sutututu]

try this:

1. Reset PowerFC
2. Set scaling in ball park
3. Select correct AFMs
4. Turn off O2 feedback
5. Start/Rev car up to around 3000 rpm & hold (when warm)
6. Adjust scaling till car hits stoich (roughly)
7. let it idle, then adjust lag time till idle is stoich (roughly)
8. tidy up map
9. Enable O2 feedback
10. Take to tuner

[Badgaz]

what Fuel pressure reg are you running? is it 1:1?

[andre_gtr]

stock FPR unit, fuel pressure is around 3bar at idle

[Badgaz]

These are the Lag times i could find for the injectors.

Injector Flow CC/min Flow LB/Hr Ohm 10v 11v 12v 13v 14v 15v

Nissan Skyline GT-R 440 42 2 1.35 1.12 0.96 0.85 0.76 0.65

Nissan Skyline GT-R 440 42 2 0.7 0.61 0.54 0.48 0.4 0.35

RC Engineering 750 71 3 0.57 0.48 0.38 0.31 0.24 0.17

RC Engineering 750 71 3 0.88 0.66 0.48 0.32 0.18 0.05

RC Engineering 750 71 12 1.36 1.12 0.92 0.76 0.63 0.5

Edited May 28, 2014 by Badgaz

[andre_gtr]

Thanks much appreciated

[andre_gtr]

Update

I think I resolved the issue here

did a silicone grease trick on the ignition coils

degreed cams a bit +2 intake -4 exhaust

installed stock bov's recirculation

now with the setting of 59.2 and 0.24 on the injectors it idles almost perfect 14.7

acceleration is also almost find just a bit of leanness when initial pushing of the throttle

[Badgaz]

thats good news i found the opposite problem on the accelerate injector settings....went a little too rich. what setting do you have there?

[andre_gtr]

its still stock setting on the PFC initialized pfc and only set the mafs and injector settings and it was almost spot on

i will check the accelerate setting tonight and let You know