Rb20 Idle Expertise Required...

[Kane_R32]

Hey guys, start with the basics;

- RB20DET

- Kando TD05-18G

- Aftermarket Pump (unsure of brand, already in car)

- Nismo 555cc Injectors (to suit RB26 with resistor pack)

- Nistune

Let me begin with, when I initially got the car tune with Toshi, at idle on the wide band car registered 10-11 AFR's. Light throttle would see lean 15-17 AFR's but under full throttle and boost would stay at 10.8-11.3. This was with the TD06-20G I had. Mid throttle sees 13.9-15.5...

So since replacing the TD06 with a TD05 Toshi tried to set the AFR at idle to as close to stoic as possible.

With as much adjusting on the nistune, second time around, car shows 11.9-12.6 on Idle, but now has a tendency to stall after approx 10-20 seconds of idling. It can happen 8 out of 10 idle's, or not happen at all. Still has the light throttle leaness and AFR's on full boost remain the same. I run a AEM wideband also.. When it goes to stall, sometimes if I blip the throttle it'll idle, other times it will want to stall again..

Now I've tested the car with these (individually) disconnected to little to no change;

- disconnect TPS

- disconnect AAC

- disconnect O2 sensor

Car runs no BOV, with a plate made up to block where the factory one lives. And has never run a BOV since owning the car. Car retains the factory AFM.

Injectors were bought second hand. Toshi has suggested putting the stock BOV back on, I'm comtemplating doing this and maybe a AAC clean.

Open to ideas/suggestions/theories...

Kane

[Kane_R32]

So basically trying to diagnose the stalling and lean conditions. According to Toshi, its set up for closed loop on Idle and under 0psi, open loop once in boost, so dont understand how its lean with the fuel map how it is

[GTSBoy]

I don't understand. You claim idle AFR is about 12 in one sentence (rich) and claim that it is lean elsewhere.

[Kane_R32]

I don't understand. You claim idle AFR is about 12 in one sentence (rich) and claim that it is lean elsewhere.

Idle: 10-11 (too rich)

Light Throttle: 15-17 (too lean)

Full Throttle: 10.8-11.3 (very safe haha)

Sometimes on idle the AEM shows 17+ AFR and engine wants to stall. It doesnt seem to maintain stoich levels on idle or cruise... So I'm wondering if one (or more) injectors could be the issue? Or something else?

Edited January 17, 2013 by Kane_R32

[Dose Pipe Sutututu]

change your fuel reg? it could be farked

[toffy]

clean/replace your water temp to ecu sensor . take it back to toshi?

[toffy]

whoops , double post

Edited January 18, 2013 by toffy

[Kane_R32]

Toshi suggested AFM, O2 sensor and TPS. It's probably something so minor, going to put the stock BOV back on and check for vacuum leaks next weekend.

[Kane_R32]

Just some feedback;

I removed and thoroughly cleaned and reset the IAC to no avail.

I have noticed that when pulling the throttle with the IAC connected the car goes "lean" and splutters..

If during the light throttle I disconnect the IAC, car comes good and doesnt splutter.

Does this sound like my IAC will need to be replaced since I've already cleaned it and tried to reset? Though the slight lean spot on light throttle when being driven is present on the wideband..?

[Kane_R32]

Who would've thought putting the stock BOV back on has cured my problem!

[Dose Pipe Sutututu]

AFM car, stock plumb back BOV for the win..

same applied to EVOs (even more sensitive to this)

[Kane_R32]

*sigh*

Heres the scenario at the moment.

Car while driving, any gear, any RPM and any speed, from say 2%-25% throttle will show lean on my wideband 16.0+ AFR.. Then when you push the throttle past say 1/4 throttle, it will go into 13-15.0 AFR and obviously rich conditions when WOT.

Also when coming to a stop (idle), the car will idle fine for 20-30 seconds, and then the wideband shows it going anywhere from (11.2-15.7 and then to 16.0+ AFR again, this time causing the car to stall. Bliping the throttle stops brings the revs back up, but again 20-30 seconds after, same scenario.

Car has been checked over and over for vacuum leaks. O2/IAC/TPS have also been disconnected individually to no change.

I'm wondering if my Nismo 555cc injectors have a issue? Car shows 40psi fuel pressure +/- 1-2psi on idle. (and doesnt drop off during the lean condition at idle).

Stock BOV/Stock AFM.

[Kane_R32]

Ps - Can feel this lean spot while driving 2-25% throttle.

Car with TD06 + stock injectors + stock ecu idled fine. (no wideband to tell)

Car with TD06 + Nismos + Nistune idled fine (tune/untuned - no wideband)

Car with TD05 + Nismos + Nistune doesnt like to idle (tuned / with wideband)

With the info above, you would think it's possible Nistune/Tune related right?

[GTSBoy]

It should not be able to go lean at <25% throttle light load because it should be in closed loop and should command 14.7:1. The only way it could do it is if the O2 feedback has been switched off and the maps set that lean in that area. In which case it would be like that all the time, not just start out of the blue.

It is possible that something as simple as a coolant temperature sensor might have failed. That's one of the inputs that determines when and where closed loop is allowed. Do you have Nistune software? If you do, you should drive around with it hooked up and see what you see. It might jump out at you.

[Kane_R32]

You might be onto something.

Because I was originally seeing sub 11.0 AFR on idle with the TD06, he turned off O2 feedback and tried to adust/lean it out, with no result.

I think the cleaning of my AAC and any leaks has solved my rich idke issue, and I may need to have the feedback turned back on...

Hmmm. No Nistune software..

Appreciate the help man!

[_x_FiReStOrM_x_]

Injector latency?

Wait, sorry.. so is it still random stalling at idle?

Edited March 20, 2013 by _x_FiReStOrM_x_

[Kane_R32]

Wouldnt say its random. 8/10 times it will stall after 20-30 secs of idle.

Pretty sure GTSBoy is onto it..

[Kane_R32]

Went and saw Toshi, 02 feedback wasnt switched off. We did find a couple air leaks which have now been sorted, yet it still does the same thing.

Starting to wonder if my Nismo 555cc injectors have an issue.

He did mention the AFM voltage is a little low at idle... but shouldnt cause too much concern

[rx-line]

I have similar problems with nistune, I figured it was the factory O2 causing the problems. Can be from 12-16afr's on idle while sometimes perfect at 14.7. Can be lean entering boost 13's but drops to 11.3 afr's at 15lbs and holds afr's there.

Makes sense that it would be O2 or IAC.

[Dose Pipe Sutututu]

if you've swap the AFM with the Nistune, and done all that rescale business make sure you change the values to the AFM Low Voltage enrichment, a few cars I've tuned needed this changed as once the car idles the ecu starts dumping in fuel and then the o2 feedback tries to correct it causing awesome hunting