Basic Tuning - Powerfc, Lc1 Wideband, Afr's- R33Gtst

[benl1981]

With the stock ecu in place, stock injectors etc running 11psi on stock turbo.

- I fitted a wideband LC1 (did the free air calibration) and found afrs to be quite lean. I placed the wideband sensor in the stock dump pipe location hence no o2 feedback

- then went onto Fit a new fuel filter. Still quite lean so I fitted a new Tomei fuel pump.

- the only thing I did in the meantime was disconnect the wideband. Although I didn't start te car or re calibrate.

- I then refitted the sensor. Started the car and instantly got 12.5 afr on idle and on boost mid 11 afr dipping to about 10.3 afr over about 5k rpm. Running about 11psi stock turbo. So I assume my pump had been losing flow.

- With that fixed I have fitted the powerfc on base map and found idle to be about the same 12:1 but richer on medium throttle of about 11:1 and then about 10:1

A couple of questions as Im pretty new to this.

1 - does this seem normal 12.5 to one on idle as I wouldn't think the stock ecu with narrowband would be able to trim enough to bring that back to 14.7;1 I.e the afr needs to be close enough to facilitate closed loop and not stay in open loop.

2 - with stock injectors I have worked out that about 5% reduction to injectors or k value gives around 0.5 increase to afr. I.e. If you set injectors to 95% and your idle was 12.5 to 1 at 100% the new afr would be 13 to 1 if running 95%. Does that seem about right and does that correlation stay reasonably true for higher load and rpm (I wouldn't rely on it but just as a rough guide)??

3 - In the next 6 months or so i was going to do some further mods but in te meantime would have liked to have this running a bit better performance wise and economy.

With the airflow corrections I found that by reducing the lower load up to 3000mv to about 85% each I can get the cruise afr back to around 14.5 to 1 with no real increase in knock ( I realize this both reduces fuel injector duty and could advance the timing). For the higher load settings I don't want to do this as I don't want more timing. Since I'm down at 11:1 and then 10:1 on high load I was considering adjusting the k value down by about 10% to see if I could get closer to 11:1 to 11.5:1 afr. And bring up the air flow correction back to probably about 90% for low load. Once the k value is worked out you would then adjust the injectors to say 90% each so it is a permanent change.

Meanwhile you'd have to keep an eye on knock and reduce advance as required. Whilst testing the medium to full throttle runs I thought of reducing the advance in the temporary setting by up to 4 deg to start with to protect the engine

I Realize it's not probably not technically the best way but till I get the bigger turbo and z32 has anyone done something similar to get afrs close and ensure knock is not excessive?

4 - when you fit lc1s and other widebands do you guys generally take it to a tuner to validate the readings or just rely on the one you have installed

5 - the bung that comes with the lc1 is deeper than for the narrowband so since I am running the stock bung for NB sensor the WB would be sticking out a bit further into the exhaust. Has anyone had issues with that?

I have a datalogit but getting the rs232 convert working with win 7 is a pain

With the bigger turbo I will take it to the shop for a tune

I also will eventually connect the NB simulation wire back into the powerfc and run 02 feedback.

Some of this may seem pretty basic but any help is appreciated.. Thanks

Edited January 19, 2013 by benl1981

[DVS JEZ]

I always cut the supplied threaded bung in half before installing. Theyre too long for my liking. So the stock NB location is fine.

If ur unsure of the afr's redo the free air calibration again.

[89CAL]

Best to tune your idle and cruise AFR's and leave 02 feedback off anyway. Should be able to plug the wideband into the datalogit and bring up your AFR's in FC Edit in map watch (20x20 view of AFR that corresponds with your inj map)

Were you trimming the entire inj map with what you were doing? Better to just get your AFR's up in FC Edit as above and tune cell by cell. If your not confident then just don't go to lean

[benl1981]

Ok thanks.

Still need to get a compatible rs232 converter.

However, what strategy do you use?

- Say all cells below 3500rpm and below load point 10 you would target 14.7

- From load point 11 to 13 say 12.5:1. (assume this is where boost would be building)

- Load points 13 to 16 say 11:1

I am measuring at stock sensor location so believe that reads a couple of points lower.

With stock injectors do you usually find about 5% drop in injectors gives about 0.5 increase to afr no.?

[benl1981]

Anyone?

Also the inj map jumps from about

100 at load point 9 to

117 for load point 10 then

126 for 11

Will have to check if this is the stock maps but as soon as you see about 5 psi boost afr is about

11.5 to 1.

Seems very rich?

When I run full throttle 11psi

Afm: 4.95v

Injector: 77% (stock)

Afr drops to in the 10-11: 1 range

[STATUS]

Ok thanks.

Still need to get a compatible rs232 converter.

However, what strategy do you use?

- Say all cells below 3500rpm and below load point 10 you would target 14.7

- From load point 11 to 13 say 12.5:1. (assume this is where boost would be building)

- Load points 13 to 16 say 11:1

I am measuring at stock sensor location so believe that reads a couple of points lower.

With stock injectors do you usually find about 5% drop in injectors gives about 0.5 increase to afr no.?

no to the first 3 it should be a sliding scale (smooth too) and dont change the inj % numbers to tune it, change the map values.

and finally no it does not read lower @ the front it reads spot on, if tuning at the rear you need to compensate for the cat (will read leaner than it is)

i have attached a sample fuel map of a 350rwkw track car (abeit slightly changed before upload) we look after, its done 4 years of work at this power on std rb25 hence its a little rich up top but its a guide and use it only as a guide for sliding fuel delivery scale.

ooh tune it with o2 off then turn it back on once finished, it will generally always give better results on (may need feedback ratio adjusted) unless the sensor is shagged.

[benl1981]

Ok thanks a lot for the map as indication.

1. So you don't tune all those low load cells to be right on 14.7 to 1- you let the closed loop function achieve that.

2. Do you think I'm best to tune with the LC1 wideband (with 02 sensor feedback off), then remove wideband and replace with a nice new narrowband o2 sensor and turn closed loop on

I have heard a few people using wideband in simulation mode but not a heap. I also have the wideband in stock location so may not be good for long term use there? Maybe just check afrs with wideband every 3-6 months?

3. 350rwkw is a lot on std internals. What sort of Afrs do you target as those on the fc edit are only indicative right? If I keep injectors at 100% and no air flow correction if afr on fc edit would be 12:1 when afr on lc1 would probably be closer to 11:1 (is that normal?)

Thanks again

[STATUS]

Ok thanks a lot for the map as indication.

1. So you don't tune all those low load cells to be right on 14.7 to 1- you let the closed loop function achieve that.

2. Do you think I'm best to tune with the LC1 wideband (with 02 sensor feedback off), then remove wideband and replace with a nice new narrowband o2 sensor and turn closed loop on

I have heard a few people using wideband in simulation mode but not a heap. I also have the wideband in stock location so may not be good for long term use there? Maybe just check afrs with wideband every 3-6 months?

3. 350rwkw is a lot on std internals. What sort of Afrs do you target as those on the fc edit are only indicative right? If I keep injectors at 100% and no air flow correction if afr on fc edit would be 12:1 when afr on lc1 would probably be closer to 11:1 (is that normal?)

Thanks again

14.7 is stoich and its actually not ideal, each engine is different so some are happy to go as lean as 16 or 17:1 on cruise etc... some cars will only idle smooth at 12.5:1 and then when you add cams it all goes up in the air

350 is fine.

you need to re calibrate your afm curve in the AFM voltage table. All my tables reflect engine afr to withing a few %. the one ive posted is manipulated to make it simpler to understand (edited out some parts) but will work fine on your car (ignore scale)

onlce you recalibrate the AFM table your indicated AFR in the fuel table will deliver correctly.

[benl1981]

Thanks status - great advice.

That's in the datalogit settings isn't it i.e afm curve. Will get that set right to match up.

What about your thoughts on whether best to use new narrowband or try and get wideband to simulate narrow band to get the closed loop running best (seems like you think that is better than leaving closed loop turned off)

So your saying the afr Targets in yours would be ok for stockish skyline provided I get the afm table right and actually achieve similar afr for those load points?

[STATUS]

So your saying the afr Targets in yours would be ok for stockish skyline provided I get the afm table right and actually achieve similar afr for those load points?

should work sweet but may prefer 13 at idle.

[benl1981]

With datalogit captuing the average AFRs is this possible to get the tune 90% on the road without too much effort?

I would set slightly richer targets at the higher load points than the map status posted and keep adjusting Air flow curves to get the AFRs down to match the fuel map ratios.

Is that the way to go? Also back off timing on the higher load points to max about 16 degrees and work up from there if no knock.

Then may get touch up on the dyno?

Thanks

Edited February 6, 2013 by benl1981