Correcting rich condition after injector upgrade

[MPV TT]

First post here, so bear with me - for the last four years I been running a JDM VG30DETT, dual Z32 MAF's going through an SAFC II controller to the stock ECU. I dyno tuned the SAFC for top end and had some adjustments at idle. I went on a trip for a few weeks and saw it as the perfect time to send my ECU in to get the Nistune board installed in preparation for a built motor. I had been running that set-up with the fresh Nistune install with no problems what-so-ever. Six months ago, one of my OEM 370cc injectors died, so I decided to install the set of JECS 550cc I had waiting with my other motor rather than buy a stupidly expensive OEM replacement.

In addition to the Consult Gauges I have a boost gauge and dual widebands (one for each bank) and played around with the K constant and latency to get the VG sucking, squishing, banging, and blowing nicely (idling once warm, I also selected the auto adjust scalers to help complete the tuning). The problem has been, when I cold start I have to turn the SAFC all the way down in order to keep it from running unbelievably rich, and even then with it all the way down I can only manage to get a max of 13.7 on the AFR. As the car warms and the RPMs drop, I have to adjust the SAFC back up to keep ~14.7. Once it is warm, there is no more need to compensate with the SAFC, it cruises nicely and idles perfectly.

I have been driving my car like a grandma because I have been having diff problems, so no WOT pulls or anything like that, just working on the driveablility. However, when cruising, and I add a little throttle and start to build any kind of positive manifold pressure, the AFR's start to go rich again. My widebands are only set to read from 16.0 - 10.0 , and they get pinned there when I'm in any kind of boost.

I have read through users manual and tuning basics, and tried searching on here, but I'm befuddled. I have replaced my differential and want to start boosting again, but I also don't want to keep having to compensate with my SAFC everytime I start the car, and thought maybe since it likes to go rich in both situations there is something simple to do rather than adjust every field in the fuel maps and warm-up tables. I have been thinking of adjusting the "Fuel RPM Scale" but would like further input before I start heading in the wrong direction. Lemme know what extra info you need to make an educated assessment.

Thanks in advance

[Seank]

Two items that stick out for me, take what you will from them.
1. JECS 550cc? Nismo 555cc or JECS that have been modified?

2. Have you considered removing all SAFC adjustments and strictly use it as a dual maf solution? Nistune can do everything the SAFC can except for the maf addition. This way there isn't a potential for the SAFC and Nistune to fight one another. I've recenty been working with disabling the SAFC's dec-air setting to get my idle afr's in line. Previously I was @ 13 AFR @ ~800 rpm idle and since I've been able to adjust it down to just over 15.

The problem has been, when I cold start I have to turn the SAFC all the way down in order to keep it from running unbelievably rich, and even then with it all the way down I can only manage to get a max of 13.7 on the AFR. As the car warms and the RPMs drop, I have to adjust the SAFC back up to keep ~14.7. Once it is warm, there is no more need to compensate with the SAFC, it cruises nicely and idles perfectly.......However, when cruising, and I add a little throttle and start to build any kind of positive manifold pressure, the AFR's start to go rich again. My widebands are only set to read from 16.0 - 10.0 , and they get pinned there when I'm in any kind of boost.

I'm going to take a stab at this and say the K-const still needs work. The idle normality after warm up could be due to the open->closed loop transition. Maybe someone else with more experience will chime in with a more personalized solution. What parts of the base bin have you modified with Nistune?

Lemme know what extra info you need to make an educated assessment. Thanks in advance

There's A LOT of info here if you're diving in for the first time. If you're comfortable sharing, how about your bin, log of warmup and a log as much of a WOT run as you're comfortable with?

[MPV TT]

I know they are for sure JECS, not Nismo, and think they may be modified (included a pic below). I had taken them to my injector guy to install them in the rail and pressure test the whole thing, he also confirmed the data on the birthsheet to be true. IIRC they were sold to me as Hybrids. Seank reminded me I have some pics I took when I first tried tuning, so I posted them below, and I believe I tweaked the TTP tables as well. Here you can see the differences between the two "screenshots" I took a long while ago. The changes I notice are the lower end of TTPMIN, the upper end of TTPMAX, and CrankEnrich. This may explain my boosting issues, but does CrankErich just have to do with cranking to start, or also cold starting?

The hardest problem I have when searching the manuals and this forum is the inconsistency with terminology, makes using the search function difficult.

[Seank]

TTPmin can be a problem for rich idling, but if you can get it to idle near stoich, then this is most likely not your issue.
TTPmax would cause a lean condition up top IF there was an issue with the ecu calculating a higher TP than this limit.
CrankEnrich is for just cranking. (Though this is off the top of my head, a double check is in order)

I don't believe these fields have much to do with your rich on medium load condition. I would think K constant as well as the primary fueling map are your significant contributors.

The hardest problem I have when searching the manuals and this forum is the inconsistency with terminology, makes using the search function difficult.

I sympathize, it is difficult because the different ecu's use different parameters, along with the documentation not always matching the current bin. Some term that a SR20 user uses to fix his identical problem to yours can't be found in the VG30DETT bin...

What's your K constant set at? and How did you resize the injectors? Change the injector multiplier or use the resize injector function? I can take a look at mine when I get home this evening. I'm running a closely sized injector to yours.

[Matt]

Please post your BIN file here so I can compare against the factory one (just attach to this forum thread)

[MPV TT]

Adjusting the After Start Enrich, Cold Enrich did not seem to do what I wanted, so I just spent the last two hours trying to retune my idle with the SAFC set to zero.

Starting with
KCONST: 288
TS14V: 750

Experimenting with SAFC at zero
KCONST: 206
TS14V: 680

I experimented with a few other combos 720,173 & 570, 206 but there is a dance that the two do in order for everything to work right especially when the electric fan is running, returning to 0% throttle after revving, or starting warm; and the above seemed to do the best of the three, but still needs improvement.

[Seank]

Starting with
KCONST: 288
TS14V: 750

Experimenting with SAFC at zero
KCONST: 206
TS14V: 680

I experimented with a few other combos 720,173 & 570, 206 but there is a dance that the two do in order for everything to work right especially when the electric fan is running, returning to 0% throttle after revving, or starting warm; and the above seemed to do the best of the three, but still needs improvement.

370cc / 555cc = 0.66
0.66 * 288(K) = ~192(K) new theoretical K, so 206(K) is in the ballpark. Starting warm issue may be a enrichment table that needs re-scaling due to the injector re-size.

Does it want to stall out (lean) after revving? This has been a project of mine to resolve, though it's been a slow process. The condition improves the closer your K & latency are matched to your injectors, but I haven't been able to rid myself of it completely.

Good luck, hopefully modifying Nistune only yields better iterative testing results.

[Matt]

Stalling out after reving is to do with reverse airflow through the MAF. Take a log (stream mode) of reving the vehicle. Watch the MAF voltage on decel. If it spikes then the TP will also spike (as well as injection time). This causes a rich condition

Having to recirc BOV (or one which points returned air towards MAF) can cause a lean conditiion on deceleration also. Once again watch the log for this

TPmin/TPmax table can limit the TP spiking as well as minimum TP on decel somewhat but usually having suitable bends between turbo and MAF as well as recirc BOV will alleviate those particular issues

[MPV TT]

So I've continued to fiddle with the K and Latency time values and have gotten to

KCONST: 182
TS14V: 720

Now when I get into boost under load it stays in the 14.7 range and doesn't go lean or rich. Is there a specific direction to go in either of the two values above instead of adjusting the fuel load scale tables?

[Matt]

Increase your TTPmax table (if not maximised already after injector resize) as this limits the load the ECU works with.

Otherwise take a log with consult and AFR parameters and we can have a look

[MPV TT]

Alright, so after removing all the SAFC tuning, and several good pulls at WOT and many cold starts, I have come to the following:

KCONST - 209
Latency - 600

I discovered that I needed to increase the K constant if it was going too lean at WOT (or decrease K it if went rich), from there just adjusted the latency to get it idling smoothly and pulling max vacuum.

I knew it had to be something simple since I am running wastegate pressure, and all I changed was my injectors. Now with a little more fine tuning, I can start to crank the boost up turn by turn on my Hallman.

One final thought is on my injector birth sheet they claim a dead time of 0.7ms @ 14v, I run my car at 15v so maybe this would account for the lower 0.6ms I have for my latency???

Very pleased now! Thanks SeanK

[Matt]

Good stuff. If you run a higher voltage then it may be affecting the latency a bit. I used those latency figures as a guide (ie starting point) but then adjust further on the particular vehicle being used. 0.1ms is not much change

[Torque]

I discovered that I needed to increase the K constant if it was going too lean at WOT (or decrease K it if went rich), from there just adjusted the latency to get it idling smoothly and pulling max vacuum.

That is correct since ->

Larger K = Less Flowing Injectors
Smaller K = Higher Flowing Injectors

Or

The higher K the less CC your injectors (should) flow
(K is what the ECU uses to calculate injection times given a certain MAF signal )