[R4ND0M_AX3]

occilations during idle are almost expected but this is just weird. I'd knock out some fuelling in those RPM areas and see what happens. But first, if you plot the trim against load does that show any usefull info?

[daemon]

The idle oscillations that we are seeing are a touch more than I'd expect. Definitely not huge though. My current theory on the idle is that maybe the latencies we are using aren't following exactly the right curve. That is, maybe the 14V value is spot on, but the 12V is a tad high or low. As the voltage in the system does its little fluctuations it would then move along the latency curve, and the next point would be a tad leaner or richer than the previous point causing the ECU to add or remove fuel. But then the voltage fluctuates back to where it was and then all of a sudden the AFR's are wrong again, but in the other direction. This may or may not be it, but sounds like a hypothesis worth checking out by slowly tinkering with the latency curve.

I have plotted the trim against the load (and a bunch of other variations), and while there might be an extremely slight skewing towards the lean/high load area, it doesn't appear to explain the load vs RPM unless my load is dropping under constant acceleration above 2800 (and rising up to it), I'll have to look into that. One thought I had was that the turbo is going to be trying to get into the swing of things in that area. Which might be related to your question as well. These are low throttle plots, so the turbo is below zero, but still spinning of course.

All things I plan to look at in closer detail. I am not going to have any time to work on the car again until probably Monday at the earliest, but I will definitely keep this thread posted if/when I figure out what is going on. Or maybe WolfPlayer will beat me too it.

[daemon]

FWIW, a little log showing the issue. Notice the trims climbing as I approach 2870 RPM, then they fall right back to where "they are supposed to be". Also notice the great skill I demonstrated in maintaining a constant throttle position of 18 the whole time.

Immed.	Learned	Voltage	DynAdv	Load	RPM	Timing	Pulse	MAFvolt	Boost	Throtle	Speed	W.Duty	LM1-AFR
-0.39	0.39	13.84	4.5	0.85	2342	42	3.84	2.42	-3.92	18	23	16.08	14.67
-0.39	0.39	13.84	4.5	0.85	2342	42	3.84	2.42	-3.92	18	23	16.08	14.38
0.39	0.39	13.76	4.5	0.85	2399	42.5	3.84	2.44	-4.06	18	23	16.08	14.38
0.39	0.39	13.76	4.5	0.85	2478	42.5	3.84	2.46	-4.06	18	24	16.47	14.38
0.39	0.39	13.76	4.5	0.85	2478	42.5	3.84	2.46	-4.06	18	24	16.47	14.38
1.96	0.39	13.68	4	0.84	2513	42.5	3.84	2.48	-4.06	18	24	16.47	14.55
1.96	0.39	13.68	4	0.84	2577	42.5	3.84	2.48	-4.06	18	24	16.86	14.55
1.96	0.39	13.68	4	0.84	2577	42.5	3.84	2.48	-4.06	18	24	16.86	14.55
2.75	0.39	13.76	3.5	0.84	2619	42.5	3.84	2.5	-4.21	18	25	16.86	14.55
4.31	0.39	13.76	3	0.83	2684	42.5	3.84	2.52	-4.21	18	25	17.25	14.52
4.31	0.39	13.76	3	0.83	2684	42.5	3.84	2.52	-4.21	18	25	17.25	14.52
6.67	0.39	13.68	3	0.83	2693	42.5	4.1	2.5	-4.35	18	27	17.65	14.52
6.67	0.39	13.68	3	0.83	2693	42.5	4.1	2.5	-4.35	18	27	17.65	14.52
7.45	0.39	13.76	2.5	0.82	2814	42.5	4.1	2.52	-4.35	18	27	18.04	14.64
9.02	0.39	13.76	2	0.81	2870	42.5	4.1	2.54	-4.35	18	29	18.04	14.64
9.02	0.39	13.76	2	0.81	2870	42.5	4.1	2.54	-4.35	18	29	18.04	14.64
7.45	0.39	13.76	2	0.8	2907	42.5	4.1	2.54	-4.35	18	29	18.43	14.64
5.1	0.39	13.76	2	0.79	2962	43	4.1	2.54	-4.5	18	29	18.82	14.29
5.1	0.39	13.76	2	0.79	2962	43	4.1	2.54	-4.5	18	29	18.82	14.29
1.96	0.39	13.68	1.5	0.77	3021	43	3.84	2.54	-4.5	18	30	18.82	14.29
-0.39	0.39	13.76	1.5	0.76	3014	43	3.58	2.52	-4.64	18	30	19.22	14.29
-0.39	0.39	13.76	1.5	0.76	3014	43	3.58	2.52	-4.64	18	30	19.22	14.29
-0.39	0.39	13.76	1	0.75	3117	43.5	3.58	2.54	-4.79	18	31	19.61	14.29
-1.18	0.39	13.76	0.5	0.74	3184	43.5	3.58	2.54	-4.93	18	31	19.61	14.29
-1.18	0.39	13.76	0.5	0.74	3184	43.5	3.58	2.54	-4.93	18	31	19.61	14.41
-1.96	0.39	13.76	0.5	0.73	3222	43.5	3.33	2.54	-5.08	18	33	20	14.41
-1.96	0.39	13.76	0.5	0.73	3222	43.5	3.33	2.54	-5.08	18	33	20	14.41
-1.18	0.39	13.68	0.5	0.72	3258	43.5	3.33	2.54	-5.37	18	33	20	14.41
-2.75	0.39	13.76	0	0.7	3310	44	3.33	2.52	-5.51	18	33	20	14.36
-2.75	0.39	13.76	0	0.7	3310	44	3.33	2.52	-5.51	18	33	20	14.36
-2.75	0.39	13.76	0	0.69	3276	44	3.07	2.52	-5.66	18	34	20	14.36
-1.96	0.39	13.76	0	0.68	3367	44.5	3.07	2.52	-5.8	18	34	20	14.36
-1.96	0.39	13.76	0	0.68	3367	44.5	3.07	2.52	-5.8	18	34	20	14.6
-1.96	0.39	13.84	0	0.67	3415	44.5	3.07	2.52	-5.95	18	35	20	14.6
-1.96	0.39	13.76	0	0.65	3436	44.5	3.07	2.5	-6.09	18	35	20	14.6
-1.96	0.39	13.76	0	0.65	3436	44.5	3.07	2.5	-6.09	18	35	20	14.6

One thing that looks a tad funny is the pulse width. It is actually longer in the spots where it is the leanest.

[R4ND0M_AX3]

I wonder if doing a latencey test on the stock injectors would help. If they test just like the values in ST then we can look elsewhere. But if they come back with different numbers than what ST is using then something truley odd is happening. At least we could see if maybe we need to scale the test result numbers somehow before entering them into ST.

Just thinking outloud here.

[WolfPlayer]

Originally Posted by R4ND0M_AX3

I wonder if doing a latencey test on the stock injectors would help. If they test just like the values in ST then we can look elsewhere. But if they come back with different numbers than what ST is using then something truley odd is happening. At least we could see if maybe we need to scale the test result numbers somehow before entering them into ST.

Just thinking outloud here.

Argh! Stealing my thunder I am sending my stock injectors off to the same company that did the latency testing on my 720s. This will give a good comparison between the the 2 latencies ... and also let me know the flow of the stock injectors in relation to the flow of the Nismos. I'll be sending them off in about 2 weeks or so.

Must ... get ... more ... data ...

t

[R4ND0M_AX3]

Originally Posted by WolfPlayer

Argh! Stealing my thunder ...

At least you're doing something. I'm just sitting here on the internet.
Actually I plan on ordering a set of these injectors with the next week.

[WolfPlayer]

Originally Posted by R4ND0M_AX3

At least you're doing something. I'm just sitting here on the internet.
Actually I plan on ordering a set of these injectors with the next week.

Cool on ordering the injectors! You'll like them ... a lot. I can't emphasize enough that my car drives and reacts the same except for the very faint RPM oscillation (and again, the tach doesn't even move - lol).

... the only thing I wanted to mention is to make sure that you keep your goals in mind when ordering these injectors. These injectors are borderline for a BIG turbo upgrade. They'll be fine with a 20G. They'll be borderline for a Green. Anything bigger ... like 50+lb/min turbos then you should really go with a bigger injector like the PE850s or the Helix 860s ... or even the UR 900cc or 1000cc top feed injectors (comes with new rails). My goals are no higher than a 3" Green ... and, honestly, that is quite a ways away since I still have to install/tune my APS 70mm intake, get TGVs and port them, get a APS turbo inlet, etc. AND, if I do go with a Green ... then I want to update the intercooler with a Cobb Top Mount (just can't bring myself to do a front mount ... everybody does those and I think a Cobb top mount can handle a green).

t

[R4ND0M_AX3]

Originally Posted by WolfPlayer

Cool on ordering the injectors! You'll like them ... a lot. I can't emphasize enough that my car drives and reacts the same except for the very faint RPM oscillation (and again, the tach doesn't even move - lol).

... the only thing I wanted to mention is to make sure that you keep your goals in mind when ordering these injectors. These injectors are borderline for a BIG turbo upgrade. They'll be fine with a 20G. They'll be borderline for a Green. Anything bigger ... like 50+lb/min turbos then you should really go with a bigger injector like the PE850s or the Helix 860s ... or even the UR 900cc or 1000cc top feed injectors (comes with new rails). My goals are no higher than a 3" Green ... and, honestly, that is quite a ways away since I still have to install/tune my APS 70mm intake, get TGVs and port them, get a APS turbo inlet, etc. AND, if I do go with a Green ... then I want to update the intercooler with a Cobb Top Mount (just can't bring myself to do a front mount ... everybody does those and I think a Cobb top mount can handle a green).

t

Ya they are a little on the small side. I like them because of the ease of reverting to stock and their reputation for very close flow rates to each other. Not a fan of modified stocks. I'd get PE850's but Christians big injector post leads me to believe some wire cutting is needed.

I kinda thought I could just raise the fuel pressure a tad if required later. Is this a bad idea? I'd raise it 1:1 not RRFPR.

I haven't yet decided on the turbo.
I was thinking about a Perrin GT30R .63 kit (I hate the idea of the foam underhood intake though) or a stock location Green or SR55 (like to see what happens between SOG and Peter with their little battle ).

The stock location turbo has the advantage of being able to use the APS 70mm intake and new turbo inlet (hotttt).

If I go rotated then I have to hack a CAI to work.

If I go rotated then I'm 50/50 on going with the new APS DR525 FMIC in black (it's a little smaller and clears the foggies) or wait out the cobb TMIC. Lag/poor boost response is not my friend. This is my daily driver.

[WolfPlayer]

Originally Posted by R4ND0M_AX3

... I'd get PE850's but Christians big injector post leads me to believe some wire cutting is needed ...

... I kinda thought I could just raise the fuel pressure a tad if required later. Is this a bad idea? I'd raise it 1:1 not RRFPR ...

I think the PE's work with harness connector swaps (like the JECS)? Not sure.

If the fuel pump can flow the necessary fuel at the higher pressures then sure. But, if not, then bad things will happen. A Dual Walbro setup should take care of that though

t

[WolfPlayer]

Well ... I played around with checking out the battery voltage at idle. Honestly, I am getting hardly any deviation in terms of battery voltage at idle ... at least nothing to me that would ever cause an RPM oscillation. BTW, it is just so hard to detect my RPM oscillation. Sometimes I wonder if I am just convincing myself there is one there when there isn't.

t

[R4ND0M_AX3]

Originally Posted by WolfPlayer

...it is just so hard to detect my RPM oscillation...

Does it show up in logs (ST or logworks) or just in your spidey senses?

[Christian.]

Originally Posted by R4ND0M_AX3

Not a fan of modified stocks. I'd get PE850's but Christians big injector post leads me to believe some wire cutting is needed.

I have tuned these injectors in the past and they have worked. The PE instructions (when I read them two years ago) asked you to cut the existing terminations off the injector wire and to install the new supplied terminations. You were to insert these new terminations into the newly supplied fuel injector clip.

Originally Posted by R4ND0M_AX3

I kinda thought I could just raise the fuel pressure a tad if required later. Is this a bad idea? I'd raise it 1:1 not RRFPR.

Raising base fuel pressure will accomplish a greater flow rate. A fuel will continue to flow more until the injector can no longer open because the fuel pressure behind the injector is too high. Although, the ECU cannot be made aware that this specification has changed so all of the internal calibrations will be off. I would not suggest you do this. If you need more fuel use a larger fuel injector.

Here is the equation for the "Pressure Effect on Fuel Injector Flow"

Qn = Qc _/(Pn/Pc)

Qn = New flow rate
Qc = Current flow rate
Pc = Current pressure
Pn = New pressure
_/ = Square Root
/ = Divide

Hope this helps.

Take care,
Christian.

[04stiguy]

Originally Posted by WolfPlayer

For public record - I completed this injector install a couple days ago and started with deamon's values listed above. Car fired up and ran absolutely fine. In fact, I was telling him that I was really surprised how well these values worked for me. My Long Term fuel trims were between -1.5 to +1.5. That's pretty damn good for plug-in values listed on the internet Great work daemon.

+1. Thanks for the useful input on this Daemon.

Also, it seems that the MZM latency values as well as the Witchhunter (Wolf posted) values seem quite a bit off. Prior to Daemons post I had been using a 4205 scalar and latency value of .78ms @ 12v and .60ms @ 14v for a month or so with nearly identical results. I cannot tell the difference between the two settings.....

Originally Posted by WolfPlayer

Observations: I have a very very very faint fluctuation at warm idle when the RPMs are the lowest. It oscillates ever so slightly. The tachometer doesn't move ... but you can just get a sense of it. You can see it slightly on the boost/vacuum gauge too. Once you are off-idle everything is completely normal. The car starts up and drives like stock. The only difference you can feel (if you are anal) is this very slight oscillation at idle. I think that most people wouldn't even notice it. The car truly does drive like stock to me and I notice everything. Graphically watching the AFR (using Innovate's software) shows that there are AFR oscillations at idle that go hand-in-hand with what I am noticing in the warm idle rpm oscillation.

I have these anomalies as well.

I have been through this entire "cycle" with the PE850's already, with very similar results. The PE installation was almost identical (harness clips as well). Had the PE's for about 6 or 7 months. Installed them a week after I installed the Street tuner. The issues with tip-out were bothering me as well as the idle fluctuation. Spoke with Christian and Trey about adding some tip-out control in October. The tip-out issue did not appear to be something that I would be bothered with, but long term tailpipe / bumper soot thing started to get under my skin (yes I am probably being too anal...). Trey relayed that some type of tip-out control was under future consideration (Christian and Trey have both been very insightful and helpful by the way). So recently, was curious to see if the issues I was having could be cured by a different injector. This led me to install the 720/740's. Bottom line, it turns out they are really quite similar in all areas except duty cycle values.

Originally Posted by WolfPlayer

Short Term fuel trims are whacky compared to stock. Daemon is seeing the same thing and he noticed this first. They are just all over the place compared to stock.

t

My ST and LT teims are pretty stable, with the exception of when the tip-out richness occurs. At that moment, the ST trims go -15/-25 (and AFR is 11-12:1!) for a split second. This is a during a normal acceleration in closed loop. I believe this is where I am accumualting the tailpipe soot.

Anyone with with extended "hands on" experience like we are discussing here, but with modded stockers?

[04stiguy]

Originally Posted by R4ND0M_AX3

I'd get PE850's but Christians big injector post leads me to believe some wire cutting is needed.

I kinda thought I could just raise the fuel pressure a tad if required later. Is this a bad idea? I'd raise it 1:1 not RRFPR.

The PE's come with clips and do not require any cutting. The factory wires just get pulled out of the OEM clips and snapped into the PE clips. Super clean and easy.

Also, the OEM regulator is boost referenced and provides a 1:1 gain (if your pump will support the pressure).

[R4ND0M_AX3]

Originally Posted by 04stiguy

The PE's come with clips and do not require any cutting. The factory wires just get pulled out of the OEM clips and snapped into the PE clips. Super clean and easy.

I guess PE's are back on the table then. Hmmmmm.

Originally Posted by 04stiguy

Also, the OEM regulator is boost referenced and provides a 1:1 gain (if your pump will support the pressure).

I was just making sure others didn't assume I was talking about some variable relative fuel pressure insanity. I came from the Honda world and a RRFPR was almost always the solution when adding a turbo. I increased my fuel pressure by modifiing the stock regulator and used Hondata to scale just like we would with ST.

Originally Posted by 04stiguy

Also, it seems that the MZM latency values as well as the Witchhunter (Wolf posted) values seem quite a bit off......

So are we now questioning the latency values witchhunter provided or did I read that wrong???