SDS map - Also a question about ACC

[Drax240z]

OK, everyone with maps they want to share, please post! I found a bit of info from scotties old setup, enough to get me going anyway. The car still has some issues, I think most are related to the ACC ("accelerator pump") setttings. Acc Sense, Acc Lo RPM, Acc Hi RPM. I've searched high and low, and can't find any decent definition on what these settings do. Can anyone with SDS experience please elaborate on them a bit? I assume ACC Sense is the sensativity. I've read to keep this value low, while ACC Lo RPM in the 12-25 range, and ACC Hi RPM in the 1/3-1/2 of ACC Lo RPM value. What I'd really like is to know how they work so I can figure it out as I go.

 

Anyway, here is my current map. Comments are welcome. (L28, EM-3E, Stock turbo, Stock injectors, 2 bar map, 60mm TB, 2.5" exhaust, NPR intercooler)

 

[BRAD D]

get the NEW install manual from the SDS web page, it is a lot better than the old one.

[BRAD D]

I'm just setting mine up too

[Drax240z]

OK, so I looked in all the manuals, and in the oldest one, for the EM-2 system, I found the following information: (thanks Brad for sending me back that way)

 

Acceleration Pump (ACC PUMP)

 

This function adds to the primary injector pulse width when the throttle is rapidly opened. There are 3 adjustments to make for the acceleration pump. Two adjustments are made with the programmer and the other one is done with the trimmer potentiometer in the ECU accessed through the ACC hole in the top cover. (This is no longer the case on newer systems)

 

The ACCPUMP LO RPM value controls action from 0 to 1875 rpm. The ACCPUMP HI RPM setting controls action above 1875 rpm. Both parameters must have a proper value entered for proper engine response.

 

To set this parameter properly, snap the throttle open quickly. If the engine hesitates, change the value. If the hesitation is worse, you have changed the value the wrong way. Repeat this procedure on both HI and LO settings until engine response is acceptable.

 

The trim pot in the ECU controls the sensitivity to slow throttle movements. This control is very important just out of the idle range. Set this control by opening the throttle slowly from the idle position. Adjust for the smoothest possible acceleration. The trim pot is normally between 11 and 2 o'clock. Do not turn the trim pot fully clockwise as this causes extreme sensitivity of the circuit to randomly dump fuel into the engine resulting in rough running. (I assume this setting is the ACC Sense setting that can be programmed on the fly now) Acc pump values are generally between 10 and 50 on most applications.

 

If changing the values will not make the engine respond properly, check to make sure that the TPS is hooked up correctly. You can check for proper pump operation by first selecting GAUGE 2 mode. With an ACCPUMP LO RPM value of 10 entered, you should see the AP number increase from 0 to a higher number when the throttle is rapidly opened, then as the throttle movement stops, the number should quickly return to 0. The AP number should always be 0 when the throttle is not moving. If not, it indicates an intermittent connection or a damaged TPS.

 

[Nigel]

I think the idea is that you get a different response when you snap the throttle open from idle than from when you're cruising at say 3000 rpm. So you program in how much extra fuel you want it to add at low rpm and at high rpm. The sense value allows you to set how quickly you have to open the throttle for the extra fuel to kick in. I don't have my values handy, but I can post them this weekend.

 

You were asking for comments on your maps...

 

I noticed that you have much lower rpm fuel values with stock injectors than I had. I think 100 was the lowest value I could go at 1000 rpm for a decent idle. Even with my 460cc injectors, low 70's is the best I can do.

 

I also see that you've apparently changed your MAP FUEL values from the base settings that SDS supplies. How did you get fractional values? Also, I see that you're a few points higher than the base map up to about negative 10.5, and then you're a few points lower above that. In effect, you're running richer at idle and cruise and leaner under acelleration?

 

Finally, you have your MAP limit set at 23? You should have this set to a few points higher than your maximum boost...

 

Nigel

'73 240ZT (SDS EM3-6F with V11 software)

[Drax240z]

Oops, a few oddities that I sorted out today might answer a few questions.

 

Map limit is set to 8.86 right now, I have no idea why I had 23 written in.

The fractional values are simply rounded off when I punch them in to the controller... I just used a formula in excel to inperpolate between 2 points and the increment wasn't a whole number. I realize now that I should have left the MAP FUEL values as they were, but I have them recorded so I can always switch back. (which I think I should do)

 

Strange with the RPM fuel... I am pegged at max rich on my mixture meter at idle, even with the 75-90 range. (Granted with a narrowband O2 sensor) Idles like a champ too. Maybe the modified MAP Fuel values are compensating for the lower RPM fuel values.

 

In essence: I should probably go back to preprogrammed MAP fuel values, and up my RPM fuel values. Thanks for the comments Nigel!

 

One last thing, do you recall what you ran for ACC settings? Fiddling in the driveway today I ended up at Acc sense 4, Acc Lo 50, Acc high 25, as those seemed to work at idle with no load.

[Nigel]

Are you running a heated or un-heated O2 sensor? I have a heated sensor, and I tried it without the heating element hooked up. The readings showed rich no matter what I did, because the sensor just wouldn't get hot enough idling in the driveway to read accurately. I don't know if the same problem would occur with an un-heated 02 sensor.

 

Your MAP FUEL values aren't so far off that I would expect them to make up that much of a difference between your RPM FUEL values and mine. You should be able to turn the mixture knob equal amounts to the left and right before the engine starts to stumble if you have your RPM fuel value set right. What kind of fuel pressure are you running? I don't want to send you off on a wild goose chase here, but it just seems odd that you are able to run such low RPM FUEL values with stock 280ZX turbo injectors.

 

I don't recall my ACC settings off the top of my head. I can check them Saturday at the earliest.

 

Nigel

'73 240ZT

[BRAD D]

I have a question too, for the RPM fuel values why do people stay with the same number for a range of 1000 RPM or so? Why not go up nice a # or two each 250 RPM? like a slope not stairs?

 

My injector value worked out to be 62, so you -20% at the lower RPM then +20% at the Higher RPM.

[Drax240z]

Running an unheated sensor... good call on that. The tuning I've done has been based on the movement of the mixture knob, and finding the happy point, not off the mixture meter. I suppose if I go for a hard drive, and then tune in the driveway with the O2 sensor still hot, that would better.

 

Fuel pressure is stock, through a stock L28 FPR. Stock turbo injectors... and I am sure they are actually turbo injectors since I pulled the engine and they haven't left me. Hmm. Can't come up with anything that might contribute to my numbers being so much less off the top of my head.

 

Rechecked my Magnet position and moved it 2 degrees. So add +2 to all my RPM Ign values now. (starting at 20* and ramping to 38* at 3250) The SDS came with 10* idle programmed in and it was pretty gutless at that!

 

Hmm Brad, I don't know the answer to your question. Though this is the way SDS shows them in their manual for every setup, and what I've learded from the SDS forum as well.

 

What do you mean your injector value is 62? You mean RPM Fuel at idle?

 

Posting an updated map now too: (standard disclaimers apply if anyone thinks to copy it for their setup)

 

[BRAD D]

this is where I got the 62 fuel value from, but I can't copy the chart from SDS

 

If you know your injector flow rate then the RPM FUEL CHART will give the approximate RPM FUEL value to enter for your engine. You also need to know the engine displacement to use this chart. Injector flow rate is in cc's per minute. If your flow rate is in pounds per hour, multiply by 10 to convert to cc's per minute. For example a 30 lb/hr injector would convert to roughly 300cc/min. Take your engine displacement and divide by the number of cylinders to get your displacement per cylinder. Cross your injector flow rate with your displacement per cylinder to find your RPM FUEL value. Enter this value right from idle rpm to redline rpm as a starting point. This chart is applicable for gasoline. If you are using Methanol, double the fuel value in the box.

 

 

The value from the RPM FUEL CHART will often be roughly 20% too high at low rpm's and roughly 20% too low at high rpm's, so it is best to monitor the air/fuel ratio with a mixture meter, then make fine adjustments to get the best mixture at all rpm's.

 

 

If you don't know the flow rate of your injectors, you could assume a flow rate of around 200 to 250cc/min on normally aspirated engines. On turbo engines flow rates vary, and are usually between 300 to 400cc/min. If you estimate that the flow rate is too high, then the mixture will end up to be too lean, because the RPM FUEL value from the RPM FUEL CHART would be too low. A mixture meter will help when flow rate is unknown, and be careful not to run lean under high throttle and high RPM. If you find the engine stumbles at medium or full throttle, then this means that the RPM FUEL values are either too low(lean condition) or too high(over-rich), so just keep making adjustments to the RPM FUEL values until the engine will tolerate full throttle.

 

 

RPM FUEL CHART APPROXIMATE RPM FUEL VALUES vs CYLINDER DISPLACEMENT AND INJECTOR FLOW RATE

[BRAD D]

Hey Drax240z could you e-mail me that Excel sheet you are working with? It looks nice

[Drax240z]

Ok, its on its way.

 

Using that formula I end up with an injector value of 126, which would correspond with Nigel's question on how the heck my car is running on such low RPM Fuel values. This would lead to a chart starting at 101 at idle, and moving to 145 at redline. Quite different than what I have. WTF? Any ideas welcome...

[Scottie-GNZ]

With the number of SDS owners on this forum, this is the kind of discussion I have been longing to see you all have.

 

Couple of points and then I will fade away. The base settings supplied with an SDS are meaningless unless the base fuel value (the basis on which the fuel map is built) was derived from a factor that included the L28 cyl displacement of ~466c AND the exact flow rate of the injs YOU are using. In addition, the static timing should be 20#BTDC. If this is not the base setting in your SDS, then that base setting is nothing more than maps to maybe get the engine started for you to immediately start tuning.

 

IMPORTANT (and I think I tell this to everyone who has asked): The RPM FUEL curve should be built to match the engine's torque curve NOT the HP curve. The highest map value should be at about the same RPM as your peak torque.

 

Do not have large increases in value from one step to another. Remember that the injection rate also increases as RPM increases so it takes more than just the value you enter into account.

 

For some strange reasons, I have seen lots of L28ETs that do not idle well with the RPM value that it should have at 500, 750 and 1000. In most cases I fiddle with the values in those 3 parameters until it idles decent but leave the other numbers alone. This is usually an indication of something not right with the engine, something as simple as bad vacuum leaks.

 

Do not ever change the RPM FUEL map to add more fuel under boost. Instead, use the MANPRESS map. Whatever values are in RPM FUEL is there always. If you build RPM FUEL to compensate for boost, you will also have that fuel when you are not under boost. With MANPRESS, the values for boost will only be added when under boost. So, if you are at 4500RPMs and 10psi and running lean, do not add fuel at 4500 in RPM FUEL, add it at 10psi in MANPRESS.

 

If you are tuning for boost and adding fuel in MANPRESS then consider the following. Lets say you need to add fuel at 8psi and you increase the 8psi parameter by +3, I suggest adding +3 to every subsequent parameter. If the map causes you to run lean at 8psi, it is almost certain the same or worse will happen at 9, 10 and so on.

 

Recommendation to every L28ET owner. When was the last time you inspected or changed vacuum hoses? I suggest you invest some pennies and replace every single one AND use zipties. You would be amazed where you could be losing boost. Pull your PCV and make sure it is still a one-way valve. If it is not, you are dumping boost into the crankcase. HARD LESSONS LEARNED! I wonder how many L28ETs are still running the original vacuum hoses and PCV? :D

 

OK, I will fade away now.

[Drax240z]

Hey Scottie, don't fade away!! We need input from people like you, your last post just cleared a lot up for me.

 

Looks like I should reset my RPM fuel values to in the 101-145 range, and nix my map fuel values. Point well taken on tuning the map fuel values for boost and the rpm fuel for no load situations.

 

So likely my RPM fuel values should be up to max at around 2750 as this engine is supposed to have its torque peak at 2800rpm. I suppose it should just level off after that as well.

 

IMPORTANT (and I think I tell this to everyone who has asked): The RPM FUEL curve should be built to match the engine's torque curve NOT the HP curve. The highest map value should be at about the same RPM as your peak torque.

 

I assume this is a typo and when you say "map value" you mean RPM Fuel? Highest RPM fuel value at your torque peak?

 

A good point on the vacuum hoses... mine are all new and ziptied as I remember reading a few posts a couple years ago about people have problems with them. Actually, once you remove all the stock electronics and add the SDS, there are a lot less hoses to worry about too.

 

PCV I went through a year ago, and got 2 replacements, neither of which would seal. I ended up going back to my used stock PCV valve, which was sealing much better than the new aftermarket ones. I should order a new one from nissan however.

 

Thanks for the input... hopefully a few other more experienced SDS guys get in on this as well.

[Doug71zt]

Hi Drax - I'm trying to find my old values for stock injectors - I have 550cc ones now with 3 bar so totally different. Email me your excel sheet and I'll try to post my old values. I ran between 12.9 and 13.2 on them so they should be close. I'll be in Seattle for a couple days next week and then in Vancouver for the next 6 weeks so I may be away from the computer for a couple days at a time.

Cheers - Doug

[Nigel]

Hey Scottie!

 

I understand the theory behind what you are saying, but I have a question about the following statement...

 

"IMPORTANT (and I think I tell this to everyone who has asked): The RPM FUEL curve should be built to match the engine's torque curve NOT the HP curve. The highest map value should be at about the same RPM as your peak torque."

 

Now, I'm not going to disagree with you. What I want to know is, is there some trick to approximating this on the street? Or, can this only be done on a dyno? I kind of know what the torque curve is going to look like, and as for where the peak will be... I've no idea how to determine that.

 

Would it be sufficient to rev the engine up to redline in neutral in stages, making adjustments to the RPM FUEL values at each increment? My understanding is that the RPM FUEL values are meant to represent the fuel requirements of the engine at no load (ie to compensate for the variance in flow of the engine through it's operating range). Am I making any sense? It's 12:30am

 

Nigel

'73 240ZT

[Scottie-GNZ]

A long time ago I had a copy of the factory ign and HP/torque curves but lost it. However, that is what my maps were based on. Rules of thumb: ramp the advance to be all in by 3000-3200, use 4500 as the peak for the torque curve, build the IGN and RETARD maps to have a total of about 24* at 15psi boost. That is a starting point and where you start using that neat device on the SDS that I like to call the "What If Knob". I am referring to the R/L knob. How do you tune on the street? Lets say you are tuning for driveability and the car has a hesitation/stumble at 3000. Is it too rich or too lean? What if I richened or leaned it out? Turn the knob and find out and if it responds to Rich, add some fuel at 3000 in RPM FUEL. If you are tuning for boost and the car has a stumble/hesitation at 4500 and 8psi, turn the knob. If it responds to Rich, add fuel in MANPRESS at 8psi and up.

 

Once the car is running fine w/o boost, then you leave IGN and RPM FUEL alone. If you have to change timing under boost, change the IGN RETARD not IGN.

 

Tuning is not a set and forget operation unless you can hit it perfect the first time , so base maps and rules of thumbs should only be considered as good starting points. Folks would be surprised how easy it becomes when you understand the basic principles. It is not voodoo black magic that should scare anyone :D

[Drax240z]

Hey Brad, how is your SDS tuning going? I've put only about 50 miles on my car and haven't done much additional tuning. The car drives decently at this point, so I am more worried about shaking down loose bolts, wires, etc at this point. I've also got a vacuum leak or two right now, plan on finding those tomorrow. My intake gasket was leaking slightly, fixed that and the car has quite a bit more pep. I think I still have 1 more to find though, as I can hear it hiss out of the car when I kill it.

 

Using the 101-145 like I was saying, I think the car is running too rich at idle, though I wonder if any of that is useful data with the vacuum leak that I may be suffering from.

 

Doug, any luck digging up those old maps?

[Doug71zt]

Richard - you've got mail...

[Drax240z]

Thanks a lot Doug. I plugged in your program and it really helped. Had to make a few mods of course, but I think its a fair bit better than what I had... a bit rich though!

 

Went cruising tonight for a couple hours... moved my revlimiter up to 4000rpm. At ~5.5psi this car feels WAY faster than my 260z/L28 car. 4000rpm comes up really fast in first gear. Just got to keep driving and get some miles on this car so I can turn up the wick after break-in.