New MS Install Idles Too Rich

[DCZ]

I have a new MS install on a Datsun 280zx turbo engine that starts and runs ok, with good AFRs under boost, but idle and low speeds are pig rich ~10.8 to 11.2. It also has a lean stumble if I blip the throttle too quickly. I can't seem to change anything that effects the idle AFR, even setting bins in my Fuel VE table to 0. Here are specifics:

 

83 Datsun 280z turbo stock engine/turbo

Ford XR4ti injectors ~370 cc/min

MSIIExtra on v3.57 board

Stock (heated) Idle Air Control Valve

240sx TPS

GM Manifold Air Temp

280zxt cylinder head temp sensor

280zxt stock coil igniter triggered by MS (no BIP373)

LC-1 O2 Sensor Controller

TunerStudio Tuning Software

 

 

Timing is correct as measured by my timing light, spark appears ok, better than my carbureted Z which runs great. I've fouled a set of plugs and an O2 sensor in just a few days of driving aroung town trying to tune. Attached is my current msq. Any help is appreciated.

2011-09-24start.zip

[dexter72]

By looking at your VE tables your first set of idle bins looks ok in table 3,( 36.0 37.0 38.0) I think your problem is your second row of bins in table 3. You increased your fuel by almost double. The second row of bins should be closer to your first set of bins in all your VE Tables at Idle. Try adjusting all the your VE Table bins to that 30. range, in the first two rows at idle. Thats what will give the engine a better idle and less fuel. Remember that the second row of bins have an affect on the first set of bins. Look at some of the maps in the map sharing Faq's section, you will see what I am referring to by looking at other peoples VE Tables.

 

Which VE table is megasquirt using to run your engine?.

 

Table 1 makes no sense to me, at idle you have 3.0 4.0 and 5.0 for fuel. Then it jumps to 57.0 58.0 at higher RPM, then it goes down to 2.0 3.0 7.0. Table 2 starts out in the 70.0's and 80.0's, Thats a ton of fuel at idle.

 

Adjust those and see what your engine does. Also you shouldn't install the wideband if you can't get the engine to run leaner. A overly rich running engine will kill wideband sensors. (

Edited October 4, 2011 by dexter72

[DCZ]

Thanks for the reply.

 

AFAIK (which isn't much!) the engine is running on VE table 1 only. Table 2 is greyed out in my TunerStudio software and I can't even find Table 3! I started out with one of Cygnus' tunes, changed the required fuel to match my injectors, changed the ignition settings and started it up. Since then I have mainly been lowering the idle bins in Table 1 -- in some cases to 0 -- and I still can't get it to idle above 11.2.

 

I know what you mean about the O2 sensor - I've killed one already

[mobythevan]

Also take a look at the link from Matt Cramer in the megasquirt FAQ section that talks about how to tune idle.

[dexter72]

You can drop the required fuel down more since your running 370 injectors and others are running 440's or higher. Just noticed that now that im awake. lol Look for someone who is running a similar injector size and see what there required fuel is.

 

Try dropping it 0.5 at a time and that may help lean you out. You will be changing your VE Table 1 again. After dropping the required fuel, try the 35-40 range in the first two idle bins. One row up and one row over.

[DCZ]

Moby -- I read that thread and just re-read it. Matt is using the VE table and advance table to richen/advance below the desired idle rpm in order to "bump" the idle rpm up to the desired level - correct? The problem I'm having is that I can't get idle AFRs to lean out to an acceptable level. Idle is pretty steady, although at a low rate ~650 rpm. I think at this point I have some gross adjustment to do before I can refine it using Matt's tips.

 

Dexter -- I have played with the required fuel a bit and here is what I've found: Using my 370 cc injector value, I get a required fuel around 8.4. I can't seem to lean my idle out enough with this required fuel value. Using an injector flow rate of 440 I get a required fuel of around 7.0. Using this value I get somewhat higher AFRs, around 11.9 or 12.0, but any revving of the engine goes very lean (I have not yet tried to drive around like this).

 

It seems that playing with the required fuel is the wrong way to try to tune, or am I just being dense?

[dexter72]

Changing the required fuel setting is to see if you can get a higher AFR. You then adjust your VE Bins lower and see what your AFR's are. Its quick and takes about a minute to do, If it doesn't work just set it back to where you had it. Thats why I suggested making adjustments of 0.5 at a time. You would still need to change your VE MAP 1, which you needed to do also.

 

Did you make the changes to your VE MAP 1 yet?. Engine should not be idling good with numbers like what you have, in your first 4 Bins.

58.0 58.0 That is kind of high of a fuel value in my opinion, unless your required fuel is low.

3.0 3.0 These numbers are low. If anything put 40.0 in all those bins and adjust required fuel to 9.0 and see how that does. If you didn't change your VE map yet the engine will not rev correctly.

 

If you look at most of the posted VE Tables you will see what I am talking about.

 

Are you sure those injectors are 370's ?.

Edited October 4, 2011 by dexter72

[DCZ]

I had to work too late today to work on the tune but I will give it a try tomorrow. As you suggested, I'll lower the required fuel and put some more reasonable values in the VE map and see what I get. I ended up with the small values in the lower left hand bins because I kept lowering them in an attempt to get the AFR into lean territory. Went all the way to zero and still was idling at ~11.2. This is with the warmup enrichment off as well.

 

Where are you seeing the values 58.0 58.0? The only value of 58 I see is at 6500+ rpm at a fuel load of 30%. Maybe I'm looking at the wrong table?

 

I'm pretty sure the injectors are 370. I bought them used and searched on the part #s and everything I found indicated they should be 370cc. Then I had them cleaned and flow tested. The documentation I got back said they flowed 90cc in their test. I called the company to question that and they said to multiply by 4 to get the cc/min.

 

The other think I was unsure about was the injector resistors. I used a stock NA ZX injector pack which measured out at 6.8 ohms. The injectors themselves measure at 2.4 ohms so the total is 9.2 ohms which I took to be "high impedance" so I have pulse-width modulation off. This is all new territory for me so I could be way off base on something simple.

[Tennesseejed]

DCZ,

 

After a looking at your .msq, a few things jump out.

 

1. You disabled "Incorporate AFRTarget" under More Engine Constants. I could be off on this, but even with secondary fuel load disabled, I still believe this should be set to 'include.'

 

2. EGO control is active above 160F, at 1300 rpm, and with 15% authority. In short, while you can manually adjust your AFR and VE table to tweak your idle quality, you can use your LC-1 to to help you by lowing these value temporarily.

 

3. Warmup Enrichment goes from 102% at 130F to 90% at 160%. ???

 

Too much importance is placed on VE tables in Megasquirt tuning. In simplified form, VE tables only represent a fractional value which, when combined with the injector characteristics, result in the desired AFR target. The AFR tables, as well as knowing the correct injector characteristics, are key. VE tables simply bridge the gap between the two.

 

I am not suggesting, as both Mr. Cramer and the Megamanual state, that idle quality cannot be tuned manually by adjusting the VE tables. But you must have both proper injector characteristics and AFR values to begin with, or you will simply be chasing a ghost.

 

If I may suggest a piece of advice . . . purchase the full version of TunerStudio for $59, review your .msg settings, set your wideband to operate at or below idle rpm , and run VE Analayze Live after your engine is at normal operating temperature. If your idle quality remains poor, expirement with your AFR tables to find the best idle. You can spend hours fiddling with VE tables manually by driving and recording data logs and then running VE Analyze in MegaLogViewer. And while this approach does work, save your self a bunch of time by just getting the live version.

 

If running VE Analyze Live and adjusting your AFR tables (not your VE tables) does not get a satisfactory idle, then your idle issue may well not be MegaSquirt related.

 

My .02. And good luck.

[DCZ]

Thanks tennesseejed,

 

1. You disabled "Incorporate AFRTarget" under More Engine Constants. I could be off on this, but even with secondary fuel load disabled, I still believe this should be set to 'include.'

Is this how I "turn on EGO control"? I didn't understand how this works so I've had it off thus far. Also, what is the secondary fuel load used for (VE Table 2?) and for that matter what is VE Table 3 used for?

 

2. EGO control is active above 160F, at 1300 rpm, and with 15% authority. In short, while you can manually adjust your AFR and VE table to tweak your idle quality, you can use your LC-1 to to help you by lowing these value temporarily.

 

That makes sense, assuming EGO Control = Incorporate AFR Target.

 

3. Warmup Enrichment goes from 102% at 130F to 90% at 160%. ???

That was one of my desperate attempts to lean out the idle. I figured that if I made warmup enrichment less than 100% I would pull some fuel. It works (badly!)

 

But you must have both proper injector characteristics and AFR values to begin with, or you will simply be chasing a ghost. . . .You can spend hours fiddling with VE tables manually by driving and recording data logs and then running VE Analyze in MegaLogViewer

 

HaHa! You've been spying on me! That is exactly what I have been doing. And the ghost is giving me the finger!

 

Thanks for your advice and explanation, it helps a lot.

[Tennesseejed]

DCZ, sorry for taking a week to get back to this thread.

 

First off, Moby, Cramer and Dexter know what they are talking about. Moby, in particular, is (IMO) a Z car Megasquirt guru here on HybridZ. I mostly want to chime in because I spent a lot of time trying to tweak idle by tuning VE tables and became frustrated with the lack of measurable results.

 

With respect to your questions, I don't have many answers:

 

1. The Megamanual does not elaborate much (or at all) on the "more engine constants" selections. My opinion on "incorporate AFRTarget" above is mostly based on the fact that it is not greyed out when secondary fuel load is disabled. Rhetocially speaking, what purpose does a VE table serve if it is not tied to an AFR table?

 

2. As I read the Megamanual, EGO control is turned on as soon as anything other than "disabled" is selected under "EGO Sensor type." In your .msq, you have selected 'single wide band,' so you should be having EGO correction during operation.

 

3. I really don't know what the secondary fuel tables are for. I think they are for things like water injection/methanol stuff where you are combining two (or more) different fuels.

 

4. With your car fully warmed up, you can change your EGO Control settings to help trouble shoot your idle issues. Set your authority to 75%, the idle 'active above' to 500 (below idle) and adjust your AFR tables instead of your VE tables to obtain the best idle. Adjusting your AFR tables should noticably effect your idle. Keep in mind, that this won't change your VE tables - unless you have the full version of TunerStudio - but it will at least tell you if your idle can be improved through Megasquirt, or if your idle issues may be not Megasquirt related.

 

Here is my latest AFR table.

 

I'm not in the turbo club, but below one bar, I think you AFRs are rich. After starting out with a very rich table myself, I found leaning things out improved both performance and economy.

Edited October 12, 2011 by tennesseejed

[HowlerMonkey]

Make sure your fuel pressure regulator is doing it's job as well.

[DCZ]

Thanks for the feedback. I haven't had much time to play with it these last two weeks but I have an update. I took your advice and upgraded Tuner Studio. The VE Analyze feature is definitely worth it. VE table is much smoother and the engine is running better. Still idling way too rich though, ~10.8 to 11.2 verified by filty black plugs. I'm pretty sure I have it set so that it should be modifying the table at idle so I've still got some work to do.

 

I set "Incorporate AFR target" to yes but couldn't tell any difference. EGO communication from the LC-1 and computer seems to be fine, the laptop and AFR gauge agree. I'll doublecheck the EGO control settings and download your table and compare it to what I have.

 

What is your injector pulse width at idle? I can't seem to get mine below 2.8 ms regardless of how I modify the VE table. I seem to remember an equation for pulse width somewhere in the megamanual so I'm going to look that up and see what effects it.

[DCZ]

Make sure your fuel pressure regulator is doing it's job as well.

Fuel pressure is good, ~34 steady at idle and goes up with boost.

[cygnusx1]

I agree, you really need to make 100% sure that all the parameters/settings/constants/corrections are in the ballpark before you play with theoretical VE numbers. Don't gloss over the MS manual. Read it, question it, understand it; EVERY setting counts.

[skirkland1980]

Any updates?

[tolerate]

Fuel pressure is good, ~34 steady at idle and goes up with boost.

 

I'm having a similar issue as the low rpm and idling in the 11-12 range.  Were you able to fix the problem?

[ihiryu]

Okay, so here's a few things.

 

1) You don't really need to "incorporate AFR's" but it is very helpful.  So in the future, if you decide you want to run a different AFR in a certain load point, all you have to do is change your target AFR tables, versus trying to redo the VE map.

 

I also really, really recommend using VEAL, it's worth the 50 dollars.  You dial in your AFR table, and let VEAL do it's magic.  Give it a sanity check, and go from there.  Learn how to smooth out your VE Table in 3D.

 

2) The throttle lean issue you're having is from lack of Accel Enrichment.  Every car is slightly different in it, and it's a PITA to dial in just right.  And it's even worse if you decide to change injectors cause you'll have to do it again.

 

http://www.diyautotune.com/tech_articles/megasquirt_acceleration_enrichment_tuning.htm

 

Stare at this link until it make sense.  AE is based on HOW fast you hit the throttle.  And it's based on your driving.  I can drive my miata just fine, but when someone else drives it, it has a bit of hesitation, based solely on how they drive (I haven't had a change to really dig back into this, but people seldom get to drive my car).

 

Another strategy for AE, is getting on the highway, in your final gear (fifth), and do varying throttle tip in's (usually with someone else driving or logging when you're driving) to get an idea on how AE works, and what changes need to be made.

 

Also if your REQ_FUEL is off, you'll NEVER get it dialed in right.

 

My suggestion would be to BOX in your idle map (use the all 9 squares around your idle) to get it to where it needs to be.   Also keep in mind of the load break points, on my base map for my miata, the break points were 900, then 1200, but my idle was set at 1000, so I could never get it to idle the right AFR's because it was interpolating between two load cells, until I boxed it in, then I had an issue with tip in throttle.  I rescaled my map for 500, 1000, 1700 ETC that way I could get it to hit certain load points based on my driving habits.

 

You might want to see if you can find anyone using your injectors, otherwise, I would look into a different injector that people have some data on (such as RX8 460's).  I'm not using an L motor (obviously since my MS is in a miata), so I don't know what injectors would fit your motor.

 

Oh!  For your MAT Correction, leave it at 100, but you have to try to tune on days that are close in temperature.  Once you get your VE dialed in, at that point you'll want to play with your MAT Correction.  

 

Also, if you log take a look at GAIR, that's the MAT correction factor.

Edited June 5, 2015 by ihiryu

[ihiryu]

Oh, VEAL doesn't do idle, you have to do idle.  What happens when you lean it out via the VE table?