Reverant MS2, Lean under throttle tip-in + slight stumble, accel enrich wrong?
 

Right, so I'm running a Reverant MS2 basic standalone on a 93 1.6L car with RX8 injectors, a BMW vTPS, running NA only, have not installed turbo yet. I'm still learning tuner studio and a bit overwhelmed with all the options/menus that are present, and want to make sure I'm not missing something obvious here...

Issue:
The car runs well enough off idle, and will idle fine with some hunting around - which sounds common - except if you lightly dip into the throttle you get a stumble, or if you mash it from idle it falls on its face momentarily before revving up normally. During the stumble, it goes lean on the WB gauge and on the TS gauge, more on this in a moment From what I recall, it did not have this stumble when running the stock ecu.

Things done/tried:
1. Fuel system seems fine, new filter. Have not checked pressure yet, but assuming the pump can supply sufficient fuel at higher loads, light load shouldn't be an issue.
2. New plugs, factory gap (.035 i believe)
3. Newish NGK wires, stolen off my daily driver so they are known good w/ ~5k miles on them. Properly secured and w/ dielectric grease.
4. Intake is stock miata, thru the vane airflow meter. The meter is not hooked up, merely in the flow path so I can use the stock panel filter. Wondering if this was causing an issue, I removed the crossover tube from the vane airflow meter so that it was out of the path, yielded little to no change. Filter is new.
5. Checked resistance from block to chassis, battery to chassis. Block to chassis slightly high @ 3.5 ohms, added additional ground strap and brought it to 0.7, which seems good enough for me given that its a low end Fluke meter.
6. Double checked timing, running Reverant's timing map which seems pretty conservative and similar to DIY's. Timing matches when checked with timing light.
7. Prior to messing with accel enrich settings, I tried enriching the VE map in the 500/1000/1500 rpm range, from 35kpa to 100kpa. At times this seemed to help, maybe slightly but not much
8. Changed accel enrich settings from coming into play from 2500-5000 rpm to 800-5000 rpm (attempting to add more fuel at throttle tip-in) Also modified the curve from Reverant's original settings, testing it at more and more aggressive settings until achieving super rich readings at the same stumble. At this point the stumble felt/sounded a bit different, but was about the same length of hesitation. At this point I was using 100% TPSdot. I tried screwing with MAPdot as well with varying percentages, but it seems to just be a stumble with either a lean spike or rich spike at the stumble, no happy medium.
9. Also tried VE Analyzer Live, which was nifty but could not compensate for the stumble and ended up just giving me a hunting idle.
10. Lots of other random stuff that I tried in frustration, to no avail.

(Realized at some point that modifying the VE table as I was, enriching the hell out of the idle area, was really doing the same thing that the MAPdot enrichment under the Accel Enrichment settings was doing. So yes, my VE table is probably awful.)



So, am I missing something obvious? Is there a setting I'm not understanding that is set wrong?



Note: No, I don't have a datalog yet and haven't figured out how to export my .msq and such... working on it. Screenshots of VE and IGN tables instead:

https://www.miataturbo.net/attachmen...ine=1367196510

https://www.miataturbo.net/attachmen...ine=1367196510

https://www.miataturbo.net/attachmen...ine=1367196510

https://www.miataturbo.net/attachmen...ine=1367196510

https://www.miataturbo.net/attachmen...ine=1367196622

https://www.miataturbo.net/attachmen...ine=1367196622

https://www.miataturbo.net/attachmen...ine=1367196622

Also have EGO correction set to "off" so that variable is out.

I've read and read, and searched and searched, tried the options I found... Appreciate any insight.

Jesse

Also checked for vacuum leaks, checked for kinked vacuum line to MS2, and MS signal line already tees in @ fuel regulator.

I know my VE map is nuts, I feel like I'm compensating for something else when I add tons of fuel there or in the Accel Enrich wizard... So what am I missing?

Your settings look decent.

If you want help I suggest you make a datalog and take a screenshot of it or use MLV's convenient save to jpeg/png feature and post it.

edit: or post a full datalog :)

Fair enough, I'll get on it tonight.

not good enough.

Well I've been watching the "diagnostics" tab with the live data streams in TS - I imagine a screenshot from Mega Viewer would be similar anyhow.

Brain, what would be sufficient? the whole .msq file? Or just a real datalog? I'll do a datalog tonight - will basically be with the car at a warm idle and me slapping the gas pedal quick like, or stabbing it to the floor pretty quick.

Also, I have a bmw vTPS that seems to be operating correctly and has been calibrated.
Also, the ground for the wideband is straight to chassis, does not share with radio or ign components.
Also, the MS2 unit is velcro'd to the carpet, so it is NOT grounded (per some reading here), and only connected via Rev's adapter harness to the factory wiring.

how can a screenshot show me over 40 different data points at various points of a log

The lc1 should be grounded to the engine block at the same point as the factory grounds to avoid offset and noise issues.

11.22 - Cold start. Wideband is warming up until ~24 seconds in. Spike at the end is a quick slap on the throttle about 3/4 to the floor.

24.34 - After warm up. Two quick throttle blips, followed by a quick slap to the floor, followed by a slow press of the pedal. Stumble in the rapid blips, no stumble on the slow throttle input.

The car seems to drive fine, power and drivability are near stock. The quick throttle input only really comes into play leaving from a stop... Which coupled with an aggressive clutch isn't any fun. Also, once its above 2000-2500 rpm, this stumble with rapid throttle input seems to go away.. not sure if that's just a function of things happening faster or what. Naturally, I didn't think to log that - can do if it's important.

Thank you

Mine is the same, but it has now gotten to the point where the car will stumble at any RPM if I increase %TPS or stall if I disengage the clutch anywhere above 4k rpm and let the idles drop.

Not too much MS experience here. But you need a good VE table before being able to dial in Accel enrichments. Go run VEAL and do some driving then play with the Accel enrichments again

Agreed on the good VE table, but I started with a decent table from Reverant, and was able to autotune it a bit better... This same stumble was present the whole time. My current lumpy VE table is only a result of trying to dump in more fuel at the stumble.

I was thinking that maybe somewhere there was a lag setting awry, or I'm not setting the accel enrich curves steep enough, or some other mystery setting that I don't know about...

these are two different issues. lets first address the idle droop.

is this during overrun, or anytime over 4K?

there could be a pleathora of reasons why is does this: needs more dashpot, poorly tuned VE table, overrun returning fuel too late and the mechanical delay between injection and combustion isn't fast enough, etc etc.

Overrun/Decel fuel cut is disabled, as is EGO correction.
Again, driving around it feels fine because your rpms are almost always up off idle... My understanding is that it should idle ok @ ~800-900 rpm with the RX8 425/460cc yellows, without any mystery hesitation.

Any insight from the logs?

I ahvent looked at logs yet.

Update:

Playing around with AE wizard a bit more this weekend, I was able to get rid of most of the lean stumble that was present. previously the graph was starting at 50%/s, I brought it all the way down to 1%/s so I get extra enrichment right away, with less throttle input/speed.

Now I only get a lean spike if I just slightly touch the pedal... I don't get it, it goes lean for a split second and hesitates just slightly before revving normally. My understanding was that adding a vTPS would make this go away entirely.

No one sees anything wrong with any of the screenshots or log I posted?

thank you

what is your TPS threshold %/sec in AE?

4.4%/sec
https://www.miataturbo.net/attachmen...ine=1367885135

Seems like crazy amounts of fuel being added to me, but mostly got rid of the stumble. Obviously it does go pretty rich under throttle now, but doesn't hesitate like it was before.

One thing I see after looking at your log quickly is that when you step on the pedal lightly it pulls 2 degrees of timing right away. That cant be helping anything when it comes to getting smooth off idle response.

Hmm... Yeah I see that too, but it seems to be properly following the base ignition map (back on pg 1) I got from Reverant.

I'll try running the idle rpm columns all at a constant 14 deg and see if that helps. I did notice that this IGN map is very conservative compared to what others here are running, Joe P, Braineack, etc.

You post the lowest value point you have in your table, NOT your threshold. Why dont you scroll the window down and actually check? If your threshold was 4.4%/sec you'd be complaining about AE engaging constantly and making the drive undrivable. :)

actually...

Excellent point Brain, I'm still getting used to the software and hadn't even noticed the slider bar... Ouch. Thought you just meant threshold as in the start of the graph. Will check the settings tonight.

Oh, and AE is indeed engaging constantly, but that's what got rid of the lean stumble... I figured I was either tuning it out by MAP via the VE table, or by adding more fuel earlier with AE.. Ended up with a combo of both that helped, but doesn't seem like the right way to do things.

if ae was constantly triggering is would be horrid and constantly spiking rich at idle when triggered.

Hmm.. Duly noted, will check to see what those other settings are. It does go pretty rich when you get your foot in it, whether at idle or just will driving... Deep down into the 10's on the WB. I was just happy it wasn't stumbling as bad.

Right, here's the rest:
https://www.miataturbo.net/attachmen...ine=1367963220

Played with my newfound settings a bit, here's where I ended up. Still very rich when AE comes on, but still get that lean blip when I tap the gas lightly.
https://www.miataturbo.net/attachmen...ine=1367976822

Here's another log as well:

mapdot is filtered out. you just need fix that and tune.

Hmm, you're right. I tried changing more things around to see what effect they had..
so,
Read somewhere to put it to 100% TPSdot since I have a vTPS... So it's basically turned off now anyway.

Tubetune? I was attempting to tune AE using the little line graph display in the wizard.

https://www.miataturbo.net/attachmen...ine=1368058124


So lots of AE as you can see, and it appears to be functioning properly with pulsewidth increasing with TPSdot... But still these lean spikes? The spike is on the down thrust of the gas pedal, not after releasing it.
-injector dead time issue?
-somehow tune AE to add more fuel initially but then less, or change taper?
-possible one of my injectors is slow or not flowing properly?

Braineack, since I have a vTPS, is it worth still bothering with the MAPdot AE? I had read, I think on DIYautotune, to just set TPSdot to 100% if you are using a real tps.

Trying to tune AE by blipping throttle on idle is counter productive. If you manage to get it right, it will be way too rich in regular driving. Instead, try to get it right first by driving around at a usual rpm (like 3000) and start setting up AE for slow throttle inputs and advance towards quicker changes once you get the slow ones right.

Do not blip, instead push the throttle to a new position and hold. If you lift, you cannot see how the situation returns to normal. Usually lifting causes rich condition. I've got best results using 0.1s accel time and increasing PV so that the extra fuel comes when it's needed, not after the map sensor has sensed the change. Other than that, there's pretty much nothing you can do about it (apart from using EAE).

Once you get your AE working in normal conditions, move on to setting up for good response from idle. Do not touch the AE tables. Instead, follow the pointer on your VE table when you launch. It goes straight up, then starts falling to the right. You want to increase fuel in the cells right above your idle. After all, you only hit combinations like 50kpa, 850rpm when you are freerevving / launching.

Ps. you prolly want to view AFR and AFR Target 1 lines in a single graph (and set their axis min and max values the same) so that you can constantly see how much off you are from your target.

Hi Ode,

I think I had followed one of your posts from anther thread where you described something similar... Thank you, this is what I've done with my VE table. Also, I see what you mean with hitting the throttle and holding it, rather than blipping it.. Will try tuning that way next.

My issue is that no matter how much fuel I add via the VE table, MAPdot AE, and/or TPSdot AE, I still get that funny lean spike on the AFR which is accompanied by a slight stumble/hesitation. Above 1500 rpm or so it seems to go away. So I'm still wondering, is this some other issue/setting that is wrong?

cheers

Does anyone else do what Ode recommends with the VE table?

I leaned the AE back out to where it was previous, as it wasn't helping with that lean spike on throttle tip-in.

Also played with the Lag factors under general settings, reduced the filtering a bit. Bumped TPS lag from 85 to 100, and rpm from 50 to 85. Effects were negligible as far as I could tell... The lean spike is still present, although not quite always.

Went back thru and checked vacuum lines, all look good, and no kinks or splits. Timing table is similar to what everyone else is running. Injectors were used units when I installed them, considering pulling them and sending them out for cleaning/flow testing next.

Well, a year later and car has run excellent aside from this lean condition on low rpm throttle input. Never did get this resolved.
Any other thoughts? AE has been fooled around with quite a bit, but even dousing the cylinders w/ gas it seems to go lean that split second... Is this just normal? Anything else to mess with?

Fuel and ignition systems are in perfect repair, no issues there.

Basic MS2 IIRC?

Hi Rev - yes, exactly!

This was a thread I was also reading prior, but never understood if the car needed more/less AE, needed the VE table modified as Ode suggests, or some other issue...
https://www.miataturbo.net/megasquir...ettings-67485/

Edit:
Fooled around with this more just now, and tried SJP0tato's settings, which had much much much more fuel being added (see post #10). These settings seemed to more or less cure the stumble at idle, only occasionally there is a little hiccup with it going lean. But, now I actually get a rich stumble when I stab the gas while driving, at higher rpms. I understand the curve is based on rate of tps change, and adds pulsewidth. Is there a way to decrease the AE with higher rpms? Or just the on/off rpms in the AE settings menu? I have the low threshold @ 800rpm and high threshold @ 5000rpm. I tried lowering the high threshold down, but then ended up having a lean spike there on throttle tip-in, since there was no AE being added...

Try the latest beta firmware, 3.3.2 beta 7. It has solved any throttle response issues I've had.

I have the same exact issue. AE just adds after the lean spike. more AE = less than target (9-12 depending on AE setting) AFR after the spike to 18+. just for a split second.

Latest software I believe, purchased in Dec. 2013??.

One of my units?

I believe so, I purchased the unit used from another member here and was told it was built by you. It was tuned by 18psi, used by the orig. Purchaser then sold to me. It was for a turbo application so I started over with a diy base map. I doubt it is the fault of the unit, as I have learned that ms/ts has a steep learning curve. I was just searching threads to try and solve my situation.
My version. Of ts was purchased on December 2013. So i was under the Impression that when I registered my unit, I was on the most current code.

Rev - I've actually gotten it to clean up quite a bit by adding wayyyy more fuel, as well as using 50% MAP based/50% TPS based... Hopefully that's the right way to go about it, as it doesn't seem to really like running 100% on one or the other. Running AE on 100% MAP results in small lean spike/stumble on throttle blips no matter how much fuel is added but seems to run great once you're moving, and running on 100% TPS gives clean throttle blips, but ends up way rich/stumbling when under load and tromping on the gas pedal.

As for updating the firmware, I'll try that after an up and coming track day - afraid I'll mess it up or make it worse if I rush and try to get it sorted now. I haven't ever updated it from what you started me with, will I lose any settings or anything in the process of upgrading?

Ryan - Adding lots of fuel to both MAP AE and TPS AE seems to be working for me. Running only MAP AE, I couldn't get rid of that first little lean spike, just seems to be the nature of the beast, guess it's a lag in the MAP signal. Are you running a BMW or Wells VTPS?

No I am running the stock 1.8 tips. I'll try what you said though.

You can't use TPS based AE with the stock tps I don't think... its just an on/off switch. You can adjust the MAP based threshold and curve numbers though.

Maybe, I can definitely make it more or less rich using the tps, but still get the lean spike. I was going to try map, just to see what happens.

^ 1.8 TPS is Variable. The 1.6 one is just on/off

Ah sorry, my bad. You guys and your big blocks... :rolleyes:

why does every bit of my tuner studio, unlike everyone else who posts here? There seem to be so many selections while tuning that i do not have. enrichment wizard? what the fuck is that? what did I buy?? diypnp ms2 latest firmware.

Each firmware has different options in tunerstudio.

Have you tried idle advance? It won't cure all your problems but it would help with getting out of idle smoothly.