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Car is going lean when on the throttle

 
Old 01-17-2019, 06:15 PM
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Default Car is going lean when on the throttle

The current mods on the car are the following flowforce ev14 640cc injectors, ms3 basic, t3 chinaturbo from mkturbo kit, ngk plug wires, ngk bkr7E gapped at .28, innovate lc1 wideband and new coil packs. So the problem i'm having is that the car will go real lean like 19:1 and start bucking whenever i go past 5% tps. I've been messing with AE but the results have been negligible. The car does not go past 65 kpa which I could not find what could be cause for this. I have a small leak in my bov as of now but i'm not quite sure whether it would cause all these symptoms. I wondering whether this could be a mechanical failure or tune related.
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2019-01-17_17.04.47.msq (194.8 KB, 19 views)
File Type: msl
new datalog 3.msl (4.81 MB, 9 views)

Last edited by Timothy Tran; 01-17-2019 at 08:02 PM. Reason: adding logs and msq
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Old 01-17-2019, 06:57 PM
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have you actually tuned the fuel map? did you try to autotune?
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Old 01-17-2019, 07:10 PM
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Yeah I've done quite a few rides with with autotune running but my ve table looks so different from what I've seen from other members.

Last edited by Timothy Tran; 01-17-2019 at 07:11 PM. Reason: grammar
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Old 01-17-2019, 07:17 PM
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Have you correctly calculated your required fuel (req_fuel).
Are your engine parameters in tuner studio correct, i.e. injector size, engine size, injector dead times.
I haven't taken a look at your tune yet, i'll try take a look when home today.
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Old 01-17-2019, 07:20 PM
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So I got my deadtimes from flowforce and the required fuel is 4.1 because flowforce said the 640cc injectors would equal to 752ccs at 4 bars of pressure because I have an nb2.

Last edited by Timothy Tran; 01-17-2019 at 07:21 PM. Reason: spelling mistake
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Old 01-17-2019, 07:49 PM
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You say you have ev14 640cc injectors but have 752 entered as injector size, are you running higher fuel pressure and this is to account for that?
EDIT: Ok so you were given those dead times and the injector size is correct then. The engine parameters look all good then.

Your acceleration enrichment is enabled, you need to turn this off while you are tuning your VE table.

Your VE Table is all over the place and is WAY high, at 35% fuel load you are almost maxing out the fuel table from 3800 to 5000.
In almost all of your cells you are above 100 VE, are you idling rich, as those idle cells look fairly rich, and just about everything more than 5% away from idle is WAY off which is probably causing miss fire and hence the bucking.

You are probably miss firing due to way to much fuel causing the o2 sensor to read lean due to missfire.
With stock injectors you would have enough fuel to run past 5% throttle so your issue is almost certainly not that you don't have enough fuel.

I think you need to reload the MS3X base tune you were given, re-calculate the Required Fuel based on those details you were given for the injectors.
Then ignore the sections with more than 100 KPA (maybe make them a bit richer for safety if you wish) and go and tune your N/A areas (everywhere possible under 100 KPA).
If you have been using autotune for this then based on this all your autotune settings are wrong.

Ensure that your wideband is working correctly, ensure your Wideband, MAP, TPS are all calibrated.

I haven't watched these videos yet but the thread seems to have good praise so watch these.

https://www.miataturbo.net/megasquir...g-guide-98277/

I will look at the log when I get home.
I imagine that in the areas you are having issues in (everywhere) that if you look at the log and watch the Duty Cycle values you will see them above 50, 60, 70 or even higher percent.

At essentially everywhere except idle you are DUMPING fuel into the engine and it suffocates from fuel so it misfires. This would be why you get a lean reading as all oxygen would be present due to no fuel burning.

Hope I don't seem condescending or anything or don't make much sense, at work so trying to be quick.
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Old 01-17-2019, 08:00 PM
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Originally Posted by venetox View Post
You say you have ev14 640cc injectors but have 752 entered as injector size, are you running higher fuel pressure and this is to account for that?
EDIT: Ok so you were given those dead times and the injector size is correct then. The engine parameters look all good then.

Your acceleration enrichment is enabled, you need to turn this off while you are tuning your VE table.

Your VE Table is all over the place and is WAY high, at 35% fuel load you are almost maxing out the fuel table from 3800 to 5000.
In almost all of your cells you are above 100 VE, are you idling rich, as those idle cells look fairly rich, and just about everything more than 5% away from idle is WAY off which is probably causing miss fire and hence the bucking.

You are probably miss firing due to way to much fuel causing the o2 sensor to read lean due to missfire.
With stock injectors you would have enough fuel to run past 5% throttle so your issue is almost certainly not that you don't have enough fuel.

I think you need to reload the MS3X base tune you were given, re-calculate the Required Fuel based on those details you were given for the injectors.
Then ignore the sections with more than 100 KPA (maybe make them a bit richer for safety if you wish) and go and tune your N/A areas (everywhere possible under 100 KPA).
If you have been using autotune for this then based on this all your autotune settings are wrong.

Ensure that your wideband is working correctly, ensure your Wideband, MAP, TPS are all calibrated.

I haven't watched these videos yet but the thread seems to have good praise so watch these.

https://www.miataturbo.net/megasquir...g-guide-98277/

I will look at the log when I get home.
I imagine that in the areas you are having issues in (everywhere) that if you look at the log and watch the Duty Cycle values you will see them above 50, 60, 70 or even higher percent.

At essentially everywhere except idle you are DUMPING fuel into the engine and it suffocates from fuel so it misfires. This would be why you get a lean reading as all oxygen would be present due to no fuel burning.

Hope I don't seem condescending or anything or don't make much sense, at work so trying to be quick.
No you weren't condescending. I really appreciate you taking the time and help me troubleshoot what is going on. I'm going to go back to my base map and try to autotune it a bit after work tonight. I'll get some logs and post the results later tonight later tonight. Forgot to mention I have a innovate lc1 for my wideband.
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Old 01-18-2019, 12:06 AM
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So good news everyone, using the basetune and using autotune really helped th car run a bit smoother. I am still having the problem with going lean while when getting on the throttle. Although i forgot to disable AE until after the autotuning session. New Ve table looks close to normal.
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Old 01-18-2019, 03:47 AM
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You NEED to disable AE during autotune, else it interferes with the fuel calculation in these cells.
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Old 01-18-2019, 06:59 AM
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Originally Posted by HarryB View Post
You NEED to disable AE during autotune, else it interferes with the fuel calculation in these cells.
More importantly: move the throttle slowly so that the effects of MAP, MAPdot, and TPSdot do not affect AFR. You donít want the natural leaning that occurs on throttle open, nor an-over enrichment of too much AE to be included in your VE tuning.
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Old 01-18-2019, 07:11 AM
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Originally Posted by HarryB View Post
You NEED to disable AE during autotune, else it interferes with the fuel calculation in these cells.
My car doesn't autotune when AE is currently active, or when in overrun, and under a few other circumstances. It tells you so in the window on the right.
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Old 01-20-2019, 03:02 AM
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So I've been trying to autotune my ve table to some success(I disabled AE as well).Although I'm still having a good bit of bucking when I hit 25-30% tps. An example of this happening would be on 198, 206, 210 and 340. The car revs in neutral without a problem so I am guessing the problem is caused by my rough VE table.
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Old 01-20-2019, 09:20 AM
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Originally Posted by Timothy Tran View Post
So I've been trying to autotune my ve table to some success(I disabled AE as well).Although I'm still having a good bit of bucking when I hit 25-30% tps. An example of this happening would be on 198, 206, 210 and 340. The car revs in neutral without a problem so I am guessing the problem is caused by my rough VE table.
You're being quite rough on the pedal (high TPSdot). Try to be more smooth in throttle changes while tuning the ve table. Bucking is to be expected on quick throttle changes without (good) AE.

Looking at your Fuel VE table, below 50 there's a huge difference in fueling. What's going on there?
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Old 01-20-2019, 11:59 AM
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Originally Posted by sixshooter View Post
My car doesn't autotune when AE is currently active, or when in overrun, and under a few other circumstances. It tells you so in the window on the right.
This. No need to disable AE or any other enrichments.
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Old 01-20-2019, 12:31 PM
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If you're lean enough the car is bucking and won't accelerate you need to stop driving it. Increase req fuel until you get the tune closer to where you need to be; like +20% or something. You DON'T want to start with the car super lean and gradually richen it up as you tune. You want to start with the car rich and gradually lean it out as you tune. You're asking for trouble rolling onto the throttle with it that lean.
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Old 01-20-2019, 07:10 PM
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When auto tuning, the key is to only have the table update when your fueling is stable.

A few things I did when tuning my VE table:
1) As already mentioned, use _very_ smooth throttle transitions. Take your time with slow accelerations.
Try to stay at a throttle setting for 5 seconds before transitioning to a different throttle setting.
2) Find some long hills of varying grades where you can slowly increase your throttle to cover off different engine loads.
3) Use the custom filter in autotune to discard any records that have too much variance in fueling. I use the following:

map < 30 || abs(MAPdot) > 30 || abs(historicalValue(MAPdot,1)) > 30 || abs(historicalValue(MAPdot,2)) > 30 || abs(historicalValue(MAPdot,3)) > 30

This looks at the current record and 3 historical records, discarding any current record that is less than 30 kpa (I tend to tune manually in this area) and any records where the fueling changes too much (by my determination) over a total of 4 records.
4) Use the Cell weighting during and after a session to determine what areas are being covered / missed.
5) Record your autotune sessions so you can look at them later and learn from them.

6) Have someone with you to watch Tunerstudio ... driving and looking at Tunerstudio is dangerous for you and everyone around you.
7) Take your time.

Finally once you have reasonable coverage, use the table tools to interpolate, extrapolate and smooth your fueling map. Fueling will typically increase when moving up in load and moving right on RPM.

Last edited by VcrMiata; 01-20-2019 at 07:11 PM. Reason: numbering and clarification on kpa
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Old 01-23-2019, 10:31 AM
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You were advised that your numbers jump up significantly in your table and you are probably way too rich. I can't see the table currently but would advise you that your AFR sensor will register lean if you have a misfire due to being too rich.
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Old 01-24-2019, 10:17 PM
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Originally Posted by pdexta View Post
If you're lean enough the car is bucking and won't accelerate you need to stop driving it. Increase req fuel until you get the tune closer to where you need to be; like +20% or something. You DON'T want to start with the car super lean and gradually richen it up as you tune. You want to start with the car rich and gradually lean it out as you tune. You're asking for trouble rolling onto the throttle with it that lean.
I will try that for sure in the trouble areas. Thank you for the tip.
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Old 03-04-2019, 08:40 PM
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Sorry to revive an old thread but I finally found the solution to the bucking on throttle it was the tune and some bad injectors.

Last edited by Timothy Tran; 03-04-2019 at 11:03 PM.
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Old 03-05-2019, 09:15 PM
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1. Reviving thread to publish solutions is a good move.
2. Bad FF injectors is quite rare. Care to elaborate?
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