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Car was trailered, street tuned, brought home and is now running rich anytime in boost. Between .5-1.5 off of target. any idea what could have happened that causes it to start running rich? I was hitting the target perfect before getting the car home. The outside temperature is much warmer and about 300' difference in elevation but the ecu should account for that. It idles well starts well cold. Hot start inst very good and wants to die. It still has the stock fpr so I was thinking it may have started going bad. I have a log I can update when I get home. The cars running 10psi with a little spike on the way into full boost. Thanks for the help. Thought id see if there were any other idea. 200K mile motor thats been taken care of with good compression (175 all cylinders).
Last edited by 96Miata!; 05-29-2020 at 03:09 PM.
Reason: tune and log
I am doubtful that the elevation had any real effect if the difference is 300 feet. But ambient air temperature can be a factor. What ambient air temperature was it when the car was tuned and what is it now? There is a manifold air temperature correction table that compensates for the air temperature that can be tuned to give a more consistent fueling in different air temperatures.
For hot start, you likely need more after start enrichment. Could be that you need both more duration and pulse width.
The ecu is supposed to correct for the elevation. The temperature difference is from 55 to 80 lets say currently but it was not like that when the problem original started. It was much closer.
The ECU can be set up to compensate for barometric pressure. I have yet to see a tune on a turbocharged car that is utilizing that feature. To my knowledge, no-one has published their results of tuning for baro changes.
Meanwhile, Andy is correct that 300’ is not enough to have a noticeable effect. I suspect a storm system would have greater change in barometric pressure. Yes, I checked. 300’ is about 1kPa. A bad storm is 3kPa.
DNM
The ECU can be set up to compensate for barometric pressure. I have yet to see a tune on a turbocharged car that is utilizing that feature. To my knowledge, no-one has published their results of tuning for baro changes.
Meanwhile, Andy is correct that 300’ is not enough to have a noticeable effect. I suspect a storm system would have greater change in barometric pressure. Yes, I checked. 300’ is about 1kPa. A bad storm is 3kPa.
DNM
I gave a hand at tuning for Barometric pressure at one of the stopping points on the chereholla skyway last matg. Things were weird though. I ended up having it add way more fuel than necessary to prevent a lean situation.
What I didn't realize is that when you do a rapid elevation change, say from sea level to 5000 feet like in NC, by the time you get to 5000ft, ambient pressure instead of 100kpa becomes 81 or so KPA. My fuel table targets a very different afr at 80 kpa compared to 100kpa. I think around 80 I was around high 13's low 14's and 100 I am targeting 12.6 kpa. But without any tuning for barometric pressure, full throttle up the cherehola was getting me mid 14's for afr which I felt was scary for full throttle even though it was only 80kpa.
So I added silly fuel to get me to 13 or so afr full throttle at 5000kpa even though that is richer than my map dictates at that KPA. Full throttle doesn't have ego correction by design in case my wide band loses a signal at full throttle.
Andy, thanks. My comment about not seeing a correction curve was still referring to turbocharged vehicle.
I live within 100 miles of the highest point east of the Mississippi. Perhaps I should take a ride up there and play.
my goal would be only to make fueling at any point on my map require no EGO correction. I don’t count throttle position. Consider, with EBC at 4000 RPM, WOT can result in anywhere between 100 and 200 kPa on my car.
This is how my baro is setup. The graph is blank but again likely not my issue. My log will not upload because of file size. I attempted to trim it but i guess the trim doesn't save back to the file and only for viewing. I can try and get a shorter log sometime soon.
96Miata: Your curve is the Old Way and set for no corrections (table is all zeros). I suggest that if you ever wish to actually use this, that you transition to the new way. "0" "0" and then no correction =100%, rather than what have, the old way, with "147", "-47" and "0" = no correction.
Andy: According to the hints, both of your bottom settings should be "0". I don't know if that matters that you have the "10" in there or not.
96Miata: Your curve is the Old Way and set for no corrections (table is all zeros). I suggest that if you ever wish to actually use this, that you transition to the new way. "0" "0" and then no correction =100%, rather than what have, the old way, with "147", "-47" and "0" = no correction.
Andy: According to the hints, both of your bottom settings should be "0". I don't know if that matters that you have the "10" in there or not.
96Miata: post a log
I saw that too. I am not sure, I think I used what was in the basemap as supplied from DIY for that but then again as supplied in their basemap they had selected the wrong map sensor for barro correction and I had to call them and confirm what the correct settings should be. Then I had to figure it out on my own since it was still wrong.
I haven't been able to get a new log yet that is smaller file size to upload but I tried to zip my larger data log and see if this works for you guys.
Also I will update my tune to use something similar to the new style for elevation change.
My thoughts. Not seeing the Log from the street tuning session, it is not possible to make a comparison.
1) Not aggressive enough EGO "P". No instant correction. Possibly not enough "I" either. It does not have enough time to make a correction before you change the working point. So, you have 20% authority, but are using very little of it.
2) Not aggressive enough MAT temp correction. Really that should be #1. Your base is 100% at 86*F. so at 122*F, I would expect the correction to be 95-96%. Your's is 98.6. There is a lot of the issue.
3) Unrelated to your rich in boost: I notice you have Long Term Trim turned on. If you know what you are doing, then fine. I don't know of anyone using it on a Miata. It seems rather complex to me.
4) And, you may just need more VEAL time.
5) Unrelated to your rich in boost: Your timing map is ultraconservative assuming stock 9.0:1 CR pistons.
Thank you so much for taking the time to look it over.
1. It really only correct when cruising. So that makes sense as to why now. Any suggested numbers for P and I?
2. Again I guess what would you recommend for this tables settings?
3. My tuner turned it on and I hope he knows that. I will check with him. Should I turn it off?
4. Yeah I can do more VEAL but I would like to correct everything else I can first.
5. Stock pistons for a 96 Miata as far as I know. I did tell him to keep the tune conservative as I would rather the car run longer then have reliability issues. Are they too conservative where they will hurt something?
Again thanks for your time. No I do not fully know what I am doing and trying to learn along the way.
I haven't inspected your settings but to answer your question, too conservative can increase the EGTs and is tough on the turbo and mounting hardware, etc.
05-29-2020, 02:42 PM
Randomly running rich under boost
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