Intermittent Hard Starts (LS Swapped Mazda RX8, 2004 GTO Donor)

[jabjr26]

Probably a dumb question, but I cant seem to find a straight answer. IF (dont know for sure) my car was tuned and the tuner used lambda targeting 1.0 to tune it as opposed to targeting a specific AFR like 14.7:1 ect. Does it make sense that he would also adjust the stoich table in the tune to 14.08:1 from 14.7:1? From what i gather the whole reason you use lambda is to not have to jack with targeting certain AFRs. You just tune the car to a lambda of 1.0 and you are good to go....so if thats the case, and it was tuned to a lambda of 1.0....changing the stoich table in the tune would just jack that up wouldn't it? Can someone who knows better explain? Makes me think he was troubleshooting something during the tune process then just forgot to change the stoich table back to 14.7:1(stock). The documentation he gave me when i picked up the car shows the dyno run and HP/Torque curve with a target lambda of 1.0 along the x axis. This leads me to believe that it was tuned targeting a lambda of 1.0, and if so....shouldnt the stoich table have been left alone in the tune?

[jabjr26]

Went ahead and tried changing the stoich table to 14.7. I've had mixed results, but it does seem to have made it better....kind of. It seems now cold starts are not happy, but hot starts are (i.e the problem kind of changed). Hardware wise the only thing left is the fuel pump. At this point I may just buy a new one, but the one in there is essentially brand new, and I have the same feeling about the pump that I did about the injectors...that are seeming to have not fixed the problem, but I am just at a loss. Any help or input would be appreciated. Current tune is uploaded.True_Street_Tune_AFR.hpt

[ryan_axberg]

on the stoich I'm not positive how it works. I have always had it set at 14.7 and haven't had any issues. I live up in Alaska and don't have any e85 so I have only used gasoline. How widebands are set up for the most part, maybe some are different. But they interperate stoich as 14.7 because most people use gasoline. So even if E85 was in there it would would want idle and cruise to be set to around 14.7 from the wideband reading, even though thats not the real stoich for e85 that is what the gauge would show I'm pretty sure never done it. I will mess with my truck next time I think of it and put the stoich to like 9.9 and see if it adds like a third more fuel. Also I would zero out your ect spark correction table.

[240sxpooter]

on the stoich I'm not positive how it works. I have always had it set at 14.7 and haven't had any issues. I live up in Alaska and don't have any e85 so I have only used gasoline. How widebands are set up for the most part, maybe some are different. But they interperate stoich as 14.7 because most people use gasoline. So even if E85 was in there it would would want idle and cruise to be set to around 14.7 from the wideband reading, even though thats not the real stoich for e85 that is what the gauge would show I'm pretty sure never done it. I will mess with my truck next time I think of it and put the stoich to like 9.9 and see if it adds like a third more fuel. Also I would zero out your ect spark correction table.

People change the stoich to 14.1 because most gasoline contains 10% alcohol now.

[jabjr26]

People change the stoich to 14.1 because most gasoline contains 10% alcohol now.

Right and I understand why they would change it to 14.1, but why would you do that if you tuned using lambda? Maybe I just don?t understand how that table interacts with the other fueling tables. I just was curious since it seems I?m fighting an issue where it is too rich and that?s why it?s struggling to start.

[240sxpooter]

Right and I understand why they would change it to 14.1, but why would you do that if you tuned using lambda? Maybe I just don?t understand how that table interacts with the other fueling tables. I just was curious since it seems I?m fighting an issue where it is too rich and that?s why it?s struggling to start.

This table is kind of like a global fuel target table. If you double the AFR you just cut the fuel delivery in half. If your car is running rich overall you could use this to correct that, But that may or may not be what you would want to do. Get some good logs and people can help you out.

[ryan_axberg]

I just tried switching my stoich from 14.7 to to 12 just to see what would happen and I feel like it would be a bad way to have the fueling set up. Because even if you have some ethanol in the gas the gauge would still be reading 14.7 for stoich. It would be messing up all of the different commanded afr.

[jabjr26]

This table is kind of like a global fuel target table. If you double the AFR you just cut the fuel delivery in half. If your car is running rich overall you could use this to correct that, But that may or may not be what you would want to do. Get some good logs and people can help you out.

I have more logs then i know what to do with given i have been fighting this problem for months. Ill try to organize something that makes sense and post a few. Regardless, it looks like the tuner just changed it to 14.1 due to 93 pump gas being used. I am just concerned that he turned off certain shit in the tune while he was tuning, then forgot to turn then back on...but maybe i am just mis-understanding certain things he forced off. If you could look at this tune and give some inputs that would be much appreciated.

I just tried switching my stoich from 14.7 to to 12 just to see what would happen and I feel like it would be a bad way to have the fueling set up. Because even if you have some ethanol in the gas the gauge would still be reading 14.7 for stoich. It would be messing up all of the different commanded afr.

Agreed, thanks for doing that.

[jabjr26]

I am now 99% sure that the problem with the random hard starts is indeed with the tune like I initially thought at the beginning of this mess. I guess I just kept thinking there is no way that a reputable shop charged me 700 dollars to dyno tune this car and it be the problem. While this COVID mess is a pain in the ass, it also has given me some extra time to learn about the tuning process and realizing how much I got fu$%ed by this shop.

Here is just a small sample of what I got after paying 700 dollars for a full tune:
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I stopped logging on purpose after 15 mins because I realized that not shit had been done. Running 16-20% lean in the cruising RPM range...not only does it show they didn't tune anything its also just flat out not safe. While being this lean shows they didn't tune anything, it doesn't explain the hard start. However, on several other logs while cranking during the hard starts its clear that the tune is still the issue because it is ~9-12% rich while cranking and starting both hot and cold. Also the commanded AFR is SUPER rich on startup. Long story short once I realized how this amazing tune I got from a great shop, and professional tuner was shit....I started again from a stock 2004 GTO tune file, and was able to get things more dialed in and the hard start worked out.
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I've got the VE and MAF mostly dialed in, and now am working on the timing tuning. Which I also have found a lot of little gems (like they disabled knock retard completely) so even if the motor detects knock the tune doesn't allow timing to be taken out....which is just insane to me. Anyway just wanted to follow back up for anyone following this thread. I appreciate all the inputs/help from everyone thus far.

[ryan_axberg]

I have seen quite a few differnet people on here no be happy with their tunes that they got from shops. They might make good power some that I have seen weren't even that good at wot stuff. But I think mostly the issues with most of them is normal driveability and starting from all different temps. It takes a while to make sure that you have a tune dialed in everywhere. Like I live up in Alaska and if a shop tunes your vehicle in the summer and maybe they do a good job but then you want to also drive it in the winter you might have some issues because they couldn't get those situations with like a 20 below start. I think thats what is nice about tuning stuff yourself is that you can change that kind of stuff when ever you want

[jabjr26]

I have seen quite a few differnet people on here no be happy with their tunes that they got from shops. They might make good power some that I have seen weren't even that good at wot stuff. But I think mostly the issues with most of them is normal driveability and starting from all different temps. It takes a while to make sure that you have a tune dialed in everywhere. Like I live up in Alaska and if a shop tunes your vehicle in the summer and maybe they do a good job but then you want to also drive it in the winter you might have some issues because they couldn't get those situations with like a 20 below start. I think thats what is nice about tuning stuff yourself is that you can change that kind of stuff when ever you want

Couldn't agree more, it seems to me in this case that the shop just has a cookie cutter tune that they just load up on peoples cars, do a run or 2 take there money and send them on there way thinking they wont check. Either that or the "tuner" they have just changes the same parameters on essentially every tune and doesn't care nor check his work based on application.

On that note....is this normal? Now that i am into the timing tuning, i am comparing all the values that they changed, and unless i am reading this wrong he essentially just disabled or desensitized the knock sensors by doing this right?
Capture.JPG

These are the parameters that allow these tables to do there job, but essentially they have disabled it so these tables are not even in the story anymore.
Capture.JPG
Does that make any sense...why would they do that?

[383_Stroker]

Sometimes its better to drop back to the stock tune and start over when you develop a weird problem. Save where you're at, then flash stock and start dialing it in again (Obviously, excluding the items you had to turn off or modify for the swap itself). If it goes to crap just put it back to your saved file from now. If the setup is as stock as it sounds, I wouldn't think it would be very far out on a stock tune anyway,

[jabjr26]

Sometimes its better to drop back to the stock tune and start over when you develop a weird problem. Save where you're at, then flash stock and start dialing it in again (Obviously, excluding the items you had to turn off or modify for the swap itself). If it goes to crap just put it back to your saved file from now. If the setup is as stock as it sounds, I wouldn't think it would be very far out on a stock tune anyway,

Luckily I do have a stock 2004 GTO tune that i have been referencing and using to help troubleshoot all this BS. At this point i have the VE dialed in, the MAF dialed in, the start issues almost resolved, and the knock issues corrected. So its taking longer than i would like, but i am learning a ton, and happy to now understand more so i never have to trust anyone else to "tune" my car ever again.