Car stalls after a rev or in decel
 

Hello,

I just installed new injectors in my 1.8 mx5, the injectors I installed are bosch 640cc ev14's. I am running on a speeduino and I did all the required changes in tunerstudio that should make the injectors work (from the injector datasheet). I changed the required fuel, changed the dead time and the voltage correction. I have made changes to the VE table so my car runs and idle's fine (it wants to idle rich but that's another problem...). However everytime I give it a rev or push in the clutch when decellerating the engine stalls. I tried giving it some more timing in the low rpm to "catch" it dropping, I tried giving it more fuel in the lower rpm to see if it wants that. I also tried different voltage corrections but all with no succes. I tried it with and without the IAC connected to see if it might be that, but that also didn't change anything.

I will add my tune and datalog down below. I hope someone can help me.

Cheers and thanks,

Mats

I'm far from an expert but I am also running a speeduino on a 1.8 so I'll add pictures so others don't need to download the tune + the speeduino config files and help with the little I can.


https://cimg8.ibsrv.net/gimg/www.mia...6b2224e043.png

What is with the TPSdot here? And your TPS calibration settings are 183 closed and 225 open. Something is fucky, what TPS are you using?

For reference my TPSdot is 2. From what I've learned lurking the forums you want this number as low as possible while avoiding accidental activation due to electrical noise.
I've used my stock 1994 four-wire TPS sensor and a stock three wire TPS from an NB, both were very close in resolution. I'm currently using 24 closed and 182 open. You have VERY little resolution. I suspect your wiring is incorrect, did you use the PNP kit straight from speeduino or some other version/reseller? While it does work with the 1.8 it takes a bit of fiddling with the wiring. I need to know the year of your car and what TPS you are using to tell you more. I hope your cooling fan is working, mine didn't out of the box and I had to cross some wires at the ecu plug to enable it and the a/c fan, neither of which are mentioned in the wiki. "plug and play" my ass.

https://cimg9.ibsrv.net/gimg/www.mia...d7403ddec5.png

This AFR table could use a lot of improvement but since the topic is related to idle I'll ignore it for now.

https://cimg0.ibsrv.net/gimg/www.mia...f296be8cef.png

This seems really weird and aggressive to me but I could also be totally wrong and full of shit. What octane fuel do you run? Where did you come up with that wall of 20 degrees in the low rpm columns? I get that you're trying to idle in the 17 range and use the higher timing to bounce off of if the rpm drops below idle but all the numbers seem really high to me.

https://cimg1.ibsrv.net/gimg/www.mia...baeb7bb2d6.png

I'm going to assume you are using the free version and don't have access to VEAL based on this VE table. Look at your 3d map, see all those jagged spikes and sudden cliffs? You want nice smooth transitions, rolling hills. As for stalling in decel, look at how much fuel you're dumping in at high rpm and high vacuum. That's pretty excessive. Everything around the idle cells are big transitions, it also looks like you have only tried tuning around mid rpm and lower. I bet you run stupid rich at higher rpm.

Hi Roland, thanks for the response.

I am running a 1.8 engine in a 1996 chassis with a NB throttlebody and tps. I know the TPS is funky but the thing just won't work properly. I added an extra ground directly from the tps and made sure it's not routed close to a high voltage area, but it's still acting wonky. Sometimes it thinks that I am not on the throttle while I am cruising and sometimes it's on 10% while I am idling. I have recalibrated it multiple times but it doesn't make a difference and it gives different ADC values each time. My guess is the TPS just needs replace. But for now it works with the tpsdot set to 105.

My AFR table could be better yes, but it works so I am not worried about that for now.

I run e5 98 octane (Premium fuel) and yes the timing is like that to help it catch dropping rpm but it doesnt seem to work.

I actually own the full version of tunerstudio. The VE table is funky like that because I want my car to idle/return to idle normally before I worry about the rest of the table.

I hope you can help me out here, otherwise I might just put my stock injectors back in until the turbo parts arrive.

Thanks,

Mats

I noticed a bunch of things....It looks like your TPS never returns to zero, have you calibrated it? It looks like EGO is working hard and is hitting its max 15% trying to pull fuel when you lift from the throttle. My guess is that you have too much fuel in the idle cells and its causing your issues. Also, you have a ton of timing at idle, and are not using closed loop idle control, which will likely help fine tune things. Hope this helps!

jeez i wonder why this is happening...

https://cimg2.ibsrv.net/gimg/www.mia...a518216a62.png

Yeah tps is funky. I took it off last night and disassembled and reassembled it and it seems to be better now. It used to not remember calibrations or something, every time I calibrated and pressed the gas it would not return to 0% or it would be on 0% while cruising or something. It would be incredibly noisy as well (random spikes in throttle while cruising).

I swapped the stock injectors back in and it ran like a dream again so I guess I'll just wait for the turbo parts before installing the 640cc's. I just couldn't get it to work.

Thanks

I tried it with higher VE's on idle and it wouldn't idle normally above that. I tried everything I could think of to get the 640cc's to work like stock but it just didn't work, so I just swapped the stock ones back in. When I get my turbo parts I will install them again and see if it'll work properly.

I think the 640cc's are just too big for N/A applications.

Thanks for the reply!

Yep. After you install a turbo the engine never operates in vacuum again. Good plan.

lmao can't tell if you're serious or not. But it should work better with forced induction right? Or should it work fine N/A? I just couldn't get it to work smoothly.

Nope. You're going to need to get it working while n/a first. Get rid of that big block of 48 on your ve table, you don't want an area of cells to all be identical.

No, you don't know how to tune. I'm sure you never setup their req_fuel, deadtimes, and small pulsewidths correctly.

look how big of a ve% change between 30 and 36 kPa and you're wondering why they were hard to idle?

I actually did do all of that but I don't understand what you mean with setting up small pulsewidths? I put in all of the injector data that was given on the datasheet but it wouldn't run properly so I tried a bunch of different stuff with the VE table. That's why it looks like shit.

I guess I just gave up too early. I'll put the injectors back in tomorrow and keep trying.

Thanks for the response

Alright so I got it working now. On my datasheet the deadtime given at 13.2 V is 1.12ms; I figured because it cuts fuel on decel it must be something wrong with the deadtimes (because I don't have DFCO enabled). I changed the deadtime to 1.4ms; made some changes to the VE table and now it doesn't cut fuel anymore, the RPM drops slower and it doesn't stall anymore. yay...

However a deadtime of 1.4ms for EV14 injectors seems very high to me, but it works so I am not complaining.

My car now wants to idle at or under 13 AFR which seems very rich to me. Don't know how I would go about fixing that but I suppose it's not that urgent.

Tips are welcome

Thanks for the help!

post data sheet here.

https://cimg7.ibsrv.net/gimg/www.mia...df85d6decd.jpg
Data sheet
https://cimg8.ibsrv.net/gimg/www.mia...4ece0b5fbd.jpg
Injector settings (that work properly)
https://cimg2.ibsrv.net/gimg/www.mia...af85556076.jpg
Req fuel

whatever works. I personally would never buy DW injectors.

mine aren't DW. I bought these

https://bofiracing.co.uk/engine-part...or-mazda-mx-5/

What's wrong with Deatschwerks? I don't think I ever heard bad things about them

I have managed to fix the issue by switching over to sequential injection. It will idle at stoich now and the pulsewidth don't drop below the injectors capabilities in decel. Throttle feels way better too.