Idles great when trying to throttle surges badly (sticks op accel/decel)

[Ssquared]

OK, I have a buddies swapped miata that i'm having issues tuning. He wants to run the car in SD for hood clearance reasons. Which is fine however once i got the car to idle and the idle VE corrected. I cant get the car to drive at all. Pretty quickly with any throttle input the car goes into op accel/decel. When it does this it zeros stfts and the car starts to run like crap. Surges really badly and loses any throttle response. Is this just my VE so far off the car cant run right? Is there something else i need to look into? I added a MAF sensor for temporary hoping to get the car dialed in and drivable until i can get the VE corrected however even yet it still acts the same. I dont currently have a wb in the car, using it to tune a gen v truck at the moment.

I forgot my laptop at work with my files so i dont have any to upload until morning time. Help suggestions would be helpful. Have you seen this issue before? Am i correct in thinking my VE is just so far off that car doesnt like it?

[blindsquirrel]

I wrote up a list of things for you to check but it's on my laptop that I forgot at work, I'll post it when I get a chance. (hint: if you don't have the files to post you aren't ready to start a new thread asking for help, since 'post tune file and log file' is Step 1 of the process)

[Ssquared]

I wrote up a list of things for you to check but it's on my laptop that I forgot at work, I'll post it when I get a chance. (hint: if you don't have the files to post you aren't ready to start a new thread asking for help, since 'post tune file and log file' is Step 1 of the process)

What ground breaking information you have there. I take it you dont have this issue but truly felt the need to state the obvious. Tyler Buckman Masdarati LS Base 2.0 maf on.hptidle throttle surge.hpl

[Ssquared]

updated after a few attempts at adding fuel to ve table. its seems to let me gradually press the pedal longer. However it still seems to start to surge as soon as op accel/decel activates.

[SiriusC1024]

Overspeed/Underspeed is 10x higher than it needs to be.

[edcmat-l1]

Yeah the over/undershoot tables are insane.

The VE is terrible also. You can't just chop 20% out of one section of table and expect it to operate correctly. It's dead lean when you try to pull out of the ditch you just dug.

And what injectors are in it? Calibration details says it's an 02 F body. Vehicle platform says it's a GMT800. Neither came with 42 lbs. injectors.

[Ssquared]

Yeah the over/undershoot tables are insane.

The VE is terrible also. You can't just chop 20% out of one section of table and expect it to operate correctly. It's dead lean when you try to pull out of the ditch you just dug.

And what injectors are in it? Calibration details says it's an 02 F body. Vehicle platform says it's a GMT800. Neither came with 42 lbs. injectors.

its a hack build. i can easily put the over/under speeds back to stock. the idle ditch is what its calling for fueling wise. injector PN #0280158051. ive gotten it to rev to about 2k under very light throttle but at soon as it going into accel/decel op its shits the bed and surges with any throttle input.

[SiriusC1024]

Injector data isn't correct, either. 12576341
https://forum.hptuners.com/showthrea...l=1#post766924

[Ssquared]

Injector data isn't correct, either. 12576341
https://forum.hptuners.com/showthrea...l=1#post766924

ill look into that. Could be exactly my problem

[SiriusC1024]

Well that and fuel trims aren't calling for anything realistic with that goofy ghost cam derping spark around. Surprised it didn't go into OL-Fault.

[edcmat-l1]

its a hack build. i can easily put the over/under speeds back to stock. the idle ditch is what its calling for fueling wise. injector PN #0280158051. ive gotten it to rev to about 2k under very light throttle but at soon as it going into accel/decel op its shits the bed and surges with any throttle input.

Yeah I don't think that huge step is "what it's calling for".

[edcmat-l1]

ill look into that. Could be exactly my problem

One of many.

[Ssquared]

Well that and fuel trims aren't calling for anything realistic with that goofy ghost cam derping spark around. Surprised it didn't go into OL-Fault.

Just an FYI this isn't my first rodeo. Those over under speeds are only 2x stock. Those speeds only come into affect at idle. If you look at the log the vehicle goes into idle fine. Fuel trims call for normal +/- until ol accel/decel then they 0 and don't do anything. And yet it still idles fine 🤦*♂️🤦*♂️🤔🤔

Hopefully it's just the injector data.

[Ssquared]

Obviously the VE table is wrong if the injector data is off.

[SiriusC1024]

Just an FYI this isn't my first rodeo. Those over under speeds are only 2x stock. Those speeds only come into affect at idle. If you look at the log the vehicle goes into idle fine. Fuel trims call for normal +/- until ol accel/decel then they 0 and don't do anything. And yet it still idles fine 臘*♂️臘*♂️樂樂

Hopefully it's just the injector data.

Mine either. It's not double. I wasn't exaggerating about 10x. The overspeed/underspeed is part of the problem. How is a PI loop supposed to establish control if the input keeps oscillating wildly? Look at the O2 traces.

If it was just injector data the fuel trims would compensate enough to keep it running a lot better than that.

You have the answers you need. Do what you want.

[Alvin]

I recommend putting off worrying about the idle until the fueling is straightened out.

The idle spark adapts are way out from where they should be.. A 20 degree correction is a ton, all you would ever need and you have that in less than 25 rpm error.

[Ssquared]

I have no issue going back to stock with the Idle spark over under speeds... Again i dont believe that is part of my issue. However since I'm obviously doing it wrong ill reduce it back to stock, correct injector data and reload stock VE table.

I started with the stock VE to begin with and pulled all that fueling to get it to idle. Fuel trims at idle are correct so "thats not what its calling for" i would beg to differ.

Again I'm here to get this thing drivable so im open to trying all this. As listed in original post i dont have a wide band in the car at the moment and know it would benefit with the fueling being so far off ,or so it appears. Was hoping someone has seen the surging specifically and could tell me that its 100% the VE being so far off. It looks like my injector data may be playing apart of the issues which is good to hear. Ill make changes and update post with results hopefully later today.

[edcmat-l1]

I started with the stock VE to begin with and pulled all that fueling to get it to idle. Fuel trims at idle are correct so "thats not what its calling for" i would beg to differ.

You can beg to differ all you want. The engine is idling in one or two cells. The fact that you hacked 3 entire columns to get the one or two idle cells within trim limits is the problem here. What's happening is when you crack the throttle open and the engine moves into higher Kpa cells, it's dead lean. You can see it in the narrowbands. So no, that's not "what it's calling for".

It's funny when someone comes here looking for advice and then wants to argue about what is or isn't wrong.

[SiriusC1024]

Set O2 crossovers to 451mV when tuning CL while you're at it.

[Ssquared]

Set O2 crossovers to 451mV when tuning CL while you're at it.

im not sure where the 02 crossover table is.

I loaded new tune file with stock VE table and injector updates. Removed the "ghost cam".

Super rich at idle 30% once ltft kicks in. Once throttle input is added. Ecm goes into Accel/Decel OP, this causes the engine surge (idk how else to explain in, rpm rises and falls uncontrollably regardless of throttle input)