Carrera95

So i got my base timing set and my required fuel to a point where the car (1990 1.8 swap(1995) with MS3X and stock injectors) idles. The first time i started it today it idled very smooth, almost flawlessly. However it started to randomly jump up to 1800 or so RPM and then fall low around 500 RPM, it kept doing this until it would drop too low and stall out. I'm not sure what would cause it to be randomly start doing this but i have attached the logs i took.

Akina_Downhill

iTrader: (1)

Your tps needs calibration for starters.
Post your tune also.

Carrera95

I calibrated my tps already and it seemed to be reading correctly before taking the logs. and my tune is attached. Thanks for the help!

Akina_Downhill

iTrader: (1)

You might be experiencing a noisy tps signal, which is common. You could remedy this with a shielded signal wire and a better ground.
Perhaps the throttle itself might be the culprit, or your tps/tps mounting.
It seems like you are running a required fuel value of 16.5ms, you need to adjust this, enter 1839cc and 265cc/min as your values if you are using stock injectors and click okay.
You will be prompted to powercycle the unit for the changes to take effect.

Carrera95

16.5 is where it will idle steady though, i started from 13.1 and went up by 1 until it idled. Wouldn't i be seeing the TPS signal fluctuating if there was noise?

elior77

Set reqfuel correctly and then tune idle VE

Carrera95

I was trying that initially but i had to add like 30-50 to all the cells and it would still die after the enrichment was over. I guess i will try again and post my results.

elior77

Changing your reqfuel will change the whole ve map.

Set the reqfuel right and tune the table right - post log and msq of the problem.

vitamin j

iTrader: (5)

What year is the car?

StanTheMan

Its an NA6 with a BP8 motor in it from a 1995

Carrera95

So i went ahead and adjusted req fuel to 11.6 according to the specs. I got it idling after messing with the idle ve and now i'm getting the same unsteady idle after it warms up for a bit. It seems to be fine and steady on cold start. I took two logs, the first was a steady idle and right near the end of the log is when the unsteady idle occured. During the second log the issue was happening the whole time. Also when i try to start it after the unsteady idle happens, it won't steady out again and will continue to jump until it drops too far and stalls out in about 5 seconds of run time.

Carrera95

Forgot to attach logs

Akina_Downhill

iTrader: (1)

Have you actually tuned your closed loop idle?
Is your initial value table dialed in correctly?
This has been discussed a zilion times.

elior77

You should start with open loop, you can check my blog.

vitamin j

iTrader: (5)

Overall your idle doesn't look bad in those logs, good enough to tune CL. I recommend going to your VE table and Spark table and making all the idle cells very close to one another. So that during the full range of idle the spark maybe changes 1 degree and fuel is steady. Then just tune the PIDs.

You just started the car for the first time, gotta tune it!

Carrera95

Those logs are closed loop, i haven't messed with open loop because i've seen Brain commenting in other threads to focus on closed loop. As for initial value table, what table are you referring to?

Carrera95

I'm already in closed loop though, i didn't touch open loop. Also what does PID stand for, i can't find it for the life of me.

vitamin j

iTrader: (5)

Yes, now TUNE IT.

PIDs are the Proportional, Integral, and Derivative in your closed loop window...

Akina_Downhill

iTrader: (1)

There is a somewhat standar procedure to tune idle and it has been discussed, step by step, a thousand times.
Use search function, or get someone to tune your car.

PSI

I struggled with idle also and couldn't figure out what I was doing wrong. Then I discovered braineacks website and copied his closed loop settings from his base tunes and it was almost perfect immediately!