Enhanced MS2 drivability issues: Stalling, Hunting Idle, Poor Throttle Response
 

Hi everyone,

I could use some tuning advice. My car has become nearly undriveable lately. Once it warms up the idle is constantly hunting, it stalls almost every time I put it in neutral or depress the clutch, and the throttle response is terrible out of boost. When I'm moving it drives fine and pulls good in boost no problem.

I attached my tune and a datalog that I took during a drive today. I'm a big NOOB when it comes to tuning my ECU and would love it if you could take a look at my log (yes, I do want you to look at my "log") and tune and give me some pointers as to what to fix. At this point I'm getting fed up with the car and wishing I had left the engine stock.

As background, I have a 1995 with a FM II turbo kit and an Enhanced MS2 from Reverant. I installed the turbo and ECU early 2013 and it's been running great until recently. There were some small issues (non-boost throttle response, idle droop with light throttle), but I was too busy playing at the track to worry too much about them.

Thanks,
Jon

To give some more detail, here are some times in the log when I noted events that were problematic:

Engine stalling: 544 sec, 1013 sec, and nine times after 1380 sec
Hunting idle: 805 sec, 915 sec, 1306 sec, and 1435 sec are some of the big examples
Idle droop at light throttle: 542 sec (led to a stall) and 943 sec are a couple examples

These are just a few examples. Pretty much from 1250 seconds in the log and on, the car became very undriveable in a stop and go environment. Every light the car died, and a couple times the car died while shifting to go around corners. Nothing like losing power steering and brake boost when going around a corner in a city.

Since this problem has just recently started I'm wondering if perhaps my WB02 sensor is going bad and that is driving the EGO correction and causing problems.

Thanks again for any help you can provide.

544, 1013 look like lean condition caused by throttle application causing stall

1380+ is weird. Possible bad tuning of the idle controller?

Fuel calibration seems not too good, under steady state driving I see anywhere from 16 to 10 AF.

Some of the stalls seem to be from maybe too aggressive decel cut, disable it and see if it helps and if so tune it better.

Just some ideas. Do some specific tests and see what conditions make it the worse then work on the stuff that cause or are affected by those conditions.

Cardriverx thanks for the suggestions. Yes my tune needs a bunch of work. And lean throttle tip in is certainly one I need to focus on.

Good news though, I seem to have figured out most of the craziness. I turned off the EGO feedback and the car drives fine. Well at least like I'm used to with my not great tune. I think the WBO2 sensor is going bad and was driving the EGO correction to do screwy things.

Time to focus on fixing the tune and getting a new O2 sensor.

I dunno how old the sensor is, but before you buy a new one make sure there are no air leaks in the exhaust system between it and the engine. Any external air will throw it off.