Ds1's Horrible ECU Tuning Thread
 

Hey all,

So just before Christmas I got my turbo install all done, and got the car up and running. I'm having a lot of trouble with the idle on the car (seemingly only when its warm?). It hunts, fluctuates like crazy, and dies if I take my foot of the accelerator. I'm new to MegaSquirt, and new to tuning, and I can't figure out if it is just settings or what.

Here is a post in the build thread with Pics and Video: https://www.miataturbo.net/build-thr...5/#post1080227

I am going up to the shop right now to work on the car and diagnose it more. I also bought an automatic throttle body to do the 1.6 TPS to VTPS conversion, as I have read that could be a big part of the issue (at least the stalling).

The car is a '92 1.6, with Greddy-based turbo setup that now includes an intercooler, MAF delete using GM IAT, BOV, and the DIY Autotune EBC solenoid. The ECU is a Brain-built MS3X. Injectors are RX7 460cc's. Wideband is Innovate MTX-L.

Any ideas what this could be? I will be checking for vacuum leaks today. I will also record the setting file and post it later so you can see the idle settings. Right now they are whatever Brain sets (or doesn't set) them to. Thanks!

I don't want to sound like too much of a dick but...

How about tune your idle, then if it's still bad make a thread. Instructions on msextra or look at the tens of threads about it here.

Tune it

Yeah I was working on finding that reading yesterday. We made some progress, and I think I've determined (from home) that the idle needs more fuel at the warmer side of the warm up curve. My AFR's start to creep up, but thats when it will begin to oscillate and hunt.

I'm going to try that today and go from there. I also just bought TunerStudio with the new auto-tune warmup, so that should be a big help :D

Okay, tuned the warmup a little. It's much better already, but it has a tough time getting off the warmup curve and idling normally. It will start out rich, end up closer to where it needs to be (13-14) then hit 15 for a second, then get worse and worse in fluctuations until it dies.

keep tuning it

Trying to use the binary 1.6 tps is part of the problem. Everything in your tune that uses throttle position will fuck with you.

I locked the timing at 11, made the entire corner of the Fuel table 40.0, and messed with some other settings like the IACV frequencies and stuff and got it to idle when warm. Relatively roughly.

Problem is I can't change anything even the slightest bit without it going into isolation again.

I don't know where to go from here. I've tried every thread, every forum, every article. Fricken everything. And literally two days of time.

Did you unplug the stock tps yet?

I've heard about this. I'm working on trying to figure out how to hook up my automatic throttle body but haven't found definite wiring.

Could this be a big issue, even on idle when using literally NO throttle at all?

Just.... Unplug it?

I'm back to this project now and have posted the MSQ here: https://www.miataturbo.net/build-thr...5/#post1115803

I still have not unplugged or changed the VTPS.