Jacob Yeager

I need someone who knows what they're doing


So I installed an MS2PNP ECU on my 1995 Miata and a BRP supercharger. Default 94-95 Map that is found on DIYautotune site. I also have AEM wideband installed. When I start the car the idle shoots up to and stays at around 2300RPM. Not good. So I tried taking off the supercharger and running it naturally aspirated/complete stock and it still idles the same 2300! I have tried dorking around with idle setting like closed v open loop to no fix. Tried adjusting the TB, nothing works. The car pulls plenty of vacuum (18-19) too. I'm all out of ideas and I'd love some from you pros


Edit: played with the TPS and got idle down to 1400RPM and I corrected the VE table a little to get it to 14.7 at idle. Still not good enough though :(

dglb99

Posting your tune would be the first step. Maybe it is just me, but your log doesn't look right to me. AFR goes to 14.8 immediately and doesn't change, is your wideband set up correctly? Your PWM Idle Duty never moves from 5.9, there is no TPS, and timing is stuck at 10 degrees. Also, your closed loop idle target rpm goes from 1100 rpm down to 530 rpm in the first three seconds of the log.

Jacob Yeager

I think you are right about the AFR being not right, I could have set it up wrong but I cannot seem to find a good install guide for a 1.8 with a 4 wire O2 sensor and megasquirt.

Right now I know the actual gauge is reading correct, and I have the White (0-5v) cable going to the option port on the ECU

dglb99

If the gauge and tunerstudio do not have the same afr reading then it is set up incorrectly. You should only need 4 wires. 2 wires power the wideband, the other 2 send the afr signal. If the wideband gauge is working fine then you probably wired up the two power wires correctly. Look up your wideband model and see which wires are the 0-5v analog output. One is positive, the other is negative. The positive analog output goes to the o2 sensor input in your megasquirt, and if I remember correctly there is a signal ground that the negative analog output goes to.

miatatam8

have you used the idle control valve test to find your min and max duty?

thebigtuna

Did you tell the ecu what afr gauge you're using? You can also set up custom voltages so tunerstudio and your gauge reads the same. Sounds like your afr was wired correctly to me, assuming the signal wire went to the right wire off the ecu. There is generally only one wire you need, other was optional on my aem uego. Have you set up all the basic parameters so tunerstudio knows what is going on? Sounds loke you just did tps, but there are others. The basemap only gets you started and then you need to start tuning. Not to be rude but it seems like you need to read a little more, to get the basemap towards being dialed on the car. Figuring out your problem atm is like shooting in the dark.

Also post tune.

When you said you ran it completely stock, is that including stock ecu? If so its something mechanical, probably vacuum leak. You changed alot at once, something could have gotten missed or cracked.

Jacob Yeager

Thanks for the input, turns out the issue was a vacuum leak through the injectors. Which is funny because I used stock new seals.

As as for the afr not reading on MS I’m still stuck.

thebigtuna

So the wideband itself is reading accurately but tunerstudio isn't showing the correct afr?

If so there are two options. You didn't configure the wideband in tunerstudio or you didn't wire it correctly. Check/do those things.