Alright, new guy to EFI/tuning here. 1990 mustang LX, 331 stroker motor with GT40P heads, E303 cam, single turbo, 60lb injectors. I'm running the microsquirt system with a single wideband (AEM X series) and using the "base" tune supplied with the ECU, cannot get the car to idle. It'll run (ROUGH) with throttle input, but it is pig rich and runs like trash. I've set base timing at 15*, firing order is right, all the low hanging fruit has been covered. I've watched plenty of other guys fire their cars up fine on the base tunes, so i feel like i'm missing something. MAP sensor, TPS, wideband have been calibrated. Any/all help is appreciated.

 

I have experience with microsquirt....I do not have experience with the 5.0 base tune.

First place I would look is your injector sizing/characteristics in "req fuel". The base tune likely has the stock (~19lb from memory) injector sizing/characteristics.

 

I would also double check your map through tunerstudio gauges with KOEO....it should read ~90-100 kpa depending on your elevation/conditions.

 

Set the req fuel like SS said for the 60's. Also I find the injector settings for dead time to be too slow for a decent injector.
Have you downloaded and read the manual?

 

I have set the injector size to 60lb in the fuel requirement section. I’ve skimmed the manual, but haven’t sat down and read through it in depth. My eager nature is getting the better of me.
I’ll check the MAP value and verify that it it is reading accurately. I’m around sea level so I should be around 100.

 

For the deka 60's I use a .620 dead time. And a voltage correction of .165. If you look at the correction table for the actual injectors versus voltage, it varies from volt to volt, but the average correction over the range we are likely to see (10.5-15) was .165 so thats what i used to fill the "one size fits all" compensation value.
A good way to really nail down voltage correction is to get the car tuned properly and then disconnect the alternator. As the voltage falls you can adjust the comp to keep the afr the same. Keep in mid its best to use a wideband that is not part of the cars electrical system as the lack of voltage to it may cause an output slew all its own.

Also once you get the injector data right and the car will run, don't stress the idle. Just get it running with correct injector data and accurate sensor inputs and get it warmed up and start hacking a VE table into it once all the ASE and WUE stuff shuts off. Almost all the fueling is figured from a valid and accurate VE table, so trying to get it to idle properly before you have a good ve table is just an outstanding way to waste some time.

 

Made some adjustments after work today, changed the injector dead time and voltage correction, and calibrated the MAP sensor, it was reading 270 kPa KOEO. Talk about out of whack. Although now, the MAP value doesn't change at all, so something isn't right. It sits at 101.5 kPa no matter what, so I need to get that sorted out. Also have an air pocket in the coolant system causing the coolant temp sensor and gauge to disagree, so i'm letting the car cool off so I can sort that out. The car will idle now though, and runs much smoother. I pulled some fuel out of the VE table and it seemed to like that. Thanks all for your help so far. Definitely making progress.

 

is map plugged in? both electrically and with a vac hose?

 

Well, the supplied paperwork for the MAP wiring included two different wiring paradigms; one for 1986-1990 and one for 91-93. I misread that and wired my damn MAP wrong. Got the MAP working and tried it out, and it surges pretty bad but the exhaust has cleared up considerably. AFR swings from around 12~13 at the low RPM to 15~16 when the RPMs swing up on the surge. But considering where I was yesterday, I think i'm definitely making progress.

 

So you are useing the baro/map sensor wiring in the factory harness? If so that makes sense. Should be around 30-50 kap at idle, 100 koeo and wot.

 

Yep, GM 3 BAR sensor wired in where the old BAP sensor used to live. Those values sound about what I was getting.

 

Sounds like you are getting there!


I agree with the below 110%

 

Do not let it go into closed loop at idle. That just gives the ECU and opportunity to mess up the fuel table you got like you wanted it.

 

Ok, thanks all for your input. I've gotten the car to idle pretty decent and I am working on a VE table and timing table with the help of another user's tune for a similar engine setup. I have done a couple short drives,(not getting into boost) and datalogged. AFR has maxed out at 13.8 at 42% throttle input with a manifold pressure of 99 kPa, so I guess just on the verge of going positive pressure.

One thing i've noticed is on deceleration, AFR spikes up to 18-19:1, and there is a lot of lean popping. I have an open downpipe so i imagine it is a little more noticeable/obnoxious than if i had full exhaust, but is that normal/OK? Or is there action I should be taking in order to mitigate that?

 

The lean spikes on decel (high vacuum, closed throttle) wont hurt anything. In fact many (including OEMs) completely cut fuel during decel under certain conditions (over running fuel cut).

If it bothers you...add some fuel in the decel areas.....if not keep chipping away at the rest your tune.

Usually, anything above around 80 kpa you want to get out of "economy mode" and start bringing in some power enrichment.......id be looking for around 12.5:1 at your ~100 kpa area.....again application dependent....

Mine usually go something like this......70-75 kpa --> 14.7:1 (or leaner) 80 kpa --> 13.5:1 100 kpa --> ~12.5:1 depending what ratio makes most power for the application.