Trouble with 1.6 parallel MS install - going lean
 

This is my first attempt diving into a MS install into my 91 so please bear with my noob-ness.

I purchased a MS1 parallel box from one of the guys on the forum about 2 years ago who was running a similar set up to mine (Drewkeen). He had a similar set up to mine (92 with a GReddy kit). The box was built by Braineack.

I had a couple of friends come over today and help get it installed and started up now that I have got my stock GReddy setup running well. Once we got it hooked up with the parallel harness we could get it to run, but as the coolant temp starts going up it goes progressively leaner and the idle rpm drops until the engine starts missing and dies.

We did a bunch of searching on the site but couldn't find anything that indicates what's going on or how to fix it. Does anyone know the fix for this?

We were able to capture some data and I've got some shots of the top and bottom of the board. Hopefully from this you can tell me where I'm going wrong.

stock 91 engine, GReddy kit, 3" Artech DP/exhaust, 5 speed, LC-1 Wideband.

I'd reflash the firmware with easy therm, sounds like your coolant sensor parameters are either wrong or screwed up.

If you're using a different coolant sensor than the previous vehicle, or if you suspect that the temp readings are out-of-whack, it would probably be wise to reflash with EasyTherm and eliminate that possibility.

Just another thought though: Have you set up the car with your req fuel and injector settings? Have you played with the idle VEs and warmup wizard? What are the current settings on the CLT-related air density?

In otherwords, have you adjusted the tune on the MS for your specific application or are you mostly just running with what the previous owner had on it?

We kept most of the settings the same since it came of a similar car and set up. We did adjust the fuel for my stock injectors because it was originally set up for RX7 red top injectors that are almost 2x the flow. After that we were able to get it to start and run for a bit before it began to warm up.

It also seemed to be looking for throttle position and the value would creep up continuously as it ran. We tried calibrating the sensor but in the 1.6l it seems like more of an on off switch than position.

It's possible this box was set up for a different throttle body sensor and the guys helping me suggested I post the pictures of the board so that someone might be able to identify how it was wired and if I need to change any of my existing sensors.

We were doing the tuning on my friend's computer because what I have wasn't the proper setup to run the programs. My friend is going to give me an old laptop that I can use shortly so I can connect to the box again and start running the programs you are suggesting.

In the meantime, from looking at the board, do you see anything special I will need in terms of sensors?

It sounds like it was set up for a car that had swapped in a TPS from a 1.8NA, which would probably be a useful mod for you to make as well.

If you're unsure of what configuration he was using for the CLT and IAT sensors, I would highly recommend reflashing it with EasyTherm just to be on the safe side and make sure that your MS is reading the sensors accurately.

The VE maps are probably off a bit given the different injectors (req-fuel will help account for this some, but you still need to rebuild your VE map to your particular setup). Additionally, did you change any of the injector properties other than req fuel? Make sure you've entered the proper dead time (latency) values and such for the stock injectors.

It might be running fine when it's cold because of warmup enrichments, and then as it warms up those are tapering off and it's trying to run directly from the VE values at idle, which may be too small. I'd suggest using the laptop to monitor things as it warms up and raising the VE values to keep a stoich mixture during the warmup process. Once you get it idling OK at temperature, you might want to decrease the warmup values some so that it's not crazy rich when you start it cold.

Thanks for that info. I'll be sure to check those items as soon as I have the laptop set up.

Since it is a parallel set up I thought that the stock ECU handled warm up and idle and that the MS didn't kick in till there was positive pressure. Since it seems that the MS box is working all the time, what functions are still left to the stock ECU?

idle control, a/c control, egr (if you have it), purge solenoid, and throwing codes.

that's about it.


(BTW, I might have built that initially, but it appears someone modded it after the fact)