KA-T won't run right, Megasquirt EMS

[ZiG]

Yeah, so being back in college and all, I sort of need my car to work again.

The problem is this: It will start up fine, but after a few seconds of running it starts to miss. The wideband will start reading lean (meaning it's missing because of no spark?) and I can watch the timing drop way down. It will run just fine at 1000 RPM but then it bogs down, goes in pretty good cycles until it eventually stalls.

Now I've been asking on several forums, including the megasquirt forum, but so far I haven't had a lot of help so I thought I'd try here..

The setup is this:

Megasquirt 1 pcb 3.0, running msns-e version 029y4. The cas signal wire is done just like it says to in the writeup found in the tech articles, it's the white wire with a 1kohm pullup resistor. For now, the idle control is the a/c idle valve, and the PWM IACV is just disconnected. Oh, and I'm using a MSD Blaster SS coil, with the -ve pin going straight to pin 36 on the MS and the +ve pin getting 12v.

I verified that when it is running in its smooth part of the cycle, that the timing is at 20 degrees. Then when it starts missing and bogs down, it's kind of hard to tell because the light starts flashing really weirdly, but it looks like the timing goes down to 5 or 0 even.

So yeah, please, if you have any ideas, I'm allllll ears.

[WDRacing]

I'd love to assist, but I have ZERO experience with the MS systems. I in fact am never going to use one. I have read ALOT of horror stories about them. For anything under 400WHP I'll take a SAFCII and a MSD BTM FTW.

I edited the title so maybe some of the MS guys will stop by.

WD

[ZiG]

Well, I always seem to enjoy being just a little bit different. heh.

I was just thinking I'd post in here because people know about the car itself, not just the ECU.

[480sx]

IMO MS is not a realistic daily driving EMS. I messed with mine for about 3 months, got it running and starting great, but like an idiot lost that tune and havnt ever been able to get back to that point. I got fed up of having my DD down and driving a POS instead of my Zenki and switched to something reliable. I wouldnt exactly call my MS experience a horror story, infact it was a great lesson in MAP sensor based tuning. However it wasnt a success, yet. I plan on trying to build a track Ka-T with MS, we'l c how that goes.

Also, i can only be of limited help because i run/ran MS2, but ill try.

I see a huge problem with your setup. First of all, your saying your only idle control is the IAC-FCID valve? That is the 'AC control' valve. That would cause some serious problems. Or maybe you just have them mixed up in your head, im not sure. The main KA IAC is a thermal type fast idle valve, that only needs an on off 12 volt signal. This is the one you should be using... I have a hard time seeing your car even trying to idle with the FCID valve only, but maybe its possible. Anyway, you need to use the thermal type IAC and leave the FCID valve alone. FYI, the FCID valve is a PWM type valve.......

Does the MS1 have a 'Trigger offset value'? Have you set it yet? This can cause all kinds of problems if its not set up correctly. For a starting point, set it at 72, then fine tune it with the trigger wizard from there.... This might not be valid for you at all, but i figured id still toss the info out there.

I think your problem is all about your IAC though, make sure you disable your FCID valve and only use the Thermal type fast idle valve.

[ZiG]

I talked to another guy about the trigger angle, and he said that his optimal angle was 108 degrees. I set mine at 60 and worked up to 108 and concluded that it worked best for me too. That's why I can set the MS to a fixed timing of 20 degrees and see 20 degrees on the light, so I'm pretty sure that's all good.

I see a huge problem with your setup. First of all, your saying your only idle control is the IAC-FCID valve? That is the 'AC control' valve. That would cause some serious problems. Or maybe you just have them mixed up in your head, im not sure. The main KA IAC is a thermal type fast idle valve, that only needs an on off 12 volt signal. This is the one you should be using... I have a hard time seeing your car even trying to idle with the FCID valve only, but maybe its possible. Anyway, you need to use the thermal type IAC and leave the FCID valve alone. FYI, the FCID valve is a PWM type valve.......

Uh, what? The thermal type IAC is just a bimetallic heater with a door. All that happens is that it will get constant power when the key is on. The power going through it will heat it up, and when it gets up to its normal temperature, it will close off the air supply. It's almost exactly the same principle of operation as an electric choke on a carburetor. There is no way you could use this for your idle controller.

The AC solenoid is an on/off type. It just opens when the AC is on, to kick up the idle. So far it seems like it can flow enough air to work.

The PWM valve you are talking about is the main IACV. I can't use it right now because I don't have the correct transistor installed in my megasquirt, but hopefully it will arrive in the mail soon. For now it's just not connected to anything.

Even if there were something wrong with my IAC setup, I can't see how that could cause the engine to miss..?

[480sx]

Heh, i had a running car with MS, and you dont.. Not trying to be an ***, but im just saying. Point being, my setup worked, and yours doesnt.

The only idle control you need is the thermal valve. It doesnt work how you think either. It has a plunger that moves around depending on the engine temperature, letting different amounts of air through. If you look at it, its actually hooked up to your cooling system. The AC/ AIC-FCID valve isnt needed unless you run AC. All it does is allow a little more air to pass through the throttle plate bypass if the AC is on to bump the idle up.

Im guessing that having the FCID valve wired the odd way im sure you have it wired, its suddenly letting to much air bypass the throttle plate causing a super lean condition that your MS tune isnt ready for and it stalls the engine out.

My other theory, is that its not letting enough air through, and becomes super rich. A super rich condition will read lean on a wideband.

Check the FSM for the functionality of the AIC-FCID valve, you will see that im right.

[ZiG]

Ok, I checked the FSM and this is waht it says:



So the top valve is what I am calling the thermal valve. I don't see anything about coolant in there, but I know there's a coolant hose that goes by it, so I dunno. So it's this one you are telling me to use? I don't understand how that would work, it seems to me that the response time would be way too slow..

The second valve is the one that I am using. And I do have AC, but I don't plan to turn it on until I have switched to the IACV-AAC valve. Anyway, it looks like this valve is normally only supposed to open when the AC is on and the engine is at idle.

The third valve is what I want to use. From what I can tell, it's the PWM valve that is normally supposed to control idle. It's also what everyone seems to complain about when they get that stumble when they put the clutch in.

How I do with these cars just used throttle stops.