Strange IAC output..

UnaClocker · Post by **UnaClocker** » Thu Oct 04, 2007 6:56 pm

I had the MS1 in my car yesterday. Tossed the MS2 back in it's place for some testing last night. The wiring for my tach output is different between the two.. Well I wanted the tach working during my testing so I simply turned off IAC air control and set the tach output to IAC1. My tach is on JS1, which is IAC1B on the PCB.. It didn't work.. Tried setting it to IAC2 and it started working.. Got something backwards in the code? No biggie to me, I'm changing back to the normal pins I was using now that the Neon/420a mode is fixed in MS2E.. I just thought I'd report what I found in case it's a bug.

hassmaschine · Post by **hassmaschine** » Fri Oct 05, 2007 11:19 am

I'm using JS11 for the tach output. maybe that'll work for you too.

Post by **jsmcortina** » Fri Oct 05, 2007 1:38 pm

Did you wire up the 12v feed to the MS2 card? That is required for the IAC outputs.
However, the 12v feed MUST NOT be applied to the MS1 chip, or it will be destroyed.

James

UnaClocker · Post by **UnaClocker** » Fri Oct 05, 2007 3:52 pm

Yes.. I know JS11 works, that's how I normally have it wired. I normally use the IAC outputs for my IAC. I have the 12v feed pin removed from my MS1 chip. I was just reporting what I found. Believe it or not. ;)

Post by **muythaibxr** » Fri Oct 05, 2007 3:55 pm

Actually, this is a known problem I believe. IAC1 and IAC2 are reversed in the generic output section as well.

Ken

UnaClocker · Post by **UnaClocker** » Fri Oct 05, 2007 4:02 pm

Ok, cool. I didn't think I was imagining things.

hassmaschine · Post by **hassmaschine** » Fri Oct 05, 2007 6:06 pm

jsmcortina wrote:Did you wire up the 12v feed to the MS2 card? That is required for the IAC outputs.
However, the 12v feed MUST NOT be applied to the MS1 chip, or it will be destroyed.

James

this is only true if you're using stepper motor IAC. for PWM, you don't connect it.

UnaClocker · Post by **UnaClocker** » Fri Oct 05, 2007 6:14 pm

Speaking of strange IAC behavior.. I still get very strange behavior from the IAC when the IAC is hooked up. One start it won't open. Next start it'll open WAYYYY too far and STAY THERE.. It"s better than it used to be back in like beta 4, where it didn't work at all. It's not a new problem, I noticed it in like Beta 6, and in the MS2 standard development forums, they were discussing their code having this same problem. I haven't gone back to see if it's solved, but if it is, we should get that fix into our branch of the code.
If it helps any.. I noticed that if I turn the ignition on, and wait a bit, it's more likely to start with the valve WAY open. If I just turn the key from off straight to cranking, it's likely to start with the valve closed or almost closed, and then close it way too much. There seems to be a happy spot in the amount of time between turning the key on and going into cranking where it'll actually work right. And these were the exact same symptoms they were having in the MS2standard development thread.. It's kind of embarassing when it starts at 3500rpm and STAYS there...

hassmaschine · Post by **hassmaschine** » Sat Oct 06, 2007 7:42 pm

are you using a stepper or PWM?

if using a PWM, you probably have your max/min opening thresholds set high/low. try lowering your max and raising your mins. my max is 50% and min is 20% - it does do what you describe sometimes (open too far, and start at 2500rpm). mine seems pretty random though, and it doesn't stay there long. I think maybe a slightly sticky valve has something to do with it. I've never had mine stick closed, however.

also, the stock ECU did the same thing once in a while - only it was worse in some respects. at least with MS, I have some control over it..

UnaClocker · Post by **UnaClocker** » Sat Oct 06, 2007 7:58 pm

Nope, I'm using a stepper. Sounds like they finally have a stepper motor to do some bench testing with. It should be pretty apparent when they test it out on the bench.

Post by **jsmcortina** » Sun Oct 07, 2007 3:09 am

UnaClocker wrote:It should be pretty apparent when they test it out on the bench.

It isn't that easy actually. I really need to set it up with a dial gauge to measure - doing it by eye isn't enough.

James