IAC STILL Does Not Follow Temperature Curve

[69 1/2 Six Pack Bee]

Hey, m0ntecarloss
I hear ya, bro.
I too have set an unusually high step number (245) but it still won't close. I took the IAC and measured the exact measurement with a pair of calipers to see how far it was when it is completely closed. I determined that this was 215 steps to the fully retracted "open" step number. This is not rocket science. The manual states that I should set the "closed" number a few steps past this 215 number...so I had set it (at one time) to 220. Well, of course it did'nt close from a standing start. But, if I restarted the engine, you guessed it. It was closed and the engine idled normally. I said, "Okay, maybe I need to add several more steps to get it to close"..sounds logical. I did that,...and it made no difference. I played with the step speed,...etc, well, I have listed what I have tried so it bears not repeating for the sake of saving bandwidth
I have pretty well given up on trying to get the IAC dialed in and will move on to dialing in the rest of the system. Hopefully by then someone else might come up with a logical explaination and fix for this malady
Later...

[Philip Lochner]

You guys are REALLY scaring me! If an experienced squirter is having issues what hope is there for me, a newby?

I've posted under the Subject "IAC: How to close?" but reading this thread it is clear that I'm not the only one having such battles.

I THINK 've managed to get my MS2 to do what its supposed to on the bench but only as far as the intial retracting upon switch on and then the extension to the cranking position. It seems to me that my MS-2 ignores the "Time based after start" settings as well as the "Idle step" (temp curve) settings.

The following is also weird:
If I retract it too much, it refuses to extend (cleaning the IAC did not help) BUT if I reverse the wires and I then switch MS-2 on, it quite happily runs all the way to the fully closed position almost as if the MS2 has more oomph in the one direction than the other.

[69 1/2 Six Pack Bee]

Mr. Lochner,

Just because the avitar says "Experienced Squirter" don't think for a minute that I am truly one ..(LOL)

Just a little tidbit. When I had the MS-I running it was very nice, smooth and quite tuned in. It was getting better performance and fuel mileage than my old carbureted setup. That being said, I figured that the MS-II with the added features would take me to the next level. After some re-configuring for the new ignition and some more external wiring changes I was ready to fire it up. I transferred my previous settings and VE table (now in 12x12 format but still pretty much the same) with the new IAC in place and I hit the key switch. I got the ingintion dialed in..that works just fine. But everything else, not so lucky. It starts harder and runs not quite like it did before. And I pretty much mirrored the existing file. I put in a guesstimated AFR table and timing table so these might be contributing factors since the old setup was obviously devoid of these features but I know that these estimated figures are pretty much close to being correct as I have put alot of time in research and tuning to come up with the figures I needed. Please do not get discouraged as I am hoping that my problems are isolated to my setup specifically. I am sending the MS-II chip back to Glen so he can evaluate it to see if maybe that is giving me grief. I know the previous setup worked flawlessly and I know the MS-II should be that much better. I am just not seeing it in my setup, yet.

All of the claims are there that the IAC works as intended but after 4 different IAC's with all the same results then obviously something is awry with my MS-II. I hope this is not the case with yours too. I know that the folks here will help you get the bugs ironed out of it and I will help as much as I can as well.
Good luck and keep us posterd!

...Bud

[Philip Lochner]

Good news: Made some progress!!...

Shorted out the two resistors on the bottom of the MS-2 daughterboard. Now at least the IAC moves in the closing direction even if it was fully retracted.

Bad news:
Other than the initial opening and the cranking position, I find no relation between the figures entered on MT and what really happens. Eg My IAC even OPENS a little at some stage!! I thought it would only move in the closing direction after the initial opening.

Can someone please explain to me the behaviour seen in the attached log against the MSQ settings as I am totally lost on this matter (especially the bit where the IAC opens again a little...)

[69 1/2 Six Pack Bee]

Phil,

I looked at the .msq and I see that your idle steps in the TABLES>IDLE STEPS are all at 210. The IAC won't move in this configuration.
Try: TABLES>IDLE STEPS>TOOLS>CURVE GENERATE> make sure that "linear" is highlighted, un-check "use existing X" and in the "X[F] change that to something in a negative temperature like "-10" and "80" steps then click "OKAY"
This will give you a curve that should show a definate increase as the temp rises.
Try changing the start steps in your idle control settings to something higher like 100 and try the "always on" setting. Move the speed down to about 2.2 and see what happens.
Let us know what you find.

Good luck,
Bud

[Philip Lochner]

Hi Bud
 
Thanks for the help!
 
A bit of background (which perhaps I should have volunteered before).  Ms-2 is running in my car but I'm only doing ignition at this time.  However, all this is in preparation for taking control of FI but I'm trying to really understand all aspects I will face BEFORE I get there.  IAC is the last on my tick list.
 
I'm testing on the bench.  I don't have stim (bit of an oversight on my part...) but I've made up a cable with resistors which gives me a constant CLT temp of 81 degC (sorry this part of the world we don't know about degF). By now I have determined that my IAC needs 185 steps from fully closed to fully open and it seems to work fine with "moving only" (Gets warm pretty quick on "always on" - I've tried it).  I have a V8 dissy which I spin with my drill to simulate starting and running.
 
What I'm trying to achieve is this:
1) See that IAC moves to IAC start (this it now does reliably)
2) See that IAC moves to the crank position (this it does).  Now I want to see the IAC move to one of the following points but this is where things don't go according to my expectations.  I can see it move away from this crank position but it moves to points that I simply can not explain, especially when it starts RETRACTING when NONE of my settings would seem to give it reason to do so.
3) IF CLT is less than "cold temp" (by setting cold temp at eg 90) it should move to "cold position" not so? 
4) If CLT is more than "cold temp" (by setting cold temp at eg 50) it should move TO the "Idle steps" curve (with 210 effectively closing the IAC) not so?  The reason I have all Idle step temp points at 210 is to see IAC move TO ANY point on this curve (effectively fully closing the IAC = clearly visible) from the crank position.  At this time I am not trying to see it move ALONG this curve but only "on to" this curve from one of the previous operating modes.
 
Is what I'm trying perhaps simply not possible ?  Does the fact that my temp curve not have a gradient result in division by 0 somewhere causing random numbers and behaviour? MUST ms-2 see a changing CLT to behave correctly?
 
Also, I can't figure out what the effect of the time based parameters are or should be based on what I see on the bench, despite well worded info in the MS-2 site.  English is not my 1st language but I did not think it was that bad (or me that stupid   We have an expression in South Africa .... "Eish!!"
 
PS: I don't see IAC move back to the crank position when I simulate a stall (simply stopping the drill). It seems to require ign off, ign on?
 
Kind regards
Philip

-----Original Message-----
From: 69 1/2 Six Pack Bee [mailto:bud.weaver@ectinfo.com]
Sent: 27 March 2006 08:19 PM
To: megasquirt-fuel@msefi.com
Subject: IAC STILL Does Not Follow Temperature Curve



Phil,

I looked at the .msq and I see that your idle steps in the TABLES>IDLE STEPS are all at 210. The IAC won't move in this configuration.
Try: TABLES>IDLE STEPS>TOOLS>CURVE GENERATE> make sure that "linear" is highlighted, un-check "use existing X" and in the "X[F] change that to something in a negative temperatore like "-10" and "80" steps then click "OKAY"
This will give you a curve that should show a definate increase as the temp rises.
Try changing the start steps in your idle control settings to something higher like 100 and try the "always on" setting. Move the speed down to about 2.2 and see what happens.
Let us know what you find.

Good luck,
Bud



This post is at: http://www.msefi.com/viewtopic.php?p=110398#110398



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Posted by email.

[69 1/2 Six Pack Bee]

I have a V8 dissy which I spin with my drill to simulate starting and running.
.

Are you running the drill motor less than 150 RPM (300 simulated crankshaft speed) when you are checking for starting steps?

Do you then wind the drill up past 300 (simulated engine) RPM to check the other aspects of the IAC operation?

[Philip Lochner]

Are you running the drill motor less than 150 RPM (300 simulated crankshaft speed) when you are checking for starting steps? 
PL: Yep, I watch the MT rev counter when I do this. Ive got the drill on its "low range" setting and running it at its lowest speed produces about 150rpm on the rev counter.

Do you then wind the drill up past 300 (simulated engine) RPM to check the other aspects of the IAC operation? 
PL: Yep, again the rev counter is the reference. 
 
The log I posted also confirms the revs.
 
Kind regards
Philip



Posted by email.

[Philip Lochner]

Update: Good news mostly
 
Well, decided to put MS2 back into the car and see what happens in the car.
 
I set "Cold Temp" to -5segC effectively disabling that part of the IAC control (at least in my part of the world).  So, now it opens to 185 steps, then closes to 130 steps for cranking (this makes it rev up to about 1300rpm after start when engine is hot) and then it jumps onto the temp curve pretty quick (crank to run time = 1 sec) which makes it settle down to idle at 170 steps.  Will see later tonight what it does when the engine is cold.
 
Another step closer to FI - the NEXT step and the ultimate goal!
 
Kind regards
Philip
 
 

Posted by email.