MS2 + jeep stepper IAC not working as it should

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Yves
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MS2 + jeep stepper IAC not working as it should

Post by Yves »

I have been trying to install my Jeep IAC valve with the IAC valve block. I want to use it as my cold idle rpms are dropping to low for my liking.

After sorting out some wiring issues, I did the idle test in tunerstudio. Basically, I set it on 'on' and run, then on home. The valve went to the seat and then retracted fully, so I thought all was well.

However when connected to the ECU and playing with the values in the Idle valve curve to make it move, nothing happened. I thought that maybe the engine needed to run for that. At first it didn't seem to have any effect, although I could feel some air getting sucked in. When she was around 150°F she suddenly went a lot higher in rpm and the vacuum it drew through the valve was a lot greater. Nothing special in that area.

I then did a static test, with the engine not running, but the valve doesn't seem to move.

What am I doing wrong ?

MS2 V3.57 board.
Matt Cramer
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Re: MS2 + jeep stepper IAC not working as it should

Post by Matt Cramer »

:msq:
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

I got some working out of it when switching to closed loop Always on, but it stays to high in rpm although the graph is set lower. Sorry I made no logfile of the idling with the valve.
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

You must get open-loop working before trying to use closed-loop.

The test mode should be used first.

James
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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

Well, the thing is it worked in the testing module, but not in open loop. It did work in closed loop however. Not sure what I was doing wrong.
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

Yves wrote:Well, the thing is it worked in the testing module, but not in open loop. It did work in closed loop however. Not sure what I was doing wrong.
Well, I'm afraid that without an MSQ and a datalog of the open-loop configuration, we can't tell you either.

James
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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

I tried working on it some more, but no succes.

This is a log of the run with me trying to figure things out under stepper always on. I have not log of my previous try out with closed loop stepper always on.

I include the 2 msq's, one with the setup under open loop always on and one with closed loop always on.

When in closed loop, the IAC seems to control rpm, when in closed loop it has no effect. I put a IAC stepper gauge on the dash and that doesn't move either.
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

It is likely worth upgrading to the current MS2/Extra firmware. The test mode is improved and the idle valve configuration is clearer.

As I mentioned before - you must get open-loop (warmup only) idle mode working before trying to use closed loop.
Likewise - if the test mode doesn't work - idle control WILL NOT WORK !

So the order of play:
1. upgrade firmware and get your engine up and running (make sure you read the RELEASE-NOTES.txt)
2. configure your stepper idle valve in open loop mode
3. get it working in test mode
4. get it working in open-loop mode
5. only if everything is perfect, consider closed-loop mode

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

In test mode, the valve moved apparently correctly. Not sure why it doesn't move during open loop.

I have firmware 3.2.4

If I upload the new firmware, what about my current settings ? First time I upgrade so bear with me please.
Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

I redid a couple of tests with a IAC position gauge on the dash of TS. When doing the test it indicates the number given to where it should go.
However under open loop Always open. The meter says that it should be position 136, but the valve is completly closed and the IAC steps are all set to 0 with a start position of 255. So basically the valve should be fully open.

I also tried various steps sizes and the minimum size is 2 ms which seems to function with the test.

What I don't understand is why the ecu is able to control the valve correctly in the test but it can't do the same when in open loop control. Is there something else besides the settings under the start tab ?
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

Yves wrote:the valve is completly closed and the IAC steps are all set to 0 with a start position of 255. So basically the valve should be fully open.
Zero steps is fully closed.

James
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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

jsmcortina wrote:
Yves wrote:the valve is completly closed and the IAC steps are all set to 0 with a start position of 255. So basically the valve should be fully open.
Zero steps is fully closed.

James
Well, I've found something in the manual that states that the number of steps you put in the graph, is counted FROM the start position which in my case is 255 (fully open).

Anyway, I also set the values to 255 and the valve remained closed with the IAC counter at 136. :shock:
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

Yves wrote:Well, I've found something in the manual that states that the number of steps you put in the graph, is counted FROM the start position which in my case is 255 (fully open).
Where was this?

James
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My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

http://www.megamanual.com/megatune.htm#sd

"This table tells MegaSquirt-II how to position the IAC stepper motor at various temperatures. There are ten temperature bins. At start-up, MegaSquirt-II 'retracts' (opens) the stepper motor by the number of steps specified in the 'Idle Control/Start Value' field. The number specified in this table are how many steps the stepper closes when the coolant temperature reaches the specified temperature. So if you want the stepper to be completely closed at idle, you would set the last bin (160°F) to equal the start value"

Admitted it's something out of megatune, but if anything of the code still works the same ...

It still doesn't explain why the valve moves in test and closed loop, but not in open loop...
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

The Megamanual should never be used with MS2/Extra.

Please use the current manuals only.

James
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Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

jsmcortina wrote:The Megamanual should never be used with MS2/Extra.

Please use the current manuals only.

James
Ok, but is the working of the IAC so different in this respect ? Anyway not that it matters much since setting to either 0 steps or 255 steps doesn't yield any reaction.
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Re: MS2 + jeep stepper IAC not working as it should

Post by jsmcortina »

MS2/BG has IAC steps "backwards" compared to MS2/Extra.

In MS2/Extra 0 steps (and 0% PWM idle duty) means closed i.e. 0% extra air.

How are you confirming that the test mode is working? How does it respond to different step values?

Are you saying that the stepper motor doesn't move at all in open-loop mode ?

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

jsmcortina wrote:MS2/BG has IAC steps "backwards" compared to MS2/Extra.

In MS2/Extra 0 steps (and 0% PWM idle duty) means closed i.e. 0% extra air.

How are you confirming that the test mode is working? How does it respond to different step values?

Are you saying that the stepper motor doesn't move at all in open-loop mode ?

James
I had the valve open during testing and visually verified its movement.

Yes the stepper didn't move. Yesterday I fiddled with it some more and I set the cranking taper to a lower time which seemed to help some since the iac counter moved. Still have to get it to work properly though. The rpm when cold wasn't moving much, but maybe it needs more fuel in warmup enrichment to get it to go higher in rpm's.
Yves
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Re: MS2 + jeep stepper IAC not working as it should

Post by Yves »

So far the stepper seems to move accordingly to the graph, however I do not seem to get a higher idle rpm. I tried running autotune in warmup enrichtment at the same time, but it had no appreciable effects.

Any ideas on what is going on ?
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