Iv searched the forums and i still cant find a solution. I am attempting to get my 89 Jeep YJ running using Megasquirt II V3 running V2.88 Code . My problem is that the IAC stops working after a couple of seconds. When I power up Megasquirt (key to run position) the IAC retracts and then extends (zeros itself) like it should but then will not move with the temp change when the engine is warming up. If I restart Megasquirt again the stepper motor will not move/zero. I have to wait at least 30 seconds before powering Megasquirt and then the IAC will usually move/zero again. When I am able to get the IAC to zero, if I immediately change the idle steps it will move to where ever I set it and then after a couple of seconds of not moving it, it wont move again unless Megasquirt is turned off for about 30 seconds. Even with a cold engine and the IAC removed if i power Megasquirt and the IAC moves/zeros and then restart Megasquirt right away it will not move/zero a second time.
Here are some of the things I have tried and checked so far:
- Wearing an anti-static wrist strap i felt for hot chips after leaving megasquirt on for 10-15min with the IAC hooked up.
- My first Thought was stepper motor was bad so i tried one from a working car and it did not help. I checked the coils resistances (about 50 Ohms each) no continuity between coils.
- Then I tried jumping the two resistors on the bottom of the Daughter Card. Thinking the over current circuit was turning on. that did not make any difference.
- I checked that all jumpers were correct and that my wiring and boards had continuity all the way back to the Stepper Chip. From where the wires plug into the IAC to the stepper chip pins (14,17,20,23) there was about .1 to .2 Ohms. Is this to High?
- Checked for shorts.
- And finally I replaced the Stepper Chip. (surface mount is not fun) and it is still doing the same thing.
-Tonight I am going to reflash Megasquirt and if that doesn't help try an older version.
Any one think of any thing else i could do? Before i buy a new Daughter Card and/or a different model stepper motor. I wish i had an Oscilloscope.
Thanks,
Neil
IAC Stepper Motor Stops Working After Couple of Seconds.
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
IAC Stepper Motor Stops Working After Couple of Seconds.
One other thing i just remembered. Before and now after i jumpered R5 and R6 on the bottom of the Daughter Card. There was 0 Ohms between the two resistors. That doesn't seem right? Does it? i did not jumper the resistors together but separately.
Thanks,
Neil
Thanks,
Neil