DIYPNP: PE1 flyback issue? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-15-2011, 08:57 AM   #1
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Default DIYPNP: PE1 flyback issue?

Hi guys,

I didn't want to clutter the nice closed loop idle discussion in the other thread, so I made a new one for this issue.

I ran a wire from PE1 to 1J, so I could use the AC trigger signal to also trigger spark table switching. Worked fine, until I noticed these symptoms:

Car warm, turn off AC blower, with AC compressor button still pushed in/ON:

The AC clutch engages and the spark table switching engages.

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If I push the AC compressor button to turn it off, the symptoms disappear. When both the blower switch and AC switch are on, there are no issues.

Is this flyback to the 1J wire? If so, why does it stop with the AC compressor switch, and not stop with the blower switch off?

Could it be a bad AC switch?

Could the source of the ground be PE1 itself? I double checked the wires/soldering, no issues with excess solder or bad insulation.

Thanks! XD
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Old 05-15-2011, 11:02 AM   #2
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AC, I think works with a 2 switch to on. Button in AND fan on to work.
You'll need to set it up only to switch tables when both are on, no idea what to wire it to as I'm a
Interested to find out as I would like to do the same.

What happens when you turn off the AC button but leave the fan on???
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Old 05-15-2011, 11:38 AM   #3
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did you connect PE1 straight to 1J? you cant do that. it must run through one of the spare relay circuits.


so PE1 > Relay 1 IN > Relay 2 OUT > 1J
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Old 05-15-2011, 09:14 PM   #4
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Quote:
Originally Posted by Braineack View Post
did you connect PE1 straight to 1J? you cant do that. it must run through one of the spare relay circuits.


so PE1 > Relay 1 IN > Relay 2 OUT > 1J
Oops! So it is flyback?

Well I did ask you before I did it, I assumed silence was consent

Wait wait. Relay 1 is taken by the AC fan. Here's a (blurry) pic:
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So it's PE1-->relay 2 IN-->relay 2 OUT---> 1J
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Old 05-16-2011, 06:24 AM   #5
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But wait-- isn't the signal for table switching FROM 1J to PE1? So shouldn't it be 1J-->RELAY 2 IN--->RELAY 2 OUT--->PE1???

Electronic type guys, help me out here...
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Old 05-16-2011, 09:18 AM   #6
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What is 1J again?

If that's the case it would be 1J > Input 1 or 2 IN > input OUT > PE1
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Old 05-16-2011, 10:38 AM   #7
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1J is the AC signal to the compressor.
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Old 05-16-2011, 11:01 AM   #8
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Ah yes. You have 1Q going into relay, and 1J out to activate the A/C. IJ should be bale to go into PE1 just fine and be protected with the diode from that relay, but it could be overloading it.

Try running 1J to, input 2 IN, OUT to PE1, see if it clears up.
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Old 05-16-2011, 11:38 AM   #9
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Houston, we have a problem...

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What's the difference between 'input' and 'relay'? Cos as it is, 1Q-->input 1 IN-->input 1 OUT-->1J. Do I need to move THOSE to a relay?

Input 2 is used by the launch control circuit.



Greg
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Old 05-16-2011, 11:50 AM   #10
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use a spare relay circuit then.
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Old 05-16-2011, 11:57 AM   #11
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For which?

1J-->RELAY 2 IN--->RELAY 2 OUT--->PE1?

The 1Q-->Input 1 IN-->Input 1 OUT-->1J is OK? No need to move it?

Which brings me back to--what's the difference between 'input' and 'relay'?

Sorry, need to be specific, I don't wanna open it up a third time
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Old 05-19-2011, 08:21 PM   #12
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From the CR thread, reposted here for completeness/ future reference...


Quote:
Originally Posted by Matt Cramer View Post
PE1 should be routed through Input 1 or Input 2 to filter out flyback spikes.
When you say flyback spikes, that's flyback from 1J to PE1? Not something from PE1 to 1J?

Input 1 is used by the AC, Input 2 by launch control. Can I use relay 2 instead? Like this: 1J-->RELAY 2 IN-->RELAY2 OUT-->PE1?

Quote:
Originally Posted by Matt Cramer View Post
Right, the relay produces flyback spikes that you shouldn't be feeding into PE1.
The Input circuits produce a 0-5 volt non-inverting output, the relay circuits go from floating to ground. They're not interchangable.
So I have to give up launch control then?

Quote:
Originally Posted by Matt Cramer View Post
You'll either need to give up the function you're using for one of the circuits or build a buffer circuit that clamps the voltage at 5 volts.
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Old 05-24-2011, 06:22 AM   #13
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So I Gave up launch control (for now) to free up input 2. Wired 1j-->input2 in-->input 2 out-->pe1.

Sorry for the cam pic.
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So far, no flyback observed. Yay me
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Old 06-18-2011, 10:14 PM   #14
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Default It's back!!!

I thought I had this issue resolved already. I routed the trigger from 1J through Input 2 to eliminate the flyback. But it's back!

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I notice when this happens I have an issue with the compressor not turning on when engine is hot. I assumed it was an issue with the AC compressor clutch, but the clutch has been replaced. Since flyback from 1J is already a non issue, I'm now looking at a cause upstream, affecting the 1Q (input from AC switch). The only things on that circuit are the AC switch and the thermoswitch. Could I have a bad switch (the button part controlling the compressor)?

The issue is worse now because I have a working TPS-- so AE is being triggered at idle!
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