Medusa Megasquirt.... help lol

a91what

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Apr 6, 2011
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The issue is the actual input to the MS... it should NOT move around with the engine OFF. there is a WIRING ISSUE or some problem with the input.

The AFR should be static or moving very little with the engine off.... WIRING ISSUE or an issue with the WB output.
 
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Jun 15, 2019
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I see that the issues are not fixed.

check out the battery voltage, notice how it is only 12v with the engine running but it goes up to 15+ with the koeo... unless there was a battery charger on the car causing this. I still think there is a voltage/ground issue.

This is your car. Notice all the static on the AFR guage when the car is not running..... your WB reading is completely unusable. The running voltage on the engine is low in the 12v range and cranking I see it drop down to 6-7 volts. The voltage actually goes up when the car is not running. according to the ECU that is. there is a wiring issue, where does the ECU get power from? I assume you are using the EEC relay and the ECU is seeing power directly from the battery when the engine is running... if the ECU is being powered directly by the ignition switch then it is wrong.
medusa battery voltage issue..PNG



For reference here is a snip from a random datalog. notice the AFR and the Batt voltage.
Medusa comparo.PNG
OK I'll have to look at wire harness. Also alt won't charge until 2500 rpm it's designed that way I guess.
 

a91what

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I also just moved the power source to a switchso when I put the main power switch, it won't come on so it's like a should be better that way also I guess. .. the key is only to unlock the steering wheel
ok, you said you had to rewire the majority of the car. Where does the ECU get its power supply from?
 

a91what

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I have a one wire alternator on my car and it charges at idle, I run a standard size alternator pulley and a Overdrive crank pulley for the blower. Its all on one common belt
 

a91what

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The only other thing I can think is the ms is faulty. ...it wasn't brand new. Feel like I'm chasing the stuff I've done already. ....

now it's getting off switch from power block
I am mainly hunting for information, trying to trouble shoot the issue i see from thousands of miles away. I will ask alot of questions dont let it bug you too much. :D
 
Jun 15, 2019
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lake george, ny
I am mainly hunting for information, trying to trouble shoot the issue i see from thousands of miles away. I will ask alot of questions dont let it bug you too much. :D
its ok im not bugged by you im just stressing you know how it is lol ... im deff a fabricator trying to be a diagnostic guy lmao...
 
Jun 15, 2019
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lake george, ny
I think we need to inspect the wiring between the WB and the MS. can you give me a part # for the WB kit you are using please.
ok........ from what can remember ....its a AEM 30-4110 afr 52mm wide band 4.9 lsu..... i just bought brand new n its the same plug n wir combo... the orig one burned out... its a bosch sensor
 

a91what

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Ok those things do burn out more often than they should. I have lost 2 of the AEM units from just normal use. If it happens again do not buy another, I have a much cheaper/better option for you. The AEM do not put out a "stable" voltage signal they just spit out what they interpret and its up to the device to smooth the signal to something use-able... I can do this no problem.
 
Jun 15, 2019
64
5
18
46
lake george, ny
Ok those things do burn out more often than they should. I have lost 2 of the AEM units from just normal use. If it happens again do not buy another, I have a much cheaper/better option for you. The AEM do not put out a "stable" voltage signal they just spit out what they interpret and its up to the device to smooth the signal to something use-able... I can do this no problem.
ok ... i moved it about 18 inches back... si i could keep away from the heat. its in the second bend but the first bend is like a 3/4 90 so its kinda spitting the air right to it but safe from the header heat
 
Jun 15, 2019
64
5
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lake george, ny
ok ... i moved it about 18 inches back... si i could keep away from the heat. its in the second bend but the first bend is like a 3/4 90 so its kinda spitting the air right to it but safe from the header heat
ok i noticed i had a switch providing power into another power wire i am not sure why n how i did that... i found it just before it started pooring ... i gues im on hold for a bit uhg thnx
 

Blucifer99

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Jul 15, 2018
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we just figured out that he has his 0V-5V reference wire wired wrong... the white wire should be going to the connector on top of the megasquirt Not the blue wire.. so i belive thats the problem with the wideband... He has the blue wire wired into the top of the ms which is the serial wire and not the 0v-5v reference wire
 
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