1mz tach w/ megasquirt2-extra (and other questions!)

buriguri · 03-19-2009, 09:48 PM

im going to try and use a '92 camry V6 tach with the tach output from the ignitor. before i get frustrated with wiring am i going to run into issues?

im hoping it will work just like every other v6 tach

also, im not sure how to wire in the A/C compressor. i read in the excell sheets that the MR2 signal is inverted...since im not using the camry ecu need i bother? seems like i only need to provide a 'high' signal to engage the clutch

im very close to completing my project. rebuilding some ported heads and my ACT clutch taking a month to come in slowed me down a bit.

V6'er · 03-20-2009, 07:46 AM

If the tach got it's signal from the Igniter in the Camry, then you just need to change it out in the cluster. You'll need to pull the needle to change the tach face, so once it's all running, you'll need to calibrate it against a known tach.

The 1MZFE ECU wants an inverted signal. You just need to program the correct logic state in the MS.

buriguri · 03-31-2009, 05:24 PM

alright. i have the tach bit sorted out but im still unsure as to how i want to wire up the A/C

im think i can use the 1mz's VSV for A/C idle up using the MR2 harness EA3's 2 pins... which fixes idle. looks like the signal from the A/C amp does the same for the 3sgte

my concern is ive no idea how to invert the mr2's A/C amplifier clutch signal? i assumed all i needed to do is simply engage the A/Cs magnet and call it a day------buuuut im kind of confused as the diagrams and bgb explaination dont help me much. is it just +5VDC from the A/C amp?

my plan is for it to all be self-contained and just run a few wires, keeping it simple.

V6'er · 03-31-2009, 09:04 PM

1. You have the MS ground the "Idle Up" pin on the 1MZ ECU to raise the idle with the A/C running. There is no VSV for idle control, the ECU simply raises the idle with the ISC (IAC).

2. I don't see why you need to invert the clutch signal, as the MS should be programmable for logic level. In this case however, you want Positive Logic anyway. In other words, a signal level of +12V is ON.

buriguri · 04-07-2009, 05:02 PM

1. i guess my method is more complex than needed? the A/C amp has 2 VSV pins and ive got the 1MZ's stock A/C idle up VSV wired to it (its near the upper manifold inlet where it meets the TB)

2. so i suppose ill just check what the A/C amp is sending out. if its +12V ill wire it straight to the compressor.

i think there is some confusion here, im using the MS2-extra as a standalone w/COP with help from Gimpy's work and not a piggyback. this is my first run with a standalone so im takin a lot of time into research. i have a background in TMDE so im used to staring at wiring diagrams for hours

buriguri · 04-07-2009, 05:05 PM

also i found something odd as far as retaining cruise control and powersteering with a '91T. the tranny speed cable has the 3 wire plug that drives the cruise control AND power steering ECU. if im correct in this to get both working im simply plugging into those.

ive only got the harness mock wired with electrical tape binding all my solder points atm. im trying to be very careful and plan it out in steps so my write-up is easy to do and post..lol

ive attached the VSV im talkin about, im using a '94 1mz-fe the later models maybe dont have this?

V6'er · 04-07-2009, 07:35 PM

Ah, did not know that your 1MZ was so early. Nevermind.

You are correct, only the early 1MZ's have the VSV for idle. The later models use the idle speed valve attached to the TB.

03-19-2009, 09:48 PM	#1 (permalink)
buriguri No Skills Join Date: Jan 2008 Location: Lancaster, CA Posts: 30 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (2/100% )	1mz tach w/ megasquirt2-extra (and other questions!) im going to try and use a '92 camry V6 tach with the tach output from the ignitor. before i get frustrated with wiring am i going to run into issues? im hoping it will work just like every other v6 tach also, im not sure how to wire in the A/C compressor. i read in the excell sheets that the MR2 signal is inverted...since im not using the camry ecu need i bother? seems like i only need to provide a 'high' signal to engage the clutch im very close to completing my project. rebuilding some ported heads and my ACT clutch taking a month to come in slowed me down a bit.

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03-20-2009, 07:46 AM	#2 (permalink)
V6'er All Torque, All the Time Join Date: Apr 2005 Location: Charlotte, NC Posts: 899 Thanks: 0 Thanked 26 Times in 19 Posts iTrader Rating: (1/100% )	If the tach got it's signal from the Igniter in the Camry, then you just need to change it out in the cluster. You'll need to pull the needle to change the tach face, so once it's all running, you'll need to calibrate it against a known tach. The 1MZFE ECU wants an inverted signal. You just need to program the correct logic state in the MS.

03-31-2009, 05:24 PM	#3 (permalink)
buriguri No Skills Join Date: Jan 2008 Location: Lancaster, CA Posts: 30 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (2/100% )	alright. i have the tach bit sorted out but im still unsure as to how i want to wire up the A/C im think i can use the 1mz's VSV for A/C idle up using the MR2 harness EA3's 2 pins... which fixes idle. looks like the signal from the A/C amp does the same for the 3sgte my concern is ive no idea how to invert the mr2's A/C amplifier clutch signal? i assumed all i needed to do is simply engage the A/Cs magnet and call it a day------buuuut im kind of confused as the diagrams and bgb explaination dont help me much. is it just +5VDC from the A/C amp? my plan is for it to all be self-contained and just run a few wires, keeping it simple.

03-31-2009, 09:04 PM	#4 (permalink)
V6'er All Torque, All the Time Join Date: Apr 2005 Location: Charlotte, NC Posts: 899 Thanks: 0 Thanked 26 Times in 19 Posts iTrader Rating: (1/100% )	1. You have the MS ground the "Idle Up" pin on the 1MZ ECU to raise the idle with the A/C running. There is no VSV for idle control, the ECU simply raises the idle with the ISC (IAC). 2. I don't see why you need to invert the clutch signal, as the MS should be programmable for logic level. In this case however, you want Positive Logic anyway. In other words, a signal level of +12V is ON.

04-07-2009, 05:02 PM	#5 (permalink)
buriguri No Skills Join Date: Jan 2008 Location: Lancaster, CA Posts: 30 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (2/100% )	1. i guess my method is more complex than needed? the A/C amp has 2 VSV pins and ive got the 1MZ's stock A/C idle up VSV wired to it (its near the upper manifold inlet where it meets the TB) 2. so i suppose ill just check what the A/C amp is sending out. if its +12V ill wire it straight to the compressor. i think there is some confusion here, im using the MS2-extra as a standalone w/COP with help from Gimpy's work and not a piggyback. this is my first run with a standalone so im takin a lot of time into research. i have a background in TMDE so im used to staring at wiring diagrams for hours

04-07-2009, 07:35 PM	#7 (permalink)
V6'er All Torque, All the Time Join Date: Apr 2005 Location: Charlotte, NC Posts: 899 Thanks: 0 Thanked 26 Times in 19 Posts iTrader Rating: (1/100% )	Ah, did not know that your 1MZ was so early. Nevermind. You are correct, only the early 1MZ's have the VSV for idle. The later models use the idle speed valve attached to the TB.