Trying to get tacho to work in lexus GS300 with infinity 506 | AEM
5 posts / 0 new
Last post
presterone
Offline
Last seen: 5 months 1 week ago
Joined: 09/20/2014 - 06:34
Trying to get tacho to work in lexus GS300 with infinity 506

Hi, 

I was told I could use the lowsideswitch 5 output to drive the tach in this 2002 lexus gs300 with an Aristo 2jz gte swap. The setup is retaining the factory ecu which had some sort of signal from the ignitor to run the tacho. What I am doing now is using GM LS2 ignition coils and no igniter. When I configure the lowside swtich 5 output in infinity tuner to "tach" the tach will work but the engine misfires and will not idle. I am not sure how to configure my outputs to run this tach and looking for help.

thanks,

 

TJ

presterone
Offline
Last seen: 5 months 1 week ago
Joined: 09/20/2014 - 06:34
So I figured out the VVTi

So I figured out the VVTi solenoid was wired to the only output that would drive the tach. So when I jumpered the signal to the tach the VVTi solenoid went nuts and thats why the car ran rough. I have to switch the VVti solenoid to Lowside switch output 4 wire so I can use lowside switch 5 to run the tach at 3pulses per rev.

AEM_NS
Offline
Last seen: 17 hours 18 min ago
Joined: 06/06/2014 - 09:31
Hold up a minute. Let's

Hold up a minute. Let's think about this. It's true that by default, the setup wizard is hard coded to set LS 5 to tach output. But what makes LS 5 work as a tach output is that it has a 12v pull up resistor on its circuit. This is where you look at the Series 5 Hardware Spec document to see which other outputs have a pull up. As it turns out, LS 4 also has a pull up. When you look at what the wizard does to actually setup the tach, all it's doing is setting a frequency based on RPM with a fixed duty. You can do the exact same thing for LS 4. I personally never use LS 5 for tach because IMO using a 6A rated output for a tach is a waste. I'd much rather use a 6A rated output for something that's actually driving an actuator - like say a VVT actuator which is exactly how your harness was setup. If I were you, I'd leave the VVT actuator on LS 5 and setup the tach on LS 4 since it's a lower rated output.

This also brings up an important point that you just learned - check how your harness is wired before you just go and turn on outputs in the cal. Best case scenario is that nothing happens but worst case, you could really do some bad stuff without checking things out first.

presterone
Offline
Last seen: 5 months 1 week ago
Joined: 09/20/2014 - 06:34
Ok thank you. I just need a

Ok thank you. I just need a little bit more guidance. So when I go to use LS4 instead of having the tacho option where I can change how many pulse per rev, I should just change it to a duty cycle and modify the Hz until my tach correlates with what the rpm is in live data?

AEM_NS
Offline
Last seen: 17 hours 18 min ago
Joined: 06/06/2014 - 09:31
Yes, that's exactly right.

Yes, that's exactly right. Set the duty to 50% everywhere and then set the frequency to be variable based on Engine Speed. You can test out a few different frequency values to figure out which freq's equal what tach value. You can do this without the engine even running - just type in different values at the 0 RPM breakpoint and the tach needle will move. Once you figure out what freq's you need, populate the table accordingly.