Tach Voltage M42 DASC & Piggyback.

[axisofjustice]

Cliffnotes: What is the tach voltage signal range for 91 318is m42? 5v square wave or ?

I have a piggyback wired in and working with my 91 318is to tune fuel for my dasc, vs. using a RRFPR. I recently began to start looking at the basics of tuning it and hooked it all up and interfaced my WBO2 with the ECU (NBO2 programmed) and my Piggyback.

I am getting live data from AFM, WB, and I noticed that the RPM was behaving funky, not reading until the car revved.

I need a minimum 7v signal for my piggyback, and I am wondering if the car only puts out too little voltage to get a good reading?

[nando]

5V square wave

Imo, id ditch the fpr and piggyback, get an ostritch 2.0 and tune the DME directly. Piggybacks havent made sense for a long time.

[axisofjustice]

Thank you!

At this point I need to move this car along I'm losing my patience. When I'm further along I'll be making some updates. I've had these parts sitting for a while! I'm not running the fpr now that I'm piggybacked, it's just an option.

I now need to find a way to make 5v appear as somewhere between 7-20v. Pull-up resistor maybe?

[squidmaster]

Ditch the piggyback and do the ostrich as nando said. Best, easiest, and least time consuming option

[axisofjustice]

Guys, my least time consuming and easiest option is to solve my voltage issue. I know a tuner isn't ideal and I can't even pull timing, but I've got to get it to the next step and then save some more for round 2.

To keep my project on budget I've got to use what I've got for now. If d/a does it with an fpr I can do it with a tuner. I want to run standalone or programmer someday, but that's not until I do cams, cop swap, pulley, and after cooler.

I just need a reliable richer tune right now so I can reassemble and drive it to shows and meets. No drifting or auto-x until I refresh the bushings and axle boots anyway.

[squidmaster]

You're going to have to literally design a ground-up circuit. Especially going to 17v... that's highly irregular. What piggyback are you running?

If you really need to adjust the mixture, just adjust the AFM until you can solve the problem correctly.

[axisofjustice]

A minimum of 7v needed by the tuner was told to me by another person. I do not fully trust it as I thought it kind of odd. I am attempting to look at other solutions despite my lack of an O-scope. I am awaiting a response from 14point7.

I was reading about a similar issue concerning ls1 swaps in gm cars and the solution to upping the voltage of a 5v square wave was a 1k ohm 1/2w resistor wired into 12v and the other into the signal line to work as a pull-up. Pull-up resistors are used in motor controllers of DIY electric cars for the same purpose.

I've been researching myself, but I wanted to see if anyone building on a low budget had encountered a problem as such. I appreciate your input, please don't mistake rudeness for my determination to solve the problem without more money.

[nando]

Guys, my least time consuming and easiest option is to solve my voltage issue. I know a tuner isn't ideal and I can't even pull timing, but I've got to get it to the next step and then save some more for round 2.

To keep my project on budget I've got to use what I've got for now. If d/a does it with an fpr I can do it with a tuner. I want to run standalone or programmer someday, but that's not until I do cams, cop swap, pulley, and after cooler.

I just need a reliable richer tune right now so I can reassemble and drive it to shows and meets. No drifting or auto-x until I refresh the bushings and axle boots anyway.

Your priorities are mixed up. Tuning first, then mods.

[squidmaster]

A minimum of 7v needed by the tuner was told to me by another person. I do not fully trust it as I thought it kind of odd. I am attempting to look at other solutions despite my lack of an O-scope. I am awaiting a response from 14point7.

I was reading about a similar issue concerning ls1 swaps in gm cars and the solution to upping the voltage of a 5v square wave was a 1k ohm 1/2w resistor wired into 12v and the other into the signal line to work as a pull-up. Pull-up resistors are used in motor controllers of DIY electric cars for the same purpose.

I've been researching myself, but I wanted to see if anyone building on a low budget had encountered a problem as such. I appreciate your input, please don't mistake rudeness for my determination to solve the problem without more money.

Knowing what piggyback you're using would allow us to help you further. A range of 7 to 17v for any signal input sounds highly incredulous.

[axisofjustice]

I am running a 14point7 uafc because I had one laying around. They are cheap but pretty capable of tuning fuel for low boost and also have data logging to help me tune easier. I recieved a reply from Alan today, he said my issue must be elsewhere because 5v square wave is fine. Bad info, I suppose, is what I got from a third party.

This car is a cheap project. I have like $3500 including the car and dasc in it and most of that is on the floor waiting to be put together. If the car comes together nicely and on a good timeline I will have some more to spend in the fall next year, but right now I just want to move along.

I know where I am in this project and getting it in one piece is job one right now. I can't have it sit in my garage for another year. It will be fine until next year with wideband, injectors, and piggyback. That's not my concern. I just needed to figure out rpm signal.

If I go and blow a wad of cash on an advanced tuning device like moates stuff, or go standalone, I'll need a dyno tune and will just be paying for another dyno tune later. I'd rather treat this as stage one and that as stage two. On e36 and z3 this charger uses an rrfpr and does fine, are you not seeing that I am doing more than that here? It's only half a bar of boost!

[nando]

An ostritch is like $250.. you're going to have to tune it twice anyway.

[axisofjustice]

An ostritch is like $250.. you're going to have to tune it twice anyway.

I don't have it right now, holidays and college budget don't mix. I'm going to tune it once, myself. But when things get real and timing comes into play, I'll be going to a dyno tuner.

[nando]

So leave it stock and do the SC when you can tune it properly.

Or do it your way, and do it twice. Then you will come back and say yeah, you guys were right... you wont be the first.

[axisofjustice]

I don't have an intake. I am not doing anything twice, the charger's been on for over a year and I've been driving it with the bypass open to meets and events just to show people my project who wanted to see it. Driving a car for a year and then upgrading it more won't be a major inconvenience. What's better? Let it sit for a year then build it or enjoy it and then spend more time having fun building it up more?

Why can't you guys just be relevant? How far do you have to push people that respectfully disagree with your opinions? It's not like I am professing my choice as best, being an asshole, or doing anything dangerous or that's going to hurt the car.

Maybe you've never been on a budget or a little stale on a build, but I am. I want the car to be safe and driveable to move it along in other areas. When it's a nice and properly built car, and all I am missing is more power and a quality solution to tuning, I will move along to more extreme measures.

[squidmaster]

Uhhh well good luck then if that's how you feel.

Knowing what piggyback you're using would allow us to help you further. A range of 7 to 17v for any signal input sounds highly incredulous.