1994 Nissan Sentra SE-R going VEMS, then turbo.

[BenFenner]

The forum is listing Rob as the last poster, so I think Rob has missed my questions.

Bump.

[rob@vems.co.uk]

You can connect the sensor grounds to the common point, you want as many ground wires as you can possibly have.

VEMS should be powered when the key is in the ignition on position.

Tacho you can use a p259 channel, run a wire to the tacho out and use a 330-500ohm pull up resistor from the 5v supply to the tacho line.

It is necessary to connect all of the sensor grounds to the pin-26 wire, and then have 20mm of wire until the common point, or can they all just be connected to a common point?

Also, I asked a question about powering the VEMS in my last post. Do you have an answer to that? More generally, should VEMS be powered all the time, or just when the key is in start/on position?

One more question. Do you know what to do for the tachometer signal on a Nissan? Which pin in the VEMS connector should I use to send a tach signal to my dash tachometer?

[BenFenner]

Okay, just to clarify; VEMS gets power when the key is in the on position, but what about in the start position? Yes?

For the tachometer signal, you want me to hook up one of the P259 channels to the tachometer, and also connect a wire from EC36-pin28 (+5V supply) to the previously mentioned wire, with a 330-500 ohm resistor in series?

[rob@vems.co.uk]

If start position means when the engine is cranking then yes.

And yes on the resistor in series.

[BenFenner]

Thanks for the help Rob. I don't think I have any more major issues left. You should see regular progress from here on out. I'm almost finished with my wiring harness adapter. I just have to connect a few sensor grounds to the "ground blob".


I've just spent 4 hours replacing my original distributor with the new style. It was a lot of work getting the wiring correct, but now it runs with my factory ECU. I feel like I've completed a major milestone. Now I just have to get access to a timing light so I can get it running well again. Right now it's pretty low on power.

Updates and pics soon.

[BenFenner]

Pictures and descriptions are coming soon, I promise. In the meantime I'm knee deep in the installation of VEMS. I've got it powered up and talking to my computer. I'm doing the first step of configuring the crank trigger. I've ran into a problem, so I've got that discussion here:

http://www.vems.co.uk/forum/index.php?topic=261.0

[BenFenner]

New problem with ignition. Discussion is here:

http://www.vems.co.uk/forum/index.php?topic=262.0

[BenFenner]

The ignition problem is mostly solved.
On to the next step: idle control.

I don't think my idle control valve is being activated. I don't know which output corresponds to EC36-pin9 (injector 5, channel 16). I pick INJFET, but I don't know what channel to pick to drive it. I've tried almost all of my choices, and none seem to work.

[dnb]

I only have my VEMS powered with the ignition on.  It doesn't require any "keep alive" to store settings.

You can use any of the digital out signals to send a tacho signal.  I favour one of the P256 outputs since they are my only spares (I have a fully sequential v8) but other people use spare inj FETs or coil drivers.  Just configure it in the tacho settings bit of Megatune.

It's best to get the grounding done as closely as possible to the diagram.  The measurements themselves are approximate, but the concepts are important - the sensors will suffer a bit less from noise with the extra 20mm of wire from the ground point. 

[rob@vems.co.uk]

The ignition problem is mostly solved.
On to the next step: idle control.

I don't think my idle control valve is being activated. I don't know which output corresponds to EC36-pin9 (injector 5, channel 16). I pick INJFET, but I don't know what channel to pick to drive it. I've tried almost all of my choices, and none seem to work.

Working from Extras->Idle Settings General
The Idle solenoid channel should be INJFET (as selected) but the Idle solenoid channel # can be a little more confusing as it relates to the output setting in Settings->Injector Outputs.  So... if you set:
Extras->Idle Settings General - Idle solenoid channel # to 7
And then in Settings->Injector Outputs set the box labled as 7 to 16

The same sort of mentality works for the boost control solenoid and so on.  What I tend to do is to setup my injector pattern in Settings->Injector Outputs boxes 0-3 (as I tend to deal with 4 cylinder engines) then set 4 to 7 as 16, 32, 64, 128.

Why is this so confusing you may ask?  Well its because we've made it possible to activate multiple Injector FETs for batch fire and so on.

[BenFenner]

This morning the car wouldn't start. I've lost all spark. I've spent a long time figuring out, but I'm taking a break. Suffice it to say, I'm back to square one. I'll bring up any issues if I run into some, but for now I'm just cranking away at the diagnosis. Maybe one question. Is it possible that running four ignition outputs to channel 0 the way I am, could burn out channel 0? Not likely I figure, but I thought I'd just ask.

[BenFenner]

After hours of checking and re-checking things, I finally decided all of the wiring and hardware was good. I could take the ignition pin out of the EC36 connector and ground it myself, which would produce a spark in the plug. When VEMS was controlling the wire, nothing was happening. I decided to start from the beginning and load firmware. A couple firmware loads later, and I've got spark again.

Seriously. Wtf?


Okay, so now it should run again I figure. No dice. Another couple hours go by and it turns out none of the P259 channels are responding at all. The fuel pump relay is on P259 channel 5, and I'm sure it's not working as I can't hear it anymore. The tachometer in my dash stopped working (P259 channel 1). I found it easy to test, as the coolant fan relay is on P259 channel 0, and it was working like clockwork yesterday. When I set the temperature setting for the coolant fan, and burn it to the ECU, the fan would immediately turn on, and when I set the temp. high, it would immediately turn off. No such luck today.

Any ideas on what's up with my P259 channels?

VEMS seems to act completely randomly sometimes (in bad ways). It's gotten to the point where my friend and I haven taken bets on which set of outputs will fail tomorrow. =/

I should add though that Rob's help has been indispensable. =D

[rob@vems.co.uk]

If you disconnect all the P259 channels, do you get a regular spark?
What I'm thinking is that we initally remove all the P259 connections and see if one is holding the chip high in some way or we've got a ground loop - which I've seen cause strange issues.

Rob

[BenFenner]

So you want me to disconnect all the P259 channels, then change the ignition outputs back to 00 only (instead of 03..00) and see if I get the four sparks I should have been getting from the beginning?

You did catch the part where I said ignition is working now?

[rob@vems.co.uk]

Leave the 3..0 part as it is, and just disconnect the p259 pins.