So my car runs well but It keeps disconecting every time I get on the gas hard. I cant figure out why. I checked the serial adapter was plugged in well and changed out usb cable. I just dont get it but I cant get auto tune to help at anything above 3-4psi because is disconects. Any ideas?

how much boost? what spark gap?

15psi. .25 spark gap on none res plugs. I did not figure that would have anything to do with it. Why do you ask?

cause i've something similar happen on high boost levels with stock ignition.


has it always been okay otherwise? they are pretty finiky to cheap usb cables as well: http://www.tunerstudio.com/index.php...b-connectivity

It has always done it a little but when I first installed it. It only happen every once and a while. now it is everytime I get in the throttle and some times I have to restart the lap top just to get it to reconnect. Maybe it is the laptop i dont know.

Just something I went through:

I had problems with switching to a longer USB cable also. I used the RS232 cable directly from the megasquirt to a serial/USB converter plugged directly into the laptop and haven't had problems with that. It's only when the converter is on the megasquirt and I use a longer USB cable that tunerstudio likes to crap out, so you may be having a problem like that?

My hook up right now is the RS232 bluetooth offered by EFI analytics hooked up to my laptop and it works great. The only downside is it takes a few seconds to sync the bluetooth pairing in the beginning. To me, it's absolutely worth the cost and I don't have to worry about putting straight on the USB port and the wire (broken cables suck, especially for diagnosing a problem)

Non resistor plugs could be a problem. Replacing them with resistor plugs should help.

What he said-- that's almost certainly the issue.

Well I am sure it is not helping but I just changed spark plugs a month ago. Was running with resistors and still had the issue has gotten no better or worse. How about the data rate adjustment in ts would that help.

Brain. I dont think it did it day one but has for all most the whole time.

Bmx So you ran a seriel cable then hooked the serial to usb adapter to that. I will try that and report back

Non-Resistor plugs are one reason you could be having a problem with the ECU disconnecting-- not the only possibility, but bottom line-- non resistor plugs will not play nice.

Solid core and/or Spiral non-suppressed plugs wires can cause the same thing... and the two together almost certainly will cause a problem.

Other things can cause a problem too-- a super hot ignition system for instance, particularly if the ignitors/coils are grounded near the ECU ground, or if any of the ECUs wiring is running near the high tension leads or coils. This can be worked around though with proper grounding and/or re-routing of the wires that ran across the coil and/or plug wires.

Slowing the data rate can help as well as it makes it less susceptible to noise, it's a bandaid but might help if you'd rather not chase down the source of the noise issue.

__________________
Jerry a.k.a. 'FoundSoul'
DIYAutoTune.com
'91 Miata BEGi S3 GT2560 w/ MSPNP - 14.1psi - 253whp, 232wtq
'95 Miata n/a
A few other cars....

So look for things grounded near the passenger foot well? I will reground the ignitor that seems easy enough.
Coil is grounded on the mounting bracket?

Thanks for the advice.

Yesh. I found with the serial cable hooked up directly to the MS, it never lost signal. Much less noise in the cable than a USB cable. The serial/usb adapter I had came with a short usb cable. Even with that 1.5 ft cable connected to the adapter, it would lose signal sometimes. With the serial, it's rock solid

If you grounded your ECU to the passenger foot well, that could be the problem too. It should be wired to the stock ECU ground on the head.

I did not change the ground just used the stock stuff. Should I reground it and if so where.

For spark plugs you might want to look into the NGK R5671A-7 Stock number 4091. They are what FM recommends for their LS coil conversions and high boost applications.


Edit:
So looking at what Matt and Ben and Jerry are saying resistor less plugs are bad. FM claims that they have not had any issues with them, nor have their customers. I am planning on giving them a try and seeing what happens.

Well the seriel cable extension worked. With no usb cable at all I have constant connection. I will try the supplied usb cable to see if I can use it to tune from drivers seat.

My car will not run with R5671A-7 plugs. They run great with the stock ECU and not at all with the MS2. The MegaManual cautions against their use. Maybe a power filter will help? Is it worth the effort of installing one just to run resistorless plugs?

no not at all.

I had simular connection issues, my solution was just use qan older lappy with comm port rather than an adaptor, but i might try again using a serial extension and no usb cable as suggested here at some point . Tuning with 45min battery life is slooooooow. I was told this works because the car enviroment is generally too noisy for how USB works.

Glad its going for you