Need help troubleshooting a formerly working board.

[16FW]

I have a V2.2 board (green), that had been working since 2005. Today I was doing maintenance, like changing fuel filters, etc. When I tried to start it, I got strange symptoms. In the past when I turned the key to ignition position, I could hear the fuel pump, and the injectors clicked for a couple seconds. Now the fuel pump doesn't come on, and the injectors click continuously. It fires when I turn the key, but won't run, even while holding the switch in start position. The LEDs nearest the RS232 jack flash, but the farthest one doesn't do anything. I have misplaced any documentation that tells me what the LEDs are supposed to indicate.

[kjones6039]

I don't suppose you have a stim, huh? That would quickly tell you if the issue is with the car or the MS.

Ken

EDIT: the left LED is the injection... the middle is WUE..... the right one is ACCEL....

[16FW]

I don't suppose you have a stim, huh? That would quickly tell you if the issue is with the car or the MS.

Ken

EDIT: the left LED is the injection... the middle is WUE..... the right one is ACCEL....

Nope, I used pots, signal generators, etc to do the original testing. What I am hoping is I knocked a wire loose, or something like that. but I haven't spotted anything.

[trakkies]

Does it connect to Tuner Studio ok - no error messages? The lack of pump pre-run and injector priming pulse makes me suspect a code problem. I'd be inclined to simply re-load it. All those should work normally with nothing connected other than power. Which makes a broken wire or whatever less likely.

[16FW]

Does it connect to Tuner Studio ok - no error messages? The lack of pump pre-run and injector priming pulse makes me suspect a code problem. I'd be inclined to simply re-load it. All those should work normally with nothing connected other than power. Which makes a broken wire or whatever less likely.

I haven't had a need to even try Tuner Studio. Last time I tuned it (years ago) I used Megatune. I will download Tuner Studio and try it.

Thanks.

[trakkies]

You could do the same the MegaTune. Just trying to find out what is and isn't working. However, TS is much easier to use.

[16FW]

Some new information. I can't communicate with the MS with Megatune, or Tuner Studio. The MS still sends pulses to the injectors, but appears to be dead otherwise.

Can above normal voltage kill part of a board? The battery was dead, so I put on a charger/booster, and I see that it is putting out 16-17 volts.

I removed the MS, and am going to check it inside. It is too cold outside to do much of anything.

[trakkies]

I'd say the high ripple from a battery charger is more likely to mess with the code.
I'd first do a proper port check if you can't get Megatune or TS to recognise it.

[16FW]

I'd say the high ripple from a battery charger is more likely to mess with the code.
I'd first do a proper port check if you can't get Megatune or TS to recognise it.

"port check"?

EDIT: Nevermind, I see what you mean now. I did communications, settings, click to test, and it reported "no response".

[kjones6039]

"port check"?

EDIT: Nevermind, I see what you mean now. I did communications, settings, click to test, and it reported "no response".

Actually I think what Dave was referring to is the portcheck.exe program. You can find the download link on this page: http://msextra.com/doc/ms3/serial_setup.html (about 1/2 the way down the page)

Ken

[16FW]

I pulled the MS out of the car, and brought it inside. I can communicate with it fine in the house. It leads me to believe there is something I did to the wiring harness that is keeping it from working in the car. Whatever it is causes the injectors to constantly click (and the LEDs flash at the same rate). The LEDs aren't flashing when it is in the house.

Is there some input that if shorted/open would cause the injectors to fire (well past the normal priming period)?

[16FW]

It got up over freezing today, so I spent a couple of hours troubleshooting. I checked every wire in the cable to the MegaSquirt. Each pin is connected to what sensor it is supposed to go to. I also checked for shorts, but didn't find any. I still can't get it to talk to my laptop in the car, but it works fine inside. I did get inconsistent voltage on the power pin to the MegaSquirt. Could low voltage cause the symptoms we are seeing?

[kjones6039]

I did get inconsistent voltage on the power pin to the MegaSquirt.

A bit vague..... What constitutes "inconsistent"?

Could low voltage cause the symptoms we are seeing?

Low voltage can/will cause all kinds of issues! If you are in fact, having power issues you will need to get that corrected before trying to diagnose any other issues.

Ken

[DonTZ125]

+1. Not only can you get dropouts at the regulator causing intermittent function of the processor chip, but the voltage correction function measures the voltage at the MS power pin - NOT at the injectors or coils where it really matters. If the voltage at the injectors is not the same as what the MS thinks it is, your pulse widths will be wrong. Same with the coils and dwell, although that's not always as critical.

[16FW]

I did get inconsistent voltage on the power pin to the MegaSquirt.

A bit vague..... What constitutes "inconsistent"?...

The first time I checked, it was a good solid 12.5 volts. An hour or so later, it was varying from 9-10 volts. I am now thinking we knocked something loose on the ignition circuit, or the ground while changing fuel filters, etc. We also put in a new battery. When it warms up some, I will check/clean all the 12V and ground connections.

Thanks guys!

[16FW]

I guess you change this to "solved" It was the power connections. The main relay terminals, and the ground lug were a little corroded. After I cleaned them up, the power is stable, and the MS work like it always did.

Thanks Everyone!