Trouble shooting resets

[Eds]

I need some help trouble shooting a reset problem. I have MS-II v3 operating on 2.891 code. The MS-II was installed approximately 2 years ago and is controlling a GM v6 with HEI (small cap 8 pin module) ignition.

During this time I have experienced periodic misfires (resets) but they were seldom and I could not associate the cause to any particular thing. I have driven the vehicle many times without any problems. Recently while on a short trip to the store, I had one misfire on each leg of the trip. The next time I drove the vehicle, the same thing occurred. The last time I tried to drive the vehicle it started misfiring repeatedly and I parked it. Now when I turn the key on, I get resets without starting the engine. The LED’s flash randomly and the fuel pump cycles with each reset.

In trouble shooting the problem, I have: Re-confirmed all grounds. All grounds terminate on the engine at the same location as the negative battery cable. Traced the power leads and verified all connections with no problems found. Inspected the MS-II circuit broad for cold joints solder connections and did not find any problems. I tested the MS-II power lead with a test light and vom. Test light burned brightly and volt meter did not show any variations in voltage. I also put a volt meter on the MS-II power lead during the resets. Volt meter did not show any voltage variations. Put MS-II on stimulator for approximately 30 minutes and did not experience any resets. Re-install MS-II into the vehicle, started the engine, drove out of the garage and shut the engine off. A few minutes later I turned the key on and the resets returned immediately.

Anyone have any ideas on trouble shooting this problem?

[Matt Cramer]

Are they misfires or resets? A reset will be indicated by the SecL count dropping to zero and a RESET in the data log.

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Matt, thanks for responding. I was able to determine the cause of the problem late yesterday afternoon. The cause of the problem was confusing to me because of the indications of both the volt meter and test light. They were resets due to a momentary loss of power to MS-II and felt like a misfire because of the momentary loss of power to the ignition control modual. I was able to determine the cause by providing a deticated fused circuit to MS-II. While observing the LEDs I could see during cranking the ECM did not lose power but did randomly lose the ignition pulses.

Thanks again.

[Matt Cramer]

Interesting, glad to hear it's fixed.

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Matt, I thought I had the problem solve but apparently not. I replaced the ignition switch which did correct the electrical issue. When trying to start the motor, I hear the fuel pump cycle and see the ignition pulses on the LED but no fire. I connected MS to JimStim. All indications viewed on TunerStudio appear normal although I discovered injector LED's on JimStim were not pulsing . Not knowing if the code had become corrupted I attempted reload the code into MS but for some reason I can not load code. I installed boot jumper, powered up MS-II, saw LED's flash, started downloader and selected .S19 file. Nothing happened. Any recommendations?

[Matt Cramer]

Please post a screen shot of the error message you get with the downloader. It'll give me more info to go on.

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Matt, I do not get an error message. All I get is the downloader page. I can sellect for example the com port and I see the % download at the bottom of the page but nothing happens when I sellect the .S19 file.

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Matt, I need to edit the last post. After I posted last I was able to reload the .S19 file. Now I will test to see if that corrects the problem.

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Update - After reloading code to MS I have the following indications. All LED's on MS operate nomal. AFR as viewed on TS is non-responsive to input from stimulator. Pulse width gauge is erractic. No injector pulses indicated on JimStim LED's. Other functions such as fuel pump or fidle us to control cooling fan relay operate normal. I have tried other MSQ's and have the same indications.

[Matt Cramer]

Could you post a data log of the erratic pulse width and a copy of your MSQ?

[Eds]

I may have found the problem. I built a test light per trouble shooting guide. I see an output on pins 21 & 22 of the CPU (U1). The signal appears FET driver U4 pins 2 & 4. I do not see an output signal on pins 5 & 7 of U4.

I also attached MSQ and Data log you requested.

CurrentTune.msq

Trouble shooting data log.msl

[Matt Cramer]

If you ground pins 21 and 22, do you get an output on U4? Remember, it's an inverting driver.

[Eds]

Yes when grounding pins 21 and 22 on U1 I get an output on pins 5 and 7 of U4 respectively.

[Matt Cramer]

The driver is working, then. I'd follow the signal through the rest of the circuit and see where you lose the signal.

[Eds]

Matt, I went back and again traced the signal. I made an error in my discription of the signal in an earlier post. When using the test lamp, the lamp glows brightly when connected to pins 21 & 22 but does not flash as seen on the injector pulse led. When I ground pins 21 & 22 as you recommended, I can trace the signal all the way to the injector leds on JimStim. Am I correct then to assume I have a problem within the MS-II daughter card (U1)?

[Matt Cramer]

Something seems to be wrong with the MS2 daughter card - not necessarily hardware; it may be a settings issue or not seeing RPM.

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Matt, I ordered and received a new daughter board. I loaded the code and I now have an output to the injectors that varies with rpm but also have problems with the new daughter board. The MAP output as viewed on TS is max. I have no tps control and can not calibrate tps. IAT is a constant 170* F. I have traced all the circuits and checked voltages while on the stimulator. The voltages vary on pins 24, 25 and 25 when I adjust the associated pot on stimulator but I do not see any changes while viewing TS. If I re-install my existing daughter card all my functions (MAP, IAT, TPS) return to normal but of course no injector output.

What am I missing?

[Matt Cramer]

Well, I'm missing a copy of the MSQ file in the new daughter card. That would help give me a better idea of what's going on.

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Matt, The MSQ that you requested.

CurrentTune.msq

[Matt Cramer]

No obvious problems in that one - try reloading firmware without loading an MSQ and see if that changes the problem.