megatune - can't see o2 or rpm

[redstar]

Hi there.

I've finished assembling my MS-II v.3 board and the MegaStim 2.21 adapter.

When I run the MegaTune 2.25 p3 software (I think I have it set correctly, but I'm not totally sure) I can fiddle with the pots on the MegaStim and they each move the meters around when I choose Tuning -> Realtime Display, with the curious exceptions of the RPM and O2 (air-fuel ratio) gauges.

On the MegaStim board, the only LEDs that light are the PMP light for a second or two when I first power it up. But then that light turns off a moment later. The IG light is solid. No other LEDs illuminate.

I've attached a copy of the .msq file and a screenshot of the MegaTune screen in .pdf format.

Thanks!

-marcus

[Nizm0zed]

have you chosen what sort of ignition system you'll be running? and selected the correct jumpers on the stim? and on the MS board?

If your missing either, or they are conflicting, it may cause the RPM signal to be completely absent from the Megatune screen.

I have a second board (MS-II v3.0) that has the same problem on the stim, no RPM.
After going over its assembly, the previous owner had cut the jumpers off that selected the type of ignition input.
I haven't tested it yet but i believe that was my issue.
I cant recall whether the O2 sensor was registering or not, but i do remember that the O2 trimpot on the stim is quite sensitive.

[8974Ollie]

You will not have a RPM or O2 unless the MegaSquirt is connected to an engine.

[DonTZ125]

You will not have a RPM or O2 unless the MegaSquirt is connected to an engine.

He's talking about problems with the Stim - the entire purpose behind the Stim is to give signals (including RPM and O2) to the MS board when NOT connected to a Stim.


The base MegaStim only give continuous pulses, like a distributor or coil -ve - that's what the original MS1 was designed for, after all. If your engine is going to use a patterned wheel (like a missing tooth) you either need to use a JimStim or temporarily re-configure the tune file and MS board to 'basic trigger'.

[Byrdhouse9]

When I assembled my MS II and JimStim, I had no RPM readings on Megatune and O2 was stuck at one number. I had set up my ignition to use a Ford 36-1 trigger wheel and VR sensor. I wasted lots of time troubleshooting the O2 circuit. When I gave up on O2 and started looking at the RPM problem, I adjusted the R56 and R52 pots on the MS board (as mentioned in the manual) and MS suddenly started recognizing the trigger signal, and Megatune started displaying RPM AND displaying O2 correctly. I did not find this mentioned anywhere in the manual, but O2 does not work right without RPM working...Then I realized, there is no point in calculating or displaying O2 when the engine is not turning, since it would not be valid data.

[jaywiz]

I have the same issue as the previous poster,i have mine set up for vr and the manual says the jimstim isn't set up for this.I have turned both pots on the ms board an can get no rpms or O2.It does say to test the o2 you can power the unit down move the o2 adjuster and power it back up.You should see a change in the o2 gauge(won't be able to adjust it but it will change from where it was b4 the power down).My o2 does change so everythings alright there but for the life of me i can't get any rpm change.Anyone know how to test all the input circuts for the rpm?

[jaywiz]

So here is a new question for ya,is the jimstim capable of producing a tach signal for testing the vr circuit? I have everything else up and running but can't get a rpm reading no matter what i do.The manual says the stim isn't capable but if you cranck on r52 and r56 you should be able to get a useable signal...What does that mean yes or no??? I can not, someone help please.I have chased every connection,and every part on the circuit(they all test good).Should i just go on and complete the build because i'm not getting what i need to test the vr from the jimstim,or stay stuck on this problem?

[DonTZ125]

Check the JimStim manual - there's something about adding a capacitor to get a zero-crossing signal that the VR circuit will recognize.

[Matt Cramer]

The V3.0 VR conditioner will work with square wave signals. Some other VR conditioners, like the LM1815, will not.