Edis running Ok But no Rpm readings or Advance from MJL ??

[simon w]

It Lives !
At last finally found time and replacement Edis to try & Bingo...sparks galore and engine running at 10' no problem...I have connected MJL but I cannot get any rpm readings on software, or any ignition advance at this stage. I have connected a volt meter and I am seeing a volatge going into the MJL. I cannot see any voltage coming out down the saw line? should I ? I have sheilding around pip/saw cable from Edis, properly earthed etc
Also my software / screen shows a reading of around 450 rpm as soon as I connect to the mjl when ignition is on ? and stays there regardless of engine rpm ?

Any Ideas?


would be appreciated..

regards
Simon

[brentp]

Hi Simon,

What voltages are you reading on pin 1 of the EIDS module (PIP)? You should be seeing about 4.5 - 5v with the engine running. Trace the signal all the way to MJLJ and make sure this same signal is getting to the inside of the unit. Also, double check the MJLJ plug wiring - ensure you have the PIP input on the correct pin of the MJLJ.

And just a sanity check, you can communicate with the unit using the software- read/write ignition maps, etc?

Regards,

[simon w]

thanks for the reply Brent..
I firstly double checked the connections are in the correct place and I have checked the pip voltage coming into the mjl and its around what you say..
I double checked the voltages / connections make it all the way inside of the MJL aswell.
I can communicate and read / write / save maps to the unit, but when I re-read a configuration I have saved on the MJL the RPM goes to around 450 and sits there? obviously the advance display sits statically also.



a puzzled new-comer?

regards
simon

[simon w]

Brent,
this morning i rechecked the pip voltage coming into the mjl and i actually found it to be around 2.6 as oppsed to the 4.5 /5v you had quoted? doe this mean Edis again, I have againg checked the voltage goes onto the board.
i did'nt assemble the board, but i have taken the time to read through the assembly info etc and have checked for the different volatges over the board as explained at the different assy stages, these check out ok...
what do you recommend?
could this lead to the 457 rpm that the software show when i plug into the unit ?

regards
simon...

[simon w]

ok. have been to scrappy, and sorced another edis module - car running at 10' . now just like the last one i have still got arund 2 volts going into the mjl down the pip line ? the run time display stays at 457 rpm, the TPS indicator (thats the model i am using) is working. The mjl is reading / writing and storing maps ok. Its a version 3.0 board, and i have tried version 3 & 3.2 software but to no effect ? (with regards to rpm showing on runtime display)..

Help needed urgently.....really struggling now..


regards
simon...

[brentp]

Simon,

The fact that the software is communicating shows that the MJLJ is basically alive. Now, we need to figure out why the PIP signal is not getting to the CPU on the board.

Here are a few more tests:

With the engine running but with the Megajolt disconnected, what voltage do you read on the PIP line? does it go up?
With the ignition to 'on' but the engine not running, what voltage do you read on the PIP line and then with the Megajolt connected?

With the engine running what voltages do you observe on:

pin 8 of the MAX232A (U2)
pin 4 of the processor(U1)
Please perform this test with the engine running and not.

Refer to the schematic here:
http://www.autosportlabs.net/asl_dist/m ... v3_sch.png

If you're not comfortable identifying the proper pin on the ICs let us know and we'll illustrate which one to test.

be very careful when measuring voltages- don't let your probe slip and short out contacts!

Let us know what you find out.

Thanks,

[simon w]

hi brent,
yep please can you identify the teminals i need to measure, i know where the items are but at which location the pins numbers start / stop isnt clear to me thanks

Simon

[simon w]

Brent
through powers of deduction i have managed to work out the pin numbers using the schematic and data sheets I found on the web supplied by component distributors etc. Readings are as follows:
pip voltage - mjl disconnected (not running) - 12.9 vdc
pip voltage - mjl connected (still not running) - 1.50 vdc
engine running - mjl disconnected - 7.15 vdc (15.2 vac(on my 200~ scale presumably volts a.c ))
this increased to 15.3 when revved lightly.
pin 8 on max232 - not running = 1.41 vdc (2.4 vac)
pin 8 - running = 0.77 vdc (2.0 vac)
pin 4 on processor u1 - not running = 0.015/0.02 vdc (0.0 vac)
pin 4 - running = 0.015/0.02 vdc(0.0vac) - gave the same readings ?
Sorry Brent, I came make engines work - but electrics....not my specialty....having to learn fast...
Hope you can make sense more than I can -
regards
Simon

[brentp]

Good job being resourceful- and the data looks like the problem is around the signal not getting through the MAX232 on it's way to the processor.

Can you measure pin 9 on the MAX 232 as well?

As you've figured out, the pinout on these chips (processor and MAX232) is this, viewed from the top of the device:

notch
1 16
2 15
3 14
4 13
5 12
6 11
7 10
8 9

[simon w]

Brent,
measured pin 9 - readings are
running - 0.02vdc (0 vac)
standing - ignition on - - same reading 0.02 vdc (0vac) ?

I suppose this means the chip is duff?
What do i do to replace? if necessary


regards
Simon..

[simon w]

brent,
I have seen some posts about dodgy capacitors, or even wrongly valued ones is there a way to check this or am I barking up the wrong tree?

simon...

[MKnight702]

Your problem sounds very similar to mine. My Megajolt was doing everything it should but the car was running on 10 degrees advance. My problem turned out to be a wrong value resistor, R1 was 10,000ohm not 100ohm. Everything worked as it should but the EDIS wasn't getting a strong enough signal to trigger it so it stayed on limp home mode. Took me a while to find that one!

[brentp]

R1 isn't the problem in this case. It seems the MAX232A chip might be bad. you may want to consider reflowing the solder on pin 8 and 9 of the MAX232A just in case there is a bad solder joint.

If you're referring to the mismatched charge pump capacitors vs. the MAX232, I do not believe that to be a problem since that only affected firmware upgrades, where the problem was exposed when using a higher baud rate- It never affected processing the PIP signal. But, if you do want to check, the *correct* capacitors should be 0.1uF (marked 104 on side of capacitor) and the chip should be a MAX232A, not a MAX232.

[simon w]

All,
I have contacted some one who can fully test out the megajolt for me, and hopefully make some repairs as necessary..

MKnight702 -
yes I followed your thread, and tested the values around the board aswell just incase, but no luck there unfortunately..

I will keep you all posted on my progress......soon.

thanks for the help so far



simon...

[simon w]

At last mjl installed and working fine...thanks to MartinM (really recommeded him if you get stuck like I did)...
Turns out rs232 chip was kaputt - replaced, and now ok...
I have loaded a base map (2.0 pinto - twin 40's / mild cam) and this seems to do ok.
I am planning to get the car onto a rolling road to tune up & to iron out some small carb issues - at least when the engine is more run in anyway.

Chuffin' Great !



simon ..