Help please! No saw signal

General Megajolt Questions and Answers

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Spuddy
Posts: 2
Joined: Fri Feb 03, 2017 6:40 pm

Help please! No saw signal

Post by Spuddy »

Hi all.
Just finished installing a megajolt/e controller, combined with a efis 4. Thought all was going well until we tried to upload a map to the ecu. All loaded fine but despite what happens or what we load we are constantly getting a fixed btdc ignition timing. Looks to be the static 10 degrees btdc from the edis.
Anyway followed online instructions and trouble shooting and confirmed vr sensor correctly wired, Rpm gauge showing nicely on computer. Getting no a good pip signal therfore and also conformed voltage at the MJ ecu for the oil signal, however found we have no output SAW signal coming from the megajolt ecu. All wiring checks out all power and earth connections are good. We have re flashed tge megajolt with the firmware but nothing has solved it. I think we have a faulty megajolt ecu out of the box?!

Any advice woukd be greatly appreciated as we have spent hours now and alot of money trying to get such a simple thing working.

Thanks, Spencer

brentp
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Posts: 6274
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi Spencer,

Thanks for the detailed post. I take it you've followed the guide here for verifying signals? https://wiki.autosportlabs.com/MJLJ_V4_ ... ng_Signals

When you were measuring the SAW output, did you use a volt meter, or oscilloscope?
Brent Picasso
CEO and Founder, Autosport Labs
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Spuddy
Posts: 2
Joined: Fri Feb 03, 2017 6:40 pm

Post by Spuddy »

Hi Brent thanks for the reply. Yes followed that page and can confirm the vr sensor is working and the wires for that are OK. That is also double confirmed when the vr sensor is disconnected and the car does not start.
The pip signal is also OK and all wires between the MJ ecu and edis are 100% OK.
I measured the output of the saw on the MJ ecu with a a multimeter, tested for a ac and dc voltage. I do not have access to a oscilloscope sorry. Will I not see any voltage reading from this output? If the saw signal was working however, it would surely adjust the ignition timing? So even if I had a oscilloscope, it wouldnt show anything anyway as if it did I would not have the problem in the first place?

Thanks
Spencer

brentp
Site Admin
Posts: 6274
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi, Sorry for the late reply here.

Are you saying you are measuring 0v on the SAW signal right at the molex pin of the Megajolt, when the engine is running, *and* you are observing RPM on the software? If so, then there might be an issue that may need repairing.

email us at [email protected] and we'll help you get it resolved.
Brent Picasso
CEO and Founder, Autosport Labs
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