Revs not registering on the Megajolt and timing not adjustin

Beakster · Post by **Beakster** » Sat Sep 01, 2007 5:28 pm

Hi,

I installed my Megajolt in my 2 litre Capri. When I first set it up I checked the timing with a light and it seemed to work. I was having major misfiring probs tho, so put a new EDIS in which sorted that, but it still wasnt right.

I couldn't get my computer to monitor the MJ while it was running, I kept getting a "Timeout reading runtime data" when ever I started the engine, but this was fixed by buying a new high quality fully shielded gold plated serial cable from Maplin.

The current situation is that everything is connected but the Megajolt is not showing the revs on the computer, although it is showing the air pressure correctly. I checked again with the timing light and it is not changing the timing either. I have checked the wiring about 5 times and its all fine! I've checked for short circuits between pins and it seems fine. The cable seems to be correctly shielded too.

I have replaced the HT leads, Coil pack, EDIS module and VR sensor and all are fine. As I say I have checked all the wiring and it seems fine too. The engine runs fine, so I know the EDIS, VR and Coilpack are all working fine and talking to each other. The computer reads the map and the air pressure from the MegaJolt no problem so I know the Megajolt is powered up and working to some extent. So why isn't it reading the revs or changing the timing?

I had a quick look inside for dry solder joints but it seems fine. Are there any tests I can perform on the circuitry that receives the signal from the EDIS? Or is there anyway I can monitor the signal from the EDIS without attaching the MegaJolt?

Thanks
-Chris

Supercharged Nat · Post by **Supercharged Nat** » Sat Sep 01, 2007 6:05 pm

Hi mate sorry to hear your still having trouble. firstly you can test the pip and saw lines for voltages with the engine running and mjl powered up/ connected. i forget which one will show a voltage (possible pip). that way you know its receiving the signal it needs from the edis moduel.

if theres no voltage at either of them, then the signal isnt getting to the mjl. if theres a signal going too but not from the mjl, you know its the mjl. if there one going to and from, well then i stumped!

also sounds like the vr sensor wires could be the wrong way round?- have you tried swapping them?

Beakster · Post by **Beakster** » Sat Sep 01, 2007 6:42 pm

Hey,

I'll check the voltage on PIP and SAW sometime soon. Between either of them and earth do you mean, or between each other?

VR sensor wires cant be the wrong way around, or the engine wouldn't run on EDIS, which it does.

Cheers
-Chris

Supercharged Nat · Post by **Supercharged Nat** » Sat Sep 01, 2007 7:47 pm

between either of them and earth mate.

Supercharged Nat · Post by **Supercharged Nat** » Sat Sep 01, 2007 9:26 pm

could also be something as simple as the molex connector terminals not connecting properly?

Beakster · Post by **Beakster** » Sat Sep 01, 2007 11:15 pm

Supercharged Nat wrote:could also be something as simple as the molex connector terminals not connecting properly?

Pins on megajolt and EDIS plugs all triple checked. Defiantley making contact.

Post by **brentp** » Sun Sep 02, 2007 7:03 pm

Hello,

You did mention you checked the wiring- but be especially sure the PIP output from EDIS is connected to the correct PIP input of the MJLJ. Same goes with the SAW.

Basic rule of thumb:

* MJLJ cannot see PIP signal

1. No revs will be seen
2. Ignition advance will not vary.

* EDIS cannot receive SAW

1. MJLJ shows RPM activity
2. Ignition advance does not change.

Also covered in the FAQ: http://www.autosportlabs.net/Troublesho ... RPM_signal

If you don't have access to an oscilloscope you can use a volt-meter set to read AC voltages. You should see an AC voltage on the PIP line while the engine is running. Make sure this signal makes it all the way to the MJLJ.