Hey guys
I've got a ms V3 with a 2nd VR conditioner that seems to be working fine, running 029y4. I've been trying to start my s4 rx7 t2 and it stumbles when I hold the throttle down on flood clear mode and actually started and ran for 5 seconds. My wideband flashes rich at me and I can smell petrol. I took the upper intake manifold off to investigate, and was shocked to find that on the priming pulse, the injectors held open for around 2 seconds!!!! It just poured petrol in and that was from the secondaries, so I would presume the primaries are doing it too.

My megatune settings are 7.9 for required fuel and 0.1ms priming pulse.

How long should the priming pulse go for?

 

This probably means you have a miswiring somewhere or the injectors are stuck open... Try disconnecting them and doing the same test...

IF they still squirt then the injectors are bad, if they don't, you've miswired something. The fuel pump should stay on for 2 seconds when you first turn on the MS. The pin for the fuel pump is near the injector pins, maybe you wired the secondaries to the fuel pump pin.

Ken

 

I've checked out the connections on my loom and they all seem ok :
pin 32 to 3E
pin 33 to 3C
pin 34 to 3H
pin 35 to 3F
and the fuel pump is tee'd into the yellow check connector positive to pin 37

It appears that my fuel pump has lost some of its zing. It's definately not as loud when switched on. It's still got pressure as the secondaries are still squirting there hearts out.
Whats interesting is that like you said the secondaries appear to be working on the fuel pump circuit and stay squirting as long as the pump relay is open for. They are not connected to the pump on the loom . I unplugged the secondary injectors and and turned the pump on and they don't spray so the injectors are fine. I found 14V going to them and only 8V going to the primaries. I tried starting the car with only primaries but they don't appear to be spraying any petrol.

Could I have accidentally joined circuits on the board? Easy around the transistors. Any ideas?

 

You could have shorted something in any number of places... on the board or in the harness...

I'd check the harness first as that seems more likely.

Ken

 

Thanks Ken for your help.
I've checked the harness and it's fine. I've spent alot of time connecting it to an old computer socket so it's plug and play and I'm pretty certain it's fine. I'll poke around with the multimeter and see if I can find the problem. Maybe I'll pull out and re-solder the basic components on the board.
Thanks again, I'll let you know what it is when I fix it.

 

If you're getting 8v at the primaries, something is wrong in the harness. The positive for the injectors is supplied directly from the main relay, it never goes through the ecu.

 

It's easy to accidently bridge solder across the little NPN transistors on the board. Get a magnifying glass and double-check those as well as the small solder pads for the db37. Also wash the bottom of the board with 70% alcohol and a toothbrush to remove excess resin and any "solder *****" that may have crept underneath the db37. It's not a bad idea to (carefully) remove the processor first, and let the board dry out for a couple hours before powering up.

 

Thanks for the help so far.
Just checking the final bits before I try it on the car tomorrow. Can you guys confirm if these transistors are meant to have continuity?

Q2: No continuity on any pin
Q4: No continuity on any pin
Q10: No continuity on any pin
Q13: No continuity on any pin
Q14: Continuity only on square and middle pins
Q15: Continuity only on square and middle pins
Q19: Continuity only on square and middle pins
Q20: Continuity only on square and middle pins

I presume Q6 Q7 Q8 are working fine as I have spark.

I fixed up some solder joints as some of these transistors had continuity in different places. Just need to make sure these are right.
Thanks again
Jono