Wasted spark and rev counters - again........

[Dave_M]

Hoping someone can help me here. Modded my car to run wasted spark using the P8 onboard wasted spark driver - no MSD baby board. At the same time I switched the rev counter for one from an RS2000 as the consensus was that these worked correctly without any other mods. I've used an MSD wasted spark loom which I had to mod slightly as their loom connects the rev counter wire to pin 21 of the ecu - which provides a rev counter signal from their baby board. I connectwd this wire instead to one side of the coil pack.

Problem is that the rev counter appears to show the right revs at idle, but it never shows more than about 2500rpm irrespective of how mamy revs the engines doing . It's also really sluggish to move if you blip the throttle. Should I have connected the rev counter wire to the ignition amp drive signal from the ecu rather than the coil negative (ie to pin 3 rather than pin 1of one of the ignition amps)? Or is there something else I need to do?

Thanks
Dave

[kjc300]

Should be straight from the coilpack neg (one of the two outside wires) . Thats where mine comes from.

[kjc300]

Make sure your ign amps have good connections, as that's caused mine to do strange things before.

[Dave_M]

Kev

That's how it's wired at the moment - but it's not working right . Does yours work correctly like that, and was it an RS2000 rev counter?

Thanks
Dave

[hughy]

Dave i was told today you have to modify the chip when going wasted spark on the P8 ecu?

[Dave_M]

Kev - I'll double check that. The engine's running fine and I soldered the rev counter wire on so should have good connections.

Hughy - you do, but that's not connected to this problem - the engine would only run on 2 cylinders without the chip mod as you wouldn't have the signal to drive the 2nd ignition amp .

Dave

[Rolls]

Agree with Kev - when i had wasted spark on the old car it would never run right at first - although the connections for the ign amps appeared to be correctly in place, they weren't!

[kjc300]

Kev

That's how it's wired at the moment - but it's not working right . Does yours work correctly like that, and was it an RS2000 rev counter?

Thanks
Dave

Yes mate, it's on stack now wired the same. But it was an rs2000 counter.

[SECS]

Make sure the ignition amps (both of them) have a very good bond/connection with the vehicle chassis.

A resistance check may show this bonding to be ok but when running, the high peak currents can cause a high resistance to form during running.

I personally would make up a couple of wires and connect the heatsinks to the body directly and each other to be sure

[Dave_M]

OK - thanks guys. Simon - I'll earth both ignitions amps directly and hopefully that will fix it.

Dave

[Dave_M]

Removed both ignition amps tonight (glad I did as there was no heatsink compound on the back of one of them) and added a wire from the securing bolt of each amp to the chassis. Checked resistance - zero near as dammit from the amp mounting bolt to chassis (and same to engine) but resistance is 2 ohms between chassis and battery negative.
anyway, poxy rev counter still not working .

Any othet ideas?

Thanks
Dave

[SECS]

Are you sure the RS2000 rev counter input is connected to one of the coil negatives ?

[Dave_M]

I'll double check tonight - but I'm sure that's how I wired it.

[Dave_M]

Ok, checked the connection today - the RS2K rev counter is connected to pin 1 of one of the ignition amps - which is the pin that goes to one negative side of the coil. The connection is via the standard wiring loom - and therefore still has the rev counter filter connected - would this cause a problem?

The heatsink back plate of the ignition amp is obviuosly connected to pin 3 of the amp (zero resistance between them) - but interestingly there's no continuity between pin 3 of the ignition amp and the negative of the battery - I know this ground goes via the ecu but would have expected that to be a "hard wire" to ground.

Dave

[The Radman]

ive never known any other mod cause as much problem as these things,id have thought it would all be sorted out after all these yrs,glad i dont need one lol