Hi all,
Im having some real trouble with a V8 on wasted spark, it resets randomly and intermitantly under 2000rpm. I have the main MS earthed at the battery and the 4 x VB921's earthed at the engine block, Ive tried different combinations, etc and its always the same.
Its soo bad that sometimes the ECU wont restart untill I turn it off and on again. Ive tried new HT leads and new coil packs, the leads and coil packs are the same as Ive used in the past on other installs and they are running fine. Im running out of ideas
Phil
Ive cleaned the plugs and Ive checked the plugs, they arent resistive, but then neither are the ones on my setup that Ive been running this setup on for ages now, so Im no closer now
Phl
Try resistor plugs, anyway. It can't hurt and you'll only be out a few bucks (pounds? euros?). I didn't use them initially and resets were so bad I blew up my MS. Putting them in cured the reset problem. Even if your other setup works, this one might need them. People with setups similar to mine assured me that resistor plugs weren't necessary but, in my case, they were.
Hi all,
just to update this, Ive been away so little time to fix it, but I scoped around today, the +12V is excellent, the plugs aren't replaced yet, but thats due to me finding time to get some. Ive also scoped the VR sensor and thats perfect even during the resetting. Ive scoped the MS earth to the engine earth and thats got some nasty looking spikes on it, so its got to be that, Im going to replace the earth wire between the engine and the chassis, as its a feeble wire, and replace the plugs with resistive ones over the weekend and I'll let you know,
Phil
Hi Phil .
Resistor plugs and wires seem to help alleviate the problem a lot
If you run loZ, try running the +12 V feed to the flyback transistors ( TIP 125) separately from the other 12 V feeds to + 12 V ( switched . have helped other people here recently
At the end of a squirt the flyback current is closed thru the power supply circuit , so proper grounding is very important .
Did your scope show transients in sync with end of injection events ?
In that case you can also try a 1000 µF cap between +feed of MS and MS ground , directly on the MS .
It might also be an issue with radated emissions going into the RST pin of the processor . This was a problem for me on a MS 1 , cured by a resistor of 10 k from pin 6 to + 5V and a 100 nF capacitor from same pin 6 to grnd .
Hi all,
well I finally got some resistive plugs for it (NGK BR7ES thanks for that James). I also found the originals were all different and they were all set at around 0.7mm where as I have always run mine at 1.1-1.2mm on the coil packs. Anyhow, Ive just been out in it and it hasnt reset once!!!!!!! Really pleased, thank you all so much for the help!!
Phil
