Missfire and terminal 30 codes....

[vdublighty]

ok so i need some advice on what to do next because ive run diagnostics on my 1.4 mpi and its come up with random/multiple missfires on all cylinders and a low voltage from terminal 30. since then i've replaced the battery, coil, leads and plugs with no change. what could it be? thanks

[alexperkins]

Check your earth straps

[vdublighty]

Where would I find those?

[vdublighty]

Saying that, I was having a poke around today and plugged it in again and it came up with camshaft postion sensor signal too high. So I'll replace that and see what happens

[alexperkins]

If you replace it, use a genuine one. Copy parts of those don't tend to last

The earth straps are between the gearbox and the chassis on the battery side of the engine

[vdublighty]

ok cool, what do the earth straps look like and whats the best way of getting to them?

i've replaced the camshaft sensor, and that got rid of the DTC for that, i disconnected my sub and now its not showing a terminal 30 code anymore. the missfire codes are still there, but its fine until i rev it up to 3k and then the MIL light flashes and it starts missing and dies. switch it back on and its fine, until i rev it back up to 3k and it starts missing again etc etc. really getting on my t**s now! i'll have a look for the earth straps, failing that, what else do you think it could be? thanks for your help

[alexperkins]

Can you post up the actual error codes?

Earth straps are thick black cables that go from the engine to the chassis. There's one right next to where the battery sits

[vdublighty]

Ok ill take a look. I can take a picture of the screen and post it seeing as I have a 'stand alone' scanner rather than a pc programme to be able to screenshot it but I'm nowhere near a pc at the moment to do that. I did a readiness test today and it came up as a fail on the o2 sensor. Could this be at fault? Maybe causing it to send the wrong signal and applying too much air or fuel to the mixture?

[vdublighty]

well it seems like problem solved! although i had already changed plugs and leads, it seems the leads were breaking down at high revs! weird. anyway, glad that long lasting problem has gone lol