Thread: Misfire at certain revs

And the shielding must be earthed at both ends.
Regards Philip A

Also doesnt hurt to twist the wires at aprox 1 twiwst per 25mm of cable. This helps to shield the signal from noise.

Exactly my problem. I retrofitted a bosch alternator after I couldn't get a spare regulator for my MM. I have a miss at 2200 rpm esp when I increase the electrical load, air con, lights, etc. Took the alt belt off, prob went away. Interestingly not noticeable when running on LPG, only on petrol. I haven't fixed it yet, as it is fine on gas. But will in near future. Tried the extra shielding/earthed at both ends as PhillipA suggested to no avail.


93RR3.9

George

But how bad was the miss you guys were experiencing? Mine is extremely bad, as in if i had it in drive and tried to drive normally it would never get past the miss, I have to drive it hard, and it still struggles to get past the miss

I hope this sheilding works as I would much prefer to keep my alt, I might just shield everything

I also suggest that you route the wiring away from the alternator, eg run the shielded wire straight back along the injector wiring on the LH bank to the firewall then along the LH guard.
I have 2 Bosch alternators and no problems.
My wiring is shielded and goes back to a Unichip piggybacked on the ECU, then forward along the LH guard to an amplifier mounted on the LH guard then to the coil.
Regards Philip A

So what size shielded wire do you reccomend and where abouts did you earth the ends to??? I am assuming I am just to replace existing wiring with higher quality shielded core. Sorry I am a noob when it comes to motor vehicle electrics.

I can wire up a stereo and maybe an amp or two but never done anything else. But would really like to learn

I didn't install mine and it looks a size that is not readily available. Maybe it came with the Unichip.
AFAIK , you can get 2 sizes at Jaycar, and both are intended as speaker cable (aside from the TV antenna cable). I would use the larger size . If you can only get two core, just pull one wire away from the other to make a single core.
To earth the outer, I usually bare about 80MM and twist it into a wire. I then seal the end where it enters the outer insulation with shrink tube. It should then be earthed as near as possible to the source, eg a mounting of the amplifier on the distributor or another convenient bolt and on to the coil mount.
I didn't do mine but that is how I did my O2 sensors.
Regards Philip A

two easy mate thanks