VT tacho moving without revs

[Huntington]

Hi all, i have a VT s pack L67
just had a new engine put in and having some teething problems, one of them is when idling, the tacho is moving up and down without any revs. its not a rough idle, the idle feels smooth, but the tacho has jumped as high as 5k without any revs at all.

also if i pulse the throttle a touch i get the occasional flicker of a check engine light or a battery light, but they go out as soon as the revs go down. these only occur in neutral, when actually driving i dont get either.

any thoughts?

[daggett]

I have had a bad earth on a VX I replaced the engine in cause a very similar problem.

[dinnzyvrv8]

i had a similar problem myself with my vr it could be your speed sensor on the tranny.

[dinnzyvrv8]

does it idle properly?

[Huntington]

yeah it idles like a dream, i think the bad earth idea is one to check as a couple of the dash warning lights are playing up and coming on here and there to, and they dont stay on, just flash. just that they all the earths look really good, clean and tight, but a double check wont hurt.

my fans are also staying on constantly if the engine is on, so theres a wiring issue somewhere, unless thats unrelated and just a relay.
at least i have some ideas to check in the morning.