vl rough idle

[guidos]

hello again all :)

Finally thought maybe i should post something about this.. My VL's idle is slightly rough, its always been like that and i dont understand why! I'm starting to think its an aftermarket cam though.

It just has a bit of a shake to it, but its very consistant. If you say unplug one lead or injector, its like that, but not quite as bad.

Its got a reco head, compression is good, new plugs and gaps checked, done CAS dizzy, all sensors good, etc. never misses a start, fuel consumption is ok.. tuned properly (timing idle speed etc).

But in the cold the idle is much smoother. not so much of a 'lope' to it.

Any ideas? Its a bit annoying that i cant seem to figure it out.

The reason i think it may be an aftermarket cam is because there is a pretty nice rush of torque from around 3000-5000rpm that no other n/a VL i have been in or driven has.

Sorry if the post seems silly, but maybe there is something i'm missing.. and since im picky and notice everything, i cant help but wonder whats causing it!

Thanks
Nath

[OVL087]

natho
it may sound odd but i did this for a mate and it actually worked.
pull the computer completely out. unscrew the cover to expose the 2 circuit boards , then give it a good liberal spray with some contact cleaner/circuit board cleaner (computer shops sell it) (my bro is a comp tech so i used his) and also thouroughly clean the male/female parts of the plugs for the comp.
as youd know water and dust etc easily finds its way into our comps.

a long shot to try but it may be the fuel reg also .
good luck anyway

[InsaneVL]

If you've ever heard my car idle, you know what a rough idle is... sounds like a lumpy v8 on idle (yes, i got quite a lumpy cam in there)

has a definate rush of power over 3000 rpm (is a damn slug before that though) and redlines (6200) VERY easily...

although cam timing is retarded some (need some adjustable cam gears) and the ecu isnt chipped at all causing quite a few problems (namely reduced vacuum on idle - 10psi at best)... 120 rwhp with the problems in the recent dyno day at RDP (hope for quite a bit more once i fix up the ecu, and cam timing probs !)

[CLA]

120rwhp

Fully sik habib

Isn't that only like 5rwhp over standard ?

[guidos]

I have also tried a different ECU. One i have is chipped and the other standard. funnily enough its worse with the standard one.

also something worth noting is that it misses a bit.. not noticeable when driving but if ur under the bonnet and give it a small rev it misses randomly..

yes plugs and leads are new, and i swapped the whole ign system with my brothers VL (no problem there at all) and it didnt make a difference.

i'm putting in a new trans soon, i think i'll just try to grab a good motor too.. $300ish to get a motor here in adelaide and that would easily be blown trying to solve something like this i think!

and yeah insaneVL its not all THAT lumpy but i was just using that to explain how it is.. its pretty slight really.. but enough to feel it and see the passanger seat shake at idle.

still annoys me its fine in the cold! lol.

[InsaneVL]

Originally posted by CLA
120rwhp

Fully sik habib

Isn't that only like 5rwhp over standard ?

yep.. got it on the nose... car made 114.9 RWHP with just extractors, 120.4 with a larger cam (running retarded timing and stuffing round with the ecu), and extractors... a whole 5.5 rwhp increase !!! wow.. im sooo proud.. (not) - hence im expecting a bit more once i've sorted the cam timing and ecu probs out.

[tez]

Wwhat does the car idle at when warm??

[Bitza]

Have you checked all the vacuum hoses that go to the intake/throttle body and check the breather hose from the rocker cover to air intake. Its a short hose that can cause trouble.
Other silly thought, is the cam timing itself set correctly??

[guidos]

Originally posted by Bitza
Have you checked all the vacuum hoses that go to the intake/throttle body and check the breather hose from the rocker cover to air intake. Its a short hose that can cause trouble.
Other silly thought, is the cam timing itself set correctly??

timing belt is new, cam timing is slightly advanced (have an adjustable gear). doesnt make a difference to the idle if its retarded, advanced or 'spot on' standard.

i have used up a lot of aerostart trying to find vacuum leaks and have found nothing so far...

[guidos]

ok guys i tried another set of plugs and leads to try to solve the missing - it also misses randomly.. not noticeable if you are driving but if you rev it a bit while under the bonnet u can feel the odd shake as it misses. anyway the plugs and leads didnt change a thing.

i also did a compression test... last time i did one was a year ago when i put the reco head on. it was 1196kpa (spot on spec) on all cyls.

now i get:

cyls 1,2,3,4... ~1250kpa 182psi
cyls 5,6 ~1280kpa 187psi

what does that mean? :(