LS2 rough start after parking on a hill?

[Stewge]

Hi guys, been running into a very weird problem recently.

Recently moved office and the new parks are on an angle (into a wide gutter). It seems, if I back into the park (such that the nose of the car is higher than the back), when I get back to it in the afternoon it runs extremely rough on start.

Symptoms include:
- More rev hunting than usual at idle (running a GMM TK cam 237/242 so it does a bit anyway).
- Exhaust has lots more bark/popping
- Loses revs much quicker when backing off throttle.
- Strong petrol smell (maybe running super rich?)

Weird part, is after a minute or 2 it all goes away and seems to sort itself out. Similarly weird, if I park the opposite direction (nose down) I have no issues.

Recently it's had some work done. New morel lifters (with accompanying rods) and xtreme clutch from GMM. Consequently the oil pump shat itself the day after and had that replaced with a high volume pump from GMM.
The tie-bar lifters also seem to make more noise. Less of a metallic tick and more of an airy/wider noise? (sorry about the shitty explanation, hard to describe it, but definitely not the short clacking it used to make when the old lifters got bad). This only occurs between 1500-2000rpm on little throttle. As soon as there's any load or go over 2000rpm the noise disappears. Recently changed to Penrite 10w-70 full synth which has helped a bit.

For the moment, I just park nose down. My first thought was o2 sensors, but I can't see why they'd be sensitive to sitting on an angle all day? Might plug the scantool in and see what comes up.

[Peter B - CV8]

Plenty of fuel in the tank ???

[Micks]

If you recently had work done either shoot it back to the repairer or look for obvious signs of something loose, eg plug wires, earths, wiring plugs/connectors.
Remember the o2's are out of the equation probably for first 2 mins until the engine starts to warm.
The tie bar lifters are never quiet so that is normal, recommend you use good quality oil & slightly over fill. ;)

[white lie]

Sounds like it's sucking air or the check valve may be leaking slightly allowing a little fuel to go back down the line in to the tank

[Stewge]

Plenty of fuel in the tank ???
Happens whether I'm at full or (in the case of yesterday where I dared back in instead) quarter tank. I rarely run it below red (1/8th) though since it's a pig on fuel (20l/100km around town/traffic).


If you recently had work done either shoot it back to the repairer or look for obvious signs of something loose, eg plug wires, earths, wiring plugs/connectors.
Remember the o2's are out of the equation probably for first 2 mins until the engine starts to warm.
The tie bar lifters are never quiet so that is normal, recommend you use good quality oil & slightly over fill. ;)
Good to hear about the tie-bars. Had no idea what to expect and I do usually go an extra .5 litre on oil change, particularly with the high volume pump in now.


Sounds like it's sucking air or the check valve may be leaking slightly allowing a little fuel to go back down the line in to the tank

I'll get my mech to check these. Thanks for the tips fellas. Still boggles the mind as to why the behavior is reproducible by simply parking on an upward angle.