Small vibration at idle.

[haydar]

Do all VR4s vibrate very gently at idle? The rev are rock solid at about 6k rpm in 'D' but the car seems to vibrate gently. It's never really intrusive, but you are aware of it.

My local tuner believes it's not quite right and thinks possibly there is a problem in the compression of one piston. He also wants to relieve me of £250 for doing this. Is there any histroy of VR4s losing compression in one one piston? How could I check this without losing £250.

Part of the problem for me is that I've never driven another VR4 so don't know if mine is down on power, indicating a loss of compression?

Any views would be appreciated.

[jaysback]

i not a mechanic but have worked at a garage and a compression test would tell if there is a problem.
this does not take long and only needs the spark plugs taking out and the engine turning over.
if u have the v6 this is a slight problem because of the inlet manifold.
but £250 is a bit extreme.
p.s. if u need plugs do it at the same time

[haydar]

Originally posted by jaysback
i not a mechanic but have worked at a garage and a compression test would tell if there is a problem.
this does not take long and only needs the spark plugs taking out and the engine turning over.
if u have the v6 this is a slight problem because of the inlet manifold.
but £250 is a bit extreme.
p.s. if u need plugs do it at the same time

That's the real pain. I've just had the bloody things changed a few months ago.

Is there a special tool to do the compression test? Could I do it if I had such a tool?

[jaysback]

yep.
evil2: its called a compression testerevil2:
the plugs are very deep in the head so i am guessing that u need an extension piece that fits on the gauge.

the gauge itself just looks like a big boost gauge and fits in the spark plug hole, when u turn the engine over the needle rises and should peak hold.
if it dont rise, or does'nt rise very far then there is a problem.

if u have 1 cylinder down try the 1 next to it.
this will tell u if the head gasket has gone and burnt through to the next cylinder.

note:- can also burn through to the water jacket as well but u would have white smoke coming from your zorst.

dont flame me guys if i am wrong tho..............
as its only what i have picked up from working in a garage
end of disclaimer

[Brind]

You would know if your head gasket has gone INSERT INTO post VALUES (blown) because the car would chugg! and the power would be much lower than usual.


All engines have fluctuations.
Mine is very smooth but you can feel it, mind you my exhaust causes a bit of vibration because of its resonance.
Check to see if your brake pedal is stiff because if it is spongy that will tell you if your brake servo has an air leak.

Could be nothing.
But unless it is very irratic and you're losing alot of power it is probably nothing to really worry about.