"Clunk" when engine is cold

[Blake8828]

Hi all, just wondering if what i'm about to explain is normal.
When the engine is dead cold and I start it, I always wait a little while until the revs drop and I assume it goes from closed to open loop.

For the first 20-30 meters the car is somewhat sluggish and unresponsive, then a loud "clunk/thump" noise comes from the front of the
car (I think its the drivers side) and all of a sudden the car drives fine.

Just wondering if this happens to everyone and if anyone knows what makes the noise?

Thanks guys.

[Robbks]

not normal.

Any chance of a video.

can you feel it through the drivetrain or steering. could be a brake caliper issue

[Blake8828]

I'll attempt a video tomorrow morning.

There is no sort of 'dragging brake pad noise' or increased rolling resistance when the car is feeling sluggish... Good suggestion though.
Can't feel it at all, only hear it and then notice the car is no longer sluggish.

It kinda sounds like a heavy plastic lid slamming shut, sharp but hollow.

I was kinda thinking it might be a flap for a secondary air pump but as far as I can tell our cars don't have a SAP, could be wrong though!

[KiDo_Tuning]

No SAP

It sounds like the AVCS cam solenoid may be dirty. Does it pull strongly from below 2000rpm?

[Blake8828]

The car has hardly any power at all below 2000 rpm before it goes "clunk".
To be honest it doesn't seem to have as much power as i'd expect below 2000 rpm when its
at operating temp too.

The car did the same thing on its previous engine too, the replacement engine was just a bare long
motor. So it still uses the AVCS solenoids from the previous engine, have you seen them fail before Matt?

[Blake8828]

Seems Matt is on the right track. VVT is way out of sync with the right hand cam lagging behind the left by quite a lot.

The right cam stays at 0 degrees and does not move till I hear the 'clunk' noise when the car is cold.

I've tried cleaning the AVCS solenoids with no luck. I've swapped them over and the issue seems to move to the left cam but
it didn't look exactly the same. Both solenoids seems to work fine when connected to a battery which makes me reluctant
to think its an issue with a solenoid.

I am however out of ideas so I've ordered a new solenoid to see what that does! I'll post my results when I get it in case
someone has the same issue.

[Blake8828]

So, Turns out that there is an advantage to the intakes cams being in sync, who'd have thought?

Replaced the right VVT solenoid yesterday, now both cams are perfectly in sync and the car pulls
like a train!

Also is a lot smoother between 1000 and 3000rpm, would lunge a lot when driving around car parks.
I'd say it feels like an extra 20kw between 1000 and 3000 rpm. $88 including express post from
Partsouq.com was also great value, dealer wanted around $300!

Anyone having trouble with the car being sluggish with non linear throttle response should defiantly
check out what their intake cams are doing

Bad news is, it still makes that noise! When I get a chance i'll get a recording and post it here.

[KiDo_Tuning]

So, Turns out that there is an advantage to the intakes cams being in sync, who'd have thought?

Replaced the right VVT solenoid yesterday, now both cams are perfectly in sync and the car pulls
like a train!

Also is a lot smoother between 1000 and 3000rpm, would lunge a lot when driving around car parks.
I'd say it feels like an extra 20kw between 1000 and 3000 rpm. $88 including express post from
Partsouq.com was also great value, dealer wanted around $300!

Anyone having trouble with the car being sluggish with non linear throttle response should defiantly
check out what their intake cams are doing

Bad news is, it still makes that noise! When I get a chance i'll get a recording and post it here.

Excellent result!

The solenoid becomes 'magnetised' by the ABS module on the drivers side

Lets catch up for a tune on my next trip down

[Blake8828]

Sounds good! Let me know when you're down next