Annoying problem.

[sjc]

I have had a intermittent hesitation above 5000rpm on my M400 on and off for a while now.On the advice of Joust and others I got the dealer to adjust the plug gaps, and it cured the problem,(Ta!)Around the same time my chocolate exhaust bracket broke and was welded, but I ended up with an annoying ticking noise(a bit like someone rustling tin foil) from the passenger footwell and behind the driver.I thought this might be manifolds, but the it was suggested by the dealer that it could be the wastegates rattling slightly, they were turned half a notch and it did quieten them down, but now the bloody hesitation is back.Its becoming a pain in the arse now,as there are other bits I want doing (Roush map etc)but can't until its sorted. Any suggestions welcome!

[georgeM400]

Hi Andy,

Lovely Holden BTW. I got a ticking noise too when my chocolate bracket snapped. Does the number of ticks increase depending on the revs?

[NobleGuy]

Yeah, my hesitation was caused by one of the HT leads becoming corroded - replaced this and it's been fine since. Was small to start with then it became a small backfire.

The exhaust on mine rattles slightly when cold on a section just under the engine (drivers side) where it sits close to the chassis.

Edited by NobleGuy on Thursday 20th December 08:47

[RobP]

Andy - plug condition is vital for sweet running. When were they last changed? Heat kills them. I change every 2-3K miles in the summer months when doing a lot of trackdays.

[pbsaxman]

Yeh my hesitation was caused by corroded coils also. The back 3 seem to be worst. Sorted under warranty and runs sweet as anything now!!

[gadgeroonie]

sometimes in cold weather the car may over boost slightly

the ecu may be holding back due to overboost, is the boost a bit on the high side ?

[sjc]

Plugs were changed in August at the service ,which is when the hesitancy started due to the gaps being set wrong.When that was resolved the exhaust bracket broke and since then I've had the ticking noise.The ticking noise quitened a bit when the wastegates were turned a notch (coincidence?), but the hesitancy returned. Not sure if any of the above are related !

[F.C.]

M400, valve surge due to overboost???
F.C.