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acer54
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Joined: 25 Feb 2019
Posts: 15



PostPosted: Tue Apr 30, 2019 3:14 pm    Post subject: Lumpy when cold Reply with quote

My 3.2 V6 is always a bit lumpy when cold but once it's warmed up it goes like a rocket, any ideas as to what could be causing it?
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6490
Location: Brighton


PostPosted: Tue Apr 30, 2019 7:57 pm    Post subject: Reply with quote

i'm afraid that's an absolute needle in a haystack ..

Fouled plug , old plugs poor injector spray pattern ... a coil faulty , secondary air injection fault .. valve timing .. i could go on to be honest ..

I would sit there looking at the engine values on a tester and probably over several mornings to try and figure out what might be causing it .

not something i can give an answer to Sad
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acer54
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PostPosted: Wed May 01, 2019 12:19 pm    Post subject: Reply with quote

deMort wrote:
i'm afraid that's an absolute needle in a haystack ..

Fouled plug , old plugs poor injector spray pattern ... a coil faulty , secondary air injection fault .. valve timing .. i could go on to be honest ..

I would sit there looking at the engine values on a tester and probably over several mornings to try and figure out what might be causing it .

not something i can give an answer to Sad


It's not registering any codes either which makes it more difficult to diagnose as well.
All plugs were changed last October and coil packs on cylinders 2,3 and 6 were changed (maybe the unchanged coil packs should be changed)?
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MarkGolf
Hockenheim


Joined: 13 Nov 2012
Posts: 670
Location: S.London


PostPosted: Wed May 01, 2019 12:29 pm    Post subject: Reply with quote

Going back to my VR6 days, lumpy when cold was always an air leak after the MAF or secondary air pump.
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acer54
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PostPosted: Wed May 01, 2019 2:24 pm    Post subject: Reply with quote

MarkGolf wrote:
Going back to my VR6 days, lumpy when cold was always an air leak after the MAF or secondary air pump.


I'll have that checked, also it's been pointed out if the idle speed is the same hot or cold and I can confirm that it is, opinion is that it should be elevated during a cold start until engine is up to temperature.
Once engine is up to normal temperature it runs normally.
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MarkGolf
Hockenheim


Joined: 13 Nov 2012
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Location: S.London


PostPosted: Wed May 01, 2019 3:58 pm    Post subject: Reply with quote

Yeah, VR6's do that, funnily enough, I spent yesterday adjusting the cold idle on my VR6. In the current temp, it idles at 1050 on the cold map and then drops to just below 800.

I used to have an issue with being lumpy when cold and resolved that over Christmas by replacing the intake manifold gasket.

1 big thing I forgot which effects the VR6, R32, is the PCV, these always break and introduce an air leak.

Provided the plugs/coils aren't old, then the above would be where I'd be looking.
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