[v12-engine] Lumpy in Park not Drive

I too have just installed the new single coil. Since then I have
experienced the following:

I note that the cold idle in the AM is very brief. Perhaps only
10 seconds or so, at which time the RPM now drops to about 600 in P
and lumps. After warm up and driving and stopping 1 block away. The
idle has returned to it’s normal 750 in D and smooth.

I’m baffled by this, and it is probably just coincidental to the
coil replacement, but I thought I’d fish for some ideas here :slight_smile:

Cheers–
Larry Karpman '88 V12 SIII, '94 MX-5
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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Larry,

I’m wondering if that is the difference in open and closed loop and the
time it takes for your O2 sensors to heat up. Mine is smooth from idle,
goes to about 900 on cold start up and then drops to 750 as it warms up.
Or, are you sure that your AAV is working correctly? I’m suspecting that
your brief fast idle is just the fuel from the startup enrichment, and
the AAV is stuck. It’s easy to remove and put in a pot of boiling water
to see if the piston moves. If it is stuck, H&H Prestige makes a rebuild
kit that works well for about $125, vs $600 for a new one.

Try measuring the O2 sensor output at the port in the trunk, as per the
directions in Kirby’s book and see what values you get.

Craig
92 VDP

Larry Karpman wrote:

I too have just installed the new single coil. Since then I have
experienced the following:

I note that the cold idle in the AM is very brief. Perhaps only
10 seconds or so, at which time the RPM now drops to about 600 in P
and lumps. After warm up and driving and stopping 1 block away. The
idle has returned to it’s normal 750 in D and smooth.

I’m baffled by this, and it is probably just coincidental to the
coil replacement, but I thought I’d fish for some ideas here :slight_smile:

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

In reply to a message from Craig Talbot sent Fri 16 Jul 2004:

Thanks Craig. I’m not really concerned about the cold idle speed,
or the AAV right now. Could be, like many, that the AAV is now
toast.

My concern is the fact then when warm (or cold) the car suddenly
has a lumpy 650 RPM idle in P and a smooth 750 RPM idle in D.
Before it was 750 in P or D and very smooth.

I was wondering what must have recently gone wrong to cause this
sudden onset. Thanks for the input.

Cheers–
The original message included these comments:

I’m wondering if that is the difference in open and closed loop and the
time it takes for your O2 sensors to heat up. Mine is smooth from idle,
goes to about 900 on cold start up and then drops to 750 as it warms up.
Or, are you sure that your AAV is working correctly? I’m suspecting that
Try measuring the O2 sensor output at the port in the trunk, as per the
directions in Kirby’s book and see what values you get.
Craig
92 VDP


Larry Karpman '88 V12 SIII, '94 MX-5
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !