[V8] hard starting sometimes and fluctuating idle

Buchholz, Steven Steven.Buchholz at kla-tencor.com
Tue Mar 14 19:22:02 EST 2006

... as already discussed, reading codes might give some key clues ... 

I would recommend that you pull the ISV to see if it happens to have any oil in it, and if so, clean it out.  I have most definitely seen cases where the ISV is sticky, and it causes symptoms very similar to the ones you describe ... once the ISV has had some exercise it works fine, but it gets sticky after sitting for a while.  I think the FPR might be a bit more of a stretch.  Remember that all this thing is doing is setting the pressure in the fuel rails dependent on the manifold pressure ... 

Steve B
San José, CA (USA)
> I looked through the knowledge base and tried using the search function but
> couldn't come up with anything definitive about the problem that has started
> occurring with my V8.
> Over the past week whenever I start the car up it takes a little longer to
> start and when it does for the first 3 to 5 seconds the idle fluctuates from
> around 300 to 800 rpm. It then steadies out and I have no further problem with
> the idle. In addition a couple of times the car stalled out on the startup and
> I had to crank it for about 5 to 10 seconds for it to restart.
> My thoughts are that it could be the ISV, but if it's that then I would think
> the idle would jump around whenever I'm at a standstill and it doesn't. The
> other item that might be the culprit is the FPR. But, I would think that that
> would only cause a problem if the car had been sitting for a long time, say
> overnight. Last night though I had a hard time starting it after it had sat
> for only an hour. It took 4 tries to start it and the rpm was very low once it
> did start, but then jumped up after about 5 seconds of running. Which brings
> me to the last item which is the crank sensor. I believe the car needs this
> sensor to start and if its problematical and gets heat soaked it would cause a
> hard start problem.

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