> wrote in message
oups.com...
> I'd look at the O2 sensor directly, either with a digital meter that
> includes a bar graph display (responds faster than the digits) or an
> oscilloscope.

Unfortunately I don't have access to that kind of equipment... maybe my
analog meter would still give a good idea of how often the voltage is
swinging back and forth though.

>> This also would explain why the problem is more noticeable after a
>> semi-warm
>> restart since the heater might not work at idle speeds. A lot of
>> supposition, yes, but I don't have much else to go on.
> Most heaters are run all the time.

Sorry, that was wasn't worded quite right, what I meant was, if the heater
was not working 100%, it might explain the increased hesitation after a warm
restart because the engine hasn't run enough to warm the sensor back up to
normal temp.

>> Already checked the TPS,
> How did you check it? It takes only one bad spot to cause poor
> response. Turn it very slowly and check for smoothness of resistance
> change. Better yet, inject a weak signal into it and look for noise on
> the scope as you turn it.

Again, I don't have a scope at my disposal, but I have checked the
resistance while opening the throttle, and got a smooth increase or decrease
in resistance (forget which way it goes). This was with my digital meter
though, so maybe I should try with the analog in case it does a better job
of reporting any momentary dropouts.

>> and fuel pressure (not sure if that = delivery rate or how to test rate),
> Pressure and delivery are different. You measure pressure with a
> guage, delivery rate by running the pump for 30 seconds to see how much
> gas it pours into a coffee can.

Ok, I did come across something like that in the service manual, but they
want you to do it by pulling the fuel rail and putting a bucket under each
injector. That's a bit further than I want to go in my driveway, but maybe
your method would be possible. I would expect though if there was a volume
problem I would have issues at WOT, which I don't.

>> and the pressure does hold after shutdown.
> How long? An hour?

Not sure about how long, but at least 30 minutes... I just know from having
had a fuel pressure gauge connected recently and having left it connected
after I had shut the engine off for at least that long. Also I can leave
the car sitting all day and it will start on the first 1/4 crank most of the
time, so if it is losing pressure it can't be too much.

> I hope you have a factory or Mitchell book because for fuel system
> problems they're far better than a Chilton's Hayne's. I'd also check

I do, I've got the factory service manual.

> www.nissanforums.com and www.nicoclub.com. One of those has
> factory-trained mechanics.

Thanks, I've posted on a few forums before, but not those two I don't think.
I'll give them a try.