'98 Quest emissions problems---KS, EGR, TPS

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JJR2 - 19 Nov 2008 07:16 GMT

My '98 Nissan Quest was up for inspection, and a borrowed scan tool
showed 0325 (Knock Sensor) and 0400 (EGR Flow Error). After the usual
drill where the local shop tried to convince me to pay $1000 to have
the knock sensor replaced, I did some more digging and figured out
that I needed to check the BPT vacuum line. It was, in fact, so
degraded that part of it disintegrated in my fingers on contact. I
replaced that and cleared the codes from the computer. I can't find
out if that fixed the EGR problem, because....

--Issue 1: The Emissions Monitors will not reset. The state
inspection shop can't finish the emissions inspection until they do,
and my 15 days is up. We have driven it under all conceivable
conditions for over 200 miles, and three monitors are still INC. This
includes several dozen cycles of up to 45 mph, turn it off, repeat.
The Nissan dealer service dept. said they typically had to drive them
3-4 days to reset them. It's been over two weeks. Anybody got any
ideas?

---Issue 2: I looked through the "Review Data" feature on the scan
tool. It appears to be reading the van's condition in real time
pretty well. Pressing the accelerator ( in Park, in the driveway),
causes the RPM reading to increase, but the "ABS TPS" reading remains
at 0% when I move the pedal. Should I expect a change in the TPS
reading under these conditions?

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e.meyer - 19 Nov 2008 16:09 GMT

> My '98 Nissan Quest was up for inspection, and a borrowed scan tool
> showed 0325 (Knock Sensor) and 0400 (EGR Flow Error). After the usual
[quoted text clipped - 13 lines]
> 3-4 days to reset them. It's been over two weeks. Anybody got any
> ideas?

There is a specific sequence that has to be followed in a specific
order to get through all the self tests and set the ready indicators.
Your best bet is to try to find a downloadable copy of the factory
service manual online. Its in there. The Nissan site will sell you a
24 hour license to download anthing you want, but I'm not sure if it
goes that far back. Check first before giving them a charge number.

Don't worry about the knock sensor, it doesn't show up on the state
inspection and it won't turn on the engine light by itself. If the
EGR is not fixed, the engine light will come back on as soon as it
sees the error condition on 2 consecutive drives.

Since the Quest also was sold by Ford as the Mercury Villager, you
might give the local Ford garage a call for a second opinion.

> ---Issue 2: I looked through the "Review Data" feature on the scan
> tool. It appears to be reading the van's condition in real time
> pretty well. Pressing the accelerator ( in Park, in the driveway),
> causes the RPM reading to increase, but the "ABS TPS" reading remains
> at 0% when I move the pedal. Should I expect a change in the TPS
> reading under these conditions?

Don't know. ABS units usually don't initialize until the car is
moving at about 15 MPH.

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JJR2 - 19 Nov 2008 18:50 GMT

> Should I expect a change in the TPS
> reading under these conditions?
>
> Don't know. ABS units usually don't initialize until the car is
> moving at about 15 MPH.

I was hoping the Nissan service dept. was giving me the right drive
cycle information, but it doesn't seem to work, so I guess I'll have
to find the manuals.

Is this reading referring to the throttle position sensor?

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