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* Sentra 97 AFM or fuel pump? (or maybe something else) - 5 messages, 2
authors
http://groups.google.com/group/alt.autos.nissan/t/dd7dae047a0c4c8c?hl=en
* TPMS on 2009 Frontier - 3 messages, 3 authors
http://groups.google.com/group/alt.autos.nissan/t/25d1f7cc8d62d1e2?hl=en
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TOPIC: Sentra 97 AFM or fuel pump? (or maybe something else)
http://groups.google.com/group/alt.autos.nissan/t/dd7dae047a0c4c8c?hl=en
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== 1 of 5 ==
Date: Thurs, Feb 3 2011 1:28 pm
From: Me
On 4/02/2011 5:06 a.m., willshak wrote:
> robbie wrote the following:
>> On Feb 3, 10:11 am, willshak <wills...@00hvc.rr.com> wrote:
>>> Me wrote the following:
>>>
>>>
>>>
>>>> Symptoms - seems like fuel starvation under load. Idles smoothly, and
>>>> runs fine under low/normal load, but cuts out up hills etc. No CEL.
>>>> No black smoke - it just dies.
>>>> Have replaced filter as first step.
>>>> Used parts supplier has a bin full of used pumps for about US$60 each,
>>>> and doesn't sell many or hear of many failures, so he suggests that
>>>> it's the AFM rather than the pump or relay etc. He could be right,
>>>> but it doesn't seem like the AFM to me, as it's running very
>>>> well/smoothly under low load, not hesitating etc on acceleration etc
>>>> and only starts cutting out when it's been under load for 10 seconds
>>>> or so.
>>>> I also checked MAF signal voltage, and that's looking okay (I think),
>>>> at warm idle, it's steady at around 1.4v, signal voltage increases and
>>>> falls smoothly, it's steady at about 2.5v @ 3,000 rpm. But, I also
>>>> hear that the AFM unit failures are related to internal dry solder
>>>> joints, so it might test okay but fail on road test.
>>>> On the other hand, the pump also seems to be operating as normal, can
>>>> hear it when the ignition turned on, and it's cutting out after about
>>>> 5 seconds. (not sure if that initial 5 second run is just based on a
>>>> timer circuit though - the fact that it cuts out "as normal" might be
>>>> meaningless wrt fuel pressure)
>>>> I don't have a fuel pressure gauge, but the fuel hoses feel much
>>>> softer at idle than I'd have expected if they were at about 34psi (FSM
>>>> spec).
>>>> Any suggestions appreciated for "next step"?
>>>> Should I go out and buy a fuel pressure gauge, or perhaps set up some
>>>> long leads for multimeter probe to see if I get some strange readings
>>>> from the AFM when it's on a test-drive?
>>> Don't dismiss a clogged cat converter.
>>>
>>> --
>>>
>>> Bill
>>> In Hamptonburgh, NY
>>> In the original Orange County. Est. 1683
>>> To email, remove the double zeroes after @
>>
>> My older Sentra had a bad problem that felt like fuel starvation. I
>> diagnosed FOREVER until it quit running entirely. Then i found out the
>> coil was bad. It had evidently been "going bad" for quite a while, but
>> I had checked it and it had a spark and was within specs when cold but
>> evidently did not work properly under load.Never a CEL in all that
>> time... If you have a junk yard nearby it would be worth your time to
>> swap it out. Instantly cured hesitation, a crappy idle, lower power-
>> the 1.6 runs like a sewing machine again.
>
> I wasn't suggesting that the cat was the problem, just suggesting
> another thing to check.
> I had a similar problem with my 86 Pulsar. It didn't happen all at once
> but just got worse over time.
> It turned out to be a clogged cat. Replaced it and all was well.
>
Thanks for that.
Robbie, I saw your other thread, and assumed, as I was with mine, that
AFM was the most likely culprit as it's a common fault, but it checks
out okay, the signal voltages are even, within spec, - and the typical
MAF failure symptoms of uneven idle / hesitation aren't there.
Bill, I've got a spare cat/exhaust manifold assembly here, but I doubt
that's it, as when it's not missing/cutting out, it's running very well
under load/high revs. (OTOH if it's coil/ignition related and I don't
get this sorted properly, I guess I could kill/overheat the cat)
Plugs are fairly new, leads etc seem good, and anyway when it cuts out
under load it's a very hard abrupt cutout on all 4 cylinders, not a
typical symptom of one or two bad leads or plugs.
I now think the fuel pump etc is okay, I removed back seat and cover,
and can feel the fuel hose pressurise and pulse when engine is revved. I
don't have a gauge to put inline to check pressure, but it's probably
okay. If I pull the fuel pump fuse under load, cutout from fuel
starvation isn't as sudden/abrupt as what's happening, it slows,
sputters and dies, rather than just completely cutting out "hard".
It is also only happening when engine reaches normal operating temp -
when it's cold/warming up, it's running perfectly. Danmed nuisance, as
it takes a couple of "laps" up and down around local hills for a test run.
This car (japanese domestic market model) doesn't have an OBDII
connector, it's not throwing a CEL and I can't check for (pending) codes.
It's making more sense to me now that it could be the coil,
breakthrough/arcing only when engine is warm/under load, as the ECU
changes ignition signal based on load and engine temp. The distributor
was leaking oil from internal seal, fixed some 20,000km ago and clean as
a whistle now, but it has had engine oil sitting in it, so that might
have eventually "got to" the coil (coil is inside distributor).
== 2 of 5 ==
Date: Fri, Feb 4 2011 7:38 am
From: cselby@mts.net
>This car (japanese domestic market model) doesn't have an OBDII
>connector, it's not throwing a CEL and I can't check for (pending) codes.
No OBDII connector?? Seems to me that all cars {Asian at least} were
OBDII compliant starting in 1996. Prior to that they were propriatary
OBD using various methods for pulling codes.
P
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== 3 of 5 ==
Date: Fri, Feb 4 2011 10:43 am
From: Me
On 5/02/2011 4:38 a.m., cselby@mts.net wrote:
>> This car (japanese domestic market model) doesn't have an OBDII
>> connector, it's not throwing a CEL and I can't check for (pending) codes
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