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Today's topics:
* Sentra 97 AFM or fuel pump? (or maybe something else) - 6 messages, 4
authors
http://groups.google.com/group/alt.autos.nissan/t/dd7dae047a0c4c8c?hl=en
* 91 Nissan Sentra 1.6 4speed manual question about timing- - 1 messages, 1
author
http://groups.google.com/group/alt.autos.nissan/t/dead845dbec56614?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
==============================================================================
== 1 of 6 ==
Date: Wed, Feb 2 2011 4:32 pm
From: Me
On 3/02/2011 12:26 p.m., Me wrote:
> 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.
Found spec in FSM (GA16DE):
1.0 - 1.7v at idle (in "N", no load)
1.8 - 2.4v @ 2,500rpm (in "N" no load)
Rechecked, unless it's an intermittent "dry solder" problem with AFM the
AFM is within spec.
== 2 of 6 ==
Date: Thurs, Feb 3 2011 7:07 am
From: cselby@mts.net
>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?
>
I wired a test lite at the fuel pump and laid it on the rear window
shelf. When the car was running the lite would be on - when it
stalled the lite stayed on, meaning I was getting power to the pump. I
would jump out and squeeze the fuel return hose while cranking the
engine from under the hood. No fuel pressure pulse detected. Fuel
pump faulty. Replaced pump - problem solved.
On my kids car the same sort of symtoms. I wired a test lite as
before. Except no power to pump when it stalled. Located the fuel
pump relay and when it went into a stall, I jumped out, felt the relay
and it was way hot. Replaced the relay, problem solved.
Both situations were intermitant without any set times of failure.
And if I let the car cool down for 5-15 minutes it would clear up
until next time, Maybe 5 min or an hour.
I would also chech the Crank and Cam sensors. These should show up as
a "no crank signal detected" or "No crank reference". You might want
to get an OBDII reader and see if your storing any codes (The idiot
lite on the dash doesn't always come on for all trouble codes).
P
--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
== 3 of 6 ==
Date: Thurs, Feb 3 2011 7:11 am
From: willshak
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 @
== 4 of 6 ==
Date: Thurs, Feb 3 2011 7:53 am
From: robbie
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.
== 5 of 6 ==
Date: Thurs, Feb 3 2011 8:06 am
From: willshak
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.
--
Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @
== 6 of 6 ==
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).
==============================================================================
TOPIC: 91 Nissan Sentra 1.6 4speed manual question about timing-
http://groups.google.com/group/alt.autos.nissan/t/dead845dbec56614?hl=en
==============================================================================
== 1 of 1 ==
Date: Thurs, Feb 3 2011 8:03 am
From: robbie
On Jan 27, 7:04 pm, nucleus <rose122...@yahoo.com> wrote:
> if the wires on the 91 MAF sensor are totally sealed, you may find
> it acceptable to insert a (straight) pin into each wire near the
> connector,
> to allow access for voltage measurement. if the wires are NOT totally
> sealed, you may find it acceptable to "back probe" the connector pins
> with (straight) pins for voltage measurement. respondent "Me" is
> correct
> about faulty MAF sensors, the MAF allows the ECM to calculate the
> injector pulse width. if you ever have the need to see if the ECM is
> sending a pulse to each injector, you can insert a "noid" light into
> the
> specific injector circuit (i once used an analog voltmeter to see the
> pulse,
> when diagnosing an engine that would not start).
>
> does your 91 have the TPS (throttle position sensor)? if it does,
> you
> can check he TPS using the (straight) pin method, however, i would be
> surprised if this is your problem.
>
> can you give more details about the "stumbling" problem? does it
> occur when you suddenly open the butterfly when NOT driving?
> or does it occur only when you are accelerating (under load) while
> going through the gears?
>
> this thread assumes you have checked for constant fuel pressure to
> the injectors (and that the fuel pump is NOT an issue).
>
> would be interested in more details about your Consult device.
The car finally died and the coil completely died- after replacement
the car is 100% again. So if someone says "the coil either works or it
doesn't" DONT BELIEVE IT
About the Consult:
The Consult device for my car I got from an ebay buyer- it has the
ConZult free version of software shipped with it. It is a serial
device so I had to get a USB to serial adapter to use a laptop in the
car. I am currently trying to get some other more extensive software
to work with it, but so far haven't found a complete package that will
recognize this particular consult device. Link to ebay item I
purchased:
Without full-featured software it is not that useful, but I was
looking into buying a software package if I was sure it was
compatible.
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