Need help interperting OBD II information

On 20 Nov 2006 18:39:08 -0800, wrote:

>I feel your pain. The CPS is behind the harmonic balancer. You have to
>take that off to get to it.

My idea is to leave the HB where it is, and come at the CPS from an
angle that will allow removal and reinstallation. I have all kinds of
*ideas,* many of which make no sense at all ;-|

I would swap it myself anyhow, even if I had to lie down on top of the
engine, or crawl under the car. No way I have access to $380.

Lg

In article >,
Lawrence Glickman > wrote:

> On 20 Nov 2006 17:00:42 -0800, wrote:
>
> >Hello Everyone,
> >
> > First, thank you for trying to help me. I have a 1997
> >Buick Riviera with a GM 3800 II supercharged engine. Two dealers and my
> >local mechanic can not figure out what the problem is. The problem is
> >as follows:
> >
> >1. The car will attempt to stall out (and sometimes does) at red
> >lights. Sometimes it will restart, others it will just crank. If I let
> >the car sit there it will eventually start.
> >
> >2. If I drive the car to operating temperature and then allow the car
> >to sit there until the temp is around 160 the car will not restart, it
> >will only crank. I do hear the fuel pump prime. If I let it cool down
> >to under 160 it starts. Recently the car has not restarted at 200
> >degrees.
> >
> >3. If I am driving, the car will just turn off. Sometimes it will
> >restart on its own. Sometimes I have to pull over, wait a few seconds
> >and then it will start. Sometimes when I pull over, the RPM gauge is at
> >0 and the engine is very faintly firing.
> >
> >I have replaced the ignition module and the coil packs. I have replaced
> >the plugs and plug wires. The car throws a Crankshaft Position Sensor
> >but the dealers and mechanic checked the crank shaft position sensor
> >and say it is OK.
> >
> >I purchased OBD II software and recorded a few pages. If you could take
> >a look at it I would appreciate it.
> >
> >The first was sitting at idle at operating temp. The second is at 2500
> >RPM. The last shot was the code that was thrown at a stall and the
> >freeze frame.
> >
> >http://www.wildlifereserve.org/riviera_112006.doc
> >
> >OR
> >
> >http://www.wildlifereserve.org/riviera_112006.pdf
> >
> >The doc is 700K the PDF is 1MB. Sorry they are so big. Thanks for
> >checking it out.
> >
> >Any questions, or ideas please post.
> >
> >Thanks,
> >
> >Sam
>
> B1S2 fuel trim reads 99%
>
> that is way out of bounds for a normal engine.

In 1997, GM didn't use the post cat oxygen sensor to calculate
fuel trim. IOWs, it's a bogus reading.

The OP may want to purchase the enhanced software from Auto
Enginuity and use it to graph the two crankshaft position sensor
signals at the time of stall. (if the enhanced does in fact
report the two crank position sensors as a PID)
The OP may also want to verify the P0336 trouble code with a
different scan tool/code reader because there have been instances
of AE reporting trouble codes incorrectly.
The OP should verify that there is no coolant leaking from the
water pump onto the crankshaft position sensor(s).

On Mon, 20 Nov 2006 19:40:07 -0600, Lawrence Glickman
> wrote:

>On 20 Nov 2006 17:00:42 -0800, wrote:
>
>>Hello Everyone,
>>
>> First, thank you for trying to help me. I have a 1997
>>Buick Riviera with a GM 3800 II supercharged engine. Two dealers and my
>>local mechanic can not figure out what the problem is. The problem is
>>as follows:
>>
>>1. The car will attempt to stall out (and sometimes does) at red
>>lights. Sometimes it will restart, others it will just crank. If I let
>>the car sit there it will eventually start.
>>
>>2. If I drive the car to operating temperature and then allow the car
>>to sit there until the temp is around 160 the car will not restart, it
>>will only crank. I do hear the fuel pump prime. If I let it cool down
>>to under 160 it starts. Recently the car has not restarted at 200
>>degrees.
>>
>>3. If I am driving, the car will just turn off. Sometimes it will
>>restart on its own. Sometimes I have to pull over, wait a few seconds
>>and then it will start. Sometimes when I pull over, the RPM gauge is at
>>0 and the engine is very faintly firing.
>>
>>I have replaced the ignition module and the coil packs. I have replaced
>>the plugs and plug wires. The car throws a Crankshaft Position Sensor
>>but the dealers and mechanic checked the crank shaft position sensor
>>and say it is OK.
>>
>>I purchased OBD II software and recorded a few pages. If you could take
>>a look at it I would appreciate it.
>>
>>The first was sitting at idle at operating temp. The second is at 2500
>>RPM. The last shot was the code that was thrown at a stall and the
>>freeze frame.
>>
>>http://www.wildlifereserve.org/riviera_112006.doc
>>
>>OR
>>
>>http://www.wildlifereserve.org/riviera_112006.pdf
>>
>>The doc is 700K the PDF is 1MB. Sorry they are so big. Thanks for
>>checking it out.
>>
>>Any questions, or ideas please post.
>>
>>Thanks,
>>
>>Sam
>
>B1S2 fuel trim reads 99%

Whenever you see that the data is not valid due to scan tool function
or other cause.

Don
www.donsautomotive.com
>
>that is way out of bounds for a normal engine.

wrote:
> Hello Everyone,
>
> First, thank you for trying to help me. I have a 1997
> Buick Riviera with a GM 3800 II supercharged engine. Two dealers and my
> local mechanic can not figure out what the problem is. The problem is
> as follows:
>
> 1. The car will attempt to stall out (and sometimes does) at red
> lights. Sometimes it will restart, others it will just crank. If I let
> the car sit there it will eventually start.
>
> 2. If I drive the car to operating temperature and then allow the car
> to sit there until the temp is around 160 the car will not restart, it
> will only crank. I do hear the fuel pump prime. If I let it cool down
> to under 160 it starts. Recently the car has not restarted at 200
> degrees.
>
> 3. If I am driving, the car will just turn off. Sometimes it will
> restart on its own. Sometimes I have to pull over, wait a few seconds
> and then it will start. Sometimes when I pull over, the RPM gauge is at
> 0 and the engine is very faintly firing.
>
> I have replaced the ignition module and the coil packs. I have replaced
> the plugs and plug wires. The car throws a Crankshaft Position Sensor
> but the dealers and mechanic checked the crank shaft position sensor
> and say it is OK.
>
> I purchased OBD II software and recorded a few pages. If you could take
> a look at it I would appreciate it.
>
> The first was sitting at idle at operating temp. The second is at 2500
> RPM. The last shot was the code that was thrown at a stall and the
> freeze frame.

OK, the first thing I thought before getting halfway through your post
was intermittant crank position sensor (CKP) failure.

You have spent a fair amount of $ already on parts that haven't fixed
the problem. The CKP is the most likely component to cause this on
your engine, followed by the ICM (replaced), followed by compromised
wiring or shielding of the CKP circuit, and finally the PCM. For the
cost of a CKP sensor I would not hesitate with replacing it. I think
they are around $30 to $60.

I can't physically inspect your car to look at the wiring or test the
circuits to verify this diagnosis but I speak from experience. It's
too bad you had several mechanics supposedly test (good) your sensor
and then condemn a $300+ ICM! + 3 coils!

It is difficult and time consuming to test an intermittant stall like
this, but with the code P0335 you know right where to start. I would
hook a 2channel scope up to the ICM connector as follows: channel 1 to
the yellow CKP to ICM 18X reference wire; channel 2 to the blue/black
ICM to PCM CKP 18X reference wire. You should see square waves on both
wires. They should be sharp and defined. Nonsensical stray voltages
would be a sign of poor shielding. The wrong number or inconsistently
shaped waves would be a sign of CKP sensor breakdown on the yellow
wire; ICM failure on the blue/black wire. If both signals are perfect
when the vehicle dies and sets a P0336 concurrently you should suspect
the PCM.

The sensor sits beside/behind the crankshaft pulley on the front of the
engine. Other than loosening and tightening the crank pulley bolt,
it's a fairly easy replacement. It would take a tech about 15 minutes
of mechanical work to do.

NOTE: You are supposed to do a "CKP sensor variation learn" procedure
following replacement. This is a simple scantool operation that
requires a Tech II (GM mega$$ scanner), or a SnapOn with newer
software. If I were you I just would replace the sensor, clear the
codes, then drive it and monitor the MIL. If you never get a P1336
(variation relearn procedure not performed) then the new sensor is
lined up close enough to be a nonfactor.

If you want to explore this relearn dealio, I would suggest you contact
Jay Horak of Auto Enginuity. He designed your scan software and
constantly responds to tech questions via email. Ask him if the GM
software addon (about $150) has the capability to perform the CPK
sensor variation learn function on a 1997 Riviera 3.8SC. He's very
good about product support. I guarantee that you will be happy with
the functions and data you will be able to retrieve with his GM
software. His enhanced software packages can be glitchy but the
reports from the field are that they get markably better and more
powerful with each upgrade. One year of quarterly upgrades comes with
the enhanced software package. An additional year of updates is $50
last time I checked. I figured since you already purchased the $250+
OBDII package it would be a no-brainer to buy the 'good stuff' : )

Toyota MDT in MO

When I wrote:
It is difficult and time consuming to test an intermittant stall like
this, but with the code P0335 you know right where to start.

I meant P0336
D'oh!

Toyota MDT in MO

On Tue, 21 Nov 2006 02:59:32 GMT, aarcuda69062
> wrote:


snips:
>> B1S2 fuel trim reads 99%
>>
>> that is way out of bounds for a normal engine.
>
>In 1997, GM didn't use the post cat oxygen sensor to calculate
>fuel trim. IOWs, it's a bogus reading.

Ok

>The OP may want to purchase the enhanced software from Auto
>Enginuity and use it to graph the two crankshaft position sensor
>signals at the time of stall. (if the enhanced does in fact
>report the two crank position sensors as a PID)
>The OP may also want to verify the P0336 trouble code with a
>different scan tool/code reader because there have been instances
>of AE reporting trouble codes incorrectly.

money spent, and no guarantee that the *new* software is going to have
a bullet proof CPS algorithm.

>The OP should verify that there is no coolant leaking from the
>water pump onto the crankshaft position sensor(s).

This is true. On my car, it would have to be a major leak. Anything
short of that is going to flow away from my CPS. But the geometry of
his engine is no doubt different.

I think on my car, I would buy the part ( after making certain the
water pump isn't leaking onto it ), and install it myself, thereby
saving labor costs. If I could not, for some reason, pull off the
part swap, that's another story. But I would _have_ to give it a try
first. That's just *me.*

Lg

On Mon, 20 Nov 2006 21:06:20 -0600, Don
> wrote:
>>
>>B1S2 fuel trim reads 99%
>
>Whenever you see that the data is not valid due to scan tool function
>or other cause.
>
>Don
>www.donsautomotive.com
>>
>>that is way out of bounds for a normal engine.

Okay, well it caught my eye. I didn't think it looked right, so
that's why I even mentioned it.

Lg

aarcuda69062 wrote:

> The OP should verify that there is no coolant leaking from the
> water pump onto the crankshaft position sensor(s).

Good point! That's a sign that you do this kind of work every day : )

Toyota MDT in MO

P.S. I have no doubt his OBDII AE software is reporting the P0336
correctly given the circumstances. I think the problem is more
prominent with the enhanced software screwing up FR and other GM
specific historical code data. I'm really leaning towards getting AE
based on the price. It's a hell of a hobby scanner if nothing else.

In article
.com>,
"Comboverfish" > wrote:

> aarcuda69062 wrote:
>
> > The OP should verify that there is no coolant leaking from the
> > water pump onto the crankshaft position sensor(s).
>
> Good point! That's a sign that you do this kind of work every day : )

naaah... some days, I do front end rebuilds... ;-)

> Toyota MDT in MO
>
> P.S. I have no doubt his OBDII AE software is reporting the P0336
> correctly given the circumstances. I think the problem is more
> prominent with the enhanced software screwing up FR and other GM
> specific historical code data. I'm really leaning towards getting AE
> based on the price. It's a hell of a hobby scanner if nothing else.

I'm pretty happy with it.

Very strong on Ford, very strong on GM, as strong as I've seen on
Toyota, a little weak on Chrysler but they (Jay) say it's in the
works.

In article >,
Lawrence Glickman > wrote:

> money spent, and no guarantee that the *new* software is going to have
> a bullet proof CPS algorithm.

No, he can call them and ask whether the crank sensor is a
supported PID. If not, then he doesn't spend the money.
Generic OBD2 scan data is a lot like eating a T-bone steak with
chop sticks, it can be done, but it will take a long time and
there will be a lot of teeth gnashing. IOWs, he doesn't know all
of what he's missing not having the enhanced software.

> >The OP should verify that there is no coolant leaking from the
> >water pump onto the crankshaft position sensor(s).
>
> This is true. On my car, it would have to be a major leak. Anything
> short of that is going to flow away from my CPS. But the geometry of
> his engine is no doubt different.

Coolant leak from the water pump wiping out a crank sensor is
fairly common on the Buick 3800.

> I think on my car, I would buy the part ( after making certain the
> water pump isn't leaking onto it ), and install it myself, thereby
> saving labor costs. If I could not, for some reason, pull off the
> part swap, that's another story. But I would _have_ to give it a try
> first. That's just *me.*

The OP needs to be advised, the crank sensor splits two sets of
shutters on the harmonic balancer, the sensor needs to be set so
that the shutters do not rub, hit or in any way make physical
contact with the sensor. One can buy the special tool from Kent-
Moore, or he can cut two strips of plastic bottle and use them as
a feeler gauge.