RX-8 PCM

Last week, I took my 2004 RX-8 to the dealership to replace the sun
visor. When the service advisor entered my VIN, he found that Mazda's
MSP16 service program applied to my car so they flashed my PCM.

Afterwards, my car stalled when I stopped for traffic lights. I
immediately took it back and they verified that the parameters were
correct. They said that it needed to "learn the way I drive." This
sounded bogus to me because what kind of program would allow the idle
speed to drop below 500 rpm. Nevertheless, I decided to drive the car
for a few days and see what happened. The car has not stalled once
since yesterday.

What's going on here?

Bob Simon <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> Last week, I took my 2004 RX-8 to the dealership to replace the sun
> visor. When the service advisor entered my VIN, he found that Mazda's
> MSP16 service program applied to my car so they flashed my PCM.
>
> Afterwards, my car stalled when I stopped for traffic lights. I
> immediately took it back and they verified that the parameters were
> correct. They said that it needed to "learn the way I drive." This
> sounded bogus to me because what kind of program would allow the idle
> speed to drop below 500 rpm. Nevertheless, I decided to drive the car
> for a few days and see what happened. The car has not stalled once
> since yesterday.
>
> What's going on here?

The PCM indeed had to learn the car's particulars, including your
driving habits. This is not unusual at all.

On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:

>Bob Simon <(E-Mail Removed)> wrote in
>news:(E-Mail Removed) :
>
>> Last week, I took my 2004 RX-8 to the dealership to replace the sun
>> visor. When the service advisor entered my VIN, he found that Mazda's
>> MSP16 service program applied to my car so they flashed my PCM.
>>
>> Afterwards, my car stalled when I stopped for traffic lights. I
>> immediately took it back and they verified that the parameters were
>> correct. They said that it needed to "learn the way I drive." This
>> sounded bogus to me because what kind of program would allow the idle
>> speed to drop below 500 rpm. Nevertheless, I decided to drive the car
>> for a few days and see what happened. The car has not stalled once
>> since yesterday.
>>
>> What's going on here?
>
>The PCM indeed had to learn the car's particulars, including your
>driving habits. This is not unusual at all.

Thanks for the reply, Joe.

I don't know much about ECUs but before they became popular there used
to be a screw that was used to set the idle speed. Isn't this one of
the parameters?

Right after flashing, does frequent stalling at idle suggest some
other possible issue such as dirty plugs or cracked wires? I have not
checked these.

The car seems to be running well now but I should mention that I use
regular gas so the accelleration (while fine for me) is not as good as
when I used premium.

Bob Simon <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:
>
>>Bob Simon <(E-Mail Removed)> wrote in
>>news:(E-Mail Removed) m:
>>
>>> Last week, I took my 2004 RX-8 to the dealership to replace the sun
>>> visor. When the service advisor entered my VIN, he found that
Mazda's
>>> MSP16 service program applied to my car so they flashed my PCM.
>>>
>>> Afterwards, my car stalled when I stopped for traffic lights. I
>>> immediately took it back and they verified that the parameters were
>>> correct. They said that it needed to "learn the way I drive." This
>>> sounded bogus to me because what kind of program would allow the
idle
>>> speed to drop below 500 rpm. Nevertheless, I decided to drive the
car
>>> for a few days and see what happened. The car has not stalled once
>>> since yesterday.
>>>
>>> What's going on here?
>>
>>The PCM indeed had to learn the car's particulars, including your
>>driving habits. This is not unusual at all.
>
> Thanks for the reply, Joe.
>
> I don't know much about ECUs but before they became popular there used
> to be a screw that was used to set the idle speed. Isn't this one of
> the parameters?

Idle speed is set by the ECU. The stop screw is obsolete.

> Right after flashing, does frequent stalling at idle suggest some
> other possible issue such as dirty plugs or cracked wires? I have not
> checked these.

No, the computer has to "get used to" the particulars of the vehicle.
Believe it or not, it adapts over time to the vehicle's "personality"
(for lack of a better term).

> The car seems to be running well now but I should mention that I use
> regular gas so the accelleration (while fine for me) is not as good as
> when I used premium.

Many vehicles designed to run well on premium can be run at a reduced
performance level on regular. I believe the RX8 is one of those.

In article <Xns9B1484179E2D1nospamforme@216.77.188.18>,
Joe <(E-Mail Removed)> wrote:

> Many vehicles designed to run well on premium can be run at a reduced
> performance level on regular.

There's more power in "regular" gas though... Premium is needed if using
regular gas causes pre-ignition due to an engine having high
compression. Premium is LESS volatile than regular. But you knew that...
;-)

The big mistake many make though, is putting premium into an engine that
was only ever designed for regular gas, as all you are doing is REDUCING
your performance, not improving it!

If that RX-8 engine was meant for premium, he should be careful as there
is possibly very hot conditions in the combustion chamber with some
pre-ignition that he isn't hearing... A quick check of the plugs should
determine whether this is happening. How much is a rebuilt motor going
to cost you? There's always mid-grade... probably a better choice to go
with than just regular grade.

On Tue, 09 Sep 2008 16:54:21 GMT, Joe <(E-Mail Removed)> wrote:

>Bob Simon <(E-Mail Removed)> wrote in
>news:(E-Mail Removed) :
>
>> On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:
>>
>>>Bob Simon <(E-Mail Removed)> wrote in
>>>news:(E-Mail Removed) :
>>>
>>>> Last week, I took my 2004 RX-8 to the dealership to replace the sun
>>>> visor. When the service advisor entered my VIN, he found that
>Mazda's
>>>> MSP16 service program applied to my car so they flashed my PCM.
>>>>
>>>> Afterwards, my car stalled when I stopped for traffic lights. I
>>>> immediately took it back and they verified that the parameters were
>>>> correct. They said that it needed to "learn the way I drive." This
>>>> sounded bogus to me because what kind of program would allow the
>idle
>>>> speed to drop below 500 rpm. Nevertheless, I decided to drive the
>car
>>>> for a few days and see what happened. The car has not stalled once
>>>> since yesterday.
>>>>
>>>> What's going on here?
>>>
>>>The PCM indeed had to learn the car's particulars, including your
>>>driving habits. This is not unusual at all.
>>
>> Thanks for the reply, Joe.
>>
>> I don't know much about ECUs but before they became popular there used
>> to be a screw that was used to set the idle speed. Isn't this one of
>> the parameters?
>
>Idle speed is set by the ECU. The stop screw is obsolete.
>

OK. I presume the idle speed is set to 750 or 800 because that's
where it idles now (which is just fine).

I'd still like to understand why the idle dropped to less than 500 rpm
for the first few days after the flash. It seems like the ECU program
should prevent that even BEFORE the computer gets used to my car's
"personality". No?


>> Right after flashing, does frequent stalling at idle suggest some
>> other possible issue such as dirty plugs or cracked wires? I have not
>> checked these.
>
>No, the computer has to "get used to" the particulars of the vehicle.
>Believe it or not, it adapts over time to the vehicle's "personality"
>(for lack of a better term).

<snip>

Anonymous <(E-Mail Removed)> wrote in news:anonymous-
B11AA6.08012710092008@[74.223.185.199.nw.nuvox.net]:

> In article <Xns9B1484179E2D1nospamforme@216.77.188.18>,
> Joe <(E-Mail Removed)> wrote:
>
>> Many vehicles designed to run well on premium can be run at a reduced
>> performance level on regular.
>
> There's more power in "regular" gas though... Premium is needed if
using
> regular gas causes pre-ignition due to an engine having high
> compression. Premium is LESS volatile than regular. But you knew
that...
> ;-)
>
> The big mistake many make though, is putting premium into an engine
that
> was only ever designed for regular gas, as all you are doing is
REDUCING
> your performance, not improving it!
>
> If that RX-8 engine was meant for premium, he should be careful as
there
> is possibly very hot conditions in the combustion chamber with some
> pre-ignition that he isn't hearing... A quick check of the plugs
should
> determine whether this is happening. How much is a rebuilt motor going
> to cost you? There's always mid-grade... probably a better choice to
go
> with than just regular grade.

The best choice is to just go with what the owner's manual recommends.

2 cents:
If you buy a car that's designed to run on premium but can't/won't pay
the extra dime or so per gallon, you shouldn't have bought the car in
the first place.

Bob Simon <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> On Tue, 09 Sep 2008 16:54:21 GMT, Joe <(E-Mail Removed)> wrote:
>
>>Bob Simon <(E-Mail Removed)> wrote in
>>news:(E-Mail Removed) m:
>>
>>> On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:
>>>
>>>>Bob Simon <(E-Mail Removed)> wrote in
>>>>news:(E-Mail Removed) m:
>>>>
>>>>> Last week, I took my 2004 RX-8 to the dealership to replace the
sun
>>>>> visor. When the service advisor entered my VIN, he found that
>>Mazda's
>>>>> MSP16 service program applied to my car so they flashed my PCM.
>>>>>
>>>>> Afterwards, my car stalled when I stopped for traffic lights. I
>>>>> immediately took it back and they verified that the parameters
were
>>>>> correct. They said that it needed to "learn the way I drive."
This
>>>>> sounded bogus to me because what kind of program would allow the
>>idle
>>>>> speed to drop below 500 rpm. Nevertheless, I decided to drive the
>>car
>>>>> for a few days and see what happened. The car has not stalled
once
>>>>> since yesterday.
>>>>>
>>>>> What's going on here?
>>>>
>>>>The PCM indeed had to learn the car's particulars, including your
>>>>driving habits. This is not unusual at all.
>>>
>>> Thanks for the reply, Joe.
>>>
>>> I don't know much about ECUs but before they became popular there
used
>>> to be a screw that was used to set the idle speed. Isn't this one
of
>>> the parameters?
>>
>>Idle speed is set by the ECU. The stop screw is obsolete.
>>
>
> OK. I presume the idle speed is set to 750 or 800 because that's
> where it idles now (which is just fine).
>
> I'd still like to understand why the idle dropped to less than 500 rpm
> for the first few days after the flash. It seems like the ECU program
> should prevent that even BEFORE the computer gets used to my car's
> "personality". No?
<snip>

The ECU is doing a lot of stuff all at once. Until it's learned all the
particualrs, it's going to be changing all kinds of parameters, which
affects things like idle speed.

I'm sure they could've engineered the ECU to behave better while it's
learning, but the improved programming might've cost more than the bean
counters would've wanted. Everything's a trade-off.

Generally, the thing to remember about idle speed, idle "dip" and ECU vs.
mechanical adjustments--
Something (usually the mechanical adjustments) establishes the minimum idle
speed when the ECU is running in "open loop" mode.
When the ECU "hunts" for proper settings, it can really cause some odd
behavior. Minimizing this may be as simple as increasing the open loop idle
speed mechanical adjustments. The basic idea is to make the
conditions/combinations/tuning that the ECU is trying to find and set to
more easily reached. Part of the problem has to do with tolerance/accuracy
of the various sensors. The ECU is stupid, and only understands what the
sensors are telling it. The tolerance on the sensors is perhaps wider than
it might be. This means that the ECU must learn how they respond in
relationship to each other, and decide what the "proper" output is.

(Not to mention that the OBD2 standards were setup to subsidize dealer shops
with Mfr specific testers.)


"Joe" <(E-Mail Removed)> wrote in message
news:Xns9B157E78963EEnospamforme@216.77.188.18...
> Bob Simon <(E-Mail Removed)> wrote in
> news:(E-Mail Removed):
>
>> On Tue, 09 Sep 2008 16:54:21 GMT, Joe <(E-Mail Removed)> wrote:
>>
>>>Bob Simon <(E-Mail Removed)> wrote in
>>>news:(E-Mail Removed) :
>>>
>>>> On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:
>>>>
>>>>>Bob Simon <(E-Mail Removed)> wrote in
>>>>>news:(E-Mail Removed) om:
>>>>>
>>>>>> Last week, I took my 2004 RX-8 to the dealership to replace the
> sun
>>>>>> visor. When the service advisor entered my VIN, he found that
>>>Mazda's
>>>>>> MSP16 service program applied to my car so they flashed my PCM.
>>>>>>
>>>>>> Afterwards, my car stalled when I stopped for traffic lights. I
>>>>>> immediately took it back and they verified that the parameters
> were
>>>>>> correct. They said that it needed to "learn the way I drive."
> This
>>>>>> sounded bogus to me because what kind of program would allow the
>>>idle
>>>>>> speed to drop below 500 rpm. Nevertheless, I decided to drive the
>>>car
>>>>>> for a few days and see what happened. The car has not stalled
> once
>>>>>> since yesterday.
>>>>>>
>>>>>> What's going on here?
>>>>>
>>>>>The PCM indeed had to learn the car's particulars, including your
>>>>>driving habits. This is not unusual at all.
>>>>
>>>> Thanks for the reply, Joe.
>>>>
>>>> I don't know much about ECUs but before they became popular there
> used
>>>> to be a screw that was used to set the idle speed. Isn't this one
> of
>>>> the parameters?
>>>
>>>Idle speed is set by the ECU. The stop screw is obsolete.
>>>
>>
>> OK. I presume the idle speed is set to 750 or 800 because that's
>> where it idles now (which is just fine).
>>
>> I'd still like to understand why the idle dropped to less than 500 rpm
>> for the first few days after the flash. It seems like the ECU program
>> should prevent that even BEFORE the computer gets used to my car's
>> "personality". No?
> <snip>
>
> The ECU is doing a lot of stuff all at once. Until it's learned all the
> particualrs, it's going to be changing all kinds of parameters, which
> affects things like idle speed.
>
> I'm sure they could've engineered the ECU to behave better while it's
> learning, but the improved programming might've cost more than the bean
> counters would've wanted. Everything's a trade-off.

Chuck,
Are you saying that the RX-8 has a mechanical idle screw? If so, I
just need to take my car back to the dealer and ask them to adjust it
to a min of 500 and my problem will be permanently fixed.

(I forgot to mention, a couple of days ago, my car started dying again
when I put it in N at traffic lights.)
Bob

On Sat, 13 Sep 2008 16:24:03 -0400, "Chuck" <(E-Mail Removed)>
wrote:

>Generally, the thing to remember about idle speed, idle "dip" and ECU vs.
>mechanical adjustments--
>Something (usually the mechanical adjustments) establishes the minimum idle
>speed when the ECU is running in "open loop" mode.
>When the ECU "hunts" for proper settings, it can really cause some odd
>behavior. Minimizing this may be as simple as increasing the open loop idle
>speed mechanical adjustments. The basic idea is to make the
>conditions/combinations/tuning that the ECU is trying to find and set to
>more easily reached. Part of the problem has to do with tolerance/accuracy
>of the various sensors. The ECU is stupid, and only understands what the
>sensors are telling it. The tolerance on the sensors is perhaps wider than
>it might be. This means that the ECU must learn how they respond in
>relationship to each other, and decide what the "proper" output is.
>
>(Not to mention that the OBD2 standards were setup to subsidize dealer shops
>with Mfr specific testers.)
>
>
>"Joe" <(E-Mail Removed)> wrote in message
>news:Xns9B157E78963EEnospamforme@216.77.188.18. ..
>> Bob Simon <(E-Mail Removed)> wrote in
>> news:(E-Mail Removed):
>>
>>> On Tue, 09 Sep 2008 16:54:21 GMT, Joe <(E-Mail Removed)> wrote:
>>>
>>>>Bob Simon <(E-Mail Removed)> wrote in
>>>>news:(E-Mail Removed) m:
>>>>
>>>>> On Tue, 09 Sep 2008 01:41:20 GMT, Joe <(E-Mail Removed)> wrote:
>>>>>
>>>>>>Bob Simon <(E-Mail Removed)> wrote in
>>>>>>news:saoac4d68trid1jua0ueslb0e9gpi523qj@4ax. com:
>>>>>>
>>>>>>> Last week, I took my 2004 RX-8 to the dealership to replace the
>> sun
>>>>>>> visor. When the service advisor entered my VIN, he found that
>>>>Mazda's
>>>>>>> MSP16 service program applied to my car so they flashed my PCM.
>>>>>>>
>>>>>>> Afterwards, my car stalled when I stopped for traffic lights. I
>>>>>>> immediately took it back and they verified that the parameters
>> were
>>>>>>> correct. They said that it needed to "learn the way I drive."
>> This
>>>>>>> sounded bogus to me because what kind of program would allow the
>>>>idle
>>>>>>> speed to drop below 500 rpm. Nevertheless, I decided to drive the
>>>>car
>>>>>>> for a few days and see what happened. The car has not stalled
>> once
>>>>>>> since yesterday.
>>>>>>>
>>>>>>> What's going on here?
>>>>>>
>>>>>>The PCM indeed had to learn the car's particulars, including your
>>>>>>driving habits. This is not unusual at all.
>>>>>
>>>>> Thanks for the reply, Joe.
>>>>>
>>>>> I don't know much about ECUs but before they became popular there
>> used
>>>>> to be a screw that was used to set the idle speed. Isn't this one
>> of
>>>>> the parameters?
>>>>
>>>>Idle speed is set by the ECU. The stop screw is obsolete.
>>>>
>>>
>>> OK. I presume the idle speed is set to 750 or 800 because that's
>>> where it idles now (which is just fine).
>>>
>>> I'd still like to understand why the idle dropped to less than 500 rpm
>>> for the first few days after the flash. It seems like the ECU program
>>> should prevent that even BEFORE the computer gets used to my car's
>>> "personality". No?
>> <snip>
>>
>> The ECU is doing a lot of stuff all at once. Until it's learned all the
>> particualrs, it's going to be changing all kinds of parameters, which
>> affects things like idle speed.
>>
>> I'm sure they could've engineered the ECU to behave better while it's
>> learning, but the improved programming might've cost more than the bean
>> counters would've wanted. Everything's a trade-off.