Miatapower List Archive

This read-only message was archived from a public mail list.
Mail From: "Mark A. Painter" <(email redacted)>


I have a strange problem with my turbo car. Basically, the colder
it is when the engine is started, the richer it runs...forever.
The strange part is that it doesn't change even after the engine is fully
warmed up. I have a 30-minute drive to the office, and the abnormal
enrichment will persist the entire way, even though normal operating
temps are reached within 5 - 10 minutes. However, if I shut the car
off anytime after it has reached operating temperature, wait a few
seconds, and then restart it, everything is normal!

The car is a '90 with a '94 1.8L handled by a 1.6L FM ECU Mk2, with a
1.8L FM II turbo setup (560cc injectors). The ECU software is fairly
recent (MAZ16XJ 05AUG99), but not one of the fabled "Ray" chips
(hey, Bill! When are you going to send me one of those?).

The problem has been occurring for the past month or so, when overnight lows
have been approaching or going below freezing. I never seem to experience
the trouble when going out for lunch (engine temps at start anywhere between
30 - 60C), but sometimes when leaving the office at night if it has gotten
cold enough.

To put a numerical perspective on things, I normally have Master Fuel
set to 21%. To properly compensate for the mysterious enrichment
(based on O2 readings shown on the keypad), I have to drop Master down
to 13 - 14%.

Something has to be getting stuck when the temperature drops low enough,
but I don't know what, and why does it take switching the car off to
release it? It is not due to a problematic MAP sensor; with the engine
not running, the keypad always shows MAP values in the 100 - 103 range,
whether the engine temp is -2C or 92C.

???

Mark A. Painter
(email redacted)
'90 blue FM II

This read-only message was archived from a public mail list.
Mail From: Ray Ayala <(email redacted)>



No mystery. It's a bug in the earlier chips. The cold start enrichment
is calculated at keno time and it never gets reduced as the engine warms
up.


"Mark A. Painter" wrote:
>
> I have a strange problem with my turbo car. Basically, the colder
> it is when the engine is started, the richer it runs...forever.
> The strange part is that it doesn't change even after the engine is fully
> warmed up. I have a 30-minute drive to the office, and the abnormal
> enrichment will persist the entire way, even though normal operating
> temps are reached within 5 - 10 minutes. However, if I shut the car
> off anytime after it has reached operating temperature, wait a few
> seconds, and then restart it, everything is normal!
>
> The car is a '90 with a '94 1.8L handled by a 1.6L FM ECU Mk2, with a
> 1.8L FM II turbo setup (560cc injectors). The ECU software is fairly
> recent (MAZ16XJ 05AUG99), but not one of the fabled "Ray" chips
> (hey, Bill! When are you going to send me one of those?).
>
> The problem has been occurring for the past month or so, when overnight lows
> have been approaching or going below freezing. I never seem to experience
> the trouble when going out for lunch (engine temps at start anywhere between
> 30 - 60C), but sometimes when leaving the office at night if it has gotten
> cold enough.
>
> To put a numerical perspective on things, I normally have Master Fuel
> set to 21%. To properly compensate for the mysterious enrichment
> (based on O2 readings shown on the keypad), I have to drop Master down
> to 13 - 14%.
>
> Something has to be getting stuck when the temperature drops low enough,
> but I don't know what, and why does it take switching the car off to
> release it? It is not due to a problematic MAP sensor; with the engine
> not running, the keypad always shows MAP values in the 100 - 103 range,
> whether the engine temp is -2C or 92C.
>
> ???
>
> Mark A. Painter
> (email redacted)
> '90 blue FM II

This read-only message was archived from a public mail list.
Mail From: Ray Ayala <(email redacted)>


Sorry, I meant to type key-on time.

Ray Ayala wrote:
>
> No mystery. It's a bug in the earlier chips. The cold start enrichment
> is calculated at keno time and it never gets reduced as the engine warms
> up.