Open Loop Fault?

[bmax]

Hey Guys,

I have been chasing a problem with my firebird.

I run COS5 and don't drive the car very often.
Anyway, I had my tune running well in semi open loop
and all the sudden it started running rich.

I thought maybe it was because the weather had
gotten colder so I switched to a closed loop tune
to see if the trims would resolve the problem.
It seemed to help once it warmed up to operating
temperature.

Then I got a PO200 code, injector circuit issues.
So I checked all the wiring for shorts, none,
put an ohm meter on all the injectors, they all
were 11.8 to 12.1 ohms. They are stock 28 lb
injectors by the way. So then I took it for a drive
and everything was good again.

Next time I drove it it went back to being too rich.
Got the PO200 code again and P1133 P1153. The P1133
P1153 I think was because it was so rich the O2's weren't switching
at all. It was in open loop fault at this time also
and I'm not sure if that is related to the O2's not
switching.

I have not used a noid light as I don't have one and don't
know if that would help me because both banks go rich.
So I don't think it's one injector.

I am starting to think it's my PCM because it seems to be
an intermittent thing.

Any ideas on further troubleshooting this?
Also where is the best place to get a new PCM if I need one?

Thanks

Brad

edit: I loaded an open loop tune and took 10% out of the commanded fuel and it still goes rich about the same as before.
confused.
Nothing has made a difference, once it warms up it goes to 12-13 AFR. HO2's read rich both banks as well as wideband even with commanded EQ at .9 using a known good calibration.

[maudyZ28]

Have you check you are not in Piston protection enabled mode or CAT protection? I noticed in the COS3 when I updated the parameters were such that Piston protection was enabled

[bmax]

Thanks for the reply.

No, that's not it. If I start it from cold and watch the wideband and the narrow bands at idle, once it warms up the A/F goes to 12.6 or so every time. Even after removing 10% from commanded.

Does it with MAF or without, with or without trims also. Driving or idling, same result.

I've got a replacement PCM on the way now.

Thanks again.

Brad

[joecar]

Hi Brad,

Can you post a log showing the front O2 voltages HO2S11/HO2S21...

also include EQIVRATIO, LONGFT1/2 and others.

[ I somehow missed this thread a week ago ]

[bmax]

Joe,

Never got any good logs as I was not comfortable to drive it being too rich. Anyway, I changed the PCM and all is well again.

Thanks.