P1123/1125 cel

[Vza]

Hi All, Going to try and finally resolve my issue. 1999 Box Base throws a CEL P1123-1125 every 600 miles or so. Engine Leaned out cause of rich mix. I've been just clearing it lately....car runs GREAT throughout. New Plugs/AOS/ MAF/Fuel Filter/Fuel Press Reg/Cleaned and checked output of all injectors/Air Filter/Cleaned TB and Plenum.
Only items not changed is purge valve for the charcoal canister and fuel pump. I believe my Fuel pressure tested at 3.3Bar Engine off and 3.1Bar at idle which I think is on the low side but still within specs. Any thoughts on fixing this?? Thanks V

[Stl-986]

pull the cam plugs & check your timing?

[Vza]

Timing within spec. Deviation +3 B1/0 B2

[blue62]

Originally Posted by Vza

Hi All, Going to try and finally resolve my issue. 1999 Box Base throws a CEL P1123-1125 every 600 miles or so. Engine Leaned out cause of rich mix. I've been just clearing it lately....car runs GREAT throughout. New Plugs/AOS/ MAF/Fuel Filter/Fuel Press Reg/Cleaned and checked output of all injectors/Air Filter/Cleaned TB and Plenum.
Only items not changed is purge valve for the charcoal canister and fuel pump. I believe my Fuel pressure tested at 3.3Bar Engine off and 3.1Bar at idle which I think is on the low side but still within specs. Any thoughts on fixing this?? Thanks V

give us a little background info.
How many miles???
Any mods including air filter??
Any codes in the past other then the P1123-P1125???
Do you have an OBDII scanner such as a Durametric????
Do you have a way to get the freeze frame info related to the codes???
Do you have a vacuum gauge????Or access to one???

[Stl-986]

That's cam deviation right?

[Vza]

Yes Cam Deviation.
140,000+ miles
No Mods
Lots of CEL's in the past. I had replaced a solenoid and burned resistor in the DME had misfire codes and more. Lost timing at one point but those issues resolved.
Access to vacuum gauge.
Have Durametric
Not too sure about freeze frame.

[blue62]

Originally Posted by Vza

Yes Cam Deviation.
140,000+ miles
No Mods
Lots of CEL's in the past. I had replaced a solenoid and burned resistor in the DME had misfire codes and more. Lost timing at one point but those issues resolved.
Access to vacuum gauge.
Have Durametric
Not too sure about freeze frame.

So here are my thoughts:
A few things than can cause to rich a mixture.
To high a fuel pressure:
Leaking injectors.
A sensor that is giving the DME/ECU false readings.
So the DME/ECU can be fooled into thinking mixture is to rich.

I went back thru most of your threads and I see that your vacuum looks good.
Also that you have tested the fuel pressure and the fuel regulator in the past.
Also that you replaced the MAF sensor.

O2 sensors can give the DME/ECU false reading if the become "biased" high or low.
If they become "biased" high the DME/ECU sees that s a rich condition and trys to drive the O2signal low by taking away fuel.

So I would look at the O2 sensors with your Durametric.
First test:
Hook up the Durametric key on engine off.
click on the engine module then click on actual values.
Find O2 sensor volt for all 4 sensors.
check the boxes.
you should get a reading of 0.45mv on all four
That will check the signal from the DME/ECU

Second test:
look for O2 sensor heater circuit
Check those boxes the voltage should be 4.30V-4.50V
That will check the voltage from the DME/ECU to the O2 sensors heating circuit.

Third test:
Take the car for a drive and get it up to operating temp.
Hook the Durametric back up.
With engine running this time... go back to all four O2 sensor voltage signals
Graph then for 3-5 minutes at idle. dont rev the engine just let it idle.
The pre cat O2 signals should go up and down in a constant sine wave pattern.
The post cat O2 sensor signals should stay above .450mv and spend most of the time at around .650mv-.750mv
Post the graphs f you can so I can look at them.

[Vza]

Ok thanks for the info. I was thinking about the o2 sensors but that would mean 2 would have to be faulty being that both banks are rich.

1st test engine not running just key on?

2nd test engine running to heat up sensors?

[blue62]

Originally Posted by Vza

Ok thanks for the info. I was thinking about the o2 sensors but that would mean 2 would have to be faulty being that both banks are rich.

1st test engine not running just key on?

2nd test engine running to heat up sensors?

1st test key on engine OFF. This test looks for correct voltage signal form the DME/ECU to the sensor.

2nd test key on engine OFF. this test looks for correct voltage to the heater circuit..

The first 2 test just confirm that supply voltages are correct. so key on engine OFF.

The 3rd test is to test the operation of the sensors so engine running.

Yes both sensors would have to be faulty because both banks are rich.

the tests will let us see if they are or not.

[Vza]

OK...Strange happenings. I got another CEL after 1000 or so miles... same issue. I left the light and didn't clear it (cause I didn't have my ODB plug) 600 miles the CEL cleared itself. Whats up w/ that? Any thoughts? I never got to doing the above testing but will. V

[Vza]

I plan on doing a compression test on my newly acquired Box. Just want to go thru the procedure.
Engine to operating temp
Disconnect all Coil Packs
Remove all coil packs and plugs
Pull Fuel pump fuse
Disconnect Ignition Sys(dont know how)
Attach Tester ..Crank 5 times or so.,,,repeat on other cylinders
Repeat w/ squirt of oil in each chamber.

Just not sure how or why to disconnect ignition sys if all the coils are detached anyway.
Can I just disconnect the harness in the trunk from the DME to do this?

Thanks Vince