Lambda / Oxygen sensor voltages 3.0 24V CF3 - Alfa Romeo Forum
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(Post Link) post #1 of 7 Old 25-09-16 Thread Starter
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Lambda / Oxygen sensor voltages 3.0 24V CF3

Hello!

I'm, lucky enough to have a CF3 engine with 4 lambda's, and want to bottom out if my lack of power is due to one of them. I have connected a diagnostics tool to them with the engine running and found the following:

Bank 1 sensor 1 - 0.445V all the time, no matter what the RPM
Bank 2 sensor 1 - 0.445V all the time, no matter what the RPM
Bank 1 sensor 2 - adjusts according to RPM (0.1-0.7V), oscillating voltage on idle
Bank 2 sensor 2 - adjusts according to RPM (0.1-0.7V), oscillating voltage on idle

Does that mean that both sensor 1's are not doing anything, i.e. given up or just not warming up? Or should they be static across the rev range (which doesn't sound logical to me with increasing revs and higher fuel burn)? Sensor 1's are on the manifolds as well?

Any help appreciated!

Dave

Last edited by Mountain goat; 25-09-16 at 20:08.
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Quote:
Originally Posted by Mountain goat View Post
Hello!

I'm, lucky enough to have a CF3 engine with 4 lambda's, and want to bottom out if my lack of power is due to one of them. I have connected a diagnostics tool to them with the engine running and found the following:

Bank 1 sensor 1 - 0.445V all the time, no matter what the RPM
Bank 2 sensor 1 - 0.445V all the time, no matter what the RPM
Bank 1 sensor 2 - adjusts according to RPM (0.1-0.7V), oscillating voltage on idle
Bank 2 sensor 2 - adjusts according to RPM (0.1-0.7V), oscillating voltage on idle

Does that mean that both sensor 1's are not doing anything, i.e. given up or just not warming up? Or should they be static across the rev range (which doesn't sound logical to me with increasing revs and higher fuel burn)? Sensor 1's are on the manifolds as well?

Any help appreciated!

Dave
It looks like you have listed them wrong because what your sensor 2s are doing is correct for pre cat. and the sensor 1 results are correct for post cat. Can you list the location of your sensors and its connectors location?
I replaced both of my pre cat sensors and still had a fault, the rear bank pre cat would read a steady 0.4v, the connector was routed to the back of the plenum.
Someone on here said their connectors were by the air intake piping and not behind the plenum, which meant it routed to wrong area. I swapped the sensors over and now I get the correct reading, pre cats fluctuating and post cats steady.
Do you get any codes for your lac of power?
If you have multiecuscan or similar it may be worth checking your MAF readings too.
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(Post Link) post #3 of 7 Old 26-09-16 Thread Starter
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Thanks for your help on this, I'll have to check this out and get back to you when I'm back. In terms of power, there's a lack of power and acceleration compared to my last v6, but there are no codes. The MAF seemed to be working ok from the app, but I'll get some live data and report back.

I'm using a wireless obd2 connector to an iPhone with EOBD-FACILE, and all items it's displaying seem to be ok and logical. Tragically I gave up with Windows a few years back, and it's a shame multiecuscan is not available for mac....


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Quote:
Originally Posted by SLM3CFC View Post
It looks like you have listed them wrong because what your sensor 2s are doing is correct for pre cat. and the sensor 1 results are correct for post cat. Can you list the location of your sensors and its connectors location?

I replaced both of my pre cat sensors and still had a fault, the rear bank pre cat would read a steady 0.4v, the connector was routed to the back of the plenum.

Someone on here said their connectors were by the air intake piping and not behind the plenum, which meant it routed to wrong area. I swapped the sensors over and now I get the correct reading, pre cats fluctuating and post cats steady.

Do you get any codes for your lac of power?

If you have multiecuscan or similar it may be worth checking your MAF readings too.


Both pre-cat sensors run beside the air pipe on my car, and the post cat ones are on the RHS of the plenum chamber. This sounds similar to what you're saying above, and in the correct places I think...


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I think your sensors are fine then. Others things to check if you have them listed is load and fueling. When was your timing done?

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I think your sensors are fine then. Others things to check if you have them listed is load and fueling. When was your timing done?

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That's good then - thanks for your help.
I'll check this at the weekend for the other parameters. Timing was done 4 years ago, so due in a year. Was thinking about a fairly major overhaul next year for the engine, depending on costs!


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No problem. I always do 4 year intervals for the v6 otherwise i live the 5 year in fear ha

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