Replaced F430 O2 Sensors - big difference!

I replaced my pre-cat O2 sensors today and took the car out for an Italian tune up to clean up the cats after running a bit rich on the old sensors. Car felt like it had found another 50hp! Genuinely astounded me when I floored it down my favourite stretch of country road. Granted I've taken 100kg out the car and had a DMS map that took it up to 525bhp, but the rears were lighting up constantly. First time I have properly s**t myself in this car for a while

Thought I'd post in case others feel their car is down on power a tad. Tell-tell sign is even just the slightest of sooty deposit in the tailpipe - they should run absolutely clean. Could be other causes of course (restricted intake, dodgy MAF, cracked manifold!!, failed ECU, etc) but with new O2 sensors costing just £50 online and fitting really straightforward it's worth investigating. Pre-cat sensors measure A/F ratio, post-cat sensors measure cat efficiency by comparing readings with the pre-cat (my understanding at least). Seems that these can start failing anytime and it's seldom a catastrophic failure, more often a slow degradation in sensitivity leading to the pre-cat sensor sending lean readings to the ECU and thus causing over-fuelling. Mine was worse on one bank.

Still loving this car and no plans to rest it for the winter - although cheeky front ARB bushings refresh scheduled for the weekend hence back on the ramp.

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I bought from https://www.partsinmotion.co.uk. Left and right are the same part.
Edit: 360 and 430 are the same part.

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Sorry. Ignore the link. Purchased from them via their eBay store https://www.ebay.co.uk/itm/FERRARI-F430-4-3-Lambda-Sensor-Pre-Cat-05-to-09-Oxygen-Bosch-178290-182837-New/232464998993?pageci=d3cf721c-288a-4981-91f9-ce7a974ae0e9


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Precat means before the primary cat and doesn’t refer to the precats in the headers. I know - a bit confusing. Sensor 1, the precat sensor, measures the air/fuel ratio coming out the header and before the main cats. It’s readings determine any adjustments made by the ecu to the fuel mix.

The postcat sensor means after the main cat. It’s readings are compared to the precat readings to see how well the main cat is working.

I would start by replacing the precat sensors (sensor 1) on both banks They are easier to replace and you should do them together. They are also the ones that typically fail first, and incorrect readings from them can cause the comparison with the reading from sensor 2 to be outside the threshold.

The sensor 2s are most likely fine although while you are there no harm in unscrewing them and cleaning with vinegar and a toothbrush.



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Yup, your sensor labelling is correct. Sensor 1 is green, sensor 2 is blue.

Traditionally you address the banks looking from the front as this is the more common way to look at the engine and the way we read left to right across a page - so bank one on the left and bank two on the right. With a mid-engine car you look at the engine from the rear so bank one is on your right and bank two is on your left.

Here is a diagram with ignition order - kindly done by Stef.

Ignition order:

1. Cylinders 1 – 8
2. Cylinders 3 – 6
3. Cylinders 4 – 5
4. Cylinders 2 – 7

Ignition coils reference : BOSCH single ZS-K-1X1E
Spark plugs : NGK PMR8B


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Hmm. I get where you are coming from but removing precats from the headers doesn't remove the requirement for functioning precat sensors (actually can introduce a whole world of CEL pain). Also removing them can take the noise level over the 105db threshold in place at most tracks in the UK so eliminates any possibility of tracking the car.

 

About 26,000 miles. A lot of that on track so maybe higher temps than normal...?


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