Sunday Full of Codes

1995 348 2.7 Spider? (please fill in your profile page with car details so we don't need to keep asking you what car you have )

5~8

1212 long and short term Lambda regulation
1121 rpm sensor

1~4
4122 Cat temp ECU
1212 long and short term Lambda regulation
1211 Lambda regulation

I don't see a common power or earth issue causing all these problems. The rpm sensor problem is probably the left bank crank sensor or wiring. Cat temperature may be a thermocouple or thermocouple ECU, but may be related to your fuel regulation problems.

A history of what you have already done would be helpful:

e.g. https://www.ferrarichat.com/forum/posts/147168992/

 

Have you made any exhaust modifications?

https://www.ferrarichat.com/forum/threads/nouvalari-exhaust-for-sale.627772/

 

Good background reading for fuel trim. You can get a scan tool that shows fuel trim and see what #'s they are running. Knowing if numbers are too positive or negative is good start.

https://www.aa1car.com/library/what_is_fuel_trim.htm#:~:text=Fuel%20Trim%20is%20the%20adjustment,reading%20on%20a%20scan%20tool.

 

Ian is right on.

1121
rpm sensor, replace them both

4122
-Check cat ECU for cracks.
-Worn out cat.
-Bad thermocouple.
-It is possible something is running rich or lean which may be related to the other lambda codes below.

4122 in order of what I would do:
-O2 sensor
-FPR
-Clean injectors (do it anyhow)
-MAF out of spec (rebuild them that's my guess btw)
-Fuel pumps


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No OBD2 that I know of unless 95 is different than other 348's.
Aftermarket exhaust makes no difference on the 348 with those codes, its the 355 that gets finicky there..

All the effort swapping parts side to side. Just replace them. They are likely 25 years old anyhow and have hit high tie long ago.

Please be clear what car you have?

 

and what is it doing now? Did. you clear the codes after the swap?

 

Replace O2 sensors andgo from there. $150 for a pair at Rock Auto. If the RPM sensor was bad the car would only run correctly on one bank. The other would be dead of have a serious misfire or intermittent break up..

By the way, was the car running when you read the codes? If not, you will get an RPM sensor code for both banks. If it wasn't running you may have missed it on the other bank. If it was running and you got the RPM code, you should have noticed it running poorly.

 

Thanks for the clarification. That does point to a possible problem with the signal from the RPM sensor. Check the wiring from the sensor. Check the resistance of the sensor it should be around 1k ohm +/- a couple of hundred.

 

Bosch is OEM.

Just want to add that it does seem odd that you would get the O2 codes on both banks at the same time. That may point to something else. Not sure which bank controls the fuel pump, but I believe the fuel pump won't turn on unless the engine is cranking (i.e. it sees a signal from the RPM sensor).

 

Wouldn't each ECU control their respective fuel pumps?

Having both banks generating codes was baffling me, too. When I asked about the exhaust, I was thinking something wasn't plugged in (electrically) or wasn't fitted properly causing air leaks.

 

You are probably correct on dual fuel pump cars. I was thinking of my 355. Switched to single fuel pump some time in 95.

 

Reading codes with the car off will always throw rpm sensor error. If you don't get it with the car on that's no an issue.
Fuel pumps only run when engine is cranking, when turning key to energize before run it supplies zero power to the pumps.

 

In that case I might not be so quick to replace the O2 sensors. The O2 sensors would not result in that behavior. Need to do a proper diagnosis.

 

Some 95 355 has only 1 fuel pump.