Fuel rich and O2 settings?

[PIU PIU Person]

Hello,

New to the forum and I have a new to me 2017 PIU bought at an auction.

The first time I took it to the mechanic, the engine code showed low fuel from the fuel tank pump. That got replaced and the mechanic showed me that the results showed the fuel was burning great. Long term and short term.

Couple of days later, the code showed O2 sensor Bank 1 sensor 1not operating at standard. I swapped it for OEM. No code for a couple of days.

Code light shows up again. Take to the mechanic and its showing the same O2 sensor not operating at standard. He checks the stats and the car is running rich but couldn't see any indication for why the code was thrown.

His theory is that the agency probably knew of the failing fuel pump and changed the PCM to compensate or override the low fuel rather than replace the fuel pump... and now that the pump has been changed the system is show it as to rich...

Does any here know if the PCM / Forscan can be changed in a manner that would compensate for low fuel and what I might look for to see if the fuel mixture is other than standard PIU fuel delivery?

Hope I am making sense to you...

 

[DePolicify]

What code exactly are you getting? When I had this issue it was due to a bad cat.

 

[PIU PIU Person]

What code exactly are you getting? When I had this issue it was due to a bad cat.

PO131-00

which is an O2 sensor code. I would think, if the cat was a problem it would throw a cat code. I do think the mechanic and I discussed this, and he thought that is was not a cat problem, but I don't recall that perfectly.

 

[DePolicify]

It's been a couple years, but I had this same issue, I replaced the sensor and cleared the codes and it never came back, but the cat code popped up shortly after which I think was related, but it could have been that the first sensor malfunction dumped fuel into my cats and dirtied them up.

 

[PIU PIU Person]

It's been a couple years, but I had this same issue, I replaced the sensor and cleared the codes and it never came back, but the cat code popped up shortly after which I think was related, but it could have been that the first sensor malfunction dumped fuel into my cats and dirtied them up.

Have you ever heard of a PCM override that could mask the cat code?

 

[DePolicify]

Have you ever heard of a PCM override that could mask the cat code?

I have not, I used the 02 sensor spacers, but I also live where there are no emissions so not an issue. I know someone who has a PIU in AZ where they actually check for the spacers at emissions testing, so it won't fly in some places.

 

[PIU PIU Person]

I have not, I used the 02 sensor spacers, but I also live where there are no emissions so not an issue. I know someone who has a PIU in AZ where they actually check for the spacers at emissions testing, so it won't fly in some places.

Ah... are the spacers designed to keep the O2 in place yet not allow them to operate as usual, or what?

 

[DePolicify]

Ah... are the spacers designed to keep the O2 in place yet not allow them to operate as usual, or what?

Yes, they essentially move the sensors further away from the exhaust stream and fools the ECU into thinking that the cats are working correctly. This actually saved me fuel economy because it stopped the ECU-induced rich condition.

The spacers only install on the downstream (sensor 2) sensors.

 

[PIU PIU Person]

Yes, they essentially move the sensors further away from the exhaust stream and fools the ECU into thinking that the cats are working correctly. This actually saved me fuel economy because it stopped the ECU-induced rich condition.

The spacers only install on the downstream (sensor 2) sensors.

So this is a way to correct the fuel rich condition (as read by to O2 sensors).

 

[DePolicify]

So this is a way to correct the fuel rich condition (as read by to O2 sensors).

potentially, but if the cause was a bad cat I would expect P0320/420 as well

 

[dwu048]

I have a 2016 FPIU and had issues with the O2 sensors with those codes you mentioned. Turns out the mechanic I took it to replaced my O2s with aftermarkets. Still threw the code until I ended up getting the P0320/420 codes in addition to the O2 sensors. Turns out there were recalls on the CATS. Might be worth looking into. The link below is the recall.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10162410-0001.pdf

 

[PIU PIU Person]

I have a 2016 FPIU and had issues with the O2 sensors with those codes you mentioned. Turns out the mechanic I took it to replaced my O2s with aftermarkets. Still threw the code until I ended up getting the P0320/420 codes in addition to the O2 sensors. Turns out there were recalls on the CATS. Might be worth looking into. The link below is the recall.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10162410-0001.pdf

My cats look new. I wonder if they have been replaced, and if so, if they are oem.

No cat codes are showing though...

My PIU is the 3.5. The recall doesn't specifically exclude 3.5's but states it was issued because the 3.7's out of the Chicago plant were failing.

New cats would be nice...

 

[PIU PIU Person]

Yes, they essentially move the sensors further away from the exhaust stream and fools the ECU into thinking that the cats are working correctly. This actually saved me fuel economy because it stopped the ECU-induced rich condition.

The spacers only install on the downstream (sensor 2) sensors.

My code relates to the upstream detecting rich fuel. Would raising the downstream O2 sensors with spacers help or hurt in this case?

 

[PIU PIU Person]

Decided to discuss the possibility of a bad coolant temperature sensor (theory) as a cause for my rich fuel issue with my mechanic.

In doing so, we put the PIU on the scanner again. Same O2 sensors showing rich while the actuals are in range... but now,

there is an Open Loop Fuel System Fault showing.

My mechanic says if he had HP program files to compare to the actual readings he is getting, he could possibly narrow down why I have a rich fuel dump going on.

Again he theorizes that someone may have told the PCM to run rich for the lack of fuel pressure caused by a faulty fuel pump. The rich O2 reading happened after replacing that fuel pump.

How to I find the Police Package profiles for him to check?