Code 21 keeps coming back

[Turbo3Iroc]

I keep getting a code 21 on my Spirit R/T. It showed up with some other coolant related codes when I did the rad job last month. Fixed the coolant ones and reset the battery. After a certain number of start cycles it pops back up. I swapped in a used O2 sensor and it goes away for another couple weeks. I put in a new O2 and it just came back yesterday. All the other times my mileage has gone to ---- but it hasn't gone down yet on the new sensor. The harness wires look very good and are still very soft. I don't know what else can cause this code.

[Turbo3Iroc]

Any ideas?

[iTurbo]

Do you have a narrow band O2 gauge so you can watch the O2 output while driving? Is the O2 wiring still stock or has it been redone/rerouted? I had a similar problem when I rerouted the O2 harness on my Spirit R/T; turns out I botched the pinout in the 4-wire connector which kept the SBEC from seeing any output at all.

[Turbo3Iroc]

I have a scan tool I can put in and watch. Usually stays in the Daytona but that car is about done for the year anyway. Wiring is all stock and just routed above the airbox bracket. I think the PO replaced the harness at some point.

[Turbo3Iroc]

Bringing this one back from the dead. I have had a few electrical issues with this car since this popped up. I've managed to fix everything else but this code 21 seems to keep coming back after so many start cycles. Seems like it pops up soon after engine start because the O2 isn't cycling rich/lean. It just stays .8-.9v.

Since I started this thread I extended the O2 wires up to the firewall. All connections soldered with heat shrink. Checked the female pins in the connectors and squeezed them down a bit. Also used dielectric grease in the connectors.

[turbovanman²]

Bringing this one back from the dead. I have had a few electrical issues with this car since this popped up. I've managed to fix everything else but this code 21 seems to keep coming back after so many start cycles. Seems like it pops up soon after engine start because the O2 isn't cycling rich/lean. It just stays .8-.9v.

Since I started this thread I extended the O2 wires up to the firewall. All connections soldered with heat shrink. Checked the female pins in the connectors and squeezed them down a bit. Also used dielectric grease in the connectors.

What cal are you running?

If its staying aournd .8 then your running rich. Try this, monitor the sensor and create a vacuum leak, if it drops down to around 100, then the sensor is good and you have an overfueling issue.

[Turbo3Iroc]

Stock cal. What do you mean what you say if it drops down to around 100?

[turbovanman²]

Stock cal. What do you mean what you say if it drops down to around 100?

Sorry, .100mv, your reading .800-.900mv right now.

When you induce a large vacuum leak, the sensor should read a lean out condition unless the sensor is bad or the engine is running so rich it can't lean out enough.

http://www.turbo-mopar.com/forums/vb...e&articleid=22

[Turbo3Iroc]

Sorry, .100mv, your reading .800-.900mv right now.

When you induce a large vacuum leak, the sensor should read a lean out condition unless the sensor is bad or the engine is running so rich it can't lean out enough.

http://www.turbo-mopar.com/forums/vb...e&articleid=22

I did the check that you linked to and the volts jump around pretty fast. I had the revs around 2300 and when I opened the vack line they went up to 28-2900. I never suspected the sensor as I have used 2 others in the car since this came up and it kept repeating. One used and one new.

I last reset the codes on ~May 27th. Since then it has not come back and I have driven the car every day atleast 2 cold start cycles. Took it on a 200 mile trip last weekend. The 21 hasn't come back but that isn't to say it won't. Sometimes it would come back after a couple days and sometimes it comes back after a few weeks. I just watch for my overall mileage to drop then I know because it runs very rich once it kicks the code 21.

[turbovanman²]

What brand of sensor?

Ok, so this is what I think it can be, you either have a bad MAP that reads wrong once in awhile, bad FPR leaking gas into the engine at the wrong time or you've got a bad computer. What is your fuel pressure?

[Turbo3Iroc]

What brand of sensor?

Ok, so this is what I think it can be, you either have a bad MAP that reads wrong once in awhile, bad FPR leaking gas into the engine at the wrong time or you've got a bad computer. What is your fuel pressure?

I'm pretty sure it is a Mopar O2. The FPR is stock and I had the line off today and it was dry. Stock SBEC also. The MAP could be something. I have a stumble once in awhile going into boost. Vac lines look good.