Driveabilty issue

Hello all,
01 supercharged with methonal injection. Recently I've had this issue where you can start and drive the truck just fine but a couple minutes into the drive, truck is up to temp and just cruising or waiting at a light it will go very lean. AFR gauge will ready 20 and truck acts like its about to die. Turn it off and back on and it runs just fine. No codes fuel trims look good. Newer MAF and AFR sensor but I'm running methonal so that could be messing with the AFR sensor. I'm thinking fuel pump but idk.

 

That and verify that she isnt going in and out of open/closed loop operation.

 

Drove around some today and had it lean out again. But AFR were good. Driving home it was running a little lean, 15/1. Im thinking the AFR sensor. I'm gonna do that and probably the fuel pump just to be safe.

 

Got the new AFR sensor in. After resetting the battery it runs great but the second trip it runs a bit lean, 15.1ish. I don't know why its only the second trip after resetting the battery. First trip I did 15+ miles and it was fine the whole time. Second trip right off the bat its running lean.

 

When you say it is running lean, are you judging that by the AFR reading? I am assuming that you are considering anything higher than 14.7 to be too lean.

What are the actual long and short term fuel trim readings when this "lean" condition is happening?

 

I don't have a scan tool with me so I haven't checked fuel trims since replacing the AFR sensor. Yes I'm using a wideband to tell rich/lean. It feels like it's running pretty decent. I just drove it again and it feels fine. Watching the wideband I see it swing from 15.3 to 14.2 just while idling. It also seems to be delayed picking up the truck going rich. I hit boost and the methanal will come on and it'll take a second to see it go rich. I'm thinking I somehow killed the wideband sensor too. I already tried recalibrating it. I ordered a replacement so I'll be doing that next weekend with the fuel pump. I am running washer fluid as methanol. It's just weird it gets parked for a week and it somehow killed both 02 sensors. It did get very cold but idk.

 

Is it correct to assume you are not running any aftermarket piggyback engine management, like a URD 7th or a Haltech or one of the many others?

It would be interesting to see that same swing in the trims at idle. That would indicate the OEM ECU is correcting them based on MAF and O2 sensor data inputs.

 

Correct the only piggyback setup I have is the water methanol. I'll grab my scantool tomorrow to watch some data. I highly doubt the computer would swing wildly like that at idle leading me to believe the wideband is bad. Also to note it has not gone super lean since the 02 sensor replacement. One variable has been temps. When I was first dealing with this it was 0 to 5F. Now its warmed up to 30F ish.

 

When you're getting 14.7+ afr, what are you doing? Under boost? Cruising? Throttling off?

What meth kit and how is it controlled and how it trigger?

 

cruising and idling. The methanol kit is an AEM kit with its own standalone controller. It's boost referenced. It's set up to turn on at 1psi.

 

cruising and idling, it’s perfectly normal to see 14-15 range because you’re not producing boost. Now if you’re under load (boost) and seeing 16+, I would be concern.

maybe I’m missing the bigger picture?

 

Originally it was leaning way out, 20+ intermittently. When I was cruising before this I would never hit 15s. It always ran slightly rich so I just wanna make sure nothing is on its way out. Also I have a lot of big trips so I'm trying to make sure everything is going to be good.

 

What wideband are you running?

 

Glowshift with a new bosch sensor. It ended up being the fuel pump. Replaced along with the wideband sensor and it seems to be all good.

 

Well update it did it this morning after 65 miles it leaned way out and stumbled until I cycled the key.

 

Maybe @Speedytech7 can help me with this too. I was able to get a little data on my intermittent issue, truck will go really lean until I cycle the key. What it looks like is the computer pulls fuel slowly until it ends up dying so it doesn't seem fuel system related. If you look at the afr data it seems pretty steady as the computer pulls more and more fuel. I assume it's trying to get to 3.4v but it's stuck at 3.3v hence it pulling fuel until it dies. My question is how is it stuck at 3.3v, I've replaced the sensor so I don't think it's that. As I recall 1 sensor wire has 3.3v and the other is 3v maybe? What I want to know is how the sensor actually works. Does it need to make a complete loop through both wires or is it more a variable resistor to ground or just comparing the 2 sensor wires?

 

It's a variable resistor to sensor ground. I'm curious if you have a problem with your MAF maybe, since that pretty much directly influences mixture when O2 feedback is active. You could also try unplugging your O2 and monitoring with your glow shift and seeing what it does. If it quickly recovers after unplugging the O2 sensor then it's something related to O2 feedback. If it continues with its problem then you're just observing the failure through the eyes of O2 feedback but it isn't necessarily caused by it. Just like oddly enough misfires show up as lean spots usually

 

Sorry I forgot to attach a photo of the data. You can see the afr sensor is steady while the fuel trims are changing which to me indicates a 02 sensor issue.

 

Yeah if trims are changing at a fixed load point but AFR isn't responding then it seems like a failed sensor or something in the sensor circuit

 

That data was taken idling in park and i watched it pull fuel trims and that afr sensor didnt seek to react. I've replaced the sensor, first I had a newer Denso and had the issue then swapped for a duralast one and still having issues. Would you just ohm the 2 sensor wires from the sensor to ecu and see what I find? Probably give it the wiggle test while measuring. I was just hoping that it being stuck at 3.3v could help me figure out where or to what it's making or not making connection with.