AFR Not Reading

StreetSpeed6

StreetSpeed6

Diesel Slayer
Silver Member
What's up guys! Soo.... My car has decided to not read MAF voltage or AFRs. I'm going to try to briefly tell how this started.

I was driving and decided to try the e-brake trick and click it up one click and do a pull. This would make it work as a FWD and I wanted to see if it would feel faster. As I clicked the e-brake up and got ready to do the pull the traction light came one (car with squiggly tire marks) and the car started running a little rough but not bad. I realized while driving it home that the AFRs weren't reading and then noticed after looking that ltft's stft's and maf voltage all aren't reading. Has anyone had a speed 6 do this?

I have tried replacing my maf sensor, the primary oxygen sensor, and also the Engine + B fuse that appeared fine anyway. All fuses seemed fine in the engine bay fuse box. I have also disconnected the battery for a few days and reflashed my map with no changes to what it does. I cleared the engine codes while it was running and it immediately dies every time. Any help would be appreciated as I rely on this car for winter time mostly.
To add real quick... It starts but dies without a good bit of throttle input.
@Sho @JohnnyTightlips @Enki @alexwlwsn
 
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Obviously, one click on the ebrake wouldn't cause this unless there's a severe short in that circuit somewhere.

1. Get logs of a start (even if it won't run properly)
2. Unplug the MAF and try to start again
3. Check all wiring looms for damage, corrosion, etc
4. Try starting car in neutral with ebrake completely off
 
Enki said:
Obviously, one click on the ebrake wouldn't cause this unless there's a severe short in that circuit somewhere.

1. Get logs of a start (even if it won't run properly)
2. Unplug the MAF and try to start again
3. Check all wiring looms for damage, corrosion, etc
4. Try starting car in neutral with ebrake completely off
Click to expand...
I'll check it out and get back with you :)
 
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It's possible the AWD system is throwing a code that the AP can't read? If that is doing something wonky it could put the car into some sort of limp mode. Do you know anyone with a better scan tool?
 
Just took a datalog of it starting with maf plugged in. I will post sometime tonight. Unplugging maf didn't change anything. I am thinking there is possiblity a sensor on my rear diff that could've wemt bad. That would explain why it happened when it did and why the loss of traction light is stuck on
 
Well....I took it to a local shop and they said their scanner threw up like 30 codes and went crazy when they plugged it in. Said they wouldn't charge me for the small amount of time they spent on it but that they couldn't help a lot since I "have a lot of deleted stuff throwing codes". He said he is willing to help but doesn't know what it would be and so didn't want to waste my money with him guessing basically. I am going to look it over a bit more and take it to another local guy that is supposedly very good at diagnosis work. Hopefully I can figure something out first though.

------ Engine Codes on AP -------
P0134
P0031
P0037
P0102
P0443
P2088
HELPPPP Lol
 
So your O2 heater circuit is on a 12v power circuit but the MAF, O2 sensor, cam sensor are all 5v reference. Are any of those sensors shared on the same 5v reference circuit? Usually an ECM has a few 5V outputs that split between other sensors and then each sensor has its own signal back to the ECU.

If a sensor shorted out and brought down a 5V circuit it could bring down multiple sensors. You could also have a break between the ECM and other sensors before the 5V splits bringing down multiple sensors.

Does anyone know if those 3 sensors listed share the same common 5v reference?

It also sucks cause I'm not at the shop right now so I can't access AllData to see the wiring diagram. I'll go on there tomorrow and try to download all the wiring diagrams to post.
 
L337TurboZ said:
So your O2 heater circuit is on a 12v power circuit but the MAF, O2 sensor, cam sensor are all 5v reference. Are any of those sensors shared on the same 5v reference circuit? Usually an ECM has a few 5V outputs that split between other sensors and then each sensor has its own signal back to the ECU.

If a sensor shorted out and brought down a 5V circuit it could bring down multiple sensors. You could also have a break between the ECM and other sensors before the 5V splits bringing down multiple sensors.

Does anyone know if those 3 sensors listed share the same common 5v reference?

It also sucks cause I'm not at the shop right now so I can't access AllData to see the wiring diagram. I'll go on there tomorrow and try to download all the wiring diagrams to post.
Click to expand...
First off thanks so much for helping as I am not at all that good at diagnosing issues other than suspension and more mechanical stuff not electrical.

@JohnnyTightlips says he feels it could possibly be a bad ground or fuse of some sort. I was just driving when this happened and not doing anything out of ordinary. I need to check all the fuses but would any inside the car fuse box be this critical? I didn't check any in the car and only the ones in the engine bay.

I feel like that the traction control light is maybe a clue as to why it is doing what it is but I don't know all the reasons it would come on. It never came on when my primary o2 sensor went bad the a couple years back. Car just would barely run and wasn't reading AFRs. Could a wheel speed sensor cause this?
 
PROBLEM SOLVED THANK GOD lol And also thanks to whoever recommended the Engine Bar fuse! I somehow thought that the Engine B fuse was short for bar but apparently they're different and ai didn't take the time to look long enough or overlooked it somehow. I will update to make sure it is still running properly after I actually drive this thing a bit.

Also, I'm assuming what caused it was a bare wire I had found on my o2 sensor that I fixed while troubleshooting. It now has been crimped back together with a marine heat shrimp crimp fitting. Thanks so much guys!
 
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