So I ended up repairing 3 wires at the DLC, all apparently GMLAN.

High speed (-) was very expose but not broken
Low Speed was iffy and High speed(+) was probably fine but rewired them nonetheless.

For the first time in months, no low key fob battery warning haha very interesting lol.

Oh jeez, I’m gonna go on a limb and say that pin wasn’t getting contact. Cooling Fan 2
https://cimg8.ibsrv.net/gimg/www.cob...0ab8d599d.jpeg

Ouch, and those relays are not cheap.

Yeah not great lol. don’t know when or how I managed that..

loss of communication codes should be gone for good now though so just gotta sort out the remaining stalling/ odd fuel trims.

added back evap dtcs. O2 heater readiness passed. Will probably end up pulling my MAF this week verify it’s okay up close and make sure there’s a silicone gasket on it.

Yup gonna pull MAF tonight, possibly front O2 as-well.

Came across an article that linked torque timing to fuel trims, so I set some torque management back in for 1st gear, which had previously been edited this year..

Otherwise, no evap codes yet, purge solenoid tested fine, evap vent solenoid has been in open status all day, gas cap seal looks poor so maybe I should change that out. I wonder why ZZP turned all my evap stuff off, thought a code would pop up immediately..

Not sure what else it could be, the list is getting smaller and smaller.

One thing that's buggin me this morning. When I start my car, occasionally I will hear the sound of fluid rushing at the rear of the vehicle. And there's only one fluid back there.. wonder if my fuel pump could be cracked but still could enough to let the car run? Note no fluid can be observed hitting the ground*

Perhaps I should test injectors next, or drop tank and inspect the top of the fuel pump

Maybe I'm hearing fluid rush to the filter and draining back, or the lines pressurizing. Or condensation being pushed out the exhaust

PCV is capped at the intake, could do injector seals

Wasn’t MAF. Tested methanol solenoid it was fine.

Ended up rewiring coil pack ground as it was bent and pretty dirty. Car does seems a little happier this evening but not 100%.

Injector seals might not be a bad thing to try.
I’ll pull front O2 soon, it’s pretty wet and gross out.

tmr thinking I should test my purge solenoid backwards just to be safe.
cant be tune. It worked for years with the same fuel data, may not be perfect but it never stalled out.

Careful when extracting the 02 sensor, it is in a bitch of a spot. Had to change mine when I had the GT (and did it again with my SS). You're better off using a swivel head adapter if you can.

I’ve had it off probably 3 years ago should come off nicely. long tubes lots of room

Another thought crossed my mind today.
I changed air filters probably back in September.

went from a really dirty oiled 7” zzp filter to a new Injen dry filter which was a smidge smaller.

Could that have a large enough affect on the MAF to cause STFTs swings.

Wasn’t front O2. Came off really nicely, almost didn’t have to get underneath it too! Almost haha..

purge valve doesn’t leak backwards.

Gonna post a log when I go back inside from lunch.
threw some codes today P0121 and P1101.

Pulled over plugged in scanner to see if there was anything my little gauge couldn’t see (nothing more) kept driving around parked shut my car off for a second to run inside, data logger was still going when I came back out, fired it up and drove away looks like I lost about 90% of sensor data. Really weird

Scanner failed to communicate after. Dropped connection have way through writing.
And boom can bus codes again. Okay something is fucked here. Added back O2 dtcs
https://cimg6.ibsrv.net/gimg/www.cob...a5a54d575b.jpg

lmao, why does Pro Demand say the top repair for fixing a U2105 is replacing a turn signal bulb,

So things I want to try ( would like communication codes solved before moving on to fuel/trims at the slim chance they are related)

Rewire G105
Bypass VICM
Inspect G301 under drivers seat,

I really don't know. This is silly. Should leave my multimeter in the car to test DLC next time U2105 pops up.
And maybe I'll have to unplug every module in the circuit, apply dielectric grease, note which codes are thrown when their unplugged and re-seat.

Spoke to an old GM tech last week, he was willing to put money on it being a bad PDC, and explained erratic fuel trims fit the bill too.
Said he's replaced countless PDC's on cobalt in his 15years experience.

Looking over that log, TCM is reporting 0 volts, ECU reports 14.7V.
Engine coolant reads -40C, however manifold vacuum is being reported.
Trans temperature is being reported! Like what in the actual hell, That doesn't help me at all, its not clearly one controller or the other.

All I can think, is the computer had all the right values the engine sounded fine. Did not sound like it had -64 degrees of timing, so perhaps my problem lies somewhere between TCM/ECU and the DLC still.
Wiggling the dlc does not trigger anything anymore.

Got hit with a blizzard and temperatures should drop a lot in the next week. So might get another shot at scanning and diagnosing a stalling event.

Would love if the next two days got a little warm during the day I could try a couple more things.

I do suspect my vent solenoid is malfunctioning in some manner. It should be open when the engine is off, closed when the engine is running and the purge solenoid then takes over. With the exception of when the system is self diagnosing.

But you’d think it would cycle?, I have logs were it’s pegged open.

So things I’ve learned today, my vent solenoid is working properly according to pro demand.

But I have found an area of the purge solenoid inlet hose to have some rubbing. And so I’ve decided to cap at the throttle body and get rid of the line and put a filter at the canister.

I then moved on to play around with my tune, raised idle rpm a little, adjusted ETC scalar and I got it to idle really nicely without any huge afr swings.

decided to keep going

I Rewired the remaining 3 wires at the dlc so they’re all the same length.
after hours of playing with the dlc I think I learnt something.
-when clamping the dlc and the scanner together, pulling the pins from the back side of the dlc no codes occur.
-if I pull my scanner out a little bit it’s pretty consistent at throwing the car haywire.

However the codes still occur when both my scanners are fully seated.

It didn’t seem like moving the dlc wires did anything at this point, so I moved to the VICM, I started moving those wires around and they car went haywire pretty consistently. So I bypassed the module and it did get a little better. Wiggling the wires no longer tripped the system.

So I went back to the dlc to see if it behaved any differently. Moved the wires around let them hang and was able to trip the system again.


DLC grounds G201 and g203 on opposite sides of the IP are pristine…

I removed and cleaned up G109 At the strut tower for PSM ground…

Ive been out all day and gonna have to try more tomorrow.

I tried wiggling my key, applying pressure to the dash, moving dlc wires in every way. Nothing at this point seems consistent.

couple times the key set it off then stopped..

Pulled an cleaned dlc fuse, Bcm, ecm, tcm, display, outlet, etc fuses.

Shot in the dark, but have you checked the inner fuse panel to the right on the console under the passenger side dash? Those fuses tend to be forgotten. Otherwise, you might have to try my route and install another under hood fuse box.

checked fuses, power taps, grounds, reseated connectors at BCM, tightened the screws that hold it.

So why are you leaning more towards PDC (fuse box) over ECU, whats your logic there????? I had an old GM tech suggest is was my PDC but idk..

I got two grounds to rewire, G105 and under driver's seat.

After that I think I'll be trying either a PDC or ECU..

Mostly because I've been having electrical issues, and I've replaced most of my grounds, and cleaned up most of the wiring, and also fired the parts cannon, including new Opel injectors and additional rounds of ZZP tunes. When I did my clutch job which involves removing the the fuse box, once I was finished and put everything back on, the car was effectively dead. The GM tech told me that there's a connectivity problem with it after muxing with it several times before he was able to seat it with dielectric grease fully.

I'll start (from cold) as running very lean and eventually running full blown rich, with the occasional P0101. I've replaced almost every sensor under the hood with the proper OEM, no vacuum or boost leaks.