Weird things going on with Sonic

[JTee2017]

So no real update just that I finished the coolant draining and it was bad. Should be good now. I think next time I do it I'll replace the coolant reservoir since I couldn't get it clean 100%. Car still has original problem as before so not sure where to go from here. Might suck it up and take it to a shop and have someone look through everything and find problems. Thats the last resort though

If you mean the "dimming lights" and RPM dropping is still present, the battery may be going. Even if newer they can die or a cell might start to short out at times which drops the voltage.
Any momentary drop in car electrical supply can cause weird issues like that and even stall the engine because fuel injectors and sensors will not operate correctly with a momentary voltage drop.
The battery may even check good, because it is an intermittent thing and hard to catch when failing.
Check, wiggle and inspect all the battery wiring connection points. Find the ground points, undo the nuts or bolts, clean under them with a wire brush or lightly sand and apply some light grease and refasten.

I would also check the battery cables, especially the negative connection at both ends and grounding points. Check for the ground connection to the engine and body. They are separate I think.
Clean the battery connection posts and terminals. When a car get over 5 years old these things start to crop up.
Could you connect up the OBD device and monitor battery voltage and log it or at least check it when the problem occurs?


EDIT_ : Also, check the alternator charging voltage as well as connections to it. There is also a sensor on the negative battery terminal that provides signal information to the BCM and ECM for how much the alternator should provide in charging voltage. They usually do not fail however, but can.

 

[Fluffycakes2020]

Ok I'll take it to AutoZone and have them put the machine on the battery to check that and the alternator. The battery is fairly new since that last one had a bad cell so could be that too. I will check the grounds and cables and clean what I can. Is there a diagram online that shows where the grounds are by any chance?

 

[JTee2017]

Ok I'll take it to AutoZone and have them put the machine on the battery to check that and the alternator. The battery is fairly new since that last one had a bad cell so could be that too. I will check the grounds and cables and clean what I can. Is there a diagram online that shows where the grounds are by any chance?

csmans might have one here - - - > Chevrolet Sonic Repair Manual

Otherwise, just visually and by feel and using a good bright flashlight or trouble light observe where the wires go.

 

[Fluffycakes2020]

Yea that's what I'm gonna do. Also I have a obd plug where I can monitor stuff but I don't think battery voltage is an option. I'm gonna try and look for a different app maybe.

 

[andersondb]

Similar issue

Hello,

I’m having the exact same issue with my 2012 1.8L as far as the idle and it seeming to drop for a second every 5-6 seconds at idle or a stop light.

I was going to buy a coil pack (121k miles) but wasn’t sure if that would solve it now based on what I’m reading here.

I don’t have a can tool other than a simple one. No CEL either.

I re entry had the oil leak under the car which turned out to be the oil filter housing leaking. Had that replaced And no other issues.

I put in new plugs around 100,250k and all was good. This issue started about 119k or so. Currently at 121k. Midas says they can’t find it (Free diagnosis) but I don’t think they ran the car long enough.

I usually notice after driving short distances or off freeway then a stoplight. Not sure if starts directly upon startup or once warmed up. I will pay better attention then report.

Hope you find what it is and I can look for same. I will check vacuum leaks tomorrow

Thanks

 

[gnonne]

At 120K, the coil pack is routine maintenance.

I saw some videos online with a guy chasing down every possible reason for an erratic idle on a Cruze. Replaced the coil pack and plugs (which you have already done) and it ran like new.

 

[andersondb]

Continued testing of weird situation

So,

While i'm waiting on my coil pack to arrive I did a test this morning.
I noticed that upon the car being cold that it did not have the hesitation during idle or a stoplight.

Drove the car about 4 miles with 4 stop lights and I could tell the hesitate was starting to be very slight. Still every 5-7 seconds it stumbles (or cuts out is more like it).

Once the car was fully warmed and driven at a higher RPM (short freeway ride) the stumble (cutout) was more pronounced.

I attempted to stop on the hill of my driveway and release the break, car didnt roll back but it still stumbled every 5-7 seconds with no brake pressure.

Just wanted to throw this in for added value, checked air intake hoses etc. and all seemed fine.

Checked battery, and cables were tight, turned off Daytime Running Lights and still got same. (dash lights flash quickly and RPM looks to drop maybe 100rpm right on time every time 5-7 second.

If I had a unit to pull live data I might be able to capture more during the pulse.

I dont want to install the coil pack if I dont need to.

 

[Fluffycakes2020]

Well I have already changed out my coil pack because of a problem i had before but this is different but this does exactly as your describing. When car is cold is doesnt idle bad, once its nice and warmed up is when it starts doing it. I usually put it neutral at a light to stop it but it does it slightly. I havent really messed with anything since my last update but will once i get a chance.

 

[Fluffycakes2020]

Nothing new to share, been a crazy month. Car is still doing it and haven't changed out the little black bar thing yet but will. Haven't checked the battery or alternator but will soon.

 

[Fluffycakes2020]

Ok well one thing after another. After I did the coolant drain and stuff I was wondering why I had to keep putting coolant and researched it and figured out that probably my thermostat housing is leaking which explains why I smell the burning coolant. So any suggestions on a good brand? Should I replace with full aluminum or the half aluminum half plastic one?

 

[Fluffycakes2020]

So did an experiment today. Put dye in the coolant water and found where it's leaking at least what I can see from the engine bay. Any ideas on the source just by looking at this? Will jack up car and check soon.

 

[Fluffycakes2020]

https://pasteboard.co/JeuOvWF.jpg

 

[Fluffycakes2020]

Looks like water is on the passenger side axle so maybe water pump?https://imgur.com/EItjM68

 

[Chuzz']

Most likely the water pump as you've stated, but if there are any hoses above that side of the engine, I'd check them first. Sometimes a loose clamp or small split in a hose can fool you. I'm not familiar with your car, so don't know.

 

[Fluffycakes2020]

Well I already purchased the water pump so will be replacing that and the serpentine belt tomorrow. Problem I can't really get under there completely to see if there's a broke hose or something. I'll do this and wait and see if it still leaks

 

[Fluffycakes2020]

Finally got to get under to change water pump and it's not that. Turned out to be the ACDelco 55579102 Throttle Body Heater Outlet Pipe that broke at the throttle body.

 

[dannyg]

Thanks for letting us know what it turned out to be. I for one would never have thought of a Heater Outlet Pipe...

 

[Fluffycakes2020]

Tell me about it. One little crap cause all the water with the dye in it to leak out in the parking lot. I didn't think that much coolant came out of there but I obviously don't know how our coolant system works.

 

[Fluffycakes2020]

No real update, car still has the vibrating problem. Notice it more when the a/c is on 2. it vibrates then the fan kicks on and it stops. Havent really checked on anything else as i am out of options.

 

[Fluffycakes2020]

So no real update on the car since its been 3 months. The same vibrating issue is going on and the car has stalled a couple times just sitting at a light. The battery light comes on while driving highway speeds and then turns off and comes back on and then off so it makes me think alternator since battery is new. Any ideas on what I can look at regarding the vibration and stalling please let me know.