Need some advice on which direction to go

[iboughtatahoe23]

2014 Tahoe 177k miles. So the last few days, it’s been getting pretty cold and I noticed my truck kinda bogs down like it’s gonna stall for a split second when first starting it and than rpm go back up. I did a battery and alternator test with my OBD reader and it passed on battery but alternator failed both tests. (Took two to make sure) it has me hold the RPM at around 2000 for 20-30 seconds. So OK I’m like all right no big deal. I’ll order an alternator and get it taken care of. But I wanted to be 100% sure so I took it to AutoZone and have them tested with their little thing and I guess they are telling me my starter is failing and that my alternator and battery are fine. So I guess I’m confused because results are contradicting each other.

 

[mikez71]

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

 

[iboughtatahoe23]

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

Thanks for the reply… what’s ok exactly?

And I also had auto zone run some tests. There reader said starter was bad. But then again, everyone tells me not to trust AutoZone or any parts store for that matter.

 

[j91z28d1]

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

 

[89Suburban]

Can you post up video of what is actually happening?

 

[iboughtatahoe23]

Can you post up video of what is actually happening?

So for the bogging down thing for the split second after starting it, seems to be on the first initial start of the day after leaving the truck sit overnight or when I started after work after letting it sit all day it will do it. I’m gonna try to catch it tomorrow on video for you.


It just seems like when i start it first time in morning it will turn over and crank just fine but AFTER it starts it’s supposed to kinda rev the RPM up and than drop down. Well sometimes it doesn’t do that, it will just bog down like it’s gonna stall out and than will barely catch up and keep the vehicle running and than rpm’s go to normal. And this is all happening within like 3 seconds. Hopefully that sheds more light

 

[iboughtatahoe23]

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

I can’t speak for the wiring system at all or the negative and positive cables for the battery. The battery was in the truck when I got it in March 2023. Acdelco 94r

 

[iboughtatahoe23]

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

I will say I left the sun roof open when i first got it. Rookie mistake it was my first ride with a sunroof. Learned the hard way. I did have some strange electrical glitches and weird warning messages for a couple days after that, but I let it dry out in all of the issues went away, and the vehicle returned to normal. I don’t think that has anything to do with this, but I figured I would just mention it.

 

[iboughtatahoe23]

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

I heard these scanners can mimic just enough voltage to get a good reading

 

[iboughtatahoe23]

Sitting perfectly at idle… would that mean I can rule out the alternator? Sometimes the headlight dim when I first take off as well.

Taking it to my local
Shop tmrw to hopefully get some more answers.

 

[Fless]

Clean the throttle body and the idle air control (IAC) and check it for functionality.

 

[mikez71]

Thanks for the reply… what’s ok exactly?

The charging system.

Failing starter shouldn't cause the hesitation/bog you described..
Maybe if the starter gear wasnt retracting right away..and the engine is turning the starter, but you would probably hear some gear noise..

X2 what Fless said

 

[iboughtatahoe23]

The charging system.

Failing starter shouldn't cause the hesitation/bog you described..
Maybe if the starter gear wasnt retracting right away..and the engine is turning the starter, but you would probably hear some gear noise..

X2 what Fless said

Hmm sometimes I hear a pop or snap like for a split sec after the vehicle first starts in really cold weather. Starter grinding perhaps?


Here’s a video of me starting it this morning. @89Suburban. It was 4°. Didn’t bog down this time but cranked slow. Which I expect in my climate. But there’s that noise at the end I mentioned that could be the starter.

I’m almost tempted to just change all three… battery alt and starter. Probably do alternator first.

 

[iboughtatahoe23]

Clean the throttle body and the idle air control (IAC) and check it for functionality.

Cleaned throttle body recently… what idle air control.

 

[Geotrash]

Hmm sometimes I hear a pop or snap like for a split sec after the vehicle first starts in really cold weather. Starter grinding perhaps?


Here’s a video of me starting it this morning. @89Suburban. It was 4°. Didn’t bog down this time but cranked slow. Which I expect in my climate. But there’s that noise at the end I mentioned that could be the starter.

I’m almost tempted to just change all three… battery alt and starter. Probably do alternator first.

That's not the starter. It's your power steering pump cavitating because the fluid is much more viscous at that temperature and it takes a split second or more for the fluid to start moving. Having lived in northern climates from Alaska to North Dakota, I consider that sound normal. Many of my vehicles with hydraulic power steering would make that sound on first start.

 

[iboughtatahoe23]

That's not the starter. It's your power steering pump cavitating because the fluid is much more viscous at that temperature and it takes a split second or more for the fluid to start moving. Having lived in northern climates from Alaska to North Dakota, I consider that sound normal. Many of my vehicles with hydraulic power steering would make that sound on first start.

Ahhh ok yep. Northeast SD is where I’m at. Otherwise known as midwestern Antarctica lmao

 

[iboughtatahoe23]

I’ll keep trying to catch a video of it bogging down when I start it. Seems to come and go. Happens typically when I leave it overnight for long periods of time. Maybe none of these three things are that close to failing, idk. but I wanna catch it before it gets too cold. It could just be the cold weather. I just never recall it struggling to start in cold

 

[mikeyss]

It just seems like when i start it first time in morning it will turn over and crank just fine but AFTER it starts it’s supposed to kinda rev the RPM up and than drop down. Well sometimes it doesn’t do that, it will just bog down like it’s gonna stall out and than will barely catch up and keep the vehicle running and than rpm’s go to normal. And this is all happening within like 3 seconds. Hopefully that sheds more light

Mine is doing the exact same thing, it happens when I put it in drive or reverse (I either park in my garage or out on the side street). This is on my 09 Tahoe with a modified L9H.

 

[iboughtatahoe23]

Mine is doing the exact same thing, it happens when I put it in drive or reverse (I either park in my garage or out on the side street). This is on my 09 Tahoe with a modified L9H.

Maybe we can knock this out together

 

[Fless]

Cleaned throttle body recently… what idle air control.

The black thing is the IAC motor to control the idle.