Stumbling start (intermittently, so that's fun [still not fixed, apparently])?

[avenali312]

My car has done this a few times in the past couple of months to the point where I'm starting to get a bit concerned. I'll list out the last two times it has happened since they're fresh in my memory.

1. A couple of weeks ago I drove down to Florida (7-ish hour road trip), parked the car for an hour or two in the grass at a state park, and when I went to leave, it took a while for it to fully rollover and start. As always Florida is more humid than my home in Georgia.

2. Yesterday, I went into work a bit later than usual, so I had to park on the parking deck roof. Very foggy, dense air all day. Car sat there for the workday and when I went to leave, same slow start.

I had the electrical checked by O'Reilly. Battery, starter, and alternator all tested good. Battery is about 4.5 years old (and is a group 48 AGM). Valves were just cleaned around Christmas, so it's not carbon buildup.

But it doesn't feel electrical when it happens. It almost feels fuel related. It sounds like it's cranking strong, stumbles a bit, and then once it does start the RPM kind of flutters below 1k before going up to the normal cold start level of like 1,200-ish. It will sit there for a bit and then finally settle back down to the normal idle around 800. Once it starts, it feels fine and runs great.

My car is typically started in my dehumidified garage where I have never seen an issue.

Other things that I doubt are related, but may be useful:
- 2015 that is currently around 74k
- AFE dry flow filter that I do the full clean to every 20k
- MST inlet kit with the silicone tube and TIP
- New plugs at 60k
- Carbon cleaned around 72k
- I have fueled up a few times since the road trip, so I would hope if it was bad gas, it's out of the tank by now (always 93)

Maybe condensation affecting the coils or plugs? Any other thoughts?

 

[Diggs24]

Battery is about 4.5 years old

 

[avenali312]

Battery is about 4.5 years old

Yeah, I know that VW can test good one day and die the next haha. I was hoping the bigger, AGM would have lasted a bit longer than my original did. Well, I guess it did make it about 6 more months haha.

 

[OldVWFan]

Maybe the injectors are a little dirty and dribbling? Have you ever run some injector cleaner through it, like Techron?

 

[avenali312]

Maybe the injectors are a little dirty and dribbling? Have you ever run some injector cleaner through it, like Techron?

I have not, but with the recent carbon cleaning, probably not a bad time to run some through it.

 

[scrllock]

Very likely the battery, I'd change it and if it still does it, look at replacing injectors. When mine were going I'd usually have more trouble with warm starts.

 

[AdamSheikh]

4.5 years on the same battery - you must have some good luck. My batteries always seem to start going after 1.5-2 years down here in South FL.

But don't give the starter a pass. I was having intermittent/random slow starts a while back and it ended up being an aging starter on my 2015 with 150k+ miles. The new starter is night and day better even though my previous one was "fine" for many years - random starting issues are 100% gone.

 

[ElectricEye]

That battery is likely to leave you stranded soon whether it's the issue or not.
Best to replace it.
Try running a can of Liqui Molly Jectron through it.
My car was regularly giving me stumbling issues upon restart after a short drive. I'd drive the car to the gym - about three miles away, the car would sit for an hour while I worked out, and when I'd get in it and merge the car would stumble about three times in a row.
It felt like I was hitting expansion joints.
This happened nearly every time I made that gym run.
I've run Jectron through it a couple of times and haven't had the issue anymore.
It's been good for months.

 

[avenali312]

Thanks, everyone!

 

[avenali312]

Since I'm not stranded this time and need to get a battery at the nearest store after a jump, has anyone tried the Odyssey H6 AGM? FCP price is about the same as local alternatives from O'Reilly and AutoZone.

https://www.fcpeuro.com/products/automotive-battery-group-48-odyssey-48-720

 

[avenali312]

P.s. What is a MAP item at FCP? I've tried searching and can find nothing other than they're usually excluded from sales haha.

 

[scrllock]

P.s. What is a MAP item at FCP? I've tried searching and can find nothing other than they're usually excluded from sales haha.

MAP = minimum advertised price

 

[avenali312]

Decided to stick with my O'Reilly battery and will be picking up a new one today for peace of mind. Figured it was better to stick with something that's pretty common locally in case a warranty issue arises or something. This H6 AGM has treated me well. Interestingly enough, the H5 and H6 AGM are currently priced the same, so I'll probably just do another H6 and not care about the extra 8 pounds of weight in my daily driver haha.

Also dropped in a can of Jectron yesterday along with some Top Tier 93 from QT.

 

[avenali312]

Apologies for talking out loud so much in this thread, but I just saw that the Walmart Everstart Platinum H6 AGM appears identical in every way to all of the others (specs wise), has an extra year of warranty (4 compared to 3 at the parts store chains), and is about $70 cheaper. The casing and plastic mold also looks very similar, so is this just a case of all these batteries are made by the same manufacturer and just rebranded?

 

[AdamSheikh]

Apologies for talking out loud so much in this thread, but I just saw that the Walmart Everstart Platinum H6 AGM appears identical in every way to all of the others (specs wise), has an extra year of warranty (4 compared to 3 at the parts store chains), and is about $70 cheaper. The casing and plastic mold also looks very similar, so is this just a case of all these batteries are made by the same manufacturer and just rebranded?

There's only small a handful of battery manufacturers/factories here in the states so there's a ton of white labeling that goes on. Sounds like a solid deal with a good warranty - I'd go with that one.