So I noticed this weird thing that happens when I roll up the windows on my B7.
Basically right when the windows reach the fully closed point, the rpms slightly dip to almost stall speed for a second. I’ve only noticed it while stopped but I’ve never really looked for it while driving.
It only happens once every little while too. I can’t repeat it in succession but if I try again after an hour or whatever it’ll do it.
Any ideas? Alternator? Belts?
is it any of the windows, or only 1 in particular?
I’d peak around under the door cards to make sure a wire didnt come out of place and is shorting out
somewhat related, my brother is a vw tech, and he had a newer jetta come in a few years ago that would have all of these crazy electrical issues when it rained. He looked around, did some tests and then went to check the ecu box. Turns out the main wiring harness to the ecu had shifted and was now being hit by the wiper blade linkage, it wore through the sheathing and was causing different wires to short out everytime the wiper came down. VW ended up buying the car and sent it back to Germany for analysis.
the windows draw a fuckton of power on cars for some reason. Headlights will dim and RPMs will lilt when you close windows on many cars. Hard to believe.
makes sense, on my jeep the windows run through a 20A circuit breaker… 15 or so A on a econobox (assume you rolled up/started all 4 motors simultaneously) with a puny 70A alternator is quite a bit.
Thanks I guess that makes sense.
But why would it only happen once in a while? I’d have expected it to keep happening if I started continuously rolling up/down all 4 windows.
When it happens, are you also running other high draw stuff (headlights, a/c, heater)?
Have you replaced your battery recently?
no ideas. very weird.
You said ‘almost stall’. Is it really that bad?
mine do this as well, though i wouldn’t describe it as almost stalling. the interior lights also have a very slight flicker/pulse, both at idle. i’m guessing this is due to a wearing alternator, though this has been going on for a while and seems to be the only problem.
I would try replacing the battery, assuming this ‘issue’ just started. A weak battery could cause that dip in RPM because it doesn’t have enough juice to keep the motor going and the windows down
By almost stall, I mean the engine dips to a point where it slightly sputters then rev’s back up about 50-100 rpm past idle, then settles back down. This has only happened maybe two times. The rest of the times it drops anywhere from 100-400 or so RPMs then slowly goes back to idle.
If my windows are open then the AC and radio are usually off. The only extra thing I have is my dashcam, but this started before I installed it. It hasn’t gotten worse or better since installing it.
I’ll try checking the battery out first. Just tried reading one of the aux sockets with the car started and it was only ~11.2V for some reason.
The dipping RPMs is more of an annoyance but if it’s a sign of a failing components I guess I’d rather get it resolved.
If the voltage is that low with the car running, then it’s probably a bad alternator. Try testing the voltage at the batter with the car off. If that voltage reading is lower than the reading you got from the alternator with the car running, then you need a new battery. If the battery voltage is the same whether the car is on or off, then it’s a bad alternator.
My bet is on a bad alternator. You’d have other symptoms like weak or no starting if it was a bad battery
the 11.2v definitely suggests a weak alt, should be 13.7v. Try testing voltage between the alt and bat and voltage across the alt to make sure its a weak alt