UK Volkswagen Forum banner

Revs raising and dropping in third gear

2K views 29 replies 2 participants last post by  Crasher 
#1 · (Edited)
To understand the entire situation.

I found a lot battery acid on the battery tray.... but everything was still fine.... I still have my doubts.... Battery acid leak is not a good sign... but mechanic checked amps and it was still fine. He said test it out before we change battery.

Then the next day my start and stop started screwing around and that yellow Glow Plug/engine management light started flashing. I turned the car off and on and it disappeared. Did not go in limp mode.

Now I noticed in third gear at approx 50-60km per hour, when I accelerate suddenly.. the car power starts lagging and revs drop, for a fraction of a second at around 3k rpm. Its like it hesitates... then it continues to accelerate normally with good power.

Clutch is fine... no problems. Lots of power. Gear indicator on screen does not disappear, it labels the gear correctly. They say sign of a bad clutch is when gear indicator disappears.

Do I need a new battery? Or something else?
 
#2 ·
You need a code read before anything else. You will find the reason for the battery leaking is the battery monitoring unit which is part of the earth cable has failed, this confuses the digitally controlled via LIN BUS alternator which freaks out and sends 17+ volts to the battery which upsets it somewhat... AGM batteries don't take abuse very well. This is yet another nightmare inflicted upon us by the stupid stop/system.
 
#7 ·
I turned off traction control and it was fine, even in sport mode.

I did not know traction control was so sensitive. As well I think inflation tires to proper levels made a difference in its sensitivity
 
#16 ·
In modern cars, well maintained cars have very reliable mechanics but electrics are as vulnerable as they ever have been, more so as they have so much influence… it is ONE of the reasons I look at EV protagonists with dismay when they predict a more reliable future, they simply are clueless but have huge influence.
 
#17 ·
Ok, I will check this out. Its just strange with esc off its fine, and sports mode less evident.

In normal mode is when it happens.

I just changed air filter and changed oil as usual. Its strange
 
#20 ·
End of last week, but I thought battery was playing as came on at same time start stop error.

I have a manual gear box and this morning it flashed it appeared 4 times.

Its evident most on third and fourth.
 
#27 ·
If a clutch slips then the revs go up, not down.

The car is shown on the UK data base as being what we call SORN'd for Statutory Off Road Notification and not exported so at some point the previous owner will have to clarify the information with the DVLA or keep notifying as off road each year or they will get a fine.
 
#28 ·
They are going up now... as now its more evident. What I know is my car was bought at a auction in the uk. And I bought from dealer.
He showed me photos before they purchased it.

Anyways its mine for last 2 years
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top