Hello!

Briefing:

Audi A6, 1998, 1.8T(AEB), FWD, manual 5 gearbox (DHW), 130000km

new components:

PCV pipes/ valve
cam followers
timing chain/ chain tensioner
oil pump
aux pulley tensioner/ pulley
spark plugs
MAF
coolant temperature sensor
gearbox mounts
shock absorbers


remanufactured componenets:

throttle body
AC compressor
fan viscous clutch

Issue:

when A/C is ON and the engine/ weather is hot (above 25 celsius and sunny):

lack of response on throttle and jerky ride (engine brake is also violent and accelerating is delayed for secs)
when braking and I have to downshift, when uncoupling the clutch, the RPM goes to 500RPM and the engine shutters
when braking, the same amount of pressure on the brake pedal generates different braking behaviors (sometimes I have to apply additional pressure on the end of the brake not to smash the car in front)
on idle the car shutters (I can feel it in the pedals and seats; and also the gearbox stick is like possessed)
when applying throttle, the engine groans/ moans heavily (more under load and more in between 2000 and 4000 rpms)

The symptoms are 75% reduced when it is chilly/ cold outside (below 20 celsius) and (looks like) 100% if I turn off the A/C (I noticed however sometimes the same shutters' pattern but hard to notice)

So:

vacuums? high pressure switch on refrigerant circuit? A/C relay switch in dashboard? lack of cooling power? perforated brake diaphragm? outside/ intake air temperature sensor(s)? engine mounts? J valve? bypass valve ? blown turbo?

Let the game begins !

Alex

 

Can anybody tell me 1) how the hell you post your question in a new thread? and 2) Do you have to empty your 134a before replacing your a/c compressor switch? I have an audi TT 180 1.8L transversally mounted ATC... I checked the switch by jumping the terminals as I've read in one forum or another and that turned the compressor on but warm air was blowing. Once I replaced the terminal on the switch cold air started blowing again. Unfortunately this didn't last

 

Does any of this happen with the AC off? I only ask because you specifically mentioned that it happens with AC on. Except for the belt connection, AC is a separate system from engine and brakes.

It sounds like a cracked vac line to me. Have you tried a vacuum checker or looked into the vacuum check valves in your car?

 

Check your mass airflow sensor connected to your cold-air intake and unplug it and plug it back in.
It sounds like it is in limp/guardian mode.
I had a similar problem, I took my mass air flow sensor cable housing back about 8cm and then put some weatherwire on and made sure the housing was on good again,

Hope this helps.