My VRsick. Can anyone help?

[Matt Goodright 0]

I own a '93 VR6 automatic which has developed a fault it seems no one can explain. When started, the car will rev up and down continuously between 500 and 1500 rpm. the car will continue doing this until driven over 2000rpm. The car surges during this rev range, like a dog on a leash and it seems the only way to control my 'dog' is to keep it above 2000 rpm where the car functions as normal, although mpg is at best 18 when normally it is 25 mpg. Having taken the car to Rye Mill, the diagnostic check found a fault with the hall sender and possibly the throttle valve. Having replaced the hall sender, throttle valve and air flow meter, I am no nearer to finding the answer to my problem. Incidentally the passenger side window has taken a mind of its own and will go down when the idriver door is opened (?!!) I have been informed this maybe a result of the existing problem. Like a knock on effect. Does anyone have any ideas?

[Kevin Bacon 5]

Sounds like the MAF (Mass Air Flow meter) to me. I know you've have a new one put on but I know of 3 instances (myself included) where the new ones were faulty. Get it scanned again on the diagnostic machine and look for "Intermittant short to Ground - G40 - Mass Air Flow sensor".

 

It's normally on part throttle you notice MAF issues as the Lambda probe and MAF are constantly consulted to keep the emissions low and part throttle running smooth. Any discrepencies here will cause the car to buck.

 

Failing that, surging below 2000 can also be attributed to a faulty lambda probe, as can your 18mpg.

 

Clean the Idle valve and throttle body butterfly too as these two can cause part throttle running irregularities.

 

Not sure about your electric window problem. Didn't get any water on the switches did you as it pours through the window and straight onto the switches if the window is open when raining.

 

Oh and welcome to the forum 8)

[Guest]

If the throttle position sensor (TPS) is replaced, the transmission control module (J 217) must "learn" the voltage value of the new potentiometer (calibrate to the TPS resistance range). The same applies if the cable is adjusted or the throttle body replaced. You must also check that your kickdown switch is working in the correct range. Whoever did the work on your car should've set basic settings on your Auto transmission module. To DIY, you'll need VAG-COM & a Bentley manual.

 

The electric windows operate on different circuits depending on whether the doors are open or shut - you've more than likely got a short circuit - usually occurs where the wiring passes through the hole in the door between the hinges - it can chafe on the bodywork.