Coupe running problems

[robonmac]

Its an age old problem i know but my 2.0 16v keeps on running like a dog.The revs peak and trough and when i kept my foot on the accelerator at 2000 rpm when stationery it rose to nearly 3000 rpm by itself and again dropped from 2000 to below 1000 rpm without moving my foot.Ive cleaned the ISV, just replaced the temp sender and am running out of ideas?Cheers Rob

 

[Rev-head]

Sounds like it is drawing in air from somewere ..........check hoses ...do the WD40 trick were you spray it round the inlet manfold and if it is drawing air in round there it will suck in WD40 and engine RPM will change

Cheers

 

[Rev-head]

Was the ISV in good nick ?........the more i read this it sounds like the ECU trying to combat fuel starvation...Fuel filter as well when was this last changed?

 

[robonmac]

To be honest the ISV came off a scrapper and was in good nick,i still cleaned it out and lubed it slightly and it appears to work i.e. it makes a noise when a current is applied.As far as the filter is concerned,then i havent changed it in the year that i have had the car!
The car almost stalls sometimes when driving and the revs even when they are steadyish still rise and fall very slightly.Does anyone have a layout/picture of all the breather/vacuum pipes on a 2.0 16 valve ACE engine.
By the way,this car has been busy in a former life seeing as though it has 178,000 miles on the clock so i should expect some running faults

 

[robonmac]

Now i'm getting cross!!!!!
In the long haul that is the quest of getting this thing to run better i decided to give it a new distributor cap and rotor.Crikey! these things are a ****** to get at,anyway getting the cap of wasn't much a problem but trying to get the rotor off was a b*****d why didnt anybody tell me bosch ones were glued on! i had to chip it off with a screwdriver and hammer.So i put on the "beru" cap (£30 quid!) and the rotor went on snugly but when it came to starting up the beast it didn't want to know.I'm sure the leads all went back in order and that all connections wre correct.Could i have damaged the hall sender which may of been already on it's way out,or moved something when i was smashing off the old rotor or is it purely something straightforward,i mean it turns but doesn't fire up.

 

[Rev-head]

You need VAG.com .........save you spending money were you dont need to ................i would take one of the leads of and make sure she sparking .if not then go back to the dizzzy and double check that everything is in place correctly

 

[enda1]

This sounds exactly like a problem I had on my 2.0 80. The throttle position sensor monitors the position of the inlet butterfly valve and was faulty, this caused the erratic idle. Mines is the single point fuel injection system whereas yours is the multipoint so may not be exactly the same.

 

[robonmac]

Now then i have cross checked and referenced that my dizzy cap is a direct replacement for the old bosch one and that the rotor arm is also the correct match for the new cap according to beru's reference system(very useful)www.beru.de but still the swine will not turn over,is it possible that i have dislodged something like a breather pipe or connector?i dont know,everything seems okay and looks as it should,there's juice in the tank and the battery is fine.I know i shouldn't do this but to see if there was a spark i twisted some kitchen tin foil tightly and inserted it into one of the ignition leads and held it to a part of the body(the car,not mine) and when turning it over it didnt spark but would it anyway? Could it be a case of coincidence that this problem has occured when changing the cap,maybe,stranger things have happened.Could the coil of packed in.Come on you lot this is surely meat and drink to you ,give me a list of obvious reasons why the bleeder wont start

 

[enda1]

Robonmac.
Any easier way to test for the spark is to take off one off the HT leads and attach to a spare spark plug. Hold the electrode against the engine block (hold the plug by the ceramic piece so you don't act as the earth). Get someone to turn the engine over and check for sparks. There is nothing wrong with doing this as normally when the spark plug is in the engine the block acts as the earth. The voltage gradient across the electodes causes the spark to jump across and this ignites the fuel air mixture in the cylinder.
What you should start doing is tracing the circuit back. In the centre of the distributor cap there is a cable that runs back to a transformer mounted on the bulk head of the engine bay. This unit takes the 12v supply and transforms it up to the high voltage for the sparks. When the rotor arm spins it makes contact with the electrodes in the cap and this sends the high voltage to the various plugs and causes the sparks. Check that you are getting 12v going into this unit with the ignition on. If you are getting 12v then it sounds like a new tansformer is needed. If not then its time to start checking fuses and relays.

 

[scotty33]

If you take a running car and replace the dizzy cap and rotor with the correct parts, it seems likely that something went wrong during this process. Have you checked that the rotor actually turns when you crank the engine? i.e. the drive for the distributor is as it should be. Other likely gremlin is hall sender. This is a component inside the distributor, and the wires going to it are slender and tend to go brittle with age, so working on the distributor often breaks the wires leaving you with a non starting car. It is possible to test the function of the hall sender using a l.e.d. I don't know the details, try a search? If it is dead, try www.probedistributors.co.uk for a repair Audi will want to sell the complete dizzy!