High Idle with slight misfire

[220bhp]

Just wondering if anyone has any thing to say about the post pppppplease

[twoqu]

I had the fault codes pulled on my car today,and it looks as if you may be right Porkkis,it came up with 00513 Engine speed sender-g28 .
There where 6 other faults but they could of been caused by me pulling wires of while the car was running.They are as follows.

01257 Ideling speed stabilization valve.
Opencircuit/shortcircuit to ground [GND] I have replaced this

01247 Active charcoal filter system soleniod valve1-N80
Open circuit/short circuit to ground [GND]

01262 Solinoid valve for charge pressure control=N75
Open circuit/short to ground [GND] replaced 18mth ago

01250 cylinder 2 injector-N31
Open circuit/short to ground sporadic [GND]

01249Cylinder 1injector N30
Open circuit short to ground sporadic [GND]

Knock sensor1-G61
No signal

I confess I have no idea of the affects the above faults have on the car and would would very much like to hear from anyone who has any ideas

Many thanks Lou

Pretty sure that the speed sensor comes up even if there isn't a fault which makes trouble shooting it problematic! Did you reset the ecu and then test?
Other than that you are going to need a multimeter to do some elimination. If you have one then we can probably test some of the components to see if they are dead.
Of course it may be that you have picked up some crap in the fuel or something. Certaintly two injectors not working won't help. Depends how far you want to go. For peace of mind you could have the injectors tested and cleaned for example.
The dead knock sensor will need replacement I guess.

[220bhp]

Thanks for your help twoq. No I have'nt had it retested yet, just checked and faults cleared. I will get it rechecked to see what faults reappear.Just to exsplain I had the engine out and rebuilt last year,replaced one knock sensor ,the rear one,and the speed sender,but I think there are two right or wrong! if so I gess the other could be shot. I dont have a multy meter but I think I no where to get one. With regard to the faults logged about the injectors and the ISV I did pull the wires of while the car was running would this have logged a fault, just a thought. many thanks Lou.

[nigelm]

Idle problem

My trawl of the literature suggested:

ISV
MAF
small bore vacuum hoses of which there are plenty - replace all originals with silicone if possible
loose grounds
battery condition
lambda probe

There are posts on the original yahoo groups site with exactly your symptoms.
My bet is small bore vacuum hose leak.

nigelm

[220bhp]

Thanks for that mate. I have some new vacume hose to put on,battery is new changed ISV and MAF I will do the lambda to illiminate that and check the grounds
cheers Lou.

[220bhp]

Went to the new TT launce at my local audi dealer today,and got talking to a an audi techn'cian who has worked on the I5. told him how the car was running, ie at around 1400 revs {at standstill that is } it revs up and down on its own.
His answer was hall sender, which on my car a 3b is in the distributor. he said that if the ecu could not read TDS from the hall sender it would read it from the speed sender and the car would run but not well.
As you cant buy a hall sender on its own I have ordered a new distributor. In the mean time I have replaced the thermostate the multy function tempreture sensor ,taken the fuel rail off and checked the seating of the injectors {no 5 was not seating the same as the others } replaced some more vacume hoses, including the long one from the dv. And the result is the car runs a little better, the tempreture gauge now works,but runs at around 100degres, and there is still a missfire at low revs, it still has the id'el problem, and there is still no boost, but thats an old problem ,still waiting for the next GB on boost hoses. my main consern is the fact that it runs hot.I would like to know if anyone thinks that running problems and the fact that the car is overheating are related ,or if they could be seperate issues.

MANY THANKS LOU

[220bhp]

Anyone with any helpful answers

[Jon441cc]

You say your car is overheating, does the multi-stage fan kick in at 90 degrees, have you tried swapping your TPS sensor with the one from your S6?

[porkkis]

Well I can say that the "professional" technician didn't know what he was talking about. Hall is only used when starting to find out on which rotation the bottom end is. From there on it's there just to provice info about current cylinder for knock control. The car will run fine without it but will not start.

The RPM sensor is accurate and it alone can keep the engine running.

Indeed G28 fault shows up always if the codes are pulled when the engine is not running.

Try this: Start the engine, unplug hall from dizzy base, unplug TDC reference sensor (can't remember gray or black, the other one is the RPM sensor, if you unplug the RPM sensor engine will stall).
If the engine keeps running as it should you can be sure it's not the RPM sensor playing up.

And of course the fault may be elsewhere but misfire with combined high idle tells me that there is something wrong in the triggering system.

[220bhp]

Thanks very much for all your help Porkkis. I am out of my depth here as you can proberbly tell. I will try that today and let you know the result,but I am not sure what you mean by the triggering mech'anism.Do you think there could be a link between the cars problems and the high tempreture that the car is running,just on 100deg and it heats up very quickly. I checked the thermostat in hot water and it was ok but still replaced it with a new one and its still runs at 100deg, so I am reluctant to use the car until I find the problem.
many thanks Lou.

[220bhp]

Well I have tried all the suggestions and the car is still the same.thanks for all your help guys but I have failed you, all your wonderful and much appreciated advise and I still can't find what is wrong.I just feel that I am not following your instructions correctly and not doing things wright, so I am going to do all the test again just to make sure that its not my stupidity. however as I said pre'viously I ordered a new distributor, which arrived today. So with a bit of much needed help I set about changing the distributor,how on earth do you do that, hidden right at the back there,so any advise on changing it would be very help full.
I have managed to take the distributor cap of [Which was new by the way when the engine was rebuilt 3000ml ago] and we found that there are quite a few tracking marks where its been arching across, I have no idea what has caused this but it must be the cause of the misfire,and the idel is another issue,we will see when I redo the tests and fit the new distributor hopfully with a bit of help from you guys
Many Thanks LOU

[220bhp]

I cant seem to find the reason for my cars problems, still idels at 1200 hunts at 1450 ,missfires at revs below 2200,and running a little hot. So today I had the fault codes pulled again at a differant garage, cleared the faults ,ran the car for a few miles and pulled them again.The faults were as follows.

IDEL ACTIVATOR

CANISTER PURGE VALVE

BOOST CONTROL SOLENOID VALVE

I gess the boost control solinoid valve is the n75, which I replaced two years ago ,but I have no idea where or what the other two are, can anyone help please

Lou

[220bhp]

[twoqu]

Not having a lot of luck are you!
Have you checked all the fuses. Having looked on Paul's site it looks as though S24 feeds all those components with power. As these faults have reappeared since, its a possibility!

[220bhp]

Thanks for your help twoq,I will check the fuses. the strange thing is the main beams have just failied together with the blue light for main beam on the dash dip is ok, so I am beggining to wonder if I have a wireing fault. I will get it checked out ,
Many thanks Lou