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#11
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A6 Audi "Hunting"!...
On May 26, 12:22*pm, tony sayer > wrote:
> >> The small garage where I normally take it they have a visiting Auto > >> electrician who put it on his analyser who said it seemed alright and no > >> fault codes that he could see of. Our local main dealer said they didn't > >> have that diagnostic unit around anymore either. So before I start > >> changing bits on a trial basis anyone ever had this before and any idea > >> which part of the system it might be causing that?. > > >> Perhaps I should take the garages advice and get a younger model but > >> while this ones running fine apart from the above and has passed the > >> last 10 odd MOT tests with sod all wanting doing I'd like to hang onto > >> her for a while yet... > > >> TIA.... > > >> -- > >> Tony Sayer > > >1996 A6 1984cc ABK petrol. > >The Idle control v v can be taken apart and cleaned with WC40 *or the > >like. *The thing with the electrical connector comes out of the > >plastic air intake and the rubber hoses. *You'll see the v v part and > >you can push it in or connect it to the battery and see it work. Spray > >into the v v to clean it. *The thing with the electrical connector on > >doesn't come to pieces without hacking it. > > It has already been changed and yes, it does work the engine note alters > when you plug and unplug it. > > Odd but when its hunting up and down the rev range unplugging that does > cause it to settle when plugged back in?... > > > *Find the engine control > >relay, on my A6 it is in the passenger footwell at ones left foot. > >This can cause lots of problems. *It has a number. * > > Yes changed.. > > >The computer is > >also down in there to the front where it can get wet if the drain > >above gets blocked. *Pull the big long connector off and put it back > >on again, have a look for white powder or discolouration on the > >contacts. *Spray it with WD 40. > > All clean and dry.. > > >There is info on the net, pos in this forum. > >Check all the inlet hoses and connections. *Check all the wiring > >connectors, pull them off and push them back on again. > >An Autodata CD has some info. > >The Throttle sensor is at the bottom of the throttle housing. > >There is a setting for the Throttle you'll see an adjusting bolt just > >at the end of the throttle wire on top of the throttle housing. *If > >this is worn or loose then it could cause the butterfly flap inside to > >close. *Dirt can accumulate on the butterfly v v and inside the inlet > >manifold. > > Well thats clean.. > > I'll check the operation of the throttle stop and sensor. > > FWIW changed the water temp sender, well both of them as the motor > factors had them going cheap, anyway its now slightly better when really > warm tends to behave a bit more i.e. correct idle speed for longer. > > And the water temp gauge works.. > > thanks for all who helped .. appreciated... > > >I'll not go into detail here as there is a lot that can be done to > >sort this little problem, however there was a lot of info on the web > >about this type of problem. *It'll be easier if you have a book / CD. > >The Auto data and another that I got didn't have everything in them > >about the A6. *The Haynes isn't a lot of good these days but it might > >be better than nothing, I have never had a Bently workshop manual so I > >can't comment on it. A nice big multimeter is good, one with large > >numbers is better as sometimes one is some distance from it when doing > >checks. > >You can get a thing from Gendan that reads fault codes. > >A garage may not have the information to do a check on the idle > >control v v. *Some of the checks are done with the engine running and > >if I remember there is 14v and 5 v. > > -- > Tony Sayer- Hide quoted text - > > - Show quoted text - 1996 A6 1984cc ABK petrol. It has already been changed and yes, it does work the engine note alters > when you plug and unplug it. Some of that era had a get you home setting on the computer. So when the ICv v is unplugged the computer may go to, get thee home mode. One possible way to check that is to uplug the ICv v and then drive the car and see if the speed is limited. Odd but when its hunting up and down the rev range unplugging that does > cause it to settle when plugged back in?... Could be because the v v is closed and it takes a little time for the comp to adjust to the new info'. The MAF shall show a slight vacum/low pressure/ volume/flow of air = less fuel needed. If there is a small leak on the inlet system after the MAF/VAF (and other names) the leak can cause the exhaust oxygen content to be higher and so the O2 sensor on the exhaust informs the comp so. The comp adds more fuel and so the see saw hunting occurs. If the O2 sensor is malfunctioning it can cause hunting. If the fuel rake pressure is too high/low it'll cause hunting. If there is wear on the HAL sender spindle the timing can fluctuate as it can do it the timming belt is worn or the tensioner a bit stiff. Loads of other stuff, too much to type about. FWIW changed the water temp sender, well both of them as the motor > factors had them going cheap, anyway its now slightly better when really > warm tends to behave a bit more i.e. correct idle speed for longer. And the water temp gauge works The CT senders have to be same as the originals, ie their resistance needs to be within a window if they are not then the reading of the senders can be wrong. The VIN number needs to be used to get the correct ones. e.g I put a gauge sender from an A4 onto the A6 and it showed 52°C. I put another sender on and it showed 92°C. Basic settings needs to be done somehow, I have not found out much about it except that I need to pay for it to be done, it's not been done for 5/6yrs. Our local main dealer said they didn't > >> have that diagnostic unit around anymore either There is info' on the web about VAGCOM which is (maybe) the diagnostic gear. There is an american company that sells (www.ross-tech.com) software which can be put into a laptop (size counts) and there is a cable (special bit) to connect up to inside the black box with some of the fuses and relays in. On mine this black box (there are several black boxes) is on the RHS (UK) under the lid in the plenum below the drivers wiper. Auto > >> electrician who put it on his analyser who said it seemed alright and no > >> fault codes that he could see of The fault codes are in the comp' not in the ICv v. The diagnostic connections/connectors are not the same for OBD1, 2,3. The lecky ud need the connectors for that vehicle type and yr(s). He'd also need a VAGCOM or the Ross Tech type thingy to get accurate readings and the workshop manual to do the tests as one needs to know the voltages/ resistances. The voltage/resistance can be done with a multimeter but one needs to make up wiring to carry out the checks. Still a lecky who is familiar with the make and yr could know where to stick the probes etc and what to expect. |
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#12
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A6 Audi "Hunting"!...
>The fault codes are in the comp' not in the ICv v. The diagnostic
>connections/connectors are not the same for OBD1, 2,3. The lecky ud >need the connectors for that vehicle type and yr(s). He'd also need a >VAGCOM or the Ross Tech type thingy to get accurate readings and the >workshop manual to do the tests as one needs to know the voltages/ >resistances. >The voltage/resistance can be done with a multimeter but one needs to >make up wiring to carry out the checks. >Still a lecky who is familiar with the make and yr could know where to >stick the probes etc and what to expect. Well thanks for all that Donk, interesting stuff. Well the temp gauge registers fine (90 deg C) and on one or two days last week she was almost behaving tickover at 820 RPM all the time, other days up to the olde tricks. Seems a bit temperature related it seems on the day when all was almost well it was around 12.5 deg outside so its a good pointer as any. Might take her out later when its colder as deffo the other day when it was hot she was at it again. Still overall its a bit better so going in the right direction cheers all... -- Tony Sayer |
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