B5 Audi A4 2.6 idle and throttle control issues - Tame Tech?
Discussion
Hi guys,
Quicker summary at the bottom of this post.
Looking for the fruits of your collective knowledge here. My car's a 1996 A4 SE, with the 2.6 12v engine. She drove perfectly on Tuesday night, and I parked up until Saturday. Come Saturday morning, the engine was very sluggish to turn over (I was actually in doubt that it was going to start at all), and then fired up to hold about 1800rpm. Normal idle speed is 850rpm or so, if very cold she might start as high as 1300, so this was very worrying. Then the revs started hunting repeatedly and quickly from 1500-1800, cycling up and down maybe once a second. I shut down, restarted, exactly the same.
I didn't have much choice but to drive it to work like that, and noticed doing that that the throttle was also being released very slowly - I'd back off, the car would keep the power on for maybe three seconds then remove the throttle. Also saw that, while the analogue clock was still correct, the digital trip meter had reset as it does when the battery's disconnected.
When I got to work, I tested the battery, found it pretty knackered, replaced it. Started up, exactly the same, repeatedly hunting.
A quick look around on the web said that disconnecting the battery for a half-hour can clear the ECU's memory for throttle and so on, not sure if this has any effect on my car but I disconnected for two hours and fired her up again. Same. There's a throttle calibration method, so I tried that although again, I don't know if it works for my car (key to ignition on, throttle pedal down for five seconds, key off, release throttle, leave key in but off for two minutes) but this made no difference either.
There are two breather pipes running from each cylinder head to the inlet just before the throttle body, and these were full of a yellow gunky crap. Took those and all the inlet components up to the throttle body, blasted them all out clean and dried them, still no better. In fact, the revs weren't hunting up and down when I tried it just now, but the throttle was still taking ages to close - if I blip the revs up to 3k or whatever, it'll sit exactly there when I let off for four or five seconds before dropping down to a too-fast idle around 1400rpm.
The throttle is cable-operated, but seems to move perfectly freely by looking at how the throttle body and all the linkages move when someone works the pedal. No pipes look to be broken or leaking, though I might not have been able to check them all. I'm fresh out of ideas as to what could be causing this..
So, summary - car starts up at 1800rpm, settles to very fast idle of 1400rpm, it takes five seconds to release any applied throttle, randomly starts hunting quickly between 1400-1800rpm. Throttle cable appears to move freely and allows both fully open and fully closed.
Anyone got any ideas?
Quicker summary at the bottom of this post.
Looking for the fruits of your collective knowledge here. My car's a 1996 A4 SE, with the 2.6 12v engine. She drove perfectly on Tuesday night, and I parked up until Saturday. Come Saturday morning, the engine was very sluggish to turn over (I was actually in doubt that it was going to start at all), and then fired up to hold about 1800rpm. Normal idle speed is 850rpm or so, if very cold she might start as high as 1300, so this was very worrying. Then the revs started hunting repeatedly and quickly from 1500-1800, cycling up and down maybe once a second. I shut down, restarted, exactly the same.
I didn't have much choice but to drive it to work like that, and noticed doing that that the throttle was also being released very slowly - I'd back off, the car would keep the power on for maybe three seconds then remove the throttle. Also saw that, while the analogue clock was still correct, the digital trip meter had reset as it does when the battery's disconnected.
When I got to work, I tested the battery, found it pretty knackered, replaced it. Started up, exactly the same, repeatedly hunting.
A quick look around on the web said that disconnecting the battery for a half-hour can clear the ECU's memory for throttle and so on, not sure if this has any effect on my car but I disconnected for two hours and fired her up again. Same. There's a throttle calibration method, so I tried that although again, I don't know if it works for my car (key to ignition on, throttle pedal down for five seconds, key off, release throttle, leave key in but off for two minutes) but this made no difference either.
There are two breather pipes running from each cylinder head to the inlet just before the throttle body, and these were full of a yellow gunky crap. Took those and all the inlet components up to the throttle body, blasted them all out clean and dried them, still no better. In fact, the revs weren't hunting up and down when I tried it just now, but the throttle was still taking ages to close - if I blip the revs up to 3k or whatever, it'll sit exactly there when I let off for four or five seconds before dropping down to a too-fast idle around 1400rpm.
The throttle is cable-operated, but seems to move perfectly freely by looking at how the throttle body and all the linkages move when someone works the pedal. No pipes look to be broken or leaking, though I might not have been able to check them all. I'm fresh out of ideas as to what could be causing this..
So, summary - car starts up at 1800rpm, settles to very fast idle of 1400rpm, it takes five seconds to release any applied throttle, randomly starts hunting quickly between 1400-1800rpm. Throttle cable appears to move freely and allows both fully open and fully closed.
Anyone got any ideas?
Its it bit old really for me, but I's say clean out the throttle body, if you didnt already and have some one try to do the basic setting of the throttle propperly with VAS 505x or VAGCOM etc.
Sounds like its lost its adaption/basic settings when the battery voltage droped out, does happen, even with the cabled ones.
Sounds like its lost its adaption/basic settings when the battery voltage droped out, does happen, even with the cabled ones.
Tame Technician said:
Its it bit old really for me, but I's say clean out the throttle body, if you didnt already and have some one try to do the basic setting of the throttle propperly with VAS 505x or VAGCOM etc.
Sounds like its lost its adaption/basic settings when the battery voltage droped out, does happen, even with the cabled ones.
Alright, thanks for your reply - I would've taken the throttle body off to clean it, but it looks a nightmare to remove and is up close to the bulkhead, that's why I just took everything up to it out. I did use my phone to get a look inside it and it seems clean enough on both sides, though.Sounds like its lost its adaption/basic settings when the battery voltage droped out, does happen, even with the cabled ones.
How much should I expect to pay to have the throttle adaptation done with VAGCOM? And is there any reliable way to do it without it?
Yeah what TT said. Clean and reset the throttle body. You can't do it without some sort of diagnostic system.
If you have a laptop (or a computer near enough to the car) you can get VAGCOM yourself. It is not as expensive as you think. You need a cable, Gendam sell them for about £20, or you can get some chinese clones off ebay for about a tenner but they are risky and don't always work. VAGCOM (now called VCDS) can be downloaded from Ross Tech's website. They do a shareware version.
I think to do basic setting you might need the registered version of VAG-Com, it is $99 from Ross Tech. A garage will charge about £30-40 so it will almost pay for itself instantly.
If you have a laptop (or a computer near enough to the car) you can get VAGCOM yourself. It is not as expensive as you think. You need a cable, Gendam sell them for about £20, or you can get some chinese clones off ebay for about a tenner but they are risky and don't always work. VAGCOM (now called VCDS) can be downloaded from Ross Tech's website. They do a shareware version.
I think to do basic setting you might need the registered version of VAG-Com, it is $99 from Ross Tech. A garage will charge about £30-40 so it will almost pay for itself instantly.
I'll have a closer look at the throttle body and see if I can get it out easily, but I'll put a video up on Youtube - it looks clean enough to me, rag comes back clean now?
I'm pleasantly surprised that you can get VCDS that cheap, thanks for the heads-up
will this version do everything I need here? It specifically states you can't do the throttle body alignment without the $99 licence, but it seems there are more expensive versions ones too. And is this the one that will work with the £20 cable you mentioned?
Thanks for your help
I'm pleasantly surprised that you can get VCDS that cheap, thanks for the heads-up
will this version do everything I need here? It specifically states you can't do the throttle body alignment without the $99 licence, but it seems there are more expensive versions ones too. And is this the one that will work with the £20 cable you mentioned?Thanks for your help
Yes that version will work with the Gendan cable, double check with Gendan that the cable will work with your car but it should be fine.
The benefits of the more expensive ones are they will work with a wider range of cars but if you are just getting it for your car then go with the cheap 3rd party interface. The more expensive version does have some extra features but you will be fine with the VCDS-Lite.
Like I say they are on Ebay for about £7-£10, I bought one off Ebay and it works fine but I know others who have bought the Ebay cable and it is rubbish.
Get a cable and make sure it works with your car in shareware mode before you buy the licence as you get limited support with 3rd party cables.
The benefits of the more expensive ones are they will work with a wider range of cars but if you are just getting it for your car then go with the cheap 3rd party interface. The more expensive version does have some extra features but you will be fine with the VCDS-Lite.
Like I say they are on Ebay for about £7-£10, I bought one off Ebay and it works fine but I know others who have bought the Ebay cable and it is rubbish.
Get a cable and make sure it works with your car in shareware mode before you buy the licence as you get limited support with 3rd party cables.
Awesome. I'm planning to get an S4 after keeping this car for a couple of years, so buying a decent cable seems worthwhile - there'll be a lot of VAG product to use it on!
Come the end of the month I'll get a cable, test it on the car, then get the software registered and see what I can do. I'll come back with the result, anyway!
Thanks for your help, both
Come the end of the month I'll get a cable, test it on the car, then get the software registered and see what I can do. I'll come back with the result, anyway!
Thanks for your help, both
..Well, an update was promised, and here it is!
I went back to the car yesterday morning to go into town, fired her up, she ran perfectly smoothly at the idle I'd expect for a cold start, quickly warmed up and settled to 800rpm. Smooth as anything. Revs cleanly, throttle shuts off properly and sharply, everything perfect - she drives even better than before this whole malarkey!
Incredible. The car seems to have completely relearnt everything.. I'm impressed to say the least and glad I didn't have the money to buy VCDS straight away!!
My advice to anyone coming across problems like this will be simply to drive through it for a couple of days and a hundred miles or so - the car might figure it out.
Awesome
Thanks again for your advice, though, chaps
I went back to the car yesterday morning to go into town, fired her up, she ran perfectly smoothly at the idle I'd expect for a cold start, quickly warmed up and settled to 800rpm. Smooth as anything. Revs cleanly, throttle shuts off properly and sharply, everything perfect - she drives even better than before this whole malarkey!
Incredible. The car seems to have completely relearnt everything.. I'm impressed to say the least
and glad I didn't have the money to buy VCDS straight away!!My advice to anyone coming across problems like this will be simply to drive through it for a couple of days and a hundred miles or so - the car might figure it out.
Awesome
Thanks again for your advice, though, chaps
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