RS4 unintended accelerator surging

[minz]

Hey guys,
wonder if anyone can help with the following issue with my RS4 b8 2013. I have had the car for 2 years and was running great, no major issues. However, two weeks ago the issues started.

When driving the car at any speed it feels like it is in cruise control, for example I will be driving normally at 40mph in 4th gear, and instead of the car speed-reducing it is maintained like it has a mind of its own, in some cases the speed increases a very small amount without me touching the accelerator.

I have also notice fuel consumption has got worse, full tank lucky to get 200miles, I know it’s an rs4 but that is ridiculous.

I have also noticed a loss of power in low gears, not so much in high gears but to be honest once the v8 kicks in its hard to tell, however definitely loss its perkiness and responsiveness.

I have ross tech VCDS and no major faults recorded, no engine lights.

I have tried the following:
1. Cleaned both throttle bodies, used VCDS to successfully Align Throttle Bodies
2. Change one of the high-pressure fuel pumps, as I was told it was not running correctly. No change

Any help would be much appreciated, I am pretty handy fixing stuff on the car, so any suggestions would be most welcome.

[Outtlaw]

Surging can be down to a contaminated clutch, where one of the seals breaks down and lets fluid in!
This seems to come up a lot with those symptoms you're describing.
Just another route to eliminate.
Update us if you find a cure though please
HTH

[ryan1991]

Hello, I have this same problem too on my 2015 B8 RS4. Currenty in Audi Norwich for the second time. They tried a gearbox software update first time which did nothing (as I suspected). Now in again 4 weeks later and they have tried another gearbox software update and cleaned the throttle bodies. I have just told them thats what they did last time and suggested they do a glycol test on the gearbox oil. He has gone to speak to the technician again and coming back to me....watch this space.....

[minz]

Update: sorry for long post

Thanks for replying ryan1991 and outlaw

So car has been with an Audi Specialist for the last week, and I still don't have it back!. I booked the car in to resolve the issue I described. But because the following fault codes were recorded they suspected it was linked to this, which I explained these fault codes have been coming up way before my issue started, and this is a known issue by audi. Link below for info if people don't know of it. but they explained it could be getting worse and needed to be done and so I agreed

Faults code:
7036 - Thermostat for Mapped Engine Cooling (F265)
P0597 00 [104] - Open Circuit
Intermittent - Confirmed - Tested Since Memory Clear
7038 - Thermostat for Mapped Engine Cooling (F265)
P0599 00 [047] - Short to Ground
Confirmed - Tested Since Memory Clear

Link to resolve this issue below:
https://static.nhtsa.gov/odi/tsbs/2015/ ... 3-9999.pdf


so they completed the work and cleared the codes, and as I suspected the original issue is not resolved, they have since done the following:
1. Checked to ensure gear box has updated software: No change to my issue
2. Checked engine software updated: No change to my issue
3. Front final drive oil changed: No change to my issue
4. Rear axle oil changed: No change to my issue
5. Rear transfer box oil changed: No change to my issue

Now they don't know what the issue is and I am already £1300 in the pot! And no way closer to resolving the issue! The car is not driving as it should, now completely no fault codes. I guess the next stop is Audi

I have a suspicion it's one of the throttle bodies which has partly failed and not enough to bring up a fault code, the problem is I don't know how to check this without buying a replacement and wasting more money if it is not.

Ryan I welcome any news on the car and advice. I hope you manage to get it sorted

[ryan1991]

Hello minz,

I now have the car back and I think the gearbox map has helped the bad gearchanges, certainly the knock from 2 to 1 when coming to a stop and smoother pulling away again. However its has not cured it entirely or stopped the surging on acceleration. They did the glycol test which showed up clear and also cleaned out the throttle bodies. They did a 30 mile test drive and couldnt find any faults. They are actually being very helpful and suggested next time I am experiancing the surging to call them and take the master tech or service manager out for a drive to show him. So no complaints from a service point of view and I feel confident they will help me get to the bottom of it.

Sorry not a great deal of help but I will update you once I have had a chance to take the master tech/service manager out for a drive.

Do you think the surging could well be something to do with the throttle bodies and not necesarily contaminated clutch packs as a result of the broken gearbox oil cooler?

[minz]

Hi Ryan

Got the car back today. now has no fault codes, but the surging / sticking of the accelerator still continues, mostly noticeable in 4th gear as its town driving. i have not had any gearbox problems and it is running very smooth but i think the issue is linked to the throttle bodies and not necessarily contaminated clutch packs. I have VCDS and I need to find out how-to measure the throttle bodies when driving when the problem occurs..

hopefully, someone can advise, if not the only option is to purchase throttle bodies and hopefully it works. expensive option unfortunetly.
will keep you posted.

[ryan1991]

Hello minz, I have now done a lot more driving and the gerchanges are definately improved a lot since second software update. So perhaps throttle bodies is my issue too on the surging. Seems to be a strong possibility as the master tech cleaned mine obviosuly thinking they were a possible cause with the symptoms I have.

Interested to hear from you if and once you change them.

[minz]

Hey quick updated Ryan

Changed both throttle bodies from low mileage 2014 model, the issue of surging is a bit less, But it not fixed it unfortunately. Car is still surging at low speed and loss of power and very bad mpg. car is now booked in with Audi in the new year. Hopefully they will find the issue.

Will keep you posted.

[Outtlaw]

Nice to see a thread getting updates especially this one as this does come up quite often.
Hopefully you'll both get to the bottom of this and resolved at not too great a cost and get back to enjoying a fantastic car.

[ryan1991]

Hey quick updated Ryan

Changed both throttle bodies from low mileage 2014 model, the issue of surging is a bit less, But it not fixed it unfortunately. Car is still surging at low speed and loss of power and very bad mpg. car is now booked in with Audi in the new year. Hopefully they will find the issue.

Will keep you posted.

Hello Minz,

Ok sorry it didnt totally fix it, look forward to hearing how you get on at Audi. When is it booked in?

[Jay376]

Hi guys sorry to jump in on this but i have had a similar issue with my 2013 b8 not so much the surging i think but 3 times now when i've accelerated hard on the motorway the accelerator has literally stuck on and would not let off i had to try slamming the brakes several times to try slow the thing down, eventually it did each time .....proper scary moments when your hitting 3 figure mph and cant slow the thing down ...i've got it booked in to a local garage who know of this problem with the v8 engine so hopefully they can sort it ..possible build up in the throttle bodies holding the valves open ?? Whats peoples thoughts on this?

[Rusty Racer]

Wow, scary indeed

[ryan1991]

Hi guys sorry to jump in on this but i have had a similar issue with my 2013 b8 not so much the surging i think but 3 times now when i've accelerated hard on the motorway the accelerator has literally stuck on and would not let off i had to try slamming the brakes several times to try slow the thing down, eventually it did each time .....proper scary moments when your hitting 3 figure mph and cant slow the thing down ...i've got it booked in to a local garage who know of this problem with the v8 engine so hopefully they can sort it ..possible build up in the throttle bodies holding the valves open ?? Whats peoples thoughts on this?

Hello Jay376, sorry not been on here in a while. Thats very scary. I wouldnt be able to make any sujestions, did the local garge help at all?

[ryan1991]

Hey quick updated Ryan

Changed both throttle bodies from low mileage 2014 model, the issue of surging is a bit less, But it not fixed it unfortunately. Car is still surging at low speed and loss of power and very bad mpg. car is now booked in with Audi in the new year. Hopefully they will find the issue.

Will keep you posted.

Hello Minz, has your car been into Audi yet?

[Jay376]

Hi guys sorry to jump in on this but i have had a similar issue with my 2013 b8 not so much the surging i think but 3 times now when i've accelerated hard on the motorway the accelerator has literally stuck on and would not let off i had to try slamming the brakes several times to try slow the thing down, eventually it did each time .....proper scary moments when your hitting 3 figure mph and cant slow the thing down ...i've got it booked in to a local garage who know of this problem with the v8 engine so hopefully they can sort it ..possible build up in the throttle bodies holding the valves open ?? Whats peoples thoughts on this?

Hello Jay376, sorry not been on here in a while. Thats very scary. I wouldnt be able to make any sujestions, did the local garge help at all?

Yeah scary indeed, so my car has aftermarket diamond stich leather flooring and it turns out the accelerator pedal was getting hooked up on the matting when pressed hard, the garage ran diagnostics and found no faults but when they took it out thats when they realised it was the matting. All sorted now while it was in it had a carbon clean, fuel system clean, 4 new Dunlops and all 4 calipers were removed and overhauled and front pads replaced as the pistons were sticking on a couple of the calipers all for a really great price, i cant recomend them enough their service is outstanding.