RS4 only 263whp flat from 6k rpm ?!?!

[2manytoys]

***** UPDATE ******

Carbon Buildup caused the below! This is a serious problem, but easily checked.

The simple way to test is:
1. Drive so you can get into second gear.
2. Put your foot flat, and feel the car pull.
3. If you don't have a second burst of power around 6k, and the car revs quicker, you have a problem.

Update 25/07/2010
The engine is now being stripped by Audi to find the ongoing cause of the carbon buildup and retarded timing.

************************************************** *******************


Firstly, Hello everyone. I'm been reading these Forums since January this year and it's a great source of information.

My name is Mal, and I'm from Sydney Australia. I've owned my RS4 Cab since January. It's a great car, and even more special here given Australia only received 26!

Anyway, here is my problem. My RS4 only produces 263whp from about 6k and stays flat to 8k. It's very odd and something is obviously wrong.

Can anyone provide any suggestions about what may be the problem. See RS4 Dyno Graph below.



A little extra info:
1. Car seems to ping at random (but always used High Octane (98 in Aus = 93 in US). It doesn't only happen on high load, it can happen at any time.
2. Intake Manifold Flaps checked by Audi and they seem to move ok
3. Timing Advance is only 9-15 degrees at 6k rpm while under load (checked on VAG tool)

Any help would be great.

Thanks, Mal

[Yessir Man]

my first guess would be carbon build up

[justinperkins]

umm, why doesn't the torque line cross the power line?

edit: nm. THE METRIC SYSTEM BROSEPH!

[durrmcdanks]

^ yeah

Something smells fishy

[04-S4]

umm, why doesn't the torque line cross the power line?

I was thinking the same thing... Power and torque always cross at 5,252 rpm. Always.

[justinperkins]

I was thinking the same thing... Power and torque always cross at 5,252 rpm. Always.

apparently not when you're in the southern hemisphere

[CapeQuattro]

RS4 in Australia

...I remember stalking one I saw at the Mall, damn how expensive things get once you leave the US.

[drew]

it goes without saying that something is very wrong if you are flat from 6k to redline.

could very well be a dyno error. how does the car feel from 6k to redline on the street?

[Sharkfin]

If you've been on here since January, you've seen all the commons problems with the RS4, have you checked your car for those issues?

[2manytoys]

Yep, have read a lot:

1. Carbon Buildup, but this seems to just lower power, but the curve is still a normal power curve if you have it (just less power)
2. Faulty Vacuum, or leak, that causes the Intake Manifold Flaps to not open (got Audi to check this today, all good.. they saw the little white lever move and the computer showed it was open 99%)
3. DRC, yep had this twice so far, and waiting on new parts

Regarding the graph, I agree, you normally see the torque line cross, but this is normally just a scale thing with the plot. You'll notice on my graph torque falls away about 6k, consistant with the power flat line. Driving it is the same. It makes all it's power by 6k and seems flat from there.

Also, the Dyno was done on the same day as about 40 other cars (A4 2.0T's, VW R32's GTI's, a Ferrari, RS6 and an old Porsche (1970's putting out about 330awhp!!)). All the cars ran well with nice "normal" graphs.

My mate, and European Car Mechanic, seems to think the computer is limiting power for some reason. What could cause this?

Mal.

[fusionx]

Yep, have read a lot:

1. Carbon Buildup, but this seems to just lower power, but the curve is still a normal power curve if you have it (just less power)
2. Faulty Vacuum, or leak, that causes the Intake Manifold Flaps to not open (got Audi to check this today, all good.. they saw the little white lever move and the computer showed it was open 99%)
3. DRC, yep had this twice so far, and waiting on new parts

Regarding the graph, I agree, you normally see the torque line cross, but this is normally just a scale thing with the plot. You'll notice on my graph torque falls away about 6k, consistant with the power flat line. Driving it is the same. It makes all it's power by 6k and seems flat from there.

Also, the Dyno was done on the same day as about 40 other cars (A4 2.0T's, VW R32's GTI's, a Ferrari, RS6 and an old Porsche (1970's putting out about 330awhp!!)). All the cars ran well with nice "normal" graphs.

My mate, and European Car Mechanic, seems to think the computer is limiting power for some reason. What could cause this?

Mal.

All dynos read differently. I don't think I have ever heard of the dyno they used for your car but there could easily be an error in how they set it up or its just a REALLY low reading dyno.

[2manytoys]

RS4 in Australia

...I remember stalking one I saw at the Mall, damn how expensive things get once you leave the US.

Yeah, it's crazy. They were more than $200,000 here, and from what I've seen less than $80k in the US I need to more to the US

[2manytoys]

All dynos read differently. I don't think I have ever heard of the dyno they used for your car but there could easily be an error in how they set it up or its just a REALLY low reading dyno.

Yep, agree 100% and if I was the only one there I would have taken it to someone else for a second opinion.

Just to clarify guys, it's not the peak power I'm concerned about, it's the flat line between 6-8k rpm.

PS: My brothers 2006 A4 2.0T with REVO Stage 1 put down 178awhp (which seemed about right).

[KryptoniK]

Hmm that does look very odd. Not sure what to think about it. How does the car "feel" to you while driving? I would try another run on a different dyno if you can just to double check.



Here is a chart from my RS4 with all my engine mods listed on the chart (minus methanol):






For comparison, here is the chart from my previous b7 S4 with the same mods:

[duud40]

Jesus guys...
Torque graph crossing the power graph at 5250 or whatever rpm only happens when you use us measuring system lb-ft and hp I guess.
Check your timing mate... Stock should be in the range of 30 degrees btdc.

[justinperkins]

Jesus guys...
Torque graph crossing the power graph at 5250 or whatever rpm only happens when you use us measuring system lb-ft and hp I guess.

Please explain.

edit: nm, the magic 5250 comes from the 550 ft-lb horsepower constant

[NY07RS4]

Jesus guys...
Torque graph crossing the power graph at 5250 or whatever rpm only happens when you use us measuring system lb-ft and hp I guess.
Check your timing mate... Stock should be in the range of 30 degrees btdc.

^^^lol - you beat me to it. Different units of measure.^^^

[2manytoys]

Timing has been checked (as first post, it's between 9-15), but it's only a measure of what's happening. The thoughts are it's being retarded because of something else (faulty knock sensor, vibration somewhere etc) but either way that's the something else I'm trying to find :D

As per the two other graphs posted, yep, agree 100% there, and that's what I'd expect to see (from curve point of view, not worried about peak power at this stage).

The other odd thing is, as the power flattens you'd think you'd feel it, like ESP coming on and reducing power, but it's smooth, and drives well. I suspect it's been this way from day 1, or it's a gradual thing and I thought I'd just been getting used to the power.

Mal.

[jfunkey]

Wow look into the timing for sure. that is not right even if you are on poo gas.

[CapeQuattro]

Yeah, it's crazy. They were more than $200,000 here, and from what I've seen less than $80k in the US I need to more to the US

Oh yuh it's ridiculous. I went to go price out my current car when I was living in Australia...with all my current options it was over 100K once converted back to USD. Needless to say I moved back before I bought the car. On the plus side though, you guys do get cooler cars like RS4 avants and the C6 RS6!

[04-S4]

Jesus guys...
Torque graph crossing the power graph at 5250 or whatever rpm only happens when you use us measuring system lb-ft and hp I guess.
Check your timing mate... Stock should be in the range of 30 degrees btdc.

Crap. I fail.

kilowatts cross Newton meters at 9550 rpm, right?

Missed that one.... Damn Metric system! lol

[two2]

so have you checked for carbon?
also on some of the older audi's there were some issues with catalytic converters clogging up i heard.. was this ever true? a friend of mine had a b5 A4 and the car had lost tons of power.. turned out the cats clogged with soot and carbon.

[2manytoys]

I'm going to check carbon build up ASAP.

On that subject, my mate is a Pipe Locator and has these really small hose things with a camera and light on the end. It's sort of remote controlled. Has anyone used one of these to check for carbon? Is there anything that I should be aware of before I just poke it in the air intake (if it's even possible?)

[Nor Cal RS4]

You posted over on Audiworld that you had detonation too. Flat power and detonation seems like an exhaust restriction to me, I would look for failed catalytic convertors causing exhaust flow restriction myself.

[2manytoys]

Yep, that's right. It's the strangest thing. I use Premium Fuel (98 RON = to 93 in the US). Every now and then the car will ping. It's at random. Sometimes I've heard it just as the clutch comes out during a slow take off, other times cruising at 60k's and gently pressing the go pedal. It happens for a split second and then stops (I assume that when the timing is pulled back).

Mal.

[KryptoniK]

2manytoys:

Is your car completely stock? Not sure if I missed that bit of info...

Now that I think about it, I had a similar loss of power a while back (no dyno proof). It ended up being the rear exhaust flap vacuum tubes that were unplugged causing a leak in the vacuum system. It was as if the power would flatline at around 5-6K where I used to feel a surge of power. After the hoses were plugged, problem instantly solved!

Just one other thing to check you know..

[RS4POWER]

I'm going to check carbon build up ASAP.

On that subject, my mate is a Pipe Locator and has these really small hose things with a camera and light on the end. It's sort of remote controlled. Has anyone used one of these to check for carbon? Is there anything that I should be aware of before I just poke it in the air intake (if it's even possible?)

I highly doubt this is possible. There aren't too many borescopes I know of that can be inserted into the throttle body and snake all the way down to the intake valves (it would have to get past the manifold flaps also).

Maybe he could stick a 90-degree head ino the combustion chamber and hope the intake valves are open in that cylinder. The only thing is "most" borescopes won't provide enough light to actually see what's on the vlaves.

[richib86]

that's strange I've seen timing as high as 42.5 degrees on my car granted it's not stock, when it was stock I saw 28 degrees on a BAD day. something is def retarding the timing drastically

[RS4POWER]

that's strange I've seen timing as high as 42.5 degrees on my car granted it's not stock, when it was stock I saw 28 degrees on a BAD day. something is def retarding the timing drastically

Fuel quality, Octane, ambient temps are all key players.

[2manytoys]

Yep, car is stock and the vacuum hoses are blocked 100% (a screw and 2 clamps). This is confirmed as the Intake Manifold Valves are moving as expected.

It seems to be pinging more now (more often). I know it's predetonation, so now I'm worried it's eating the top of the piston away. Is this possible if I'm hearing it for a split second every 3rd/4th time I need to accelerate?

[LODOSS]

Is it possible the MAF is not reading correctly?

[Blackcoog]

Check the plugs yet? Pull them out and check for anything out of the ordinary. Maybe your car has a faulty coil on plug (COP) creating misfires. Do you have any check engine lights or codes? I'd think any type of sensor malfunction, vacuum leak, or misfire would pop a code.

[richib86]

^^^ you would think that, i used to get faults without a light. luckily i have a vag com and am anal enough to check the car regularly lol

[Ill 3.0]

Check the plugs yet? Pull them out and check for anything out of the ordinary. Maybe your car has a faulty coil on plug (COP) creating misfires. Do you have any check engine lights or codes? I'd think any type of sensor malfunction, vacuum leak, or misfire would pop a code.

I'd definitely do this, also might as well put in a compression tester and check cylinder compression while you're at it for peace of mind.

[Blackcoog]

I'd definitely do this, also might as well put in a compression tester and check cylinder compression while you're at it for peace of mind.

Good idea. While you are pulling the plugs it would be easy to run a compression test. Compression testers are cheap at any autoparts store and the test is pretty straight forward. Make sure you do it on the engine after it has been warmed up though. The numbers aren't valid when it's cold. Make sure ALL the COP units are disconnected, pop a plug out, screw the tester into the plug hole, gas pedal to the floor (shuts fuel off), crank for a 5-10 seconds, and record the reading. Do this for each cylinder. Google compression test for more info.

[Ill 3.0]

Good idea. While you are pulling the plugs it would be easy to run a compression test. Compression testers are cheap at any autoparts store and the test is pretty straight forward. Make sure you do it on the engine after it has been warmed up though. The numbers aren't valid when it's cold. Make sure ALL the COP units are disconnected, pop a plug out, screw the tester into the plug hole, gas pedal to the floor (shuts fuel off), crank for a 5-10 seconds, and record the reading. Do this for each cylinder. Google compression test for more info.

Yup. I think the testers are about $25-30. I pulled the fuel pump fuse (in addition to all ECM fuses). I also removed all plugs, but I'm not sure that is necessary. Make sure you use the correct threaded (14mm on my B6) end and not an extended end. Hand tighten the tester. Its nice to have someone watch the gauge while you crank the engine with the starter, usually 6-8 cranks will be enough. Stop when the pressure plateaus and avoid cranking more than 12 times so you don't risk over-heating the starter. Record value, release pressure, remove tester and you're done.

[Speed Blue]

Yeah, it's crazy. They were more than $200,000 here, and from what I've seen less than $80k in the US I need to more to the US

I own a RS4Cab as well and parted US$ 272 grand for this beauty in Singapore!

[2manytoys]

ok, I'll get the plugs checked. The car has about 40,000km (25,000 miles). The car runs smooth, even at the top end where power is reduced.

SpeedBlue - Yeah I heard cars were hugely expensive there! I guess I should stop complaining :-)

[2manytoys]

Thought I'd give everyone a quick update:

The RS4 was in the dealer today for a bunch of tests (Injectors, Coil Packs, Fuel Pressure, Mixture, etc). Unfortunately this all come up good. The tech is very thorough and quite helpful.

It'll be back in next week for spark plugs and compression test.

Not surprisingly, Audi was not interested in the dyno graph, but they do want to do an approved/recognised acceleration test. It's something like 1st gear 20kph-60kph in x seconds, 2nd gear 40kph-90kph in x and 3rd 60kph-120kph.

Does anyone know more about this test, and what the numbers are?

Mal.

[2manytoys]

Another updates guys:

Audi Australia recognised that there is a performance problem. They have replaced the spark plugs and added a fuel octane booster. They asked that I drive it for another 1000kms and report back.

After 120km the pinging is bad, very bad. It sounds like an old diesel. I'll give it a couple of tanks, but I really can't see this fixing itself.

Any and all comments appreciated.