Lousy factory tuning?

[dparm]

Lately I've been getting annoyed with the rather "fickle" tuning at partial throttle in my car. I feel like below 3000rpm at moderate throttle angles and moderate load the car does not accelerate very smoothly. Obviously there are no CELs. This behavior is sporadic.

Maintenance is totally up to date. All of the following things have been done within the last 12 months (about 6k): fuel filter, air filter, plugs, serp belt + tensioner, engine oil, Redline SI-1. Just last night I checked all the IM bolts (there's a TSB out for some of them loosening) and did the throttle plate adaptation again. I always run brand-name 93 octane gas.

The car has 68k on it right now.

Any ideas? I'm probably just being picky but it's a little weird when I want to use the motor's torque without downshifting and it does this. I have a feeling this is just due to a mediocre factory tune and the ECU's inability to retard/advance timing and cut/add fuel for every possible scenario.

 

[NHGUY]

With what they charge for Audis I would hate to think they didnt think of "every possible scenario".No cars are perfect,no matter the cost,and this is just another example.Todays vehicles are amazing for what they are...but with fuel economy/emission concerns,there is always a trade off somewhere.

 

[Rand]

probably the whole non linear(in a bad way) electronic throttle poop

 

[Highline9]

Maybe a lazy o2 sensor.

 

[CBR.worm]

I have driven a lot of new cars that have pretty poor tuning, with flat spots or stumbles at some point. Our 528i has always had a litle bit of a stumble at high load, low RPM conditions, no CEL ever and dealer has deemed it due to ethanol fuel.

Our FX45 has a noticeable dip in power between 5,200 and 5,500 RPM in every gear (or at least the ones that it will pull that high in)

I had a nissan a few years ago that in 5th gear you could not go 45. The throttle was on/off at that point, you would either accelerate past 45 or drop below it - seemed like a pretty major oversight.

I think with a manual transmission the faults are more easily noticed due to the direct connection, and such a highly tuned motor (it should be) in a small car would combine to exacerbate any tuning shortcomings.

I am sure your car has wideband O2 sensors, but at high load/low rpm it may be going open loop and using a lame map made worse by weather conditions and E10 fuel.

We had a version of that engine in an A8, and I seem to remember it liking to spin.

 

[dparm]

Yeah, the motor revs wonderfully but it just has this odd side to it.

Maybe I'll borrow someone's VAGCOM and check the fuel trims and O2 voltages as I drive around.

 

[dparm]

Originally Posted By: Highline9
Maybe a lazy o2 sensor.


This had also occurred to me. My old Integra GS-R had some weird issues like this with no CELs. I replaced both O2 sensors and suddenly it behaved itself.

 

[rpn453]

Probably emissions-related. Have you ever tried a tuner on it? Those must be readily available for that car.

 

[antiqueshell]

This might sound silly....BUT...it could be that the metal contracts within the TB have become a bit tarnished over time causing some electrical resistance in certain spots which would make for odd or uneven throttle curve behavior, simply try this with the car turned off and key removed step on the accelerator and with a quick motion press the pedal five times to the floor repeat this with quick deliberate motions (this might clean the contact points that are traveled) Go for a drive and see if there is any difference. Other than that clean the MAF sensor, and check for PENDING CODES, they will not light up the CEL lamp but the ECU will see if there have been any anomolies stored.

Also never hurts to check for vacuum leaks.

 

[JosephHarmon]

You just need a good tech........

 

[Kiwi_ME]

Perhaps one or two ignition coil units are failing?

 

[SteveSRT8]

Sure sounds like the tune to me. Usually the non-linear power delivery is caused by the knock sensors pulling timing.

 

[hypervish]

I feel the same way about my 2004 Audi A4 1.8T quattro. The tuning itself sucks, and I feel like there's a lot of turbo lag. All of a sudden, it will just have a surge of "power", and sometimes it will barely pick up speed. Very strange, to say the least. In my case, I attribute it to the turbo, as well as the tune. I've owned this Audi for about 6 years, and I'm going to sell it this summer. Awhile back I looked into tuning the ECU, but I was never really serious about it.

 

[Old Mustang Guy]

I think it could in fact be the tune. When the warranty expired on my 06 Mustang GT I had a CAI and a custom dyno tune installed by a local guy that specializes in Mustang tunes. Not only did the car gain 25 RWHP it became so much more responsive that it feels like 50. The shifting of the auto transmission is also much better (crisper). I did have it tuned for 89 octane rather than 87. I think any tune is somewhat of a compromise. The factory tune is a compromise of performance, economy, emissions and a margin of safety and longevity.

 

[dparm]

Yes, there are some aftermarket tunes that really open the thing up.

 

[SteveSRT8]

If you consult with them, many aftermarket co's like Diablo will email you a tune, you data log it a bit, send it back, they tweak... and so forth.

You can end up with many of the driveability issues of modern cars dramatically improved for a very small amount of money.

I'm talking dramatic.

 

[The_Jeff]

I noticed knock retard on my saturns when they gulp oil. In fact this lead me to do a ring job; it was so annoying. The economy-car tune would remember the knock parameters for a couple hundred miles, but only apply them over a specific load/ RPM range, making a noticeable flat spot.

I'd get a good computer on it that reads knock retard from optimal. Generic scanners only give you total advance, rather useless.

Just so we're clear, it's throttle by wire and a stick shift? It could put those flat spots in on purpose to force you to downshift. They don't want to make NOx by lugging, for example, so they take more power away than they have to.

 

[dparm]

Correct, DBW + 6MT.

 

[chrome]

Definitely do a full VAGCOM scan first, and see if the ECU is reporting anything. Often times, there are small items that will flag a soft fault code, but won't illuminate the check engine light.

 

[mechtech2]

"The behavior is sporadic".
OK, there is a hard problem, then. It is not tuning, or it would be bad all the time. The tuning did not change.
Anything from a bad ground to a bad TPS could be the problem.. Vacuum leaks, MAF sensor, electrical connections, etc..
I have ZERO to go on besides that it does not do it all the time.