Power/Acceleration Problem (1997 A3 1.6 SE)
 

Hi Guys,

I'd be grateful if somebody could help with this problem.

I recently bought a manual 1997 A3 1.6 with about 75k miles on it. When accelerating (usually in 2nd/3rd/4th gears) the power delivery can be quite erratic. Most of the time it's fine but occasionally it feels as if it's 'holding back,' followed by the power then coming on in bursts as the revs increase and 100% power 'appearing' suddenly. There are no specific conditions under which this happens, e.g outside air temp, air-con on/off, etc.

I'm pretty sure the clutch is in good shape and not slipping, and think it's fairly unlikely the fuel itself is causing this.

Would I be right in thinking the first place to start looking is the spark plugs?

Beyond this could anyone suggest any other causes which might be worth investigating? Is it possible the fuel injection system might be faulty?

Thanks.

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

I have the exact same rpblem with my 1997 1.8 20v. It feels like something is bunging up the power.
From what I've found out, it could be either the cam belt tensioners or the Mass Air Flow sensor. Hopefully it's the latter which should be a RELATIVELY cheap job. Gonna take it to my friendly local mechanic this weekend, although he's not a VAG specialist so not sure how much he can do.

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Thanks for the suggestions, guess I'll have to get somebody to have a good look at it. It's only just had its major cam-belt change, so perhaps it hasn't been set up quite right.

It's particularly frustrating that this isn't a consistent problem, it comes and goes pretty randomly...

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Hi, i think i have experienced something similar but only at low revs...but it is unnoticable.......i did read that a3 performs better at revs around 4000rpm and if i drive up near that i dont see that....
I hope its nothing serious.....

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Since my last post I've found out a bit more. It's 99% certain that in my case it is a MAF problem. This is a REALLY easy clip on, clip off part mounted just in fromt of the filter box on the cold air intake to the right hand side of the engine bay. You'll struggle to get a new one as Audi tend to recondition theirs. Therefore, you end up shelling out £90+VAT for a reconditioned unit (www.vagparts.com), but then send back your knackered unit and get a £36+VAT rebate! Alternatively, a local VAG specialist will do it for £100-120 fitted.
If you want to check if it's definately the MAF, then all you need to do is unplug the sesnsor and drive the car. If the performance improves or is close to normal, thats your problem as the MAF is not fluctuating!
Hope this helps!

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Thanks for the extra info - I'll definitely investigate the MAF as you suggest.

I also did some more research and came across the following possible causes for 'engine hesitation on acceleration':

- Worn/faulty/incorrectly gapped spark plugs
- Blocked/faulty fuel injector(s)
- Vacuum leak in throttle body/inlet manifold/hoses

Given the inconsistent nature of my problem I'm going to have a good check through the rest of the air intake system as well as the MAF.

neo283, if you have your MAF replaced and it fixes things, it would be very helpful if you could post the outcome. Thanks.

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Well they seem quite easy to fix! Blocked valves can be sorted with engine addetives such as Wynns (I think thats how you spell it) or STP injector cleaner. However, I periodically use these products so I would be surprised this is the case in my motor. It's the same for the sparks, which I would be inclined to put Bosch Super 4's in now anyway as a matter of course. Hoses is a pretty straight forward job too.
Again, in my case the air intake has been recently looked at as I have installed a K&N replacement in the last 1000 miles.
The only other option I can think of is my exhaust, as it has a TINY hole in it (which will only get bigger, but pay day isn't until Friday!)
I'm booked into the VAG specialist on Saurday to look at the MAF, and clear down a couple of fault codes which may have appeared, so I'll keep you informed.

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Thanks for the comments.

Having done more reading, I thought I would also try 'resetting' the ECU, which clears out any 'learned' settings and sets it back to defaults. This should help if the problem's being caused by corrupt data in the ECU.

I guess most people know about this anyway but if not, you do the following:

- Turn on the ignition (but do not start the engine)
- Leave it on for about 30 seconds
- Turn ignition off again and then use car as normal

At the moment my problem has cleared up, but I don't know if this is because I reset the ECU or just the random nature of the problem.

Will also try some injector cleaner and see what happens...

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

Nice hint, I will try that. So does it clear down any ECU faults in much the same way as a VAG-Com, minus the fault code reading of course? Suppose the fauts will come back if the MAF is still faulty, but it makes a DIY job a lot more appealing to me.
My problem is also being intermitant today! Probably due to the cooler temperature than last week.
Just on a side note, have you got a performance/K&N air filter installed? Read on another foruym that these can be adverse to your MAF. I installed one about 2000 miles ago, which could be just a coincidence.
Don't know if I mentioned on previous posts but I've located a new MAF for £70 (www.vagparts.com).

RE: Power/Acceleration Problem (1997 A3 1.6 SE)
 

I'm not sure whether this will clear fault codes out of the ECU.

What it does do is set the ECU's 'adaptation' back to the factory settings. Apparently Audi ECUs 'learn' how you drive and adapt their settings accordingly, so if the system's made a mistake or some of the 'learned' settings are corrupt, you can reset it so that it has to re-learn.

There's a short discussion about this here and various other articles on forums:

http://www.tyresmoke.net/ubbthreads/...sed/sb/5/o/all

It looks like you might have to disconnect the battery and/or leave the ignition on for longer than I suggested depending on the type of ECU.

Regarding the air filter, as far as I know everything on my car is Audi standard equipment, so there shouldn't be any extra problems there.