Poor pickup in low revs / occasional misfires

B

bleng

Member
Hi all, I bought a cheap 1.6FSi a few months ago and slowly getting to sort out the issues with it. I found a problem with the car needing higher revs than I expected to pull away, but also below 3000 rpm the engine felt like it was being strangled - it reminded me of a MAF error I had in an old diesel passat.
I got the mechanic to check it over and it came up with an EGR error (not sure what the code was now). Anyway I sourced a used EGR and gave it a good clean out before getting it installed. Once installed and running the adaptation program and removing all fault codes, it ran with no new fault codes logged.

However, the problem is still there. Below 3000rpm the car is sluggish and occasionally misses.. but above 3000rpm its nippy.
No fault codes.

Any ideas or suggestion on what I can try next?

Thanks
 
Firstly, there's no such thing as a "cheap FSI"
Secondly, what scan tool did your mechanic use?
Thirdly, unless it's running perfectly, (and they do), the chances of an error free scan, using a VAG specific tool, are slight.
Your symptoms are typical of an FSI with a faulty lower manifold mechanism.
Mac.
 
Strange, with the fault you describe I automatically think of flap problems (lots to read on here) but as you have no codes then not unless the the code reader was not VAG specific, say VCDS. Even so I would have thought some code would show or somebody has been deviously bodging to avoid codes.

Does the EML appear briefly at start up (and then go out)?

FSI engines are known to be difficult to cure sometimes, I have other suggestions later.

Andy

Edit. I now see Mac has said the same thing!
 
Hi, Sorry for any missing info in my 1st post - I'm pretty new here :)
VCDS was used.
I have since checked for codes again using VCDS-lite (all I personally have access to) and the only one showing in that is an intermittant AC response (saved the code somewhere on my PC and can't find it now - will check again when I get a chance).
The EML light does appear on ignition but goes out once I start the car.
THanks for your thoughts so far.
 
First question are you using premium petrol? Fsi is 98 octane or better. Tesco Momentum is the cheapest,then an Italian tune up.Also Fsi is not not recommended for E10 petrol
 

FSI hesitation under light acceleration

If anyone has an FSI with a slight hesitation when accelerating from lower RPM I may have found the problem by accident. I purchased my FSI about 5 years ago and as normal I have had a lot of frustration with it culminating in have a replacement engine at WOM,but even after that I still had this...
www.a2oc.net
Start with cheapest fix first
 
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Very mysterious.
Try this:
You'll need an assistant, to switch the ignition on and off, while you peer into the engine.
Remove the bonnet.
Locate the vacuum actuator for the lower manifold flaps, to the left of the oil cap, and at the back (pic below).
At the top is the diaphragm chamber, and there's an actuating rod at the bottom, which is, (should be), attached to the flap mechanism.
Make a mark on the rod, so when, (if), it moves you can estimate how far.
Ask your helper to turn the ignition key one click, ignition on, but not start.
You may see the rod move downwards.
Now, ask the helper to start the engine, as this happens, the rod should move upwards about 15mm.
Let us know what you see.
The idea of this exercise is to check if the flap mechanism is working.
More FSI info in the PDF below.
Worth a read, so you have an idea what's supposed to happen.

A2-engine1~2.jpg

Mac.
@Andrew , could you check I've got the instructions right please?
Mac.
 

Attachments

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1st of all thanks everyone for the quick responses - I have a few things to try now. I am away for a couple of days, but will try these out early next week.
1. New Fuel cap on order - seems like a cheap thing to test .
2. charcoal filter posts are interesting reading will need to delve deeper into those.
3. Will try the actuator test and report back.
4. Have downloaded the pdf and will read through that too
 
Glad you sound DIY, curing a 'temperamental' FSI engine fault like this is notorious for gobbling up money and getting nowhere, ten times more painful if via a garage especially a general garage.

Two areas that have been posted on here that cured this kind of problem are concerned with ventilation. Fuel line ventilation (I do not understand) such as Terry and also replacing the N80 solenoid valve on top the engine that also vents. Secondly, PCV, replacing the oil separator worked wonders on another.

I had better just check all regular servicing has been undertaken.

Other things to discuss but let me say you are very lucky not being too far from WOM, our A2 national garage who know A2,s inside out with stacks of experience and reasonable rates. It may be good advice to approach them for a diagnosis/fix.

Andy
 
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PlasticMac said:
Very mysterious.
Try this:
You'll need an assistant, to switch the ignition on and off, while you peer into the engine.
Remove the bonnet.
Locate the vacuum actuator for the lower manifold flaps, to the left of the oil cap, and at the back (pic below).
At the top is the diaphragm chamber, and there's an actuating rod at the bottom, which is, (should be), attached to the flap mechanism.
Make a mark on the rod, so when, (if), it moves you can estimate how far.
Ask your helper to turn the ignition key one click, ignition on, but not start.
You may see the rod move downwards.
Now, ask the helper to start the engine, as this happens, the rod should move upwards about 15mm.
Let us know what you see.
The idea of this exercise is to check if the flap mechanism is working.
More FSI info in the PDF below.
Worth a read, so you have an idea what's supposed to happen.

View attachment 95679
Mac.
@Andrew , could you check I've got the instructions right please?
Mac.
Click to expand...
Your instructions are okay but from memory more detail and diagrams in the P1031 thread.

fault p1031

hi guys, im new to this site and also a relitivley new a2 owner (12months), i love my little car however i have had a few niggles with it and having paid out at main dealers thought i would seek alternative advice, my latest prob is the engine management light being on, its saying fault p1031...
www.a2oc.net

The only problem is the procedure does not prove the flaps are working, it proves N42 is okay as well as the vacuum actuator main body. The actuator arm may be going up and down but the problem is the arm usually breaks at the bottom, out of view and difficult to see even with an endoscope and thus no flap movement. If the arm is broken then the ECU will notice the potentiometer reading does not responds to requests and flag error but this can verified on channel 142.

Andy
 
Andrew said:
Your instructions are okay but from memory more detail and diagrams in the P1031 thread.

fault p1031

hi guys, im new to this site and also a relitivley new a2 owner (12months), i love my little car however i have had a few niggles with it and having paid out at main dealers thought i would seek alternative advice, my latest prob is the engine management light being on, its saying fault p1031...
www.a2oc.net

The only problem is the procedure does not prove the flaps are working, it proves N42 is okay as well as the vacuum actuator main body. The actuator arm may be going up and down but the problem is the arm usually breaks at the bottom, out of view and difficult to see even with an endoscope and thus no flap movement. If the arm is broken then the ECU will notice the potentiometer reading does not responds to requests and flag error but this can verified on channel 142.

Andy
Click to expand...
Yes, but if the linkage is dodgy, you'd expect to see a DTC.
My thinking was that if there was an observable problem with the flap mech, but no DTC, we'd strongly suspect a cunning PO.
Mac.
 
PlasticMac said:
Yes, but if the linkage is dodgy, you'd expect to see a DTC.
My thinking was that if there was an observable problem with the flap mech, but no DTC, we'd strongly suspect a cunning PO.
Mac.
Click to expand...
Agreed on both points, unless we have Proboost!

Andy
 
Andrew said:
Two areas that have been posted on here that cured this kind of problem are concerned with ventilation. Fuel line ventilation (I do not understand) such as Terry and also replacing the N80 solenoid valve on top the engine that also vents. Secondly, PCV, replacing the oil separators worked wonders on another.
Click to expand...

Oil separators? Which bit is that?
 
I find it hard to associate the feeling that the engine feels "strangled below 3000 rpm" with anything other than the switch between fuelling modes.
The absence of any DTCs is worrying, given the miss fires and hesitancy.
Feels really odd to be worrying about a clean scan on an FSI though! Most FSI'ers would give their eye teeth for a clean scan ...
Mac.
 
Robin_Cox said:
usually down the back of the engine somewhere (at least it is on the 1.4i), connected by a pipe to the crankcase breather and somewhere near the throttle body?

cylinder block with pistons; oil sump Audi A2 (A2) 2003 year Audi EUROPA 103020

cylinder block with pistons<br/>oil sump Audi A2 (A2) 2003 year Audi EUROPA 103020 spare parts
audi.7zap.com audi.7zap.com

part 19 in the BAD.
Click to expand...
Good Afternoon Robin,

I had a feeling it discharges into the EGR/upper inlet manifold via pipe 28???

@4markowen, MTL put up YouTube video of him changing the separator on his TDI.

What is this part in an AUA engine? SOLVED - oil separator

After inspection I have found that I have an oil seepage from the back of the engine towards ride side just above the oil pan and under intake manifold. Engine 1.4 petrol AUA. I cannot find this black plastic part on 7zap. What is its name? Hopefully is only gasket that needs to be replaced...
www.a2oc.net www.a2oc.net

Andy
 
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Andrew said:
Good Afternoon Robin,

I had a feeling it discharges into the EGR/upper inlet manifold via pipe 28???

@4markowen, MTL put up YouTube video of him changing the separator on his TDI.

What is this part in an AUA engine? SOLVED - oil separator

After inspection I have found that I have an oil seepage from the back of the engine towards ride side just above the oil pan and under intake manifold. Engine 1.4 petrol AUA. I cannot find this black plastic part on 7zap. What is its name? Hopefully is only gasket that needs to be replaced...
www.a2oc.net www.a2oc.net

Andy
Click to expand...
yes, that's the one. The connecting pipe is visible on two diagrams. The separator in the youtube vid is the 1.4i - just like the one on ours changed last year, there are some differences in the exact shape of the unit and connecting pipes but they do the same sort of thing.
 
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