1.6 FSI (That bloody misfire)

noggen

Member
Hi, I'm having that issue with my 1.6.

Symptoms are:
When hot, engine will misfire. As soon as it reaches ~80 degrees, having the throttle barely open will cause slight juddering back and forth, a small misfire. This has been an issue since I bought it last year, but has not been major and I have slowly been trying small things (coil packs/plugs/earthing/fuel tank cap) to try and help.

I recently drove a little over 100 miles to a car show, and I noticed on the motorway by the end of the trip that now when pressing the accelerator any more than incredibly light acceleration it misfires a lot more, making the car effectively undriveable. This is with a flashing engine light, whereas the past issue never showed any engine lights other than the occasional 'catalyst system below threshhold' error.

Doing some followup testing, the car now only does this badly when hot and been running for about 30 minutes, but has an occasional, smaller misfire before this.
As well as this there is now a noticeable rattle from the engine when warm. This happens when revving up a little, but when the revs are dropping the noise gets louder and/or more noticeable.

I tried a VCDS Scan, bringing up these codes:

Address 01: Engine Labels: Redir Fail!
Controller: 036 906 013 F
Component: MED7.5.11 4628
Coding: 00051
Shop #: WSC 02138
VCID: 1257394B4D77
WAUZZZ8Z73N034025 AUZ7Z0C2390998
4 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16688 - Shareware Version. To Decode all DTCs
P0304 - 35-10 - Please Register/Activate - Intermittent
17912 - Shareware Version. To Decode all DTCs
P1504 - 35-10 - Please Register/Activate - Intermittent
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 35-00 - -
Readiness: 0000 0000


The shareware codes being a misfire on Cylinder 4 and an intake leak.

Looking on other forumn posts, people suggested that this could be a faulty High Pressure Fuel Pump. I bought spares of these, but it has not helped.
After rescanning, it brings up the same codes, minus the Catalyst System 16804 code.

Wondering if it would be an injector, but this doesn't explain the rattle? Could also be EGR valve or tubes?
Just want an idea of what to replace! Love the car, but have limited budget to try and fix this, so want to get the cause of the issue as soon as possible without trying too many wallet draining ideas.

Thanks!

Noah
 

kp 115

Member
Hi, I'm having that issue with my 1.6.

Symptoms are:
When hot, engine will misfire. As soon as it reaches ~80 degrees, having the throttle barely open will cause slight juddering back and forth, a small misfire. This has been an issue since I bought it last year, but has not been major and I have slowly been trying small things (coil packs/plugs/earthing/fuel tank cap) to try and help.

I recently drove a little over 100 miles to a car show, and I noticed on the motorway by the end of the trip that now when pressing the accelerator any more than incredibly light acceleration it misfires a lot more, making the car effectively undriveable. This is with a flashing engine light, whereas the past issue never showed any engine lights other than the occasional 'catalyst system below threshhold' error.

Doing some followup testing, the car now only does this badly when hot and been running for about 30 minutes, but has an occasional, smaller misfire before this.
As well as this there is now a noticeable rattle from the engine when warm. This happens when revving up a little, but when the revs are dropping the noise gets louder and/or more noticeable.

I tried a VCDS Scan, bringing up these codes:

Address 01: Engine Labels: Redir Fail!
Controller: 036 906 013 F
Component: MED7.5.11 4628
Coding: 00051
Shop #: WSC 02138
VCID: 1257394B4D77
WAUZZZ8Z73N034025 AUZ7Z0C2390998
4 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16688 - Shareware Version. To Decode all DTCs
P0304 - 35-10 - Please Register/Activate - Intermittent
17912 - Shareware Version. To Decode all DTCs
P1504 - 35-10 - Please Register/Activate - Intermittent
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 35-00 - -
Readiness: 0000 0000


The shareware codes being a misfire on Cylinder 4 and an intake leak.

Looking on other forumn posts, people suggested that this could be a faulty High Pressure Fuel Pump. I bought spares of these, but it has not helped.
After rescanning, it brings up the same codes, minus the Catalyst System 16804 code.

Wondering if it would be an injector, but this doesn't explain the rattle? Could also be EGR valve or tubes?
Just want an idea of what to replace! Love the car, but have limited budget to try and fix this, so want to get the cause of the issue as soon as possible without trying too many wallet draining ideas.

Thanks!

Noah
Hi noggen,
You it showed the above fault codes but i don’t see any mention of clearing these fault codes & driving again before a repeat scan to see current fault code list, this needs to be done to acutely determine these as it could be a series of old codes you’re seeing.
Hope that helps
Keith.
 

noggen

Member
Hi noggen,
You it showed the above fault codes but i don’t see any mention of clearing these fault codes & driving again before a repeat scan to see current fault code list, this needs to be done to acutely determine these as it could be a series of old codes you’re seeing.
Hope that helps
Keith.
Sorry! Didn’t mention it, but I did clear it after the fuel pump change, and drove it again, to show the same codes.
 

nod

Member
I had an FSI with the exact symptoms you describe, I never managed to fix it unfortunately, and i replaced every part of the fuel system but in mine the faults related to fuel pressure, have you checked fuel pressure using VCDs? in the end i thought it was an electrical fault, on mine it definately got much worse when upto temperature, and at that point was undrivable, stalled if any accelerator used. ran really rough after a minute or so, but started perfectly and initial tickover good. when i broke the car the wiring loom near the bottom temp sensor was full of water with sever wire inside a plastic sleeve, always wondered if it was that somehow??

other thoughts - the knock sensor? i had one FSI with this fault, a new one cured that but it did throw a specific fault code, which you don't have -so probably not that, real pain to access too, at back of engine.

i know the frustration of those issues! good luck..
 

noggen

Member
I had an FSI with the exact symptoms you describe, I never managed to fix it unfortunately, and i replaced every part of the fuel system but in mine the faults related to fuel pressure, have you checked fuel pressure using VCDs? in the end i thought it was an electrical fault, on mine it definately got much worse when upto temperature, and at that point was undrivable, stalled if any accelerator used. ran really rough after a minute or so, but started perfectly and initial tickover good. when i broke the car the wiring loom near the bottom temp sensor was full of water with sever wire inside a plastic sleeve, always wondered if it was that somehow??

other thoughts - the knock sensor? i had one FSI with this fault, a new one cured that but it did throw a specific fault code, which you don't have -so probably not that, real pain to access too, at back of engine.

i know the frustration of those issues! good luck..
Thanks for the input! Knock sensor is cheap, and I’ll have a look at all of the wiring loom for damage then.
I’ll check the fuel pressure also.
Will report back at further progress!
 

noggen

Member
A long shot I know and a bit strange,but try a new fuel cap,its cheap
Tried in the past to no effect. Cap is now only ~4 months old, and assuming this is now the same issue but worsened I’m guessing another new cap won’t help.

Obvious question, but are you using the correct grade of fuel?
Been running it on 97 octane premium fuel for months! Can’t find 99 and above, but it’s no supermarket fuel.
 

audifan

A2OC Donor
I think you may well have contributed to the problem ( and previous owners ). Your car needs 99 and above. When you are intentionally doing something wrong to the car then do not blame the car.
 
Tried in the past to no effect. Cap is now only ~4 months old, and assuming this is now the same issue but worsened I’m guessing another new cap won’t help.


Been running it on 97 octane premium fuel for months! Can’t find 99 and above, but it’s no supermarket fuel.
At present you’ll do well to find any in Gloucester!!! The Shell garage do 99 RON as that’s where I filled up mine until I sold it. Pretty sure the BP garage in Barnwood does as well.
 

PlasticMac

Member
Petrol is often sold as "Premium" it is only 95 octane. Virtually all mainstream fuels are 95 octane and have a big E10 sticker on the nozzle. This petrol is not suitable for your FSI. Two reasons, 10% (E10) alcohol and 95 octane.
Only use E5, which is max 5% alcohol, and 98/99 octane.
Audi have said the FSI is not compatible with 10% alcohol. Your handbook tells you to use 98/99 octane. I don't think 97 octane is available. Either 95 E10 or 98/99 E5.
Mac.
 

terrywindy1

Member
Now using Esso 99 with NO E5 Ethanol but cheapest is Tesco Momentum

What’s in our Synergy Supreme+ 99 premium petrol​

Our Synergy Supreme+ 99 petrol has more cleaning power than our regular petrol – and includes molecules whose job it is to reduce the friction in your engine helping the moving parts work more efficiently.*​

Although our pumps have E5 labels on them, our Synergy Supreme+ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol​

 
Now using Esso 99 with NO E5 Ethanol but cheapest is Tesco Momentum

What’s in our Synergy Supreme+ 99 premium petrol​

Our Synergy Supreme+ 99 petrol has more cleaning power than our regular petrol – and includes molecules whose job it is to reduce the friction in your engine helping the moving parts work more efficiently.*​

Although our pumps have E5 labels on them, our Synergy Supreme+ 99 is actually ethanol free (except, due to technical supply reasons, in Devon, Cornwall, North Wales, North England and Scotland). Legislation requires us to place these E5 labels on pumps that dispense unleaded petrol​


That's interesting to know because of the extra cleaners as i was talking to a friend on the phone about this last night and he said Tesco Momentum is Esso's Synergy Supreme+. I was unsure of Momentums cleaning powers hence why we do 3 tanks Momentum 1 tank V-Power. If this is true then i'd use Momentum all the time knowing it has the cleaners in it similar to V-Power.
 

Clackers

Member
I had a similar issue to you, it turned out to be an injector that had given up the goose, had the injector replaced and it ran like a dream, it also meant that the lower inlet manifold could be thoroughly cleaned whilst it was off the car. I have also broken an fsi with the same problem having thrown over £600 at it to cure the same problem....we gave up the fight with it, never worked out what the problem was though.
 

PlasticMac

Member
That's interesting to know because of the extra cleaners as i was talking to a friend on the phone about this last night and he said Tesco Momentum is Esso's Synergy Supreme+. I was unsure of Momentums cleaning powers hence why we do 3 tanks Momentum 1 tank V-Power. If this is true then i'd use Momentum all the time knowing it has the cleaners in it similar to V-Power.
The fuel may well be Esso Synergy Supreme+
but the additives may not be. Esso (and the other majors) spend millions on additive research, so are unlikely to give it away to a competitor.
Additives are injected at the gantry where the tanker is being loaded, they are not part of the refining process.
Just a thought ...
Mac.
 

Evripidis

Member
I never had a misfire but had all sorts of other trouble and having rectified everything in my pass I believe that I might have prevented the misfire issues.

For example, when replacing the rear coolant pipe, it is a good idea to clean/refurb the injectors, seals, retainers, etc. Also while at it, give it your best shot at cleaning the intake valves. Maybe even worth going down the high-pressure fuel pump issue. Start with the cheap, easy stuff and work yourself through.
 
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