Audi A2 - rough idle + no throttle after re-build

[jonny944cs]

Hello all,


(also posted in the A2 section)

Would love to hear if anybody has experience with the following and can offer any suggestions (I am new to this vehicle and VAG COM)?

Engine = 1.4 Petrol - Code AUA

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Chassis Type: 8Z - Audi A2
Scan: 01 02 03 08 15 16 17 37 45 46 56 57 75 76 77
VIN Number: WAUZZZ8Z02N036715
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HISTORY:


- Crank sprocket slipped on the cambelt due to ice formation filling in the tooth profiles => 8 x intake valves bent => no other damage => so, new valves fitted and lightly lapped = > head rebuilt with new gaskets.


- Engine started on the first turn of the key and sounded good for the first 30s or so on the rich startup map => I gently blipped the throttle and the revs rose to 2500rpm => on return to the idle position the engine was now running roughly, with a lumpy hunting idle.
- Fault code scan revealed the following:
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Address 01: Engine
Part No: 036 906 034 Q
Component: MARELLI 4LV 3415
Coding: 00051
Shop #: WSC 00579
WAUZZZ8Z02N036715 AUZ7Z0B2061291
1 Fault Found
17961 - BAROMETRIC/ MANIFOLD PRESSURE SIGNALS – IMPLAUSIBLE CORRELATION
P1553 – 350C
Readiness: 1110 0101
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- So I checked the following:
o Air leaks – Nothing visible (difficult to say for sure) Can anyone recommend a suitable test procedure?
o Cycling through test functions – each part appeared to respond
o Cam timing re-checked, case I’d messed up => all correct
o Compression test = 12bar across all cylinders (test carried out at around 30°C water temp, ECU fuel P fuse removed, foot on the accelerator. I’m not sure how the electronic throttle responds in this condition… anyone?

- No further forward, I decided to check the live data blocks:
o IGNITION ON (revs=0rpm) (MAP=999mb) (Throttle=7.5°) (Ignition=0°)
o ENGINE IDLING (revs=1275rpm) (MAP=675mb) (Throttle=7.4°) (Ignition=0°)
o ENGINE RUNNING + THROTTLE BLIP (revs=1275rpm) (MAP=690mb) (Throttle=7.4°) (Ignition=+/-4°)


- Points to note from live test
o Throttle angle pretty much constant throughout all three tests
o The MAP values seem too high (as expected with the fault code), manual states values should be between 240 and 420mb
o When blipping the throttle, the revs rise only very slightly and the ignition angle is the only parameter that appears to change in response.

- My next thought was to try and clean the TB and perform a re-align.


Any other suggestions?

Thanks in advance

Jonny

[jonny944cs]

Update 1 - Sprayed brake cleaner onto the join between the inlet manifold and the head => revs rose => removed the manifold to check the seals


Update 2 - Problem Solved - Kinked rubber seal on intake manifold port 4, I must have caught it lowering the head onto the block (see attached image).

Engine now runs sweet as a nut.

Massive sigh of relief.