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Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 20368
Experience:  BEng hons Mech engineering, in auto industry 22 years
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2.0 tdi 2006 170 - shuddered u/acceleration around 2300-2800

Customer Question

2.0 tdi 2006 170 - shuddered under acceleration around 2300-2800 and again at 4500. Does not happen if slowly increase speed.

On board computer says mpg is 10mpg higher at 2800rom in 5th vs 2300 in 6th!

Have replaced egr, erg cooler, manifold and head gasket.

The shuddering started 1000 miles after rebuild... Thought it was egr so swapped it and did not solve the problem.m

No smoke, slight smell of very hot burning oil/soot after high speed run.

Any ideas of the next things to test/do.

Am fairly mechanically minded just need to know where to look.

Submitted: 2 years ago.
Category: Audi
Expert:  Matt replied 2 years ago.

1st check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.

If the above are all OK then try checking for airleaks after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and leans the engine out causing rough running. As its a mechanical fault it tends not to turn on the fault light and you can sometime hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.
if the engine condition is the same then chances are the meter or the connection to it is faulty

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

I'd also suggest inspecting the throttle pedal sensor for corroded contacts and damaged wiring

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    Mechanical Engineer

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    BEng hons Mech engineering, in auto industry 22 years
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