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Pete, Technician
Category: Car
Satisfied Customers: 28763
Experience:  17 years automotive training and experience.
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Volkswagen beetle: Hi, surge issues on 1.8t beetle.changed

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Hi, surge issues on 1.8t beetle.changed maf , boost valve, coil packs , plugs, diverter valve ( this was faulty) now with 710n, brake switch . Only other leak at present is plastic tube with valve near manifold ( brakes component) and car still surges. It holds back then goes then back and so on. Done scan and not sure what else to look at. Graphs show spikes on boost then drops. Throttle perfect mirror on scan for each part. Forgive my ignorance as not a mechanic, just at end of tether ! Please can you help. Thank you Barry Smith . Driving a kangaroo
My name is XXXXX XXXXX I am a professional here at Just Answer/Pearl. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

With an engine rpm surge like this here I would inspect the engine for any vacuum leaks that are noticed visually and repair any that are found.If no vacuum leaks are found next I would have the intake smoke tested,the smoke will be injected into the intake and any leaks present the smoke will show these hidden leaks like around the intake gaskets that would be hard to see visually.

With a vacuum leak this will cause a lean running issue as well as an engine rpm surge like this and this needs checked first to see if this is the cause of this fault here.

Thanks Pete
Customer: replied 3 years ago.

Hi Pete, we did use ultrasonic listening device for leaks and picked up nothing other than the y shaped plastic gasket near manifold, think its a valve. Would faulty map cause this. Is it worth changing? Not showing voltage problems on scan. This is a snap on device and not a vag com. Thanks


The sound device you used is a great device for picking up on any leaks but I have seen in some cases where the leak can be missed and the smoke test is usually one of the best tests to do to try and locate a leak.If you have access to a smoke machine this may be best to use to verify no leaks are present.

If the map sensor voltage appears o.k. I wouldn't suspect it at fault but I have seen this sensor fail in the past on some models and cause issues like this.It may be possible the voltage reading is off with the map sensor and is causing this here.Unfortunately my info doesn't list what the voltage should be at idle and wide open throttle for this vehicle.

Thanks Pete
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I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete