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Td4 Performance Variable.


Mike the Bike
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Have a 2003 Td4 with std 2.0L BMW M47 engine with erratic performance issues.

Bit of history..........

Last year I replaced all injectors as they failed one after the other over 7 months period. :angry:

Had new LP pump fitted, Jan 09, I cleaned EGR and PCV in Feb and running better that ever.

But perfomance has tailed off in recent weeks, runs okay until warm but then becomes unpredictable, from smooth and torquey to noisey and gutless all in same journey.

On motorway at steady speed of 70mph, she changes from smooth to noisy on a 2 seconds cycle. When noisy, the whole vehicle frame vibrates and getting to 80 mph is a struggle.

Had a similar problem with a Vectra and the oxygen sensor had gone causing her to go too lean and get rough in sync with the lamda timing but the Td4 has no 02 sensor.

Clearly there is a leaning and enriching cycle at work to get economy when travelling at steady speeds but what drives it??

Have cleaned fuel rail pressure sensor contacts with switch cleaner, (they were dirty) suspecting low reading to pressure regulator via ECU/ fuel starvation - (still no warning lights) and she improved considerably..............100 miles later the problem has returned. :blink:

Any boffins out there with ideas, all gratefully received.

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Have you checked the intercooler pipework? This has a habit of colllapsing over time, and if it allows boost pressure to be lost will cause performance issues. If it only leaks boost once warm it may cause the symptoms you are seeing..

It is worth squeezing a pipe with your hand when the engine is off. If it seems soft, and easily crushed it may need replacing - the pipe should be fairly still and resistant to you squeezing it...

Just a thought.

Mark

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Air flow meter sometimes causes problems with a Td4.

They are stupid things and I hate them, got one at work at the moment that the computer says there is nothing wrong with - even though it won't start :rtfm:

Yeh

I got a new Pierburgh MAF going into a small custome variable gain device from Diesel-tuning website. I now have two as I bought a second kit to eliminate that being the cause. She's much more torquy at low revs when she's on song, but the problems seems to be eslewhere.

Cheers

Mike

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Have you checked the intercooler pipework? This has a habit of colllapsing over time, and if it allows boost pressure to be lost will cause performance issues. If it only leaks boost once warm it may cause the symptoms you are seeing..

It is worth squeezing a pipe with your hand when the engine is off. If it seems soft, and easily crushed it may need replacing - the pipe should be fairly still and resistant to you squeezing it...

Just a thought.

Mark

Thanks for the tip, not sure where to find the pipe so I'll look on my copy of RAVE.

PS Am based in Sutton Surrey - seen your Horsham based

Mike

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  • 1 month later...

Think I found the issue last night, hose from vaccum reservoir to EGR activation solenoid had been pushed up hard against steel pipe just above it. Had worn through the outer fabric and ruptured the rubber. Cut off 2 inches to behind the damaged section, re fitted and she appears fixed for the time being, still have to do a stead stae trip on motorway to confirm full fix. I suspect cyclic noise was EGR activation related.

Mike

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