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Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 20778
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Renault grande Espace: Renault Grande Espace 3litre diesel.

Customer Question

Renault Grande Espace 3litre diesel. Whilst driving at high speed for a few miles a sound comes from offside front wheel sounds like a clunk. It then feels like you have got a puncture for a few seconds and car shakes vigorously.The car loses power and won't accelerate. As if the automatic gearbox can't find the correct gear. If you then slow down everything after a minute or two goes back to normal. Nothing showing on the diagnostics. Could this have anything to do with CV joints?

Submitted: 1 year ago.
Category: UK Car
Expert:  Matt replied 1 year ago.
Hello

A faulty CV joint is quite possible

- typically these won't produce any vibration unless badly damaged but they can be noisy or 'clonk' for a long time beforehand, turn the steering to full lock and look at the drive-shaft rubber boot there should be no rips or tears in it and the suspension should be clean and dry of any grease. If you reverse at a reasonable speed with the steering on full lock a worn joint will 'click'.

I'd also check for worn mountings - check the tightness of the engine and gearbox mounts and their condition - this is best done by using a jack to take the weight of the engine off the mounts and seeing if any cracks or splits open up in the rubber.Also check the tightness of the mounts bolts

Also check for broken or defective driveshaft vibration damper - some models feature a rubber mass about halfway along the driveshaft - this functions as a vibration damper so 'tuning out' vibration - the rubber needs to be not cracked and the damper firmly fixed to the shaft and running true - anything other than this and the entire shaft will have to be replaced as they are bonded in place

Expert:  Matt replied 1 year ago.
Hi

do you still need help?
Customer: replied 1 year ago.

Air flow meter has been changed cv joints all checked and still the same problem.

Whilst driving car looses power shakes and won't accelerate and starts to slow down.

This seems to happen at speeds between 60mph and 70mph.

After a short while it seems to sort it self out and you are able to accelerate again.

Thanks for your time

Expert:  Matt replied 1 year ago.
Thanks for the extra information

This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter

Crank position sensor

Cam position sensor

O2 sensor

Throttle position sensor

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.

Check the resistance of the spark plug leads ( 13-15Kohm / metre) and replace if any doubt or high resistance - Also replace the spark plugs if any of them fail this checklist:

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

Also its worth checking that the electric pump that feeds the injectors is working correctly, it should run for a few seconds then switch off when you first turn the ignition on. If the connections to this are corroded or damaged then the pump could stop at any time. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, ideally measure the voltage at the pump and check its getting 12V

Also check for exhaust leaks before the o2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.