if this is OK then check for a 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
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;
Crank position sensor
Cam position sensor
Throttle position sensor
Hi Matt I have rated you and have also made a tip payment but I am not sure if this have reached you.
After a week of car working lovely apart form little jerk when clutch is down (every now and than not all the time) Yesterday the car started to vibrate really badly while in neutral just idling and making a lot of noise while accelerating and in gear driving.
I have took it to the garage today and they could not see anything on the diagnostic machine but we have discovered something quite strange while not in the gear and idling when we have switched the air-conditioning off it has started to make more noise and had more shaking than ever and that has increased when adding gas (while still being in neutral) as soon as we have switched the air-conditioning on the vibration has significantly been reduced although still there and slightly more vibration while adding gas being in the neutral.
Also when I turn on the car after 5 -6 hours not being driven the revs go up to 1300 and stay there for quite some time as soon as I put it in the gear revs work O.K although (it might be my imagination the rev needle does not go down as quickly as it should).
Now what was the usual for this car is that the revs always went up a bit (1100 - 1150) when I turn on the car but do go down rather soon after 20 - 30 seconds
Any thoughts on this two new discoveries.
As its a mechanical fault it tends not to turn on the fault light and you can sometimes 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 /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
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.
It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine