[blacktop]

When driving a steady speed at say 2000rpm, the engine speed fluctuates every 2 seconds. The engine revs up and down by approx 250rpm. I can feel the 'velle surging and hear the turbo starting to spin up but then it drops down back out of boost.
It accelerates fine, nice and smooth, and it starts fine. Everything else is otherwise fine and working correctly. I've got a OBD2 fault code reader and that showed up no fault codes present. There is no engine warning light coming on except at first turning on the ignition.
The fluctuating engine speed is consistantly every 2 seconds, it doesn't seem to be random at all.

Any ideas?. I am thinking maybe it's throttle control or turbo waste gate maybe????.
Thanks for any info you can give me,
Alan.

 

[topsparky]

When driving a steady speed at say 2000rpm, the engine speed fluctuates every 2 seconds. The engine revs up and down by approx 250rpm. I can feel the 'velle surging and hear the turbo starting to spin up but then it drops down back out of boost.
It accelerates fine, nice and smooth, and it starts fine. Everything else is otherwise fine and working correctly. I've got a OBD2 fault code reader and that showed up no fault codes present. There is no engine warning light coming on except at first turning on the ignition.
The fluctuating engine speed is consistantly every 2 seconds, it doesn't seem to be random at all.

Any ideas?. I am thinking maybe it's throttle control or turbo waste gate maybe????.
Thanks for any info you can give me,
Alan.

search for boost leaks first buddy
check all the intercooler pipes
and clamps
T:T:T:T:

 

[blacktop]

search for boost leaks first buddy
check all the intercooler pipes
and clamps
T:T:T:T:

Cheers mate. I'll try that first thing in the morningT:.

 

[blacktop]

Been busy today fitting a new oil cooler to the autogearbox, (see thread). So I checked out the intercooler pipework and joints and all seems fine. I also checked the vac hoses to the turbo and EGR etc and found some very perished pipes. I have replaced all the hoses to the N75 valve and turbo with new plastic pipe.
Haven't had a chance to test drive it yet so dont know if the problem is still there.
This is one of the bad hoses on the turbo:
http://picasaweb.google.com/lh/photo/2zuDkAiQD9F6XApVAPQYMQ?feat=directlink
and this is the N75 valve with the new plastic pipe fitted:
http://picasaweb.google.com/lh/photo/BI3Ekz_CMjVhDMXNZOUA4g?feat=directlink

Fingers crossed it's solved the problem.
Alan.

 

[blacktop]

Since fitting the new pipes the fault hasn't returned.
ResultT:T:T:T:T:
Alan.