Thread: Help needed - Surging under full throttle

Hey guys,

Strongly considering buying a tidy '03 TD5 S with 200K KM. Full log book servicing and drives well.
The only thing holding me back is under full throttle, the motor starts surging. It idles smooth and drives sweetly under normal operation. However, when you put the pedal to the metal, the revs start surging back and forth by maybe 300RPM or so. Doesn't seem to matter what speed your doing, but it definitely did it at 60km/hr and 95km/hr.
It's at a car yard and I told him to have his mechanic check the injector harness for an oil leak into the ECU. All clean there. Then I mentioned the previous owner may have adjusted the wastegate and it could be hitting overboost (all knowledge gained from this forum, so thanks to everyone for that). Can't remember if he said the mechanic looked for adjustment there or not. The mechanic's first thought was MAF sensor, so he checked that and reported back all good.
The car really is quite tidy apart from a few interior issues (drink holders stuck in, seatbelt pillar plastic cracked etc) but I can't bring myself to purchase it without having this problem resolved. But it seems like if they can't find the problem, they won't bother fixing it. So I'm really hoping for someone to give me some possible solutions.
I'd love to be joining the club of disco owners, but need to get this one nutted out first.
Cheers in advance for any suggestions. Have a good weekend.

Originally Posted by discorevy

Disconnect maf to diagnose , free and 2 seconds to do ,
If you need a boost modulator its about $65 and 10 minutes
Would recommended a nanocom .... Worthy investment
Enjoy your disco, auto or manual?

just d/c and take it for a drive?? Wouldnt that cause all sortsa funky crap?