01 TD4 Surge Under Load?

[kiwi_110]

Hi team,I guess I realy mean a negative surge...

Our Freebie just started hesitating on hills and on the straights when punching it. It felt like it was a fueling issue so I changed the fuel filter and also checked the one on the in-tank pump. No change. There are no DTC's showing on the Bearpaw scanner. After doing the filters, when it started missing again on the test drive, I wondered about the turbo sticking or something. What's the symptom of turbo issues? Any ideas?

Thanks, Ray.

[kiwi_110]

I've just changed the air filter and also put in an original Bosch MAF sensor and cannot replicate the issue so might have sorted it now. Will do some more mileage tomorrow and see.

[BogMonster]

On an older Td4, dig around behind the engine and you will find a couple of small inline filters. One of them is connected to the turbo modulator unit and the other one is for the EGR valve. They are like a little clear plastic can about 3cm round with a pipe coming out each end, one pipe goes to the turbo and one is the intake which is just a short bit IIRC. You can see the paper element inside. They get muck in and then water and will block up completely and can cause surging in the turbo, I think it's because the modulator over-corrects as it is working against a vacuum.

On my vehicle I re-routed and extended the intake pipe from behind the engine to further up in the engine bay using a bit of washer tubing, as it sucked water in when splashing through a puddle and the dust inside turned to mud and instantly blocked the filter up. IIRC later vehicles route the breathers to the main air filter box.

[kiwi_110]

BogMonster, cheers for the heads up about the little inline filters, i found the turbo one today when I did the main intake air filter and did give it a bit of attention. It may well have been contributing.