Maverik Posted December 20, 2021 Share Posted December 20, 2021 Hi folks, This has got me scratching my head so needs to fresh idea's. Defender 200tdi (freshly rebuilt) with Turbotechnics VNT upgrade turbo. This started early this year after 10 months of faultless running. I start engine, drive away, and it feels very flat. Boost pressure rises relatively normally 2nd gear and push acelerator it spikes up to 1.5+ bar then sharply drops, the VNT is set up to max out at 1.45 bar, once its done the "unsticking thing" it will then be pretty spritely up through the gears and only when you push hard and load it up will it go near 1.45 - usually operating between 0.8-1.2bar normal type driving, however hard you push it after the first spike you cant get it to spike again - unless you turn the engine off. then do a re-start. What I have done so far. VNT has been stripped and cleaned and has no damage, the vane mechanism is light to the touch with no notches or catches. VNT actuator has been replaced with like for like part. Boost pin changed. I can't for the life of me work out what could be now causing this spike of pressure what I feel is the vanes in the turbo not responding properly, but everything appears good there... Anyone any suggestions? Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 20, 2021 Share Posted December 20, 2021 When you start there is a puff of smoke as the auto enrichment kicks in. Could that be depositing soot, enough for a momentary stick, then once it clears it's gone. (Straw grasping I know) Quote Link to comment Share on other sites More sharing options...
rusty_wingnut Posted December 20, 2021 Share Posted December 20, 2021 Exactly what my VNT used to do - honestly they just don't work on TDIs in my experience. I think you require far more control on fuelling to obtain the most from your VNT, which is not easy on a TDI. 1 Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 20, 2021 Author Share Posted December 20, 2021 10 minutes ago, rusty_wingnut said: Exactly what my VNT used to do - honestly they just don't work on TDIs in my experience. I think you require far more control on fuelling to obtain the most from your VNT, which is not easy on a TDI. Hehehe hmmm I've been thinking about this a lot and I'm inclined to agree with your statement... 1 1 Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 20, 2021 Author Share Posted December 20, 2021 With the wee actuator tester I've made out of my bike pump, I'm going to go pop it on the actuator now and see what it does, if it is that sticking, if not... then next step is to look at the injector pump, make sure everything is ok in there.... Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 Reading the Bosch VE pump technical book... and this morning's googling... Yes I reckon I could be certifiable... not sure I've got the patience or the spare wallet notes but... Need to do a bit more figuring out as to whether or not I can find a controller that is controllable enough to play with... Bosch VE EDC 0460414997 Re-manufactured unit | eBay Quote Link to comment Share on other sites More sharing options...
Gazzar Posted December 21, 2021 Share Posted December 21, 2021 What does that do, that a normal pump doesn't? Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 Interesting - turns out they where used in VW T4's and it appears the ECU's are pretty easily available. Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 1 minute ago, Gazzar said: What does that do, that a normal pump doesn't? Electronic controlled, better fuel control. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted December 21, 2021 Share Posted December 21, 2021 It talks to the actuator on the turbo? Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 10 minutes ago, Gazzar said: It talks to the actuator on the turbo? hehe, in some form I imagine, its potentially a way of doing away with boost pins and having to change the gradient on them to alter the fueling - I would have though there would be a manifold pressure input into the ECU. Bit of a pipe dream idea to be honest, if I didn't have a day job this would keep me busy for a while. - interesting idea though, with a scrap T4 with the right engine would be fun to give it a go. Something like this could do... VW T4 1996-2003 TRANSPORTER GENUINE COMPLETE 2.5TDI ENGINE, CODE AJT 135K MILES | eBay Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 Apparently some Discovery's had the EDC controlled pump... A reasonable overview. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 21, 2021 Share Posted December 21, 2021 Yep, 300TDI auto had EDC, to make up for the power sapping auto box it was the most powerful factory 300TDI built. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 21, 2021 Share Posted December 21, 2021 I can see you now: Quote Link to comment Share on other sites More sharing options...
missingsid Posted December 21, 2021 Share Posted December 21, 2021 50 minutes ago, Bowie69 said: I can see you now: ? As far as I can see it mostly lost and made a carp load of cancer producing pollution doing it. WHY. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 21, 2021 Share Posted December 21, 2021 10 minutes ago, missingsid said: WHY. Well quite, I wasn't advocating it! Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 21, 2021 Share Posted December 21, 2021 Before going into the technical long grass, is everything else OK - inlet not blocking or delaminating, exhaust free? Quote Link to comment Share on other sites More sharing options...
missingsid Posted December 21, 2021 Share Posted December 21, 2021 22 minutes ago, Bowie69 said: Well quite, I wasn't advocating it! OK, just clarifying. Though I guess I was stating the obvious if you were being more subtle in your comment. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted December 21, 2021 Share Posted December 21, 2021 Is this the point where you say I'm not throwing any more money down this particular hole, I'll put a TD5 in ? Mo 2 1 Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 21, 2021 Share Posted December 21, 2021 It has been a really disappointing saga. The idea of a VNT is very appealing, and once they made them available for the Tdis, it has been quite tempting. But your experience, as well as educational for the rest of us, doesn’t seem atypical. Mike has been very critical of them on his BritRest videos, when the topic has come up. He doesn’t rate the 2.8TGV at all, but the turbo was singled out for criticism over reliability. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 21, 2021 Share Posted December 21, 2021 Well to just put the other side, I have run one of the TurboTechnics ones on a 300tdi for the last 6 years - it has been fine. 1 Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 21, 2021 Share Posted December 21, 2021 Did it make a big difference to the drive? Quote Link to comment Share on other sites More sharing options...
TSD Posted December 21, 2021 Share Posted December 21, 2021 (edited) As far as I remember, boost spikes are all but inevitable using a simple mechanical control of a VNT. If the system is damped enough to prevent the spike, then boost rolls on so slowly that (in normal driving) the engine has run through the rev band where the VNT shows an advantage over conventional turbo, before boost can build. My 2.8TGV has shown spikes since day one, more than 250k ago. After 15 years of smacking the endstop at 25psi, the boost gauge no longer reads zero with the engine switched off. I can't understand why Maverick only sees the spike once, after a restart though. Edited December 21, 2021 by TSD editted for clarity Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 21, 2021 Share Posted December 21, 2021 36 minutes ago, Snagger said: Did it make a big difference to the drive? In a word yes, it feels like you have a larger engine ( I have got used to it now) . It pulls really well. Solo it really wouldn't make that much difference I guess but pulling a trailer with a couple of horses, it helps a lot, it makes the engine more flexible . The fuelling had already been messed with when I got the vehicle, just boost pin and star wheel and it used to smoke a bit. All that smoke went - admittedly the original turbo was on the way out. But I didn't really have a standard start point. Starting on a hill with the trailer is much easier. I fitted a full width intercooler and 4-core rad at the same time, but I don't think that would make much difference at low speeds. 1 Quote Link to comment Share on other sites More sharing options...
Maverik Posted December 21, 2021 Author Share Posted December 21, 2021 Back on topic 2 hours ago, TSD said: I can't understand why Maverick only sees the spike once, after a restart though. Back on topic, just been out to fettle. Put my wee pump onto the actuator on the turbo and it didn't seem to stick or anything, The scale on the gauge isn't great a bit small, but there was nothing that indicated anything sticking - got a more sensitive gauge ordered so can try this again later to double double check. So checked the other end - I had found a bit of oil carry over into the boost line before so check this and it was super clean still from the engine rebuild. For good measure I popped the top of the boost compensator on the FIP and pulled the pin, I did find some pretty gloopy oil on the pin, so cleaned that all out and washed it with WD and dried it out a bit. I did have some generic "performance/non factory" pin in thought i'd give it a whirl but thinking I need to take it back to basics so threw the original factory pin back in and set it to what I was running it last year when everything was going ok. Will be taking for a test drive shortly see what happens if anything. Quote Link to comment Share on other sites More sharing options...
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