Keith C Posted November 3, 2001 Share Posted November 3, 2001 I have a strange query about the boost on my 95UKTT. If I put my foot down in any gear and at an rpm below about 4000, the boost goes up to about .6-.8bar, then as soon as I hit 2500rpm or so, drops back to .3bar, before then building up with the revs, until it's back to about .7-.8 >4000rpm. What sort of boost should the car be making up to 4000 - ie is this normal behaviour? Could it be the boost controller - I noticed on an invoice from the company that (re)fitted it saying 'EVC plumbed incorrectly. OE boost control system should be by-passed. Re-plumbed as necessary'. Could it be the turbos have been set to parallel. The EVC also doesn't seem to be working, as even when set to 1.2bar it still behaves as described. The car has no cats (Mongoose), and a HKS BOV (possible culprit?). Quote Link to comment Share on other sites More sharing options...
Brian Jackett Posted November 4, 2001 Share Posted November 4, 2001 I have a strange query about the boost on my 95UKTT. If I put my foot down in any gear and at an rpm below about 4000, the boost goes up to about .6-.8bar, then as soon as I hit 2500rpm or so, drops back to .3bar, before then building up with the revs, until it's back to about .7-.8 >4000rpm. Have you written this correctly? below about 4000 the boost goes to .6-.8 bar then as soon as I hit 2500. .3 bar at 2500 is correct isn't it. regards Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 4, 2001 Author Share Posted November 4, 2001 That's what I want to find out - is it spiking then going back to what it should be, or should it be higher and it's dropping off? It's not got any cats, so I'd expect the boost to be a little higher. It almost feels like it's doing the pre-spool early, and taking ages about it. About the best way I can describe it. Quote Link to comment Share on other sites More sharing options...
Brian Jackett Posted November 4, 2001 Share Posted November 4, 2001 When I de catted my JSpec it made no defference to boost pressure untill I also replaced the back boxes with a super drager. At 2,500 rpm boost will be low as the turbo is not spinning much. As you reach higher revs the boost will increase and at 4,000 rpm the second turbo kicks in and as you accelerate further boost will increase. Revs quoted are for jap spec. Have you still got stock rear exhaust regards Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 4, 2001 Author Share Posted November 4, 2001 The exhaust is a full Mongoose. If this is normal then - why does it spike at the beginning? Could it be the HKS BOV not being set correctly? Quote Link to comment Share on other sites More sharing options...
Branners Posted November 4, 2001 Share Posted November 4, 2001 I personally wouldnt expect it to spike like that, without cats you should also feel a huge kick when it hits 4000rpm. The kick is normally enough to break traction at low speed and if you arent feeling that kick then it sounds like something is wrong. JB Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 4, 2001 Author Share Posted November 4, 2001 Oh, I've got the major kick at 4000, and from 4000 up everything is how I'd expect it to be (including the lack of traction ). I was just concerned about why it spiked lower down the revs. It just feels a little odd when going along the motorway and I put my foot down, it surges forward then slackens off on the pull, before then pulling hard again above 4k. Quote Link to comment Share on other sites More sharing options...
GavinL Posted November 4, 2001 Share Posted November 4, 2001 Quote: from Keith C on 11:22 pm on Nov. 4, 2001[br]Oh, I've got the major kick at 4000, and from 4000 up everything is how I'd expect it to be (including the lack of traction ). I was just concerned about why it spiked lower down the revs. It just feels a little odd when going along the motorway and I put my foot down, it surges forward then slackens off on the pull, before then pulling hard again above 4k. Not uncommon, just more pronounced on the UK spec cars and on some cars more than others. The higher you turn up the boost the worse it's going to feel. regards..... Quote Link to comment Share on other sites More sharing options...
Guest Keith_C Posted November 5, 2001 Share Posted November 5, 2001 Oh - fair enough then. That's the sort of thing I wanted to hear - it's normal. If I put it in a lower gear it's barely noticeable anyway as the revs fly around - it was only pulling from 70-80 in 6th that made it really noticeable. Maybe I should be less lazy and change gear - not used to that though (the MKIII was an auto) Quote Link to comment Share on other sites More sharing options...
Guest Keith_C Posted November 6, 2001 Share Posted November 6, 2001 Nope - I'm still not happy. I've noticed that it spools up nice and fast between 1500 and 2500, making the sort of boost I'd expect for a decatted UK, Then at 2500 it dumps a load of air out of the HKS BOV, and the boost drops. It doesn't go back to what I'd expect until 4000+, and apparently it should be making more boost then I'm getting anyway! COuld it be a badly adjusted/faulty BOV causing the problems? Does someone have a stock BOV I can try to see it it's that? Cheers Quote Link to comment Share on other sites More sharing options...
matt Posted November 6, 2001 Share Posted November 6, 2001 Sounds wrong to me !! If the BOV is adjustable there should be a locknut and adjusting screw on it somewhere. Quote Link to comment Share on other sites More sharing options...
Guest Ash Posted November 6, 2001 Share Posted November 6, 2001 Sounds like the pre-spool circuit has been defeated. Yours, J Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 7, 2001 Author Share Posted November 7, 2001 Ash I thought that was possible too. Would that result in an audible 'dump' at approx 2500 rpm though? If so - where can I find a hosing diagram so I can return the thing back to the stock set-up. I may try the EVC again in the future, but I'd much rather know it was behaving properly at stock config before trying to do anything else. In fact, as I cant insure it with the EVC on there I'll need the diagram (if there is one) anyway. Cheers Keith Quote Link to comment Share on other sites More sharing options...
Guest Ash Posted November 7, 2001 Share Posted November 7, 2001 Which EVC unit do you have? Yours, J Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 7, 2001 Author Share Posted November 7, 2001 It's the HKS one with a dial. It was originally installed by Chris Wilson, but then TDi changed its plumbing in some way. It also occurred to me that I might have a split hose somewhere causing a boost leak. However, I also believe the BOV is adjustable - how do you adjust it? Cheers Keith Quote Link to comment Share on other sites More sharing options...
Guest Ash Posted November 7, 2001 Share Posted November 7, 2001 In the past, I've fought with TDI for months over the HKS EVC fitment issue. So it's probably best if I duck out of this one (heckling from the wings and all that). Yours, J Quote Link to comment Share on other sites More sharing options...
Alex Posted November 7, 2001 Share Posted November 7, 2001 Keith, The Bov is adjustable using a screw on the back of it. Only adjust it a 1/4 of a turn at any one time. If it seems to be letting go too easily I believe you should tighten it/screw it in further. Have you spoken to TDi? Maybe they'll know straightaway what's gone wrong. Quote Link to comment Share on other sites More sharing options...
Keith C Posted November 7, 2001 Author Share Posted November 7, 2001 Cheers for that Alex. I'm not actually too fussed about getting the EVC working as I have to unplumb it anyway - admittedly hopefully only for a couple of months (until renewal). What I really want to know is how to plumb everything back to stock. So it's screwed in to tighten, and out to loosen. I'll give that a go tonight Quote Link to comment Share on other sites More sharing options...
Alex Posted November 7, 2001 Share Posted November 7, 2001 Putting it back to stock might be difficult as they (with the blitz unit anyway) have to cut the intake manifold pressure hose and put a T piece in it to feed the EVC some info....not sure if this is how the evc works...if it is you'll need to cap the t-piece. Then disconnect both hoses that go to the turbo (make sure you know which hoses went to which actuator port on the turbo. Then take one hose and clamp it to both ports on the turbothus closing the loop....the EVC essential extends the loop with long hoses and adds a rick actuator. Well that's how it works on the Blitz units can't see the EVC being too much different. You should end up with the EVC control box under the bonnet disconnected and the turbo actuators joined by 1 pipe. Don't do it yet though...lets make sure I'm not wrong first! Quote Link to comment Share on other sites More sharing options...
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