JamesArup Posted October 31, 2006 Share Posted October 31, 2006 Hey guys, Bear with me on this one. I've had this problem for far too long now and I really want to try and get to the bottom of it. I'm going to explain the issue, and go into as much detail as possible in the hope that one of you dudes may know the answer!! The Scenario - Car was off the road for 8 months after an accident last November (don't ask!). It was started fairly regularly whilst it was off the road, and never had any issues. When I finally picked the car up, it felt ok for a few days, and the HKS BOV was 'blowing off' as expected. The Problem - After a few days, the BOV went silent and the car started to feel a bit 'loose'. I have a Blitz SBC ID3 and Powermeter and it's setup to run at 1.2 bar max. Since the BOV went quiet, I can only really seem to get between 0.8-0.9 bar. The 2nd turbo seems a bit intermittent and the car just doesn't pull and have the kick that it used to What I've Checked - - I have checked everywhere for loose hoses or split pipes, but I honestly can't find anything obvious. - I unplugged the Blitz SBC ID3 and tried a MBC instead to see if the issue was with the Boost Controller. Didn't get any more boost with that either. - I removed the HKS BOV (from the FMIC hardpipe near the Throttle Body) and I blanked it off. Ran with no BOV, just so see if that helped, but the car felt exactly the same. - I have run the car in both SEQ and TTC setups ... still not generating the boost I had before Thoughts - Having read around on the forum (lots) I had thoughts that it could be the pressure tank, or one of the VSV valve thingies. - But .... I am still getting upto 0.8 bar of boost, so the BOV should surely still be going off shouldn't it (it used to make a sound, even with the smallest amount of boost pressure)? This is why I was convinced it was faulty. - However, when I removed the BOV from the system, there didn't seem to be any improvement at all, which would seem to indicate that the BOV isn't actually the issue? But then why isn't it making a sound! Arrrghhhhh! Sorry about that. Had to try and get it all down, and show some of the steps that I've already taken to try and help explain it . Next step is to soak everything in a nice Fairy Liquid mixture to see if there are any leaks that I may have missed ..... but it still doesn't explain why the BOV has gone silent! My head is spinning Any help would be much appreciated. I'm sure I may have missed out some details, so if there is anything specific you need to know to help in a diagnosis, just let me know It's a 1995 J-Spec, 6-Speed Manual by the way!! Cheers, J Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 OK, question one, have you got any CATs in still? If you have, it's possible it's falling to bits and has formed a big restriction in the exhaust, thus limiting boost. Also, I assume you have a boost gauge. This can be rather handy - take it out of wherever it's currently plumbed in and plumb it into the vacuum reference hose that goes to the BOV instead. That way you can measure the pressure/vacuum that goes to it. It'll either show strange readings (no boost, constant vacuum, whatever) and demonstrate there is something wrong with the feed to that hose, or it'll be completely normal and show your BOV is up the spout. Another cause could be the Exhaust Gas Control Valve not opening correctly. It's the one on the downpipe. The second turbo can get choked by it not opening fully, and that will also increase exhaust backpressure and limit boost. Difficult to diagnose though... -Ian Quote Link to comment Share on other sites More sharing options...
JamesArup Posted October 31, 2006 Author Share Posted October 31, 2006 Cheers Ian I don't have any CATS, no. I have a double De-Cat, CW Style (no restrictor ring, never needed one). I do indeed have a boost guage. Actually, I have a spare one kicking about somewhere. I'll give this suggestion a go, and see what I come up with. The Exhuast Gas Control Valve sounds like a potential nightmare. Hope it's not that. Basically, it ran fine before it went in. 8 months later, with no additional miles on the clock, it's all gone horribly wrong! Cheers, J Quote Link to comment Share on other sites More sharing options...
Ian C Posted October 31, 2006 Share Posted October 31, 2006 Fear not - the EGCV can be removed from underneath without having to take the turbos off - as long as you can unseize the bolts it's probably under an hour to do it. All the plumbing is readily accessible. There are plenty of spares knocking about (I personally have two sat on my shelves) and it's possible it's rusted shut or gunked up from being stood around doing nothing You can use a boost gauge to diagnose how much manifold pressure reaches the EGCV as well Might help in the diagnosis. It could still be something completely different but it seems to fit the symptoms so far... -Ian Quote Link to comment Share on other sites More sharing options...
JamesArup Posted October 31, 2006 Author Share Posted October 31, 2006 Cool .. that sounds like an option I'm still totally puzzled as to why the BOV has gone quiet, despite me still getting 0.8 bar of boost. I was convinced that was the problem until I blanked it all off, and it still felt all wrong Thx for the help, Cheers, J Quote Link to comment Share on other sites More sharing options...
tDR Posted October 31, 2006 Share Posted October 31, 2006 Perhaps the BOV was set only to go off at higher pressures, I think the earlier SSQV's had adjustment for this. The fact you're making low boost regardless of boost setting could be an EGCV problem as described by Ian above or could be the 2nd turbo itself. Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
JamesArup Posted October 31, 2006 Author Share Posted October 31, 2006 The BOV used to go off even with a tiny amount of pressure before. I'm still generating enough boost to certainly make the BOV sound as it did before, and nothing has changed on the BOV itself. The EGCV is certainly something that I will look into (well, gotta find the damned thing first! ). As a side note to this. When I thought the issue was with the BOV, I bought one of those £30 HKS SQV 'Style' BOV's of Ebay. I figured that I just needed it to diagnose a problem, and it didn't really matter if it was rubbish! . Well ... it turned up today, and honest to God, it's IDENTICAL to the £200 HKS unit. I've compared them side-by-side and there is no difference (apart from the HKS logo ontop). The casing is the same, the piston inside is the same (same purple colour), and even the writing on the valve is the same, where is says 'Sequential Blow Off Valve'. Admittedly, I haven't tried it yet, but it will be interesting to see the difference between a £30 '3rd Party BOV', and a genuine £200 one! I'll report back if I ever get my car working to test it! :rolleyes: Cheers, J Quote Link to comment Share on other sites More sharing options...
tDR Posted November 1, 2006 Share Posted November 1, 2006 Sounds like a problem with the pressure reference line the BOV uses to activate - have you checked this for leaks / wear and that it's well secured at either end? Do you have some small internal diameter hose you could replace the current one with to test? Cheers, Brian. Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 1, 2006 Share Posted November 1, 2006 The EGCV is certainly something that I will look into (well, gotta find the damned thing first! ). Have a look here: http://www.mkivsupra.net/vbb/showthread.php?t=35925 Last piccy, bottom right. Be interested to hear about that BOV as well by the way, that could be a very useful test Quote Link to comment Share on other sites More sharing options...
JamesArup Posted November 1, 2006 Author Share Posted November 1, 2006 Ahhh ... Big fan of those pics. Very useful. It's times like this that I WISH I had a 4-post lift of something! . It doesn't look that easy to get to. I have checked all around the pipe going to the BOV, and I have replaced it too. I also removed the inline valve thingy incase that was blocked up, but it didn't seem to make a difference Will keep you updated on the BOV. The ONLY difference between the Ebay one and the genuine HKS one, is that the Ebay one doesn't have the adjusting screw on the back. Cheers, J Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 1, 2006 Share Posted November 1, 2006 Check the line to the BOV with your boost gauge, that'll tell you for sure. The EGCV will need - car up on wheel ramps, no claustrophobia, a big extension bar, a knuckle joint, a deep 12mm socket (or is it 14mm?) and a big ratchet. And wd40. Lots of wd40. Centre section of exhaust off, then the elephant's leg downpipe (three nuts that need the above to get them off), then the EGCV slides off the long studs that are left behind. -Ian Quote Link to comment Share on other sites More sharing options...
dangerous brain Posted November 1, 2006 Share Posted November 1, 2006 Techno muppet here The BOV fault if the BOV was sticking shut and not opening wouldn't be proven by taking the BOV off and blanking off the hole would it? Its not unknown for more than one problem to develope on machinery left sitting around for a while. Quote Link to comment Share on other sites More sharing options...
tbourner Posted November 1, 2006 Share Posted November 1, 2006 I was gonna say that /\ . Have you tried or can you get another BOV to swap and try that? Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 1, 2006 Share Posted November 1, 2006 "I removed the HKS BOV (from the FMIC hardpipe near the Throttle Body) and I blanked it off. Ran with no BOV, just so see if that helped, but the car felt exactly the same. " Post #1, somewhere near the top of this thread -Ian Quote Link to comment Share on other sites More sharing options...
dangerous brain Posted November 1, 2006 Share Posted November 1, 2006 Yeah I can accept that point but I am merely suggesting that the BOV may not be functioning correctly ie jamming as well as the boost problem and that just blanking off the BOV port is only going to simulate a blocked BOV not one stuck open. Quote Link to comment Share on other sites More sharing options...
JamesArup Posted November 1, 2006 Author Share Posted November 1, 2006 I do have this spare 'HKS Style' BOV that I got off Ebay. I'm going to try shoving that on tonight and seeing what happens Fingers crossed, but I'm not convinced that's the problem. If I do manage to get the EGCV off, what am I looking for? Just general blockages and 'gunk'? Cheers for all the help, given me some ideas. J Quote Link to comment Share on other sites More sharing options...
dangerous brain Posted November 1, 2006 Share Posted November 1, 2006 I'm also not convinced that the BOV is causing the lack of boost. I think however any boost when there is a dump requirement ie when you back off the throttle should be audible when you drop off the accelerator so maybe you have an additional fault of a stuck shut BOV. Thats what I was trying to get across but obviously badly Not knowing the intricacies of how a BOV works exactly I wouldn't be inclined to stand 100% by my opinion though. Quote Link to comment Share on other sites More sharing options...
JamesArup Posted November 3, 2006 Author Share Posted November 3, 2006 Well bugger me .... It works :eyebrows: Put the new Ebay BOV on last night, took it for a spin, and *whoosh*, the BOV was sounding again. The car instantly felt better and more responsive. Driving back from work tonight felt much better too ... got a nice flame all the way up the back of my spoiler too . So, against everything I thought, it seems the BOV was at fault! The Ebay 'HKS Style' BOV does actually seem to work okay. Upon closer inspection, and a test drive, it is actually clear that the HKS is the better unit though. Having said that, the Ebay one seems to do the job. The sound is pretty good, although not as good as the real HKS. Also, with the real HKS, if you hold the throttle so that it's 'just' generating some vacuum, the BOV will chatter nicely. With this one, you just get a very loud, continuous 'blast' of noise that sounds like someone using a compressor to blast air. That being said ... it seems to do the job. And for £35 instead of £200, I wasn't expecting miracles! Here are some pics I took of the HKS and Ebay BOV side by side so you can get an idea. Cheers, J Quote Link to comment Share on other sites More sharing options...
Homer Posted November 3, 2006 Share Posted November 3, 2006 So, in summary, your HKS BOV got sticky after 8 months of doing nothing. I bet if you free it up and lubricate it, it'll work fine again. Nice to hear you're back on the road again though Quote Link to comment Share on other sites More sharing options...
JamesArup Posted November 3, 2006 Author Share Posted November 3, 2006 Well .. I'm not 100% sure, but I think it may be game over for the HKS. I totally dismantled it, and gave it a good clean with a generous coating of WD-40. The valve itself doesn't feel particularly sticky, so I'm not entirely sure what's up with it! . Oh well ... I'll keep my eyes open for a nice, cheap, second-hand one somewhere as this Ebay one seems to be doing the job for now Cheers, J Quote Link to comment Share on other sites More sharing options...
Ian C Posted November 3, 2006 Share Posted November 3, 2006 I notice there is no adjustment screw on the ebay BOV? The continuous blast of air you hear is vented boost so it could really do with tightening up a bit -Ian Quote Link to comment Share on other sites More sharing options...
JamesArup Posted November 3, 2006 Author Share Posted November 3, 2006 Aye ... It does sound like it needs tightening. I'm not really sure what that screw does on the HKS one though. HKS are very specific when they say that's it's for factory use ONLY, and should never be turned by the end user. And, when I dismantled it, it really doesn't look like it does anything! There is just open space on the other side of the screw, it's not connected to anything at all Cheers, J Quote Link to comment Share on other sites More sharing options...
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