20 replies to this topic

[DudeRat]

Hi everyone. I've had my VXT for 8 Months now, and loving every minute of it, however.... A couple of months ago, just after the really cold weather, the car seems to have developed a turbo 'flutter'. Spoke to a few guys who said it was probably just a loose vacuum pipe, but i've just had the car serviced, and all pipes etc. are in place and working fine!! The diagnostic check didn't find anything either, but the power is definately lacking and there's some serious 80's style turbo lag!!!! Mechanic thought it could be an electrical/wiring problem. Any ideas? Many thanks

[Steppenwolf1980]

When you call the sound "fluttering", then check the recirculation valve of the Turbocharger. It has a rubber membrane which tears very often, making a strange noise when you get off the throttle. Otherwise you could check if the turbo's turbine wheel has got play and scratches on the housing. Also the boost control valve (it's an electronical/magnetical part) could cause problems with the boost, mine was faulty a year ago and sometime I had no boost at all because of that. You can check the wastegate, too... many errors can cause this problem.

[DudeRat]

Thanks very much for the advice, although it sounds like there are a lot of possibilities. Are all of these things that a complete idiot could find? Cheers A complete idiot

[VXTyrant]

Sounds similar to an issue both A-GAME and I are having with our tubby's at the moment. We are getting a 'fluttering' noise but my drop in power is only slight and seems to appear between 4-5,000 revs in 3rd and 4th gear. This was solved by test-fitting redvts' pro-alloy pipe to mine last week. So i've ordered my own pro-alloy pipe (in stealth black with red pipes ) from Courtenays to sort the drop in power as it seems the standard intake pipe goes very soft once the engine bay is warmed up and can collapse under heavy acceleration - thus severely reducing/restricting airflow and thus causing a drop in power.

Courtenay offer the pipe i've just bought - LINKY

Also, here is a LINK to my post (with video) so that you can see if the noise is similar to your own.

A-GAME is off to Back on Track in a few weeks so we shall await the outcome of that and see if there are any more suggestions.

In the mean time I am trying to find a time when I can take off the undertray to check all my boost pipes for splits or to see if they have popped off - i'd imagine split if anything as my noise only appears once the engine is warmed up!

[spuk87]

This was solved by test-fitting redvts' pro-alloy pipe to mine last week.

VXTyrant, are you still running a std turbo at the moment? Not stage 2 yet is it? If so that's interesting to see that the hose can collapse even on standard map. I had a big power dip at 4k revs which I put down to the same problem, but I reset my ECU the other day and that seemed to fix it. Maybe it's only a temporary fix though, I've yet to see.

[VXTyrant]

This was solved by test-fitting redvts' pro-alloy pipe to mine last week.

VXTyrant, are you still running a std turbo at the moment? Not stage 2 yet is it? If so that's interesting to see that the hose can collapse even on standard map. I had a big power dip at 4k revs which I put down to the same problem, but I reset my ECU the other day and that seemed to fix it. Maybe it's only a temporary fix though, I've yet to see.

Yeah just a lightly modded standard VXT at the mo. Done a few induction mods so air will be getting sucked through there alot faster than a standard VX so maybes that's the reason why I guess

[DudeRat]

[quote name='VXTyrant' date='26 May 2010 - 10:33 PM' timestamp='1274909616' post='1040066']
Sounds similar to an issue both A-GAME and I are having with our tubby's at the moment. We are getting a 'fluttering' noise but my drop in power is only slight and seems to appear between 4-5,000 revs in 3rd and 4th gear. This was solved by test-fitting redvts' pro-alloy pipe to mine last week. So i've ordered my own pro-alloy pipe (in stealth black with red pipes ) from Courtenays to sort the drop in power as it seems the standard intake pipe goes very soft once the engine bay is warmed up and can collapse under heavy acceleration - thus severely reducing/restricting airflow and thus causing a drop in power.

Cheers for the advice, although my symptoms are a bit different. When I first drove the car there didn't appear to be any real lag, obviously there was still the flat spot between 2-3k revs, but now it just seems like the turbo isn't spinning up very quickly, and when you come off the throttle it almost sounds like someone has fitted a dump valve to it!! I live in the North East too, so if yo're free anytime, i'll come down for a drive?

Thanks again

[spuk87]

Yeah just a lightly modded standard VXT at the mo. Done a few induction mods so air will be getting sucked through there alot faster than a standard VX so maybes that's the reason why I guess

I would have thought airbox mods would help if anything because it would reduce the vacuum pressure and potential collapse...might be wrong. Just wondered because mine is only a stage 1 (and a bit) but I seem(ed) to be getting the same effect.

[cheeky_chops]

Cheers for the advice, although my symptoms are a bit different. When I first drove the car there didn't appear to be any real lag, obviously there was still the flat spot between 2-3k revs, but now it just seems like the turbo isn't spinning up very quickly, and when you come off the throttle it almost sounds like someone has fitted a dump valve to it!! I live in the North East too, so if yo're free anytime, i'll come down for a drive?

Thanks again

sounds like recirc is split to me

[VXTyrant]

EDIT: double post - god knows why so late haha @spuk - who knows mate. All I know is my drop in power disappeared when we test fitted redvts' alloy pipe and I always intended to get one anyway (last year); I was waiting to get it with the 80mm amm (which needs remapping, hence my wait to buy the pipe originally) but I found out that Courtenays will charge the same (£40) for the larger pipes separately if you bought the alloy pipe from them in the first place @DudeRat - no probs buddy. I'll pop out with you in yours then in mine if you want!? I'm free tomorrow all day, dunno how much help I'll be mind Not even redvts (the local VX mechanic) knows what's up with mine… if only DuncanVXR lived near by - damn you Duncan; how inconsiderate

Edited by VXTyrant, 27 May 2010 - 03:49 PM.

[Whiteboy]

If it sounds like a turkey and the boost pipes are all on, then it sounds like the recirc valve. http://www.courtenay...d&productId=679

[DudeRat]

VXTyrant - Thanks very much mate, i'll be free sometime next week if you're about. It's sounding more like the recirc valve, but would be good to meet up so you can hear the turkey!! Does that mean i'll have to wash the car though....

[JohnTurbo]

Lol. I'm reminded of everyone on Skylineowners with a missfire being talked into buying "Splitfire" coilpacks to the tune of about 250quid. Car forums make me chuckle sometimes. Similarly to that case though...buying that bit of aluminium seems like a bit of a plan anyway! The Turkey you can hear is what is known as compressor surge. Because your recirc valve is split, it cannot relieve the pressure in your IC/pipes when you change gear, and when you take your foot off the gas, and the throttle plate is closed the gas has nowhere to go but BACKWARDS through your turbo. Since there is also little backpressure in the turbine, the blades go supersonic...this is the flutter. This not only hurts your turbo, but means when you get back on the gas you have to decelerate the backward spinning turbo, and then accelerate it again before you get any boost. Just in case you've not got the message yet... *cough* recirc *cough* Of course there are other things that could cause this problem, but you're very likely to find its the valve.

Edited by JohnTurbo, 28 May 2010 - 07:05 PM.

[VXTyrant]

VXTyrant - Thanks very much mate, i'll be free sometime next week if you're about. It's sounding more like the recirc valve, but would be good to meet up so you can hear the turkey!! Does that mean i'll have to wash the car though....

The only day I'm ever free is Fridays mate. I may be cycling next fri unless the weather is awful. Could meet up on an evening (6pm onwards, mon, tue or thu) Based on the description john turbo just gave I'd look at replacing the re-circ valve asap to avoid any fatal damage!

[DudeRat]

JohnTurbo - Thanks very much, i'll get it looked at ASAP, out of interest, do you know how much it is to recondition a turbo? VXTyrant - Nice one, i'll see about getting the valve fixed, and then come down for a spin. Thanks for all your help.

[VXTyrant]

do you know how much it is to recondition a turbo?

Lots of people use AET Turbos in Yorkshire, not sure how much it costs but they can recondition/repair and even turn it into a 'hybrid' turbo that can be used to tune to stage 4 iirc

Also, I've heard nothing but good things about them. That's where I'll be taking mine when planning on the stage 2-4

AET's number: 01924894171
AET's website: http://www.aet-turbos.co.uk/

[A-GAME]

From reading various past comments and fixes can we generally conclude the following?? (PRESUMING ALL PIPES HAVE BEEN CHECKED AND ARE ON/OK) - A noticeable loss of boost or lag or performance issues + a 'turkey' fluttering/chatter sound = MOST LIKELY TO BE RECIRCULATION VALVE FAULT - No noticeable changes other than a 'turkey' fluttering/chatter sound = BOOST CONTROL SOLENOID VALVE FAULT Lots of people seemed to have cured the fluttering/chattering after replacing the Boost control solenoid, when that was the only symptom experienced. This is what I'm getting at the mo. Car still feels as quick as ever though and no flat spots (stage 1 then milltek pre cat pipe). I think I'm going to get hold of a new soleniod vlave part before I drop the car in to B.O.T for it's 4 year service next week. Seems an easy enough fit and for £20 relatively cheap. I haven't been able to have a good look at the pipes from underneath yet so- unless i get the chance beofre- I'll ask B.O.T to have a good check and then fit the new BCS to see if it cures it! Anyone got the exact part number for it? Thanks and good luck solving it - I'll let you know if I get it sorted

[Zoobeef]

Dont forget the first thing to check is all the vacuum pipes for splits or if they have popped off.

[JohnTurbo]

Zoobeef makes a good point that the small vac line which connects to the valve should be checked. As for re-conning your turbo - don't worry too much. Yes compressor surge will speed up the death of your turbo, but only like smoking will speed up your death! A short stint shouldn't have caused any noticeable harm. - In fact some turbo systems don't recirculate at all, especially on diesels. The boost control solenoid points are interesting. Potentially there are two modes of failure:- 1) solenoid fails open, car runs boost equal only to the wastegate spring force = slow! 2) Solenoid fails closed, car overboosts. Typically i'd expect the ignition to retard, giving a noticable jerk. (Note it shouldn't be the solenoid affecting the OP's problem) Edit:- Actually when the spring alone is used to control boost there is a flutter, i'm just surprised the drop in power is only slight. Must be a stiffish spring.

Edited by JohnTurbo, 29 May 2010 - 03:22 PM.

[DudeRat]

Zoobeef makes a good point that the small vac line which connects to the valve should be checked.

As for re-conning your turbo - don't worry too much. Yes compressor surge will speed up the death of your turbo, but only like smoking will speed up your death! A short stint shouldn't have caused any noticeable harm. - In fact some turbo systems don't recirculate at all, especially on diesels.

The boost control solenoid points are interesting. Potentially there are two modes of failure:-
1) solenoid fails open, car runs boost equal only to the wastegate spring force = slow!
2) Solenoid fails closed, car overboosts. Typically i'd expect the ignition to retard, giving a noticable jerk.

(Note it shouldn't be the solenoid affecting the OP's problem)


Edit:-
Actually when the spring alone is used to control boost there is a flutter, i'm just surprised the drop in power is only slight. Must be a stiffish spring.

Thanks again JohnTurbo, I took the car along to a lotus specialist, which in retrospect maybe wasn't the best option since I needed the engine not chassis looked at!! Either way, he ran a diagnostic check and no errors came back, is this in line with the recirc theory, as he did mention a possible electrical fault and mentioned the solenoid? The symptoms are definately more like the recirc valve you talked about though.