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The mkiv Supra Owners Club

Lack of boost


ad500

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Did a search on this but people had various different scenarios.

 

I went to get the car checked over today and it turns out that even when the boost controller is set to 1.4 bar the car barely hit 1.0 bar. I havn't got a boost guage so never really noticed a lack of power on 2nd before. TBH i only run it at what i thought was 1.4 about 10 times in the last year and i wondered why it didn't feel any different.

 

The boost controller was disconnected and a seperate guage plumbed in, the pipe off the wastgate was disconnected so that the car should have reached at least 1.3+, even then it only just reached 1.0bar. There is a surge of power at 4000rpm but apparantley not as much as should be expected. The boost controller therefore is not suspected as faulty.

 

A couple of hoses blew off a few weeks back, but once put back in place everything seemed ok again. Having not driven anyone elses supra ive no reference as to what it should be performing like. It seems that although my car should be running at 450bhp im barely barely making much more than stock performance.

 

Thoughts are that the 2nd turbo is misbehaving or something is sticking, cracked .....i don't know. The turbo's have only got 24000 miles on them, maybe im asking too much but i thought they would last a bit longer.

 

Anyone else had anything similar happen, any answers would be appreciated. Definatley getting a boost guage now.

 

 

 

:confused:

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Originally posted by Ian C

List your mods, then :)

 

-Ian

 

Sorry, it should have been obvious that you needed these:twak:

 

Uk spec tt manual.

 

Forged pistons, 256/264 cams+gears, s type FMIC, VPC, FCD, induction, ssqv bov, EVC 4, superdragger, no cats(1st gutted, hydrids, rltc, twin power delivery, 2.0mm MHG,t timer.

 

Nothing else i can think of that is significant.

 

Its getting to the stage where i think the actuators (if thats the right term) are going to be checked and the 2nd turbo even though it seems to be working.

 

I was about to use this money for a respray, happens everytime, think of an improvement to do and the car relinqueshes you of that cash to sort a problem.

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Thanks dude.

 

Someone is doing the work for me. The vsv's are one of the next things their going to check but ive been told their not that accessable. With regards to the pressure tank, this was never mentioned as a possible cause (i don't think it was anyway) and don't think it been checked.

 

Personally im not sure where it is and how to check it, is it something i could do myself.

 

Cheers bud.

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VSV's are all accessable and should be checked , ive found that if you locate the one near the back next to the drivers side cam cover and pull the hoses off there should be a rush of air ie pressure tank ok , if you do a search you may find a how to on testing the vsv's and pressure tank (you will need a myti vac tool to do this ) but it is awkward to explain locations , have a look in the tech section , if you have trouble get back to me and i will try to help but i would go for vsv's or pressure tank , have you tried ttc to confirm .

John:flame Dev

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So far the only checks that have been done were mentioned above (road test at 1.4 checking EVC readings, disconnect EVC, then road test with seperate boost guage connected, finally road test with boost guage and pipe removed from wastegate), forgot to mention also a check with the sensor in the exhaust pipe and headphones (excuse my lack of terminollogy) which was done before the others. If i remember rightly this was done to detect det and not to do with checking boost.

 

Just thinking, is it possible that i could have connected one of the hoses that flew off a few weeks back into the wrong position and still maintained some sort of maintainable boost. i say this because there were 2 openings below where it fell off which could have fitted the pipe equally. Im doubting this because on one of the road tests a pipe flew off the seperate boost feed and we had to crawl back at 5mph for 2 miles, so i wouldn't think this would be possible, just thinking aloud really.

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Originally posted by dude

You need check 4 vsv's dude , its easy to do , if you get stuck phone me 07973 422272

 

John:flame Dev

 

Cheers mate, ill read the other thread and have look, will probably call you just to make sure ive done it right.

 

:respekt:

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The turbos should be OK at that age, I'm assuming you change the oil regularly and let them cool down after a run :)

 

JB's suggestion sounds like a good thing to check, restrictions in the exhaust are a great way of limiting your boost. Only after checking that would I start poking around VSVs.

 

-Ian

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Originally posted by Ian C

The turbos should be OK at that age, I'm assuming you change the oil regularly and let them cool down after a run :)

 

JB's suggestion sounds like a good thing to check, restrictions in the exhaust are a great way of limiting your boost. Only after checking that would I start poking around VSVs.

 

-Ian

 

The turbos get between 1 and 4 minutes cool down depending on timer and oil changed between 3-4000 miles.

 

Could there be a blockage if my pipes are straight through/no cats or are we talking about debris from the tail pipe?

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Ive just noticed the pipe set up from wipeouts thread and the picture shows the two pipes connected above the vsv. My set up is also similar but the red line that ive drawn on is to illustrate that my pipe goes direct with no connection. This was also the same pipe that blew off a few weeks back.

 

Im sure im not running a parallel set up. Any ideas guys?

supra mod12a.jpg

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Dude,

 

Leon is doing it already, the first checks were done at JPS on Monday to eliminate the easy stuff. The cars booked in again in September to continue the fault finding.

 

Im just one of those people who feel that part of owning a car like this is too understand more as you go along. At least as i slowly grasp how it all works ill understand how to sort these things out myself or at least know the possible causes.

 

Ive been reading the tech articles on MKIV this eveningn and coupled with your posts its making loads more sense.

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Originally posted by ad500

Dude,

 

Leon is doing it already, the first checks were done at JPS on Monday to eliminate the easy stuff. The cars booked in again in September to continue the fault finding.

 

Im just one of those people who feel that part of owning a car like this is too understand more as you go along. At least as i slowly grasp how it all works ill understand how to sort these things out myself or at least know the possible causes.

 

Ive been reading the tech articles on MKIV this eveningn and coupled with your posts its making loads more sense.

 

And what did leon say ??????????

 

John:flame Dev

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Well he wants to check the actuator on the wastegate. if i remember rightly (and bear in mind i probably dont, loads of info was flying around on Monday). The check involves, i think, making sure the rod is moving in or out. Checking also for any other cracks or any sticking valves within the system, etc. He does believe that turbo 2 is working, but possibly that it could be on the way out. Ive had no "death whine" noises to speak of though.

 

These next checks could end up being pretty lengthy on labour costs and could even end up with second turbo replacement.

 

I do trust Leon and have used JPS for everything since last year. Just like to get peoples opinion and arm myself with info. If theres anything else that could be checked before removing all the turbo workings id like to run it by him, at least to eliminate it.

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I think you can be confident leon will have thought of everything and having seen the car first hand he has prob. mad ehis decision , you really have no choice but too wait for him to have a better look for you dude . And tell him to answer his phone more often,lol.:thumbs:

 

John:flame Dev

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Originally posted by dude

I think you can be confident leon will have thought of everything and having seen the car first hand he has prob. mad ehis decision , you really have no choice but too wait for him to have a better look for you dude . And tell him to answer his phone more often,lol.:thumbs:

 

John:flame Dev

 

I think ill give him a bell just to ask about the hose bypassing the vsv. Cheers for all you help anyway dude.

 

:thumbs:

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