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The mkiv Supra Owners Club

No power sometimes when overtaking


Alex_GT

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This is something weird I've noticed recently, and it only seems to be when overtaking for some reason. When accelerating to overtake, the car completely dies like I've taken my foot off the throttle. It doesn't happen all the time so I'm not sure what the problem could be? A boost leak maybe?

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Sorry yes it is a turbo model. The car has no modifications I am aware of. There is a boost gauge in the dash, but I'm not sure how to read it. The markings show + 0 - from top to bottom, but I don't know what the position of the needle means at each mark?

 

When the car loses power the needle doesn't suddenly drop (if that would mean a boost problem?). I wouldn't describe it as severe as like hitting a wall, the car just stops accelerating and is then very slow at picking up speed.

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The dash board boost gauge is not accurate at all. You'd need a mechanical or digital one to get a proper reading.

 

When your problem occurs try taking your foot off the throttle and re-stamp the throttle. If that then feels as normal you have a faulty vsv on the turbo side. Theres a good guide for the vsv's here. http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system

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Can fuel cut occur on cars that have not been modified? I've been thinking of taking my car somewhere for it to be checked, but I'm not sure where. I am in the East Midlands but I am not aware of any specialists around here. I am not technically minded at all so there is no way I would be confident checking anything.

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Can fuel cut occur on cars that have not been modified? I've been thinking of taking my car somewhere for it to be checked, but I'm not sure where. I am in the East Midlands but I am not aware of any specialists around here. I am not technically minded at all so there is no way I would be confident checking anything.

 

I'd start by checking if the car still has the 2 stock catalytic converters fitted, if one has be replaced with a decat pipe it could cause it to occasionally over boost and hit the 1bar stock ECU fuel cut, especially now the colder whether is here.

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Is it a VVTi TT model? If so it may be a throttle control issue. Does the engine management light come on when it loses power?

 

From snooping previous posts is does indeed appear to be a VVTi.

 

I had a similar problem with my VVTi. You can do an ETCS-i reset by following the 2nd troubleshooting bullet point on this link: http://www.2jzgarage.com/2013/07/etcs-i-dbw-system-troubleshooting/#more-863 -that sorted it out for me.

 

Hopefully that helps to resolve it for you. When you do the reset, you should hear a faint beep. :thumbs:

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Thank you I will try that, the problem is it is rare I use a lot of throttle, and even then it doesn't seem to happen all the time.

 

Something else I have noticed, is when starting the car from hot the idle speed is very low like it is about to stall, it is fine when starting from cold. Not sure if the two things are related?

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Well I'm not sure what else to say, I'm not technically minded so I can't really give any detailed information, I can only try and describe what is happening.:shrug:

 

Your first post didn't say it's a stock VVTI TT, there are a lot of knowledgable members happy to help but they need all relevant details. The sticky link was written to help members when asking tech questions.

Edited by Nic (see edit history)
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