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The mkiv Supra Owners Club

Strange boost issue


Parry_10
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bpu, stock turbos, w58 box-

 

seems to only do it in 4th gear and at 5500rpm

 

on full boost foot to the floor it gets to around 5500rpm and then just wont accelerate anymore unless you change to 5th. Its always at the same point in the rev range as well and only seems to do it when in fourth gear 1st,2nd,3rd are fine and for obvious reasons I could test 5th. The best way to describe it is it feels like fuel cut does any ideas?

 

Chris

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What boost pressure is it making at 5500rpm in 4th? Can you hear/feel the engine missing/hesitating? In higher gears the engine will be under more load and boost pressure will be higher, it could be that the engine is misfiring.

 

Common reasons for misfire are: wrong heat range spark plugs, worn spark plugs, broken coil pack connector(s), knackered coil pack(s).

 

FAQ - Spark Plugs

 

How to: Refurbish Coil Pack connectors

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Ok on my own NA/TT, because it was an auto, you have to bridge the contacts on the auto loom to get it to start right? (I even had to do this with a manual ECU) Well due to the ECU now thinking its stuck in neutral, it imposes a 5.5-5.8k rev limit. Mine was exhibiting the exact same symptoms as yours by the sounds of it, i.e. the symptoms were only in 4th and neutral( does it do it in neutral?). The solution is to cut through a small purple wire on the ecu loom in the footwell, I shall try to find a link for a picture of this.

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Ok on my own NA/TT, because it was an auto, you have to bridge the contacts on the auto loom to get it to start right? (I even had to do this with a manual ECU) Well due to the ECU now thinking its stuck in neutral, it imposes a 5.5-5.8k rev limit. Mine was exhibiting the exact same symptoms as yours by the sounds of it, i.e. the symptoms were only in 4th and neutral( does it do it in neutral?). The solution is to cut through a small purple wire on the ecu loom in the footwell, I shall try to find a link for a picture of this.

 

im not sure I will check tomorrow if it does do it in neutral as well then it would be helpful if you could find a pic of what wire to cut cheers

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