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#1
29-04-2016, 06:35 PM
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Boost issue
Hi guys i was wondering if anyone could help? Since owning the car it's always had the same issue...and thats when you put your foot down in 4th or 5th gear it will build boost and then drop, then build and drop constantly on the motorway with your foot down.
I originally put this down to being that the car was a little scrappy when i bought it, it had a remapped td04. However now I've changed quite a lot on the car including a VF30, pink injectors, STI TMIC, RMC fuel pump along with other bits. But the car has the exact same symptons, builds to 22 PSI, then drops to 10 etc. Ive taken off the boost solanoid and cleaned it out but hasnt made a difference. What else can there be? Or is the car suppose to be like this and im a dum dum head? 
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#2
29-04-2016, 06:43 PM
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Quote:
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#3
29-04-2016, 06:58 PM
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Sounds like the boost control duty in the map is too high. It's failing to control the boost in the higher gears.
Quite a common problem with cars mapped on a dyno in 3rd. Often experienced on the drive home down a motorway in 5th. A slightly larger restrictor pill may be the cheap fix to limit the boost a touch. As Steve mentioned I hope it's mapped for the VF30 and the extra fuelling from the Pinks.
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#4
29-04-2016, 08:14 PM
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It was mapped by Duncan at surrey rolling road in Farnborough. Was recommended. He didnt mention anything about the car, i asked if it was healthy and working fine and he couldnt find fault with it. I told him i had a VF30 and what supporting mods were added to the car before he mapped.
What should i do now then? Slightly concerned tbh 
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#6
29-04-2016, 08:53 PM
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Well you went with a good mapper so that's one angle covered off. If he mapped the car with the same bits you have on it now, then i'd give him a call and explain the issues. If its an issue with the map, he'll sort it.
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#7
29-04-2016, 09:25 PM
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Nope the turbo came off a healthy car with low miles, from Stewart in Sussex
I've dropped Duncan a text hopefully get something sorted, many thanks for the help guys puts my mind at rest slightly haha
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#8
29-04-2016, 11:17 PM
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A turbo will always generate slightly more boost in each gear with 1st gear generating the least and 5th/6th generating the most, no matter how tight the mapped boost control.
I would expect a car mapped to 1.5bar to only generate about 1.35bar in 2nd. A car mapped on the dyno to 1.3bar in 4th would generate about 1.35bar out on the road in 5th. Maybe more depending on the dyno load setting. The boost control for the solenoid/wastegate has a max and min % setting (dependant on ECU model/code). If the gap between max and min is too small or when running the minimum mapped % of wastegate control (some models only have 1 map for wastegate control) causes the boost to overshoot target the safety features within the ECU will cause the boost control will be switched off. As soon as boost control is switched off boost will drop to around 0.7bar. But as soon as this happens, because it has dropped below target, the boost control will switch back on and the closed loop control nature means boost will surge up and down. You should find that if you slightly back off the throttle that boost stabilises. This is due to the throttle position being mapped to a region that has different boost control % that enables stable boost. As mentioned above its quite common and why when road mapped it's always best to squeeze in a 5th/6th gear pull from around 2500rpm and also a part throttle 5th/6th gear pull to check boost is under control in all scenarios.
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