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yet another problem!!! boost related - HELP PLEASE!


Guest joff16v

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Guest joff16v

hi all,

 

well just after ive sorted my overheating problem, ( thanks to everyone i changed the rad and it seems to be fine )

 

 

i took it out for a test drive and now ive not really got any boost!

 

it doesnt want to rev above 4k

 

its the same in every gear, it starts to spool but and then when you come onto WOT it just stops the revs and no boost!

 

 

now the clutch is absouluty fubar'd it was slipping BADLY in every gear the other night, this wouldnt be anything to do with it would it?

 

 

anyone any other ideas on possible causes?

 

its a NA-T btw with a Big single on it

 

 

thanks in advance

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Guest joff16v

well not big single, its running a t04Z so mid size single lol

 

yes stock dizzy i believe,

 

compression hasnt been lowered its only running 5-7psi

 

its on greddy E-manage blue

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If the clutch is slipping the engine won't be under load and will not boost very high. Do not drive it if it is slipping, it'll generate a LOT of heat which could do more damage. Get the clutch renewed first and go from there.

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Guest joff16v

Right changed the clutch so now that isn't slipping!

 

Car boosts fine in 1st and 2nd then u get into 3rd and give it wot it hesitates and holds back breifly at 3k then doesn't seem to boost as much, been told it could be possible over boost and the ecu not liking it?

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what's that got to do with why a car which ran fine now doesn't boost? It will be a mechanical issue of some kind

 

ok you know best

 

just for the record and to help the op, i was running a greddy 3bar sensor on my na-t and i had similar sympoms due the the greddy sensor developeing a fault. but thats got nothing to do with it

 

the reason the car wouldnt rev past 4k is because on wot at around 4k (turbo depending)the map sensor will see a change from atmospheric pressue to possotive boost. the 2jzge mapsenor and ecu are not designed to see posotive boost and so will hit "boost cut" , this would explain the car stoping at 4k , the greddy sensor at this point would take over from the stock sensor and coupled with the emanage being mapped prperly would allow the car to run in + boost.

 

now as for it being fine in 1st and 2nd but not 3rd, the car is under more load in 3rd so will make slighly more boost. if you voltage clamp on the stock map sensor has been set to 4.4v and the possibly faultly sensor is sendinf a 4.5 v signal when seeing more boost in 3rd this may expalin that

 

this may not be your problem but thats what i had with similar symptoms .

Edited by dr_jekyll (see edit history)
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