first off my car is a 87TII mods are rsr rabing beat turboback, fcd, greddy type s bov, stock ports, stock wastegate, stock intake, rebuilt engine about 50k on it.

i already checked everything for a vac leak so i ruled that out already.

first let me start off with my idle used to be perfect but suddenly became lumpy, goes up and down from 700-750. but that is not my main concern.

when i go half throttle or more my engine feels like its being choked on power for about 5 seconds then boost hits and runs fine after boost hits. the thing is that if i keep it above 4k rpms everything seems perfectly fine. this problem mainly persists at cruising rpms and only happens when i need more power to pass. downshifting is cool and all but that wont get rid of my problem.

i have done searching and the only thing i can come up with is that something is wrong with me tps. is there anything else that might be wrong? trying to save some money before taking it to an expensive shop.....

thanks in advance.

 

Are you sure your FCD is working, and that your BOV is not leaking. Also are you running stock injectors? TPS maybe the issue, but not sure.

 

how do i check if my bov is leaking? its not fuel cut because i can accelerate for a while and then all of a sudden boost hits and acceleration is just like normal. yes i also do have stock injectors.

 

^ if you guys are talking about air leaking in, than you can have yoru car sit at idle, and spray wd-40 or like carb cleaner, or better starter fluid at it, and if the idle rises, then its leaking.

 

^on the bov itself?

 

is you throttle body moded?

 

stock the only mods are what i listed (well engine related)

 

check and see if the turbo inlet duct is cracked, that will make the idle lumpy and cause strange problem

 

^that would make the idle lumpy?

but why would still hit boost consistently after 4k rpms?

i will check when i get home

 

also forgot to mention that have stock fuel system

 

you have two problems

1.) 3800 RPM hesitation

2.) you've developed a vacuum leak.

 

1. the problem mostly happens before 3800rpm read my first post (can i still have this problem even though it doesnt happen around 3800 rpm?)

2. i havent ruled that out yet

thanks

 

An outside shot at the slow to respond to boost..........remove the intercooler and work the throttle linkage while observing the secondary outer set of throttle plates. See if they are hanging up and not opening all the way each and every time. There's a CAM and a DAMPER that control the stock outer set of secondary throttle plates. There's also a double throttle diaphram involved but hopefully it isn't involved.

The outer set of plates can be wired open with wire or a tiewrap if you remove the connecting rod enclosed in a small spring.

TPS can be checked out easily if you put a digital volt meter to pin 2G on the ECU and monitor the voltage with the engine hot. At idle it should read approx one (1) volt and if you depress the pedal all the way it should read approx between 4.72 vdc to 5vdc.

Inbetween idle and full open throttle the voltage should rise without any anomalys. Same with going from WOT back to idle.

That car must have a FCD somewhere or else you'd have problems above 4000 rpm, what with the full exaust system you described.

 

update

checked for any leaks and i cant find one. also no cracks in the tid. i havent checked the tps cuz i have to borrow a digital voltmeter from my dad and i havent had time to talk to him about that.

thanks for the help

ps if there are anymore suggestions that would be greatly appreciated