few problems need lots of help

[Misuta Yancha]

ok so I will start with a couple specs on my car... I have a 420a motor that has a t3/t4 turbo with out a boost controller, which leads me to...

question 1: when the vacuum pressure gets to zero the car lugs hard core... is that the missing link? the little plastic one way air valve in mine is highly dammaged but I tested its pressure with an air compressor set to 10psi (max turbo output is 8 psi... for now)and I didn't hear it leak... it worked fine for a little while after that but now it's all crappy again.

question 2: when I release the gas after getting close to zero vacuum, I hear what sounds like turbo surge... but the guy I bought the car from said that it's the back pressure from the intercooler is that possible?

question 3: when the car idles cold or the car is moving in neutral it idles just fine, but when it is standing still it idles lean... and the rpm's drop to about 500- 600 and it sounds like crap.

question 4: when I push too hard on the gas (about 1/4 to 1/2 depressed) to accelerate ithe air fuel ratio goes extremely lean and doesn't accelerate hardly at all.

well those are all of my questions for now... if you need more info just ask and I will do my best to supply it
thanks for everyones help

 

[1slow97]

question 1: Fuel cut

question 2:Back pressure =Turbo surge, better bov will fix that.

question3: ? If i had to juess map sen....Do you have eany check engine lights?

question4: What fuel mods do you have done?

 

[marshall13]

On your third question, I had the same problem and a new throttle position sensor fixed it.

 

[marshall13]

On question 4, check your fuel pump and filter.

 

[Misuta Yancha]

question4: What fuel mods do you have done?

well I haven't done any but the owner before me said he installed a highflow fuel pump... not sure what kind

 

[Snobordin8]

What kind of air/fuel gauge do you have? The narrowband one's are pretty useless. A wideband is what you should have for reading the true air/fuel ratio. The narrowband one's typically look like a light show that goes back and forth changing colors.

 

[Misuta Yancha]

What kind of air/fuel gauge do you have? The narrowband one's are pretty useless. A wideband is what you should have for reading the true air/fuel ratio. The narrowband one's typically look like a light show that goes back and forth changing colors.

I have one of the light show ones it's an auto meter phantom

 

[Misuta Yancha]

so I got a new TPS and it deffinately helped all of my problems but it didn't completely fix everything... but I definately do have a quicker throttle response now