hey guys I’ve got a fc turbo 2 that’s having a bit of an issue, it runs great up until hitting max boost, which then it feels really off and the afr guage starts showing lean, 15-17

im guessing this is an overboosting condition, gotta hook up a boost guage to verify. just had a shop rebuild my turbo after I found play in the main shaft, it ran great for about 3 weeks and now this condition is present.

where do I begin to fix this problem? Is my wastegate broken? I’m pretty sure it’s all stock stuff. Never had this issue before.

 

You're on the right track. Is your stock gauge working? Boost creep is very apparent as your needle will "creep" up more and more. If you are running a stock set up then yes you should inspect you wastegate. When you over boost (over 8.2 psi) your ECU will cut fuel.

Have you checked for codes?

Explaining your gauge behavior during boost would help us help you.

 

Gauge operation seems normal, I should probably get an aftermarket one to see the real psi reading. How do I check codes on the fc? Seems like there is a fuel cut, the car stops accelerating when the boost gets too high.

 

actually it’s definitely not boost creep, more like the needle is maxing out lol

 

do a vacuum test on your wastegate actuator to see if the diaphragm is torn. gotta remember these parts are almost 40 years old now.

 

performed the vacuum test with a vacuum pump. It actuates and holds pressure.
is there a chance I’ve routed the vacuum line wrong at some point? There’s a metal tube that comes out from behind the alternator and that’s what it’s hooked up to

 

LOL I was right. That was the fix, didn’t notice for a while since I never really drive it that hard 😭😭😭

 

I would make this:

https://fc3spro.com/TECH/HOWTO/ERROR...KI/zerror.html

Check for codes. It's always a good place to start.

Question, do you have a stock exhaust? Could you explain your setup?

A stock car with a properly functioning wastegate shouldn't be able to overboost.

If you are bone stock then I would work on fetching codes. You might have a map sensor failure. Hard to say. Loose vac lines could be the culprit as well.

First thing you should do is build that tester. Maybe you'll get lucky and it'll point right to your problem. And if you have no codes then you know your sensors are in check and you have a mechanical issue.

 

Come to think of it, you have a vacuum pump... test your map sensor and see if it's working properly according to page 4B-77 in the FSM.