Hey guys,

Working on this 93 FD Automatic, cant get any boost out of it, cant rev past 3k in gear, very slow, a bicycle can probably beat it!

It will rev to redline in neutral, but will hesitate and then quickly rev again...

I am confused, because when I got it it was boosting, but with a bunch of upgrades installed its acting weird.

Some items that were tried:

MAP sensor verified connected and is showing on Power FC Commander what is on the manual boost gauge. Swapped ignition harness for a known working one. Disconnected hoses from the wastegates(greddy boost controller) so it should build boost with ease. Not hearing any boost leaks.

Car is running almost at vacuum even under full throttle. 35psi fuel pressure in the fuel supply line.

I plugged the OEM ECU in stand alone configuration with same result as Apexi Power FC with Banzai Harness.

PLEASE HELP!!! :/

 

Does the engine shake more than normal.

Compression check it, sounds like the same symptom I had when mine went pop.

 

Nope, idles and starts fine!

 

still have catalytic converters?

 

Car has new 3" high flow cat in it.

 

I will also note that the car was fine 3 months ago before starting this project in terms of getting boost.

 

Check your coils. Had a similar problem when mine went. What is your A/F doing?

 

My concern is that the car starts and idles smoothly! And all was good when the car was parked for service, 3moths ago...which is why I think the coils dont go out from sitting!

We only have a cheap Air Fuel gauge using the existing sensor...so that is not going to help.

 

pop the high flow cat off and see if it functions properly (even tho loud)

 

Cat should not cause this, as car was fine with it as is and the exhaust was not touched since last time.

 

clogged or plugged cat will definitely cause no power above 3k but free rev no issue.

 

Yup, can rev to redline with hesitation below 4k after 4 would just sky rocket to redline!

There must be something happening down low! I mean no power, always in vacuum, no power and even under smooth driving the car stays around 3k-ish...keep in mind PowerFC does not have limp mode and the cat would not die from sitting, I dont see abnormal back pressure, plenty of exhaust flow from the exhaust.

 

I'd say get a compression test and if the numbers are good get a good O2 reading. Also pull your plugs and see what they tell you

 

Plugs were changed as part the of the 3month as well as wires. Compression will not effect the ability to rev or limit rev under load vs neutral. Sorry to be a hard ***, but I know these cars, which makes it that much of a pain, as this forum is my last resource.

 

I'm not saying the plugs went bad, but as a standard practice to diagnosing an engine the color of the plugs (black to white) tell a lot. With the compression test, especially if you can get a three face test, you might be losing compression on one face causing the engine not to run right.

We, as a community, unless we know you have no idea of your technical experience. We can only advise you as such. As you know an engine only needs three things to run right, fuel, spark and timing. We also don't know what you've tried.

 

What was in the project? i.e. what all was done to the car from when everything was working until now?

 

Thanks yeah, I think it may be timing or Fuel related...

New Plugs
New Wires
New Battery
Boost Controller
New Fuel Filter
Intercooler and Radiator work/flush
Full set of gauges to boot.
Trans Cooler

 

Turbo / Boost Problem Troubleshooting

start on the first turbo trouble shooting and go from there..good luck.

 

You didn't put a check valve in line with your map sensor did you?

Dale

 

You did verify that the new spark plug wires are not crossed up at all? How old is the fuel in the tank?

You sound like you know what you're doing. My feeling is that it is something small and fairly minor.

 

check your afrs you may be flooding the spark plugs under load , My car did something very similar when I added an aftermarket rising rate fuel pressure regulator , underboost it would just drown in fuel.

 

Crank angle sensor messed up?

 

My initial thought would be along these lines. Likely something was not purposely done but affected your CAS sensors and/or wiring from your intercooler/radiator work. If you have a PFC, you should be able to use the diagnostic screen to check the value of the sensors.

 

Thanks guys, and Dale, no, MAP was the first thing i checked after that the TPS voltage via PowerFC. I am leaning towards timing as well so CAS is next to check via Commander or I can just do a laptop as I have access to a datalogit. Fuel would not cause this if the car starts and idles fine, the map was re-initialized after a map back up via FC-Edit. Injectors are stock. and so is the pump, with 35psi fuel pressure from stock FPR.

 

try another battery, i had similar symptoms from my last fd and it turned out to be a shitty battery