93 turbo backfiring and no power when accelerating

[Calgaryturbo]

This forum is great!!

Here we go

Car starts fine, idles great, when I give it too much throtle the car chokes and backfires. It used to run fine and started after I drove on some very dirty dusty roads. I have done everything I know how to fix it with no

Replaced: Fuel pump and filter, 02 sensor, plugs and wires, knock sensor, exhaust (removed cats, flowmaster mufler),all fluids,

Inspected and cleaned injectors.

Any Ideas!! PLease help

[Legacy777]

check your bypass/blow off valve or other areas for leaks.

[NTM]

How about your AFM - what sort of condition is it in? Almos sounds like an air leak after the AFM.

[Calgaryturbo]

what is the afm?

[Calgaryturbo]

Also where is the bypass/blowoff valve?

Thanks for your response

[Zadok]

the bypass valve is underneath the charge pipe, between the turbo and the throttle body. Its a little tiny valve mounted to the pipe.

[Calgaryturbo]

I checked it. looks fine.

Feels like the car is running very rich. BTW also checked compresion and it is good too.

Is it a possibility that one of the sensors is reading wrong without throwing a cel. Last night I was suspecting the TPS sensor

[legacy92ej22t]

I would do a Read-Check and a D-check. I had codes in both these modes without getting a CEL. Go to Joshs website http://www.surrealmirage.com/subaru/subaru.html
go to "notes and tips" then "Engine" and follow his directions. You might get a better idea whats going on.

[Calgaryturbo]

I did that and the only code I got was the neutral inhibitor swich when I floored it. Any idea whet that means?

Code 51

[-K-]

It doesn't let you start with the car in gear.

[vrg3]

You can measure the voltage from the oxygen sensor to determine if you're really running rich:

http://pw1.netcom.com/~cmathes/air_fuel_ratio.html

Keep in mind that the voltages usually have some offset to them, though... You can get a better reading if you attach a wire to the sensor body with a hose clamp and connect that to your voltmeter's negative terminal.

If your idle is good, then you probably don't have any leaks before the turbo, and you probably don't have any big leaks after it. You may have a boost leak, where the leak only becomes noticeable when the intake charge is pressurized. Those are really hard to find, though. You could start by visually inspecting the hoses and stuff.

Do you have a boost gauge? It'd be interesting to see if this problem starts to manifest only above a certain boost level.

You could also try bypassing the stock boost control (reducing boost) to see if the problem goes away or becomes a little better.

[Calgaryturbo]

Thanks so much for the advice! I was planning to get a boost guage anyways. This problem is so frustrating. Before I had these problems I had no trouble beating my friends 200hp grand prix GT.

What would happen if my mass air sensor was reading off? As I mentioned all this started when I was driving like a mad man and sucking alot of dust. Could this sensor be off but not throw a cel?

[vrg3]

Yes, in principle you could have gotten dirt in it and it could be reading wrong without throwing a CEL. It's not likely, though, unless you have a bad air filter or something (what kind of filter are you using?). But it's possible.

You could try taking the sensor off and cleaning it out with brake cleaner or something. To clean it fully, though, you really should take it apart and remove the sensor element so you can clean it directly, which is kind of a pain. But a strong spray of brake cleaner might help even without disassembling the sensor itself. There is a concern about damaging it but in my experience the hot-wire sensor element seems to be pretty sturdy.

[Calgaryturbo]

Fixed car!!!

I had an air leak at the intake. Thanks you guys for helping me figure it out!! Ready to race again. She goes loke stink now with the new exhoust and the tuneup I did. Time to increase boost!!

I will send photos of the car soon