legacycentral bbs

I have an intermittent detination problem.

Detination comes and goes. As far as I can tell it's totally random.

Detination occures with almost any throttle increase at lower rpm's but generally cleanes up above 4000 rpm.

1993 Legacy 2.2 turbo 5spd.
I have exhaust and downpipe but boost is still @ stock psi.
I have a Zeitronix z2-t wideband and a perfect power SMT6 controller installed.
Had the charging system checked.
New: Knock sensor, ECT sensor Plugs/wires/coil, fuel filter, aftermarket fuel pump, no vacuum/boost leaks that I know about.


I removed and checked the TPS sensor pins 2 and 3.

My resistance range is 0.16 to 9.60 khoms.
My book says it should range from 5 to 12 kilo-ohms.

Should I replace the TPS?

Also I am trying to test the IAC and hotwire air sensors.

? do they use the same 4 pin connector?
Which pins would I test?

Thanks

Brice

Brice k wrote:I have an intermittent detination problem.

Detination comes and goes. As far as I can tell it's totally random.

Detination occures with almost any throttle increase at lower rpm's but generally cleanes up above 4000 rpm.

1993 Legacy 2.2 turbo 5spd.
I have exhaust and downpipe but boost is still @ stock psi.
I have a Zeitronix z2-t wideband and a perfect power SMT6 controller installed.
Had the charging system checked.
New: Knock sensor, ECT sensor Plugs/wires/coil, fuel filter, aftermarket fuel pump, no vacuum/boost leaks that I know about.


I removed and checked the TPS sensor pins 2 and 3.

My resistance range is 0.16 to 9.60 khoms.
My book says it should range from 5 to 12 kilo-ohms.

Should I replace the TPS?

Also I am trying to test the IAC and hotwire air sensors.

? do they use the same 4 pin connector?
Which pins would I test?

Thanks

Brice

if the detination was sensor related, it would occur clean across the rpm band, it wouldn't clean up at 4k rpms

check your Perfect Power map, retune it or whatever, something is wrong, and the IAC/TPS shouldn't have anything to do with it.

Thanks.

I will check and tweek all the aftermarket electronix I have installed. I havent had a chance to hook it up to a laptop yet.. My brother installed all of it and has monitered/datalogged tweeked the timing and a/f with no success.

I just want to make sure all the sensors are functiong properly.

I still do believe that it could be a tps problem though
I mean if I roll into the throttle and the tps dosn't correctly report that throttle input than the ecu is kinda confused

I want to check everything involved.

So far I believe I need to check:

Cam+crank angle sensors
Air intake charge temp
Knock
Injector function/voltage
TPS
MAP?
ECT
EGR? EGR solinoid?
Check valves in the vacuum/boost lines.
continuity to ground + input voltage.


I know allot about tuning other cars ecu's

But I have to admit I don't yet know much about Subaru electronics.

Found the links here to factory shop manuals and am trying to learn.

Thanks

Brice

Brice k wrote:Thanks.

I will check and tweek all the aftermarket electronix I have installed. I havent had a chance to hook it up to a laptop yet.. My brother installed all of it and has monitered/datalogged tweeked the timing and a/f with no success.

I just want to make sure all the sensors are functiong properly.

I still do believe that it could be a tps problem though
I mean if I roll into the throttle and the tps dosn't correctly report that throttle input than the ecu is kinda confused

I want to check everything involved.

So far I believe I need to check:

Cam+crank angle sensors
Air intake charge temp
Knock
Injector function/voltage
TPS
MAP?
ECT
EGR? EGR solinoid?
Check valves in the vacuum/boost lines.
continuity to ground + input voltage.


I know allot about tuning other cars ecu's

But I have to admit I don't yet know much about Subaru electronics.

Found the links here to factory shop manuals and am trying to learn.

Thanks

Brice

Most of the ECU's stock functions revert to a base map if the sensor fails, and it also throws a CEL light.

If the cam/crank sensors are faulty, the engine won't run because it won't know when to fire the next injector or coil. So mark that off your list.

Air intake charge temp has to do with adding fuel to compensate for cold air (winter months) not subtracting it.
Knock is off your list because you would throw a CEL if it wasn't functioning properly.

Injector function/voltage is a possibility, wiring issues can be a problem with your symptoms.

If the TPS isn't working right, you -should- (I'm not 100% on this) have a high and very rich idle. High being in the vicinity of 1500-2000 rpms.

MAP, you'll have a very rich idle the ECU will overfuel to compensate, the engine shouldn't knock/ping at all.

ECT? no clue what that is.

our cars don't come with EGR or EGR solenoids as far as i'm aware. (at least mine doesn't)

a vacuum leak would lead to a low, stumbling idle depending on how bad the leak is. IIRC the only check valve is in the IAC, but I may be corrected on that.

check your wiring, start there. remove the fueling computer if you have to, I bet that's got something to do with it.


This isn't the gospel, some or most of my information may be incorrect, so feel free those who know better to correct me.

The problem turned out to be a faulty coil.

Replaced the coil and the problem went away.