I've been having some seriously bad fuel mileage in the neighborhood of 14-17mpg with a bone stock ej22t and 5sp. I thought it was just my leadfoot until I went a whole tank without going into boost (seriously). it seems to run great normally with only a hint of hesitation occasionally, barely enough to notice. but will start very hard sometimes(20 seconds of cranking). it's worth it to note that the car has a coolant leak and been run low on coolant more than once enough to start to get hot. all that I have read seems to point to a CTS. any good methods for diagnosing it's condition with a multimeter before just replacing it on a prayer? I have a revtronix cable and laptop if that could be of any use.
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other than a CTS, it could be a bad oxygen sensor right? I havent been able to detect any fuel leaks by smell.
any tips to point me in the right direction of how to attack this problem would be greatly appreciated. I did try to search and didn't find anything on here. my chilton's wasnt all that helpful either.
diagnosing bad coolant temp sensor?
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diagnosing bad coolant temp sensor?
1994 Touring Wagon: ruby mica, 5mt swapped
Section 2-7c / page 77 has the diagnostic details for the water temp senor. Josh has the FSM on his site (also in the stuff you need to know forum). 80-95* C after warmup is normal per FSM. Maybe post RevScan logs idling for a bit after warm up to compare against others.
'11 WRX Limited
'94 SS | 3" TBE, 07 TMIC, TD05H-16G, Revtronix Stage 2, Walbro -- Sold
'94 TW | R.I.P.
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Mattheww044
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I just changed mine. My symptoms were:
1. Ran like absolute crap until it was completely warmed up.
2. Horrible MPG's
Not sure if the CTS would cause this but:
3. Wouldn't start this morning, went out 10 minutes later, still nothing, went out another 10 minutes later, and it started after holding the key for ~5 seconds. Every start since then I have had to hold the key for a few seconds before kicking over.
I JUST replaced the starter solenoid contacts, and my battery is fine.
1. Ran like absolute crap until it was completely warmed up.
2. Horrible MPG's
Not sure if the CTS would cause this but:
3. Wouldn't start this morning, went out 10 minutes later, still nothing, went out another 10 minutes later, and it started after holding the key for ~5 seconds. Every start since then I have had to hold the key for a few seconds before kicking over.
I JUST replaced the starter solenoid contacts, and my battery is fine.
1991 Subaru Legacy SS 5MT: Revtronix Stage 2 Set-up with a few other "tasteful" mods :D
i got antsy and replaced it. didnt think to check if the turbo one is in the same location as the NA, it's not. actually I think it's the one part that's easier to get to on a turbo car than an NA. I found this out after pulling the turbo and PCV system. doh! at least it was an impetus to begin a round of mods including a turbo upgrade. 
1994 Touring Wagon: ruby mica, 5mt swapped
Re: diagnosing bad coolant temp sensor?
I'm having exactly the same issue. Very poor mileage.
Josh said just to replace it, but I don't like replacing parts after parts as they add up.
I measured the temperature with IR thermometer right around the pipe coolant sensor is attached to and:
Temperature taken at the surface with IR thermometer and resistance taken at sensor with cable detached.
55F = 3.7kOhm (before starting)
175F = 0.26kOhm (after 10min road test)
From what I can gather here, its following the right curve and values appear to be within reason.
Here is where I found reference values:
http://bbs.legacycentral.org/viewtopic.php?t=35204
No signs of leakage
Josh said just to replace it, but I don't like replacing parts after parts as they add up.
I measured the temperature with IR thermometer right around the pipe coolant sensor is attached to and:
Temperature taken at the surface with IR thermometer and resistance taken at sensor with cable detached.
55F = 3.7kOhm (before starting)
175F = 0.26kOhm (after 10min road test)
From what I can gather here, its following the right curve and values appear to be within reason.
Here is where I found reference values:
http://bbs.legacycentral.org/viewtopic.php?t=35204
No signs of leakage