94 Subaru Impreza 1.8L - Sensor/Fuel problem? ***UPDATE***

[Scholzpdx]

I have a 94 Impreza L Sedan, 1.8L, AT, 210K. I bought it around 193k. The car has quit working about five times now and it has rendered my car useless for an hour to weeks. I'm guessing it's a sensor. Here's the work my father, uncle and I have done.

 

Replaced:

Fuel Pump

Fuel Filter

Fuel Relays

Alternator

All fuses and relays from the main box.

Main relay (in the center, top part of the engine, by the windshield)

And many others, but I don't think those are important for this issue.

 

So my car seemingly refuses to start or dies out in motion when it gets hot or intense load. I'm not sure if its just a coincidence. Each time it's either been pretty hot outside (85-100F) or I had been carrying a lot of weight (Five mid twenties people up a hill and another time with three men and about 120lbs of weight going 80mph on i205). My battery is producing fine, my alternator is putting out, I'm getting spark, but no fuel. When this problem occurs I was able to pour some gas into my air intake and the car sputters and starts until the manually injected fuel is depleted. My uncle said it probably is the sensor that redise about a foot past my filter on my intake. I went to a pick-n-pull and found a wrecked later 90's legacy with the same sensor. Most Subarus don't have this exact one. When I got home to put it in the car started right up without swapping them out. I'm hesitant on replacing it as I want to replace it when the problems occurs again to see if that's what it was. My uncle says it sensors the air intake and tells the car to send in the appropriate amount of fuel. When the sensor goes out, no fuel is sent. So that's why we manually injected fuel.

 

I did get a check engine light for a minute ONE time while going up a hill but I turned off the car and turned it back on without major issue. It did feel sluggish and low on driving power. MY father and uncle say i'm just imagining it, but since this has been going i'm I feel like i'm not getting as much driving power as it used to put out. Sometimes it struggles up a hill and around town (ex. not revving up as much as it should while full throttle in being applied). Also sometimes the RPMs drop to around 400-500 or so.

 

This problem is very intermittent, but serious enough to keep me stranded. I've had to get 2 very expensive tow rides home now.

 

Does this sound like that sensor? Or something totally different? Anything an amateur backyard mechanic can try with a multimeter or am I going to have to take it into a shop? I'm getting sick of driving around a Dodge Stratus.

Edited August 2, 2010 by Scholzpdx

[idosubaru]

crank or cam sensors cause no start conditions, and they'll do it without causing a check engine light/code.

 

since you have easy access to a parts yard, just go pull a couple of them off and have them ready to swap out. they're really easy to replace - just a 10mm bolt holds each one in place and while tight, they are not hard to replace and dont' require removing much, if anything.

 

it's not likely to be the MAF sensor you're talking about, but i'm not against throwing sensors at weird stuff like this.

 

Subaru's very rarely have fuel issues like pump, relay, or filter.

[Scholzpdx]

crank or cam sensors cause no start conditions, and they'll do it without causing a check engine light/code.

 

 

 

since you have easy access to a parts yard, just go pull a couple of them off and have them ready to swap out. they're really easy to replace - just a 10mm bolt holds each one in place and while tight, they are not hard to replace and dont' require removing much, if anything.

 

 

 

it's not likely to be the MAF sensor you're talking about, but i'm not against throwing sensors at weird stuff like this.

 

 

 

Subaru's very rarely have fuel issues like pump, relay, or filter.

 

 

 

Thanks for the reply. Interesting it wouldnt toss a code up.

 

Would this sensor also shut off the engine while in motion? Its been that about half of the time. I only have Legacys in my part yards. Are these interchangeable on my Impreza?

 

And simple is great. I'm no actual mechanic, but I want to learn this car. After seeing my parents old loyale hit 350k, i'm going to do what I can to take this car there as well.

[Cougar]

I doubt that the MAF sensor is causing the trouble you are having. Since you have already replaced the fuel pump relay and fuel pump then I would check for a bad power connection to the pump. The grounding for the pump motor may run through the ECU so that could be where the trouble is also.

[Scholzpdx]

Update:

 

Yesteday my Impreza broke down in a fred meyers parking lot and was doing th same issue as before. No start whatsoever. It was towed to my parents any my uncle took a look at it. He called a local mechanic for advice and he too said the cam or the crank sensor.

 

Today the car wouldn't turn on. According ot my uncle the old cam sensor was only putting out 11ohms. He bought a new one at Baxters ($70) which turned out to be DOA. He then pulled one from a Legacy at Pick N Pull for $2 and then swapped it out. The car started immediately. The newer cam sensor put out 22.5ohms on the multimeter. Does this sound right? Should I assume my car is safe for daily driving now?

 

Also, my parents never had the issue of the car turning off while in motion, they just had it after turning it off and then starting it again. Would the faulty cam sensor cause my car to turn off during normal operation? Or was this separate? It only happened which there was a lot of weight in my car (250-350+ above normal driving.)

 

Again, thanks for the replies.

[idosubaru]

cam and crank sensors are known for causing no start conditions. hopefully that was it.

[Olnick]

Does anyone else think this might be caused by a faulty coolant temperature sensor?

[GeneralDisorder]

Does anyone else think this might be caused by a faulty coolant temperature sensor?

 

Could be part of it, yeah. Those do fail sometimes as well. A simple check with a DMM would rule it out.

 

Cam and crank sensors are pretty common fail's on Impreza's for some reason. I haven't had that failure on a Legacy but I don't see what the difference would be.

 

GD

[Scholzpdx]

Where is this coolant temp sensor? Will it be an easy check?

 

I cant seem to find my Chilton Subaru book now!

[Olnick]

Where is this coolant temp sensor?

 

It's on the crossover pipe--from the passengers side of the engine, look below the IACV valve.

 

Here's a thread that might help: http://www.ultimatesubaru.org/forum/showthread.php?t=75009&highlight=ects+coolant+temp+sensor

 

By the way, get familiar with the search function on here. Many, many common questions can be answered very quickly that way.

 

Good luck.