Good suggestion, a wire to my coolant temp sensor broke when the engine was put in and caused months of havoc. My mileage has dropped pretty significantly, I'll throw a new one in.
Buffman, have you tried that yet? Makes a lot of sense for your symptoms.
Weird No Start Issue.
Moderators: Helpinators, Moderators
I'm going to dig into the wiring harness probably friday. I'm wondering if I should trust an ECT from AZ to diagnose. I could go and try to find the OEM 151K in my bags of parts.
I was able to unplug the ECT, and not get it to start. Of course the fans came on, and when I cracked the throttle it would sputter to life. Log software when I checked function reported good temps from ECT, but whose to say maybe it's not bad or the wiring is toast. It's hard to look at wires covered in tape and not loom.
After replacing the fuel pump, FP is now 40psi, vacuum on, and 42 psi vacuum off. It's a walbro 255 unit. MPG before and after the pump seems about the same. Is that too much pressure, or probably about right for the 255 on a N/A car?
I have an IAC valve to swap in friday after I check the wiring harness. It seems if I open the throttle a touch and keep it open while starting it starts right up. I wonder if the IAC completely shuts itself (perhaps getting stuck) and it's not getting enough air thru a closed TB? I noticed the shaking and rough running at idle comes from the reduced idle speed. Sometimes while driving then coming to a stop, the engine will almost die (tach almost reads 0). So it seems possible that if the IAC is getting stuck or not functioning properly it could be robbing the engine of air. I guess I could block the IAC off and see if it will start.
I was able to unplug the ECT, and not get it to start. Of course the fans came on, and when I cracked the throttle it would sputter to life. Log software when I checked function reported good temps from ECT, but whose to say maybe it's not bad or the wiring is toast. It's hard to look at wires covered in tape and not loom.
After replacing the fuel pump, FP is now 40psi, vacuum on, and 42 psi vacuum off. It's a walbro 255 unit. MPG before and after the pump seems about the same. Is that too much pressure, or probably about right for the 255 on a N/A car?
I have an IAC valve to swap in friday after I check the wiring harness. It seems if I open the throttle a touch and keep it open while starting it starts right up. I wonder if the IAC completely shuts itself (perhaps getting stuck) and it's not getting enough air thru a closed TB? I noticed the shaking and rough running at idle comes from the reduced idle speed. Sometimes while driving then coming to a stop, the engine will almost die (tach almost reads 0). So it seems possible that if the IAC is getting stuck or not functioning properly it could be robbing the engine of air. I guess I could block the IAC off and see if it will start.
1992 Legacy LS Special Wagon..
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brweber352
- First Gear
- Posts: 175
- Joined: Tue Jan 05, 2010 9:01 pm
- Location: Florida
I would not rely on a ECT with 151k miles on it as a good test part, like I said they are only about $20 bucks and you'll know it's in good shape. As far as one from Auto Zone, i'm not sure. It will probably be more like $30 from them for an inferior part, really OEM is the best way to go. Mine only had 30k miles on it and no signs that it was bad except for horrible gas mileage and a hard start problem that I didn't know was related. Not really sure about the fuel pressure, I think N/A are supposed to be about 36psi with a stock pump, don't know if this is w/ vacuum or w/out.
It could be the IAC, cracking the throttle like that is a good way to check it. You may want to just try cleaning it, if you do a search for how to clean IAC you should find something. Most people use Seafoam and just pour it down the hose that connects it to the intake. Since you have a N/A you probably have better access to IAC and can probably just take it off to clean it.
I let the motor warm up then shut it off, then pour about 1/4 of the bottle in and let sit for about 5 minutes, crank it up and let idle for awhile until it stops smoking, you may have to do this a couple times. I do this as part of regular maintenence, I also run some through the little vacuum port on the throttle body per the instructions on the back of the bottle, at least once a year. My IAC is the original with almost 160k miles on it, but I have manually adjusted mine down, then used the bypass screw on top of the throttle body to tune the idle up. This works well for me, but i'm not suggesting you do this.
For the little vacuum port I use about 1/3 of the bottle on a warm engine, connect a piece of hose and rev the motor and it will suck it in, you may need someone to help you do this as my step dad usually helps me, the motor will want to bog down so keep opening the throttle so it doesn't cut off, then cut the car off immiediately, let sit for at least 5 minutes , crank car and let idle till it quits smoking then drive it down the road to blow it out. When it's smoking I find this is also a good time to look for exhaust leaks as they will be really easy to see.
If you do any of the above make sure you are in a well ventilated area, as the fumes will be extreme for awhile. Also I remember reading about someone killing a plant that was behind his car when he did this, so watch out for vegetation.
Good luck, Brian
It could be the IAC, cracking the throttle like that is a good way to check it. You may want to just try cleaning it, if you do a search for how to clean IAC you should find something. Most people use Seafoam and just pour it down the hose that connects it to the intake. Since you have a N/A you probably have better access to IAC and can probably just take it off to clean it.
I let the motor warm up then shut it off, then pour about 1/4 of the bottle in and let sit for about 5 minutes, crank it up and let idle for awhile until it stops smoking, you may have to do this a couple times. I do this as part of regular maintenence, I also run some through the little vacuum port on the throttle body per the instructions on the back of the bottle, at least once a year. My IAC is the original with almost 160k miles on it, but I have manually adjusted mine down, then used the bypass screw on top of the throttle body to tune the idle up. This works well for me, but i'm not suggesting you do this.
For the little vacuum port I use about 1/3 of the bottle on a warm engine, connect a piece of hose and rev the motor and it will suck it in, you may need someone to help you do this as my step dad usually helps me, the motor will want to bog down so keep opening the throttle so it doesn't cut off, then cut the car off immiediately, let sit for at least 5 minutes , crank car and let idle till it quits smoking then drive it down the road to blow it out. When it's smoking I find this is also a good time to look for exhaust leaks as they will be really easy to see.
If you do any of the above make sure you are in a well ventilated area, as the fumes will be extreme for awhile. Also I remember reading about someone killing a plant that was behind his car when he did this, so watch out for vegetation.
Good luck, Brian
Last edited by brweber352 on Thu Jan 28, 2010 10:23 pm, edited 2 times in total.
MY IAC has 174K on it. I cleaned it awhile ago and have cleaned it since then with TB cleaner. -
brweber352
- First Gear
- Posts: 175
- Joined: Tue Jan 05, 2010 9:01 pm
- Location: Florida
Good luck, BTW it took me forever to figure out what the hell a Arizona (AZ) ECT had to do with anything. 
93'TLegWag171k StockBlock,TD05,HallmanMBC,530cc,Walbro255,shortram,LWpulley,DIS-2,MSDcoil,cxrFMIC,trans cooler/external filter,WRX wheels/brakes,CES w/Borla muffler,QTP elec cutout,REVchip2,KYB GR2,GroupN tops/all fr bushings,STImounts,GSD3 tires,LM-1,etc
You can shoot the engine harness at the big grey plugs by the battery, that will take care of all the engine sensor wiring.question. Does the engine harness go outside of the fender, to the cabin? I recall there being a wire harness that was under the plastic fender, and that looks to be the path the engine sensor wiring harness goes. When I bought the car, driver's side was missing that fender liner....
1992 Legacy LS Special Wagon..
yes the main part of the engine harness travels from the engine bay through the drivers side fender into the cabin by the fuse panel under the steering wheel.
I believe the knock sensor, both cam and crank sensors, transmission, abs unit and a couple other connectors are the only ones to travel through the firewall directly.
I believe the knock sensor, both cam and crank sensors, transmission, abs unit and a couple other connectors are the only ones to travel through the firewall directly.
Here's some pictures of the wiring harness in the fender
http://main.experiencetherave.com/subar ... ticbraces/
http://main.experiencetherave.com/subar ... ticbraces/
Josh
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT
If you need to get a hold of me please email me rather then pm
well I took the PITA liner out of the wheel well. That Entire run of wire looks un-scathed of any harm. I didn't dare dig into it. I checked under the dash where that wire comes in. Wires under the dash looked good.
I did find this on the harness side behind the battery.
Five wires were like that. they were loosely wrapped in electrical tape, and wet.. Two yellow with red stripe wires (which from searching the sensors seems to be voltage/power to sensors), one black with red stripe, one black with a faint tan/brown/something or other stripe, and on black wire. I redid them with good insulated butt end connectors, and re-wrapped everything tightly in tape.
It's running better, will find out when I leave tonight if it starts back up...
I did find this on the harness side behind the battery.
Five wires were like that. they were loosely wrapped in electrical tape, and wet.. Two yellow with red stripe wires (which from searching the sensors seems to be voltage/power to sensors), one black with red stripe, one black with a faint tan/brown/something or other stripe, and on black wire. I redid them with good insulated butt end connectors, and re-wrapped everything tightly in tape.
It's running better, will find out when I leave tonight if it starts back up...
1992 Legacy LS Special Wagon..