I've read a bunch of posts about hard-starting Subarus. With the posts, I pretty much narrowed it down to the coolant temperature sensor because the car starts every time after it's been sitting awhile and is cold, about 25% of the time when it's hot at operating temperature, but seems to never start on its own when it's kind of warmed up. When you turn the key, it cranks but just doesn't fire up. When this happens, after a couple of tries, I get out, push it, pop the clutch, and I'm off and running. I changed the coolant temp sensor, thinking that was the problem, but it hasn't helped. I've got a 1995 Impreza 5-speed with a 1.8 engine. What else do you think it could be?

Thanks!

Samson

I've had similar hot start trouble on another car that turned out to be the crank position sensor. It's resistance went way up when hot. You should be able to check the resistance, but I don't have the numbers. I've noticed a lot of threads about crank sensors here, never see them on the other four car forums I'm on, I suspect they're a weak item. But I'm a newbie.

I'll check into it. I just find if funny how no mater what I can always push start it. One mechanic I was talking to about it said maybe it's the fuel pump relay. Any other thoughts?

Thanks

Samson

Fuel pump relays are a weak point on older Audi's, you can hear the pump buzz when you first turn the key on, 'till it builds pressure. If not, the relay is suspect. Cracking the fuel line should get a good squirt of gas if the pump is building up pressure. Yeah, the push start success is puzzling, you're just turning over the engine another way. Less demand on the electric system though, so maybe a weak electrical component has just enough power with the push start. How's your battery? Maybe try putting it on a charger with boost for start to eliminate that variable. I found slowly pouring a cup of water on my crank position sensor cooled it enough for a start, I don't suppose you're pushing it fast enough to cool anything.

ya i have the same problem

do the crank and cam sensors because if its not the temp sensor its the other two

 

do a search on i-club or rs2.5 and you will find it a wide problem that is easily fixed

 

 

http://www.i-club.com/index.php?s=

http://www.rs25.com/

i think you're getting ahead of yourself on sensors and relays. ignition components cause your symptoms more often than sensors. i probably won't see this thread again or i'd ask questions. if the wires, plugs, cap, rotor and coil aren't new or giving good spark then i'd replace them all at the same time. if this hasn't been done recently, i wouldn't touch anything else until i rule out these igntion components.

 

i've put about 350,000 miles on a couple XT6's and have only ever had one failed sensor (MAF) and no failed relays. replaced plenty of plugs, wires, caps, rotors and coils in that time though.

 

i do think it could be a sensor, but i think you're chasing your tail if you don't rule out the ignition first. make sure the harness for the coolant sensor has tight and clean connections. corrosion causes problems that may not go away with a new sensor. check resistance/continuity of the wires in the harness (at the connector) to a suspected sensor as well for a short in the wire.

I agree that is ignition related. Coolant temp sensor determine amount of fuel that injectors put out. Since your car starts when you push, it can't be fuel related, it must be an ignition related problem.Further, it would appear that your flywheel is not turning fast enough when you crank but turns okay when you push- so starter circuit. Compare crank sound when cold and warm. Start with battery - make sure cables tight...

I'm not so sure about it being battery related because I would think it would be harder to start after it sat for a while(battery drains), but I haven't tried jumping it so I'll give it a try. About the ignition, it has a direct spark ignition, no cap or rotor. Just an ignition modual or sorts, a coil(I beleive) and wires. And I tried replacing the modual(a credit card sized box that cost close to $200) and when it still had the problem I put the old one back on and returned it:D

Thanks for the ideas?

Samson

I have to agree with starting with the basics of the system. It's probably not plugs or plug wires, or you'd get ignition on the good ones. Maybe coil or coil wire or something else central to the ignition or fuel system. These components get flakey at high temps sometime, maybe finicky about low voltages. So sitting a while may help.

Starter motor and starter solenoid.

About it being the starter or solanoid: 1-it doesn't sound like it's cranking any slower when it's warm, 2-sometimes after the 4th or 5th try (before getting out and pushing it) it'll start right up while the gas pedal is depressed (even though it was depressed all the other times too).

If it was mine I would check codes first for hints. Then I would also look at ignition and sensors. It seems strange that you can push start it so if you find the answer be sure to tell us. I would have suspected coolant temp sensor too if the ignition system was fine.

Well, the only difference between key-start and push-start is that the starter motor isn't turning.

A running starting motor will easily pull 40-80 amperes. Perhaps lack of electrical power is the key?

There is one other difference between push start and key start: the position of the ignition switch (run versus start). Is it possible that is a temperature sensitive intermittant loss of contact happening at the ignition switch that is causing this?

 

 

Bill

It used to be common to have this problem when cars had seperate coils and points. On some cars there was a seperate wire to the coil for the start position, and if that contact went you could start by pushing but not with the key.

Might be worth comparing voltage at starter solenoid when doing a cold versus warm start.