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Super Fast Idle.....its gonna Blow..


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Hi Everyone,

Seems my problems are coming in bunches. I know this is an easy one, but wasnt sure since I have Fuel Injected 1.8L engine.

 

Everytime I get in to drive this thing, it has been ideling at over 2600+ NON-STOP.!!! My engine sounds like its gonna blow. Also, my brakes are getting worn down to me having to push them down so hard to stop the vehicle.

 

I know this is an easy one, I searched, didnt see anything about super-hyped up ideling problems. Please someone help me with this mystery before I back-end somebody at a light, LOL..!! :)

 

BTW - 1986 Subaru GL auto , 1.8L, 155,000 miles. F.I.

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Hey Lucky

 

Sounds like your Air Bypass Valve (for cold start) may not be closing. It uses an electricly heated bi-metal spring to close, check the connector and for power, I'm not sure what the restance of thr heatting coil should measure but if its bad it will most likely be open. I dont know where it is on the SPFI, but its on the thermostat housing in the MPFI/turbo cars. Or it could be a vacuum leak, take a good look around for losse or cracked hoses. Lastly, is the throttle returning all the way to the stop/is the idle screw mis-adjusted?

 

First thoughts

Gary

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2 things that came to mind when reading you original posting, both are related to each other in a sense.

 

1. High idle speed when cold = vacuum leak?? Whether carbed or Fi, engine gets more fuel when cold, add more air via vacuum leak, you get higher idle speed.

 

2. Brakes are harder to apply = vacuum booster not working properly?? Vacuum leak will affect brake booster, 'specially a big leak. Would look at all hoses as previously stated, 'specially the larger ones, and one going to booster can. If nothing found on hoses, remove and plug hose going to booster can, see if idle changes. If more normal, booster is fubar.... As in possible blown diaphram, causing vacuum leak, and no power brakes.

 

Quick test for bad booster:

Engine off, pump brake pedal atleast 6 times, hold foot on pedal and start engine. Pedal should "fall away" from your foot after engine starts. If it don't, booster is fubar.....

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Could it be the water temp sensor going bad also? Or perhaps the coolant level isn't full and it's throwing off the water temp sensor signal?

 

I know from experience on the XT6s, many of us experience possible high idle, idle surges, etc, from having a bad water temp sensor. The water temp sensor can be so bad sometimes that while idle, the surge can throw your car into oncoming traffic. Ask me how I know! :eek:

 

The way we can tell it's bad is by looking at the temp sensor wires. They would have the green bacteria of death growing on and around them.

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I had a similar problem with my 81 dl wagon. Upon startup it would rev really high until it was warmed up. If I tapped the throttle it would start revving even higher, sometimes continuing to climb (probably past redline as I had no tach), in which case I'd shut it down. I also had issue with the brakes as well, but I don't really think it was due to a vacuum leak (maybe in part though). I think it had more to do with the fact that the engine would hold a high rev until warmed up and when in gear it wanted to continue pushing until the clutch was engaged (rev's < redline). His car has an auto, the high revving engine is continueing to push if he's not dropping into neutral, so it's putting more pressure on the brakes because his brake system is probably heating up potentially leading to failure.

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  • 1 year later...

I wanted to update this a little bit....

 

I have been busy with my subbie, (you wont believe how much more $$ I have dumped into this thing).so... I will be updating my other posts this weekend.

 

I never really did find out the cause of this., It just sort of went away. I did get a tune-up, and that seemed to help I guess. I am guessing that water temp. control needs replacing, (located at the bottom of the radiator right?). It has that green slime of death around it.

 

Well, thanks again....

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The water temp sensor thats in the radiator is for the rad fan control and there is one in the thermostat housing for the dash gauge. The temp sender for the ECU is in the block, behind the intake manifold a bit to the passenger side.

 

Gary

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ive also seen two older subaru's have a very simple problem here. the throttle cables runs through....i don't even know what you call it, but in one case the throttle assembly was basically just sticking "open", like you were pressing the gas, but really you were'nt. so even though it was at idle, stopped, the throttle was sticking open.

 

the other instance was very similar, throttle cable was sticking due to the channel that it fed through being distorted...it sort of wedged in place at a high RPM and stayed there. hit it with your finger and it went back down.

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Your exactly right gary...

 

After looking over my repair bills this past year (ouch !!) .....

 

I noticed I told the shop to check that fast idle problem out. Well, they oiled, and lubed the throttle asembly and that must of done it.

 

I also remember the service advisor saying something like I could replace that part (throttle asembly), but it would cost BIG. I said, "Oh, hell no, just lube it, bend it, piss on it, and I will deal with it, but dont replace it.!" ... LOL!!!

 

It really has been fine ever since....

 

Well, just wanted to follow up and give some much needed updating.

 

thanks again for all your suggestions..

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