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IAC needs to be cleaned bad?

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it's starting to get a little colder in the mornings.. but here is a quick run down what happens..

 

on a cold motor I leave for work at 4 AM.. anyways starting up the car and waiting 15-20 seconds I back out of my spot and you can hear the car runs rough when under light throttle and maybe a little so for another 20 seconds then after you near 2K it opens up and it's fine until it cools down again..

 

Anyways it seems to get worst as it gets colder..

 

the things I have done so far..

 

replaced spark plugs

replaced CTS

poured seafoam on the tube that leads to the IAC 5 months ago

 

 

Here is a video I just did.. you may need to run full screen to see the tach.. I should of turned on the lights since I changed to white LED gauges.

 

anyways I stalled at first because the engine was not coming up to speed to how far my foot was pressed down.. when I move forward I tell you where my foot was.

 

it's puzzling I was going to try again with the MAF unplugged to see if I got the same issues as if the car was cold.

 

 

here is the youtube video.

 

Getting any codes? Is the CEL on?

 

Have you gotten some carb cleaner and cleaned out the throttle plates?

 

The throttle position sensor might be bad. Try swapping it.

  • Author

I cleaned the throttle body out less then 3K miles ago..

 

How can the TPS be bad but work fine once the car finally clears 2K and works for the rest of the time the car is on?

 

I have no codes or any pending codes.

It's just a guess. Might also be the mass air flow sensor. I've seen bad MAFSs cause your problem.

  • Author

Can they fail half way? I always thought it was it's working or it's not..

 

Going to try and check the fuel pressure tomorrow which I think goes between the inlet from the fuel pump to the fuel filter right?

poured seafoam on the tube that leads to the IAC 5 months ago

 

Don't know if it will solve your problem but I like to remove the IACV from the car to give it a thorough cleaning. IIRC it's just one electrical connector, 2 small hoses and 3 bolts (one is hidden underneath). Be good to have a new gasket ready if you do this.

 

Good luck.

  • Author

yeah I did not have the gaskets at the time and the dealer was closed so I did not remove it at the time.

 

 

Another thing is I want to test my fuel pressure.. maybe it's some weird thing with low fuel pressure as the system slowly goes down in pressure?

 

Does the 95 Legacy have a fuel pressure test port? Or do I have to disconnect the fuel hose between the fuel pump and fuel filter?

 

What pressures should I be seeing at idle?

When my iac needed cleaning, as in cleaning it fixed my problem, I was getting the code for idle higher than expected. And it was idiling over 1k. To clean the iac I went to the dealership and asked one of the tech how they clean it. He said he just uses throttle body cleaner by spraying it through the iac while the car is running.

  • Author

the funny thing is I have no code and no high idle like everyone else seems to get..

 

I will do a fuel pressure test when the motor is cold and when it stumbles when giving it large amounts of throttle in the first 20 seconds of being started I will note the fuel pressure with the video camera.

It's called Old and Cold. Cars old, engines cold. It needs to warm up a bit before you take off. Let the car idle for 45 seconds to a minute before you take off and see if it makes a difference.

  • Author

Not to pick on you but show me another subaru that does the same. the fact that it goes away on it's own within 30 seconds of running makes me think it's pressure related or IAC related.

 

the MAF sensor not too sure.. I'd have to check that today as well..

Got one in my driveway. Mine does the same thing on cold mornings, if I don't let it warm up it will hardly make it up the hill on my street. It doesn't like the first 2 one-two shifts, out of my driveway, and then onto the main road, but when I get it down the road 1/2 mile to the first stoplight it's fine. Then it's fine after that, until the next morning and it does it all over again.

If I let it idle for a minute before driving off, it doesn't do any of that.

I don't complain about it, the car has 178,xxx miles on it, I think it has earned the right to be a bit temperamental in the morning. :) Hell I don't like waking up in the morning either.

  • Author

I cleaned it and it helped my bouncing idle at warm up as seen here in youtube.

 

Aug 28th 2009

 

 

 

Sept 24th 2010

 

 

 

Fuel pressure

 

Seems to me that idle fuel pressure should be something like 32-35 psi. (might be wrong on that) So that might be a bit low, but I dunno if it's enough to worry about. Pretty sure I've seen you mention that you've replaced the filter. You could try a new FPR if you want, or grab 2 or 3 out of the junkyard and see if that changes it any.

 

Idle did seem a little rough. You ever used seafoam?

  • Author
Seems to me that idle fuel pressure should be something like 32-35 psi. (might be wrong on that) So that might be a bit low, but I dunno if it's enough to worry about. Pretty sure I've seen you mention that you've replaced the filter. You could try a new FPR if you want, or grab 2 or 3 out of the junkyard and see if that changes it any.

 

Idle did seem a little rough. You ever used seafoam?

the idle pressure is in spec what is not is after turning off the car a injector may be causing fuel to enter in when the car is off.

 

and I've seafoamed the car twice I can't expect motor mounts to last forever..

I can't expect motor mounts to last forever..

What do the motor mounts have to do with it? :confused: Doesn't look like the engine is moving too much in the vid. Are they flat/crushed out?

 

If you suspect a fuel injector is bleeding pressure down after shut off, get the engine warm, pull the spark plugs and turn the key ON. That will prime the system and any injector that is leaking will mist/vapor out of the cylinder.

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