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What's causing poor running and stalls at warm up

Tiny
NEWDUB
  • MEMBER
  • 1999 SUBARU FORESTER
  • 176,000 MILES
Head gaskets, timing replaced, tensioner fail so I replaced again
Now the car starts runs good cold, but once it warms it starts to idle rough,
Stalls and accelerates poor in drive and reverse. I also had problems with
Crank sensor wire splits in the harness. Car will stay idling but it is rough without
Feathering with gas. I tried to have codes read but was unable to pull codes, bad
Wiring? Also noticed car dies with mad sensor unplugged, I thought it would run
With it out, I also noticed what I thought excessive water from exhaust, and some
carbon on first start.
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Tuesday, February 28th, 2012 AT 12:12 AM

11 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Do you have a check engine light?

Go to this links: https://www.2carpros.com/articles/engine-misfires-or-runs-rough and https://www.2carpros.com/articles/engine-stalls
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Tuesday, February 28th, 2012 AT 12:18 AM
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
Sounds like you have several issues. The idle problem sounds like it could be the Idle Air Control Valve, IACV or possibly the fuel pressure is not up to spec.
The crankshaft Position Sensor splice should be ruled out by having it done correclty and saudered and then shrink wrapped so the harness is not an issue. If it is kinda spliced to gether and covered with electrical tape with the wires just twisted together, that is going to eventually be a problem. Twisted wires have higher resitance than a proper sauder and the signal from the carnk snesor is very particular in that a little extra resitance could give an improper voltage reading or heat up the wires from the amperage trying to get through...it should just be fixed right.
I don't know how and where you tried to pull codes but Advance Auto or Auto Zone will pull them for free with decent readers.

I am going to give you a link to a diagnostic walk through for engines with rough idle. It is a logicalk process of elimination and walks you through possibities while teaching you how they function, what to look for and how to repair. It is a very usedul tool.
Follow this link;

https://www.2carpros.com/articles/engine-misfires-or-runs-rough
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Tuesday, February 28th, 2012 AT 12:21 AM
Tiny
NEWDUB
  • MEMBER
  • 5 POSTS
It was a quick repair on the crank splice, so that could still be causing the problem,
Check engine light is intermittent but when it was checked it was on, I also heard crank wire could cause a no read from scanner is that true?And if I can't figure it out by Wednesday I will have someone look at it.

Here's what else I have, it misses as it gets warm also, poor acceleration, hard to start when it does die but fires good after some time, I noticed some surging when I was playing with hoses near Maf sensor, the problem with the crank wire is the farther I go back the more the wire splits and seems to ground out to the shield. My biggest fear at this point is that the compression is bad due to the tensioner braking, does it sound at all like a compression issue? It's just strange that other sensors are starting to go all of the sudden when it ran good or decent befor.
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Tuesday, February 28th, 2012 AT 12:33 AM
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
The tesnioner breaking is very bad. There could be enough slop in the timing belt/chain that either the timing is off really bad, made worse by crankshaft snesor not working right, and causing detonation which woukld eventually ruin the motor and compression. There is always the psossiblity the timing chain/belt could jump a tooth and the valves could hit the piston and that will kill the compression too.
I would start with fixing the crank sensor wire right and testing the compression to see if you need a rebiuld.
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Tuesday, February 28th, 2012 AT 12:39 AM
Tiny
NEWDUB
  • MEMBER
  • 5 POSTS
Ok thanks I will try tomorrow and then get back and donate a couple bucks thanks.
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Tuesday, February 28th, 2012 AT 12:44 AM
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
Your very welcome and we greatly appreciate the donation. Information is priceless and we have a special things going at 2carpros, helping people is a good thing and passing information and help on always comes back to you some day.
So, we greatly appreciate your donation as it will help us keep passing the help and information along.
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Tuesday, February 28th, 2012 AT 12:47 AM
Tiny
NEWDUB
  • MEMBER
  • 5 POSTS
One more thing. If the car stalls with the maf sensor unplugged does that indicate anything I should look into?
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Tuesday, February 28th, 2012 AT 4:05 AM
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
Well it is different on every car. Some run and some won't and it also dpends on there mechanical state and you have amany issues.

I am gonna give you another walk through that will help. Just follow the link;

https://www.2carpros.com/articles/engine-hesitates
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Tuesday, February 28th, 2012 AT 9:44 AM
Tiny
DRCRANKNWRENCH
  • MECHANIC
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Here is a Volvo that had some of the same issues and Crank Sensor issues that ended up not being the issue.
I just thoght it might be good reading while we work through this thing. Let me know what you think as your view on the situation is very imporatnt as I can't be there.

https://www.2carpros.com/questions/2005-volvo-xc70-car-stalls-after-starting-runs-maf-unplugged
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Tuesday, February 28th, 2012 AT 9:51 AM
Tiny
NEWDUB
  • MEMBER
  • 5 POSTS
Ok I found the air leak, I feel silly air filter housing on wrong, the idle is strong and steady untill it heats up, then same issues, it drives and reverse good untill warm, so I'm thinking a sensor is shorting out when it goes to loop. I did smell a burning smells electrical, but I'm not sure.

I unplugged the iacv car ran rough, when I plugged it in it leveled out. Hopefully I can rent a scanner today.
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Tuesday, February 28th, 2012 AT 3:46 PM
Tiny
DRCRANKNWRENCH
  • MECHANIC
  • 3,380 POSTS
You can go to any Auto Zone or Advance Auto and they will scan the codes for free.
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Tuesday, February 28th, 2012 AT 5:33 PM

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