Hard Start Problem

Tiny
KAIKIING
  • MEMBER
  • 1994 TOYOTA COROLLA
  • 173,657 MILES
My car has a hard-start problem. If the engine remain off for few days. I can start up normally. But after drive then remain off for few hours, I have to press the accelerator for quite some times before it can start properly.

Idling is also very unstable, sometimes it runs normally while at other times it drops too low, causing too much engine vibration.

What is the problem and how can it be fixed?

Thank you.

KaiKiing
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Sunday, September 11th, 2011 AT 4:05 AM

13 Replies

Tiny
PROMECHANIC
  • EXPERT
There are a number of different things that might be causing this. You should first have your codes checked as that might give you a hint as to what might be going on.
Here are a few things that need to be checked.
1) Your fuel pressure. If it is low it might cause a problem like this.
2) Your idle air control valve. It is what keeps your car running then you take your foot off the gas.
These are the first two things I would check.
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Sunday, September 11th, 2011 AT 4:13 AM
Tiny
KAIKIING
  • MEMBER
May I know how to check the fuel pressure?Can we check it our self?There is no scanner tools at my area that why cannot check for the code.

Thanks
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Sunday, September 11th, 2011 AT 4:30 AM
Tiny
PROMECHANIC
  • EXPERT
You can check it yourself. If you go to an auto parts store just ask for a fuel pressure gauge and tell them what kind of car you have. They should be able to sell you one that will fit your car.
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Sunday, September 11th, 2011 AT 4:40 AM
Tiny
KAIKIING
  • MEMBER
If the problem is because of fuel pressure then what should I do?Which part I need to change or repair?Is it high chance for the IACV to cause these problem also?

Thanks
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Sunday, September 11th, 2011 AT 4:56 AM
Tiny
PROMECHANIC
  • EXPERT
If the fuel pressure is low then it is most likely because of a clogged fuel filter or a bad fuel pump.
There is a good chance that the IAC is bad, but there is no way for me to tell. You could take it off and clean it. That might help.
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Sunday, September 11th, 2011 AT 5:04 AM
Tiny
KAIKIING
  • MEMBER
Please correct me if I've misunderstanding for the IACV location from the photo attached. Any suggestion for the cleaner can use for cleaning up the IACV?
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Sunday, September 11th, 2011 AT 5:27 AM
Tiny
PROMECHANIC
  • EXPERT
I can't quite tell if that is the IAC or the throttle position sensor. It looks like the TPS because it looks like it's adjustable. It might be under that or on the other side.
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Sunday, September 11th, 2011 AT 5:37 AM
Tiny
KAIKIING
  • MEMBER
Am I correct?Please advice me.

Thanks
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Sunday, September 11th, 2011 AT 5:56 AM
Tiny
PROMECHANIC
  • EXPERT
That looks like it.
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Sunday, September 11th, 2011 AT 5:58 AM
Tiny
KAIKIING
  • MEMBER
Did I need to dismantle the whole total body if I want to clean it up?Or just unscrew down the IAV?Anyway to confirm if the IACV is down?

Thanks
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Sunday, September 11th, 2011 AT 6:05 AM
Tiny
PROMECHANIC
  • EXPERT
Just unscrew the IAC. Clean it with carburetor cleaner.
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Sunday, September 11th, 2011 AT 6:11 AM
Tiny
KAIKIING
  • MEMBER
This result consider as idle or not?I've try clean up the Throttle body and also the IACV and get this result better than previous but still have problem with start up. Any other suggestion?
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Friday, September 16th, 2011 AT 11:24 AM
Tiny
KAIKIING
  • MEMBER
Please show me the diagram how to test for IAC on ECM. Thanks
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Sunday, October 2nd, 2011 AT 12:22 AM

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