Surging Idle and No-start when hot
07-05-2010, 02:10 PM
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Surging Idle and No-start when hot
I took my '88 4Runner to the shop to fix the miss and no-start problem I was having.
The shop identified it as a bad #1 injector.
They replaced the injector....fixed the miss.
After this I noticed I had a surging idle problem while brake was applied. I believe this issue was there before but was not as noticable with the bad injector missing. Also, after driving a while,then shutting it down. It would not start back. I let it cool down several hours then I went back and it fired right back up.
I searched the forums and found that I needed to turn down my idle, which I did. The idle no longer surges at idle with the brake applied, but now surges up and down at higher than idle rpm's with my foot lightly on the accelerator.
I also topped off the radiator with coolant, with no change.
Today I removed the throttle body and made sure the coolant lines running through the throttle body were clear, and they were. At the same time I ran very hot tap water through the TN coolant ports and then blew through the idle air control valve ports to see if the valve was closing. It seemed to be closing after I ran the hot water through it but not completely.
So, I reinstalled the TB...started it, let it warm up...same thing. Then I put electrical tape over the IAC port in the TB to stop any air from coming through
it if the IAC valve was sticking open.....no effect.
Have I missed something with the IAC?
There is no way that I have found on my TB to look at the IAC valve.
Is there something besides the IAC that could be causing this surging idle and no-start when the motor is hot?
Thanks in advance.
The shop identified it as a bad #1 injector.
They replaced the injector....fixed the miss.
After this I noticed I had a surging idle problem while brake was applied. I believe this issue was there before but was not as noticable with the bad injector missing. Also, after driving a while,then shutting it down. It would not start back. I let it cool down several hours then I went back and it fired right back up.
I searched the forums and found that I needed to turn down my idle, which I did. The idle no longer surges at idle with the brake applied, but now surges up and down at higher than idle rpm's with my foot lightly on the accelerator.
I also topped off the radiator with coolant, with no change.
Today I removed the throttle body and made sure the coolant lines running through the throttle body were clear, and they were. At the same time I ran very hot tap water through the TN coolant ports and then blew through the idle air control valve ports to see if the valve was closing. It seemed to be closing after I ran the hot water through it but not completely.
So, I reinstalled the TB...started it, let it warm up...same thing. Then I put electrical tape over the IAC port in the TB to stop any air from coming through
it if the IAC valve was sticking open.....no effect.
Have I missed something with the IAC?
There is no way that I have found on my TB to look at the IAC valve.
Is there something besides the IAC that could be causing this surging idle and no-start when the motor is hot?
Thanks in advance.
07-06-2010, 06:47 PM
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Location: Barrie, Ontario CANADA
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Check and adjust your TPS as well. When the engine is at operating temperature and the TPS idle switch is closed the rps's can not be over 1100 or so or you will start getting the hopping idle. So if your tps is out of adjustment and is reading idle when the throttle is slightly touched then the hop will start.
Make sure you burp the coolent system very well. Run it with the rad cap off, full cab heat, for 10-15 min.
Make sure you burp the coolent system very well. Run it with the rad cap off, full cab heat, for 10-15 min.
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