Idle surge RT4WD
Mark_Logan
Band Wagon
Hi everyone, and thanks for taking a look.
When my Honda warms up, the idle surges. Between 500 and 1900. Over and over. Now, I know that this has been beaten to death, and I have tried a LOT of fixes. So, I'll detail those. First of all, it's a 1991 RT4WD with a D16A2. Secondly, I've replaced the High Idle Valve, and the vacuum related assembly that goes on the back firewall. I've filled the radiator to the brim. Nothing is making a difference. The ECU is not throwing any blink codes, and the "check engine" light is not on.
Now, this is where it gets a little weird. Yesterday I noticed that the coolant system was rather pressurised, so I let it cool and then pulled the rad cap. Then I turned it on and it SHOT coolant everywhere! It's not supposed to do that. Searching more forums, people tended to think this was a head gasket issue. Thing is, there is no coolant in the oil, and no oil in the coolant and though the exhaust is a little white, it's cold here in Canada and it doesn't really smell like coolant. Finally, disconnecting vacuum hose #21 to the throttle body makes the idle stop surging, makes it sit at about 500 rpm and no white smoke is produced, just black.
Thanks in advance for your input, this thing is driving me insane.
When my Honda warms up, the idle surges. Between 500 and 1900. Over and over. Now, I know that this has been beaten to death, and I have tried a LOT of fixes. So, I'll detail those. First of all, it's a 1991 RT4WD with a D16A2. Secondly, I've replaced the High Idle Valve, and the vacuum related assembly that goes on the back firewall. I've filled the radiator to the brim. Nothing is making a difference. The ECU is not throwing any blink codes, and the "check engine" light is not on.
Now, this is where it gets a little weird. Yesterday I noticed that the coolant system was rather pressurised, so I let it cool and then pulled the rad cap. Then I turned it on and it SHOT coolant everywhere! It's not supposed to do that. Searching more forums, people tended to think this was a head gasket issue. Thing is, there is no coolant in the oil, and no oil in the coolant and though the exhaust is a little white, it's cold here in Canada and it doesn't really smell like coolant. Finally, disconnecting vacuum hose #21 to the throttle body makes the idle stop surging, makes it sit at about 500 rpm and no white smoke is produced, just black.
Thanks in advance for your input, this thing is driving me insane.
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