1993 Honda Civic throttle?

DELSOL

MEMBER
1993 HONDA CIVIC
4 CYL
2WD
MANUAL
245,321 MILES

Ok I have a honda civic delsol with a honda civic dx motor in it. Its 1.5 single cam 4 cylindar when I start this car in the morning it idles real high before it warms up but once it warms up it will rev out between 1 and 2 rpms in nuetral it does this constantly in nuetral it just idles bouncing back in fourth between 1 and 2 rpms? Its not the idle air control valve its not the thermostat and its not the radiator I have checked and replaced all these items the only other thing we can think of is its the throttle body or throttle positioning censor or maybe the air intake we have been trying everything can you please giva us a little more insight as to what else it could be, Thankyou so very much!

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Hi delsol,

When excessive air is getting past the throttle body, such as vacumn leakages, high idle adjustment, surging would occur.

Did you check for vacumn leakages?
Was the fast idle thermo valve checked?

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Monday, November 9th, 2009 AT 1:10 PM

DELSOL

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1 POST

Thank you! We did not check the thermo valve but we did check all the hoses for leaks I think we may need to check again. I appreciate your feedback! Any ideas help, thanks again

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Thursday, November 12th, 2009 AT 11:10 AM

KHLOW2008

MECHANIC
41,814 POSTS

The FITV tends to work itself loose and allow excessive air to get past the throttle body after the engine is warmed up. It should not allow air to get past once it is heated up and other possible causes could be clogged coolant hoses to the FITV and IAC.

Insufficient coolant in system would also cause the problem.

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Friday, November 13th, 2009 AT 9:24 AM