Rep Power: 0

(2001 Honda Civic EX)

I noticed this start after I changed out a faulty EGR valve. I had the battery unplugged to switch out the EGR and when I finished that up and started the car I noticed my RPMs were bouncing between 1500 and 2000 when I put it in neutral or pressed in the clutch. I brushed it off as the idle memory being reset due to the battery being unplugged for so long. So I went a head and performed the idle learn procedure and drove it around for about 150+ miles. I noticed the car jerking when pressing or letting off the gas pedal. Nothing had changed after 400 miles of driving. So I went ahead and took out the throttle body and cleaned it out with some carb and throttle cleaner. (Throttle body and IACV was filthy) After cleaning it thoroughly, I put it all back together and started it up. The issue worsened. RPMs were bouncing between 3000 and all the way up to 4000 when in neutral or with clutch pressed in. I went ahead and tried the idle learn again just to rule that out. RPMs returned bouncing from 1500 to 2000, but still would not idle the way it should. The check engine light had turned on for about 30 minutes yesterday. I tested the code and it brought up an idle air code. However, after a while the light turned off and no code was brought up. As it is right now, when I start the car and put in neutral without pressing on the gas it idles at 1000 rpm. But when I give it any gas, it starts bouncing from 1000 to 2000 and is still very punchy when driving it, but the check engine light has not turned back on. Anyone have any ideas or experiences with this? Would a new IACV fix this? Or a whole new throttle body? or is there something I'm overlooking? Anything helps! Thanks!

 
Rep Power: 211

not sure what the exact problem is, but when an engines idle speed goes up and down like that it normally means its sucking air in somewhere it shouldnt be, check all around the intake manifold for a loose, disconnected, or cracked hose

 
Rep Power: 519

Or a stuck IAC?

 
Rep Power: 0

All the hoses and seals seem to be fine. I can't find any air leaks. Next thing I'll try is replacing the IAC. My biggest question would be why would this start happening immediately after I replaced the EGR?

 
Rep Power: 519

Didn't get all of the old EGR valve gasket scraped and cleaned off, now there's a vacuum leak?

Didn't use a new gasket with the new valve, now there's a vacuum leak?

Got a cheapo gasket with the EGR valve, now there's a vacuum leak?

 
Rep Power: 0

Would an air leak in the EGR cause a problem like this? I did replace the gasket but I guess it's possible I didn't clean the rest of the old gasket off enough.
I'll take apart the EGR and replace the gasket again and see if it helps.

 
Rep Power: 519

There are 2 holes in the base under the EGR valve. One goes to the exhaust, the other goes to the intake manifold (via the EGR distribution plate). A leak to the correct hole would be an intake vacuum leak.

You could plug the holes to see if that's the cause of the high and bouncing idle too, but you'd have to get the port completely sealed off.





Whenever you have a new problem immediately after doing other work, it only makes sense to revisit what you JUST did.

 
Rep Power: 0

That seemed to have worked! RPMs are staying between 500-1000. Thanks for your help!