Sorry for making a thread, I have been out of the honda scene for a while but my friend's civic is goofing off. The car's idle is very low (200-300rpm) when started but builds up to 800 after around 20 seconds. When the throttle is opened the car dips before the rpm can go up, once released the idle drops very low and the car nearly dies.

We checked spark, and cleaned out the IACV and idle control screw. The car is throwing no codes, and there is no misfires (drives great when accelerating, just nearly dies when releasing the throttle).

Car is 97 civic and has a 2000 civic SI b16 motor...he has not done any modifications to car in months. I'm thinking it is fuel related, but I am not sure how to check on this car.

Any help is greatly appreciated, thank you!

 

Also we sprayed carb cleaner on all the vacuum lines to see if we could get the idle to move and nothing happened. Any help or links provided would be awesome because it is his only car, thank you!

 

fuel filter maybe i had a bogging problem when mine was clogged

but since its not throwing any codes its something mechanical check timing could have randomly jumped

 

Sounds like the tps sensor. Start the car, unplug the sensor for a few seconds then plug it back in. If it idles fine after that you need to replace the sensor.

 

Thanks he hasn't replaced it in years so I'll let him know since it is such a cheap easy fix.

Great we will test it out later and report back.

Thank you both for your insight and if anyone else has any ideas please feel free to post up.

Also, I am pretty sure it is not related to coolant temp or the temp sensor because the car heats up normal and guage is fine.

 

Tps sensor, low voltage from an alternator can also make the car funny. Check the tps first though.

 

He said he started the car and pulled the TPS, the idle jumped around and plugging it back in didn't fix it. Sounds like it is bad right?

 

No. If you unplug the tps and it idles fine after, thats how you know the tps is bad. If the idle is still jumping around with the tps unplugged it is something else. Try starting the car and unplugging the IACV wire and see if it idles fine after that. Even though you cleaned it, it still could have gone bad.

 

I had the same problem it was a vacuum leak the fluted from my intake chewed the metal hose to the ac and made a gaping hole did t notice it because the filter was over the hole check that. If your filter reaches that far down there

 

Sweet thanks guys, I'll check with him tomorrow!

Have a great night everyone!

 

When was the last ignition system tune up done (plugs, wires, cap, rotor)? Is the ignition timing set to spec?

Did he follow the service manual procedure for adjusting the idle speed?

 

Procedure for adjusting the idle speed on the 99-00 B16a2 engine: