Rough idle after VTEC

[Q]

Hey guys,

My '99 Prelude is experiencing a strange problem. After hitting VTEC and then coming to a stop, the car idles very rough, like it's running on 2 cylinders. If you drive for a bit, the problem goes away. This only happens after VTEC has engaged. The car idles fine if VTEC is never engaged. Do you think it might be the VTEC controller?

Sean

 

[White92]

Define "rough" a little more. Do the RPM's go way up and down or just not hold very steady where it's supposed to? Does it ever idle so bad that it dies?

 

[Q]

Define "rough" a little more. Do the RPM's go way up and down or just not hold very steady where it's supposed to? Does it ever idle so bad that it dies?

The idle holds steady at about 500 RPMs when rough. It feels like it's going to die but it hasn't yet.

 

[White92]

I can't think of why it would only do it after reaching VTEC. Maybe a bad VTEC selonoid? If it does it all the time, I'd adjust the valves and the idle control valve. Just my 2 cents though.

 

[KooLaid]

We've messed around with Vtec on another car for shits and giggles and what this prelude did was idle like crap, rough, when we engaged Vtec 24/7.

Could it be possible that vtec is stuck engaged? But disengages at a higher rpm, but lower than vtec range, just to be re-engaged at vtec range to be stuck again?

 

[Briank]

I like the stuck in vtec idea but you should get a code CEL from the presure switch. When was your last oil change?

 

[Q]

Just changed the oil about 700 miles ago. It was doing the same thing before the oil change. Just drove it and got a CEL. I'll retrieve it and let you know.

 

[KooLaid]

I like the stuck in vtec idea but you should get a code CEL from the presure switch. When was your last oil change?

Thank you Brian. From the electronical master, I find it to be an honor :biggrin: lol

 

[saint2709]

Thank you Brian. From the electronical master, I find it to be an honor :biggrin: lol

We've messed around with Vtec on another car for shits and giggles and what this prelude did was idle like crap, rough, when we engaged Vtec 24/7.

Could it be possible that vtec is stuck engaged? But disengages at a higher rpm, but lower than vtec range, just to be re-engaged at vtec range to be stuck again?

Wow I'm having the exact same problem with my car, I was wondering if you found the problem. Any help would be appreciated

 

[Q]

I gave up trying to diagnose it myself and took it to the local Honda dealer. They said that the cylinder #1 rocker assembly is getting stuck in VTEC. CEL said it was a cylinder 1 misfire.

 

[saint2709]

man my vtec engages before the engine even cranks over. i hear it clicking on and of on and of like crazy. that's 10% of the time the rest its fine. also sometimes i can swear it must stays engaged when i drive the car hard. i notice it when i down shift, its just load has hell.