RPMs problem

[Vitaliy]

Hi.
I'm facing the following problems. Very long delay when switch from R to D 5-10sec. When stop on trffic light on D holding brake the RPMs drops to ~500 and engine vibrates. After 5-10sec RPM raises to ~850 and works normal. If during the driving switch to N RPM goes low holds it until switch to D. Sometimes (usually on cold engine) all problems disappear. OBD reads P0455 and P0431. With regular gas engine detonates under load. With gas grade 91 no any detonates but all problems are same.
What can I start from? I have ELM327.

 

[Preferio]

Well the P0455 indicates a gross evap leak and the P0431 is a catalyst efficiency code...

I'd focus on the large evap leak first because this is what's causing your initial problem...

A very common cause of that on your vehicle is the canister drain cut valve at the evap canister at the rear of the vehicle... It's really easy to test- you just ground the control wire and see if it operates... if you hear a click, it's operating. If not, that's bad.

With that being said, that large evap leak could be ANYWHERE though. Check all vacuum lines to make sure they are in tact.

 

[Vitaliy]

May I have more detales about this testing? With pictures if possible. RPMs problem I had befor 0455 appeared. P0431 a have about 3 years. RPMs problem ~10month and P0455 ~ 1 month.

Found the canister drain cut valve stacked open. Fixed. Cleaned IAC. Still have problem with idle RPM. Any idea what to do next?

 

[Vitaliy]

Any help?

 

[jeffmsp]

well this is the msp section. we dont have automatics. this is also the performance section. not really for trouble shooting this sort of stuff. maybe make a thread in the right section and you will get proper responses.