Hi team

 

I recently changed my valve cover gasket and washed my engine bay. Car was behaving normally,

I have not been driving it during the week as I got a work vehicle. Yesterday I noticed it has developed strange idle. 

It is sitting around 1500rpm when coasting not in gear and only comes down once stopped completely. It comes down to 

around 800-900 and it used to sit around 750. It also stalled out in traffic twice yesterday with the ETC warning light showing on

the dash briefly. I intend to grab an OBD2 scanner tomorrow from work to check codes. I also disconnected the battery for a couple

hours to see if the computer would relearn how to idle like it used to. I am assuming that I have gotten water somewhere it should not

go and have maybe rooted the TPS or IAC or throttle body itself. Anyone else experienced this issue? what should be my plan for diagnosing 

and fixing the problem.

 

cheers

 

On 03/08/2025 at 2:36 PM, rapidyellowxr6t said:

what should be my plan for diagnosing and fixing the problem.

Did you get anywhere with this?

 

I am wondering if there is an air intake leak somewhere? - more air is same as "throttle open a bit".

 

I have diagnosed a faulty intake manifold gasket by using camping stove gas cartridge and an thin hose to direct gas around points where the air might be leaking in.

When gas was drawn in instead of air, it changed the idle and showed where the leak was happening - intake manifold gaskets are a bit of a pain to do!

 

If doing this, obviously take precautions around using flammable gas...

 

I have heard of people using other things like WD40 as well - that might be easier as it has the thin nozzle to direct the spray.

Edited August 14, 20251 yr by xr6tForMe