1992 Volvo 240 Topic is solved

[higwap]

Hello,

Hope everyone is doing well! Any advice or help would be sincerely appreciated. Two of the three Volvo mechanics in my area recently retired and the third is having some health problems.

1992 Volvo 240 sedan 4 cylinder automatic. Recently had the transmission rebuilt.

I recently started having my idle start surging up and down from normal to high (no tachometer sorry) and it was also hard to start after raining (I live in a warm, tropical environment, not sure if that can make a difference)

So I replaced the distributor rotor and cap and put new spark plugs and wires in and that fix the problem with starting after it rained.

I couldn't find any vacuum leak after looking for leaks on hoses so I replaced the idle air control (IAC) valve to try to fix the surging but that did not work. I checked the fuel regulator by pulling the hose off and no gas was coming out so that was good. I bought a vacuum gauge and tested it, it starts out at 20 and then goes down to 16 and back up to 20 and then down to 16 and goes through that cycle.

Is there something besides a vacuum leak that could be causing this, any recommendations or help would be sincerely appreciated, live in a dense city and don't have any Volvo mechanics available to me.

I have moderate mechanical experience, learning and fixing as needed so I'm more than happy to figure out anything I need to, just not sure about what this likely is.

Thank you again to anyone who responds!

Here's the link to the video if it doesn't show up well with the one I uploaded.

https://photos.app.goo.gl/EDp6P2rLxyEVfcYw5

[volvolugnut]

It may be the intake manifold gasket. Test with carb cleaner sprayed on the gasket. The cleaner spray should cause increase in RPM if sucked into intake. However, a leak on the bottom will be hard to spot.
I had a similar idle problem on 1983 245 and the new gasket solved it.
volvolugnut