Hi,

240 Volvo w/ 155,000 miles. Idles a tad rough but smooths out when you accelerate. You can go to the back of the car and it sounds like it has a small misfire.

Took off and cleaned throttle body, new plugs, wires, cap and button. Replaced all 4 injectors w/ upgraded 4 hole Bosh. Also found a broken motor mount so replaced mounts as well as tranny mount and removed and clean the air mass flow sensor as well.I also checked signal going to injectors with a noid lite and all seems good but....I can pull off the injectors wires and get a response from engine idle all all three except the front one. I pulled the wire off the air mass and engine runs rough and then gets better when I hook it back up. Idle surges up and then goes back down to the rough idle. Any ideas from here would be most appreciated...

Thanks

 

 

that would be nice...but I have a 1991 240

 

any 240 since 1989 has onboard diagnostics you read with a LED and pushbutton under the hood, but these don't tell you much except in specific cases.

 

The video has some useful information about what may be causing the misfire. While it isn't your specific engine the same things cause misfires in any engine. Just gives you a clue as to what areas you might want to check: vacuum leaks, dirty plugs, etc

 

Thanks for everyone's input.

Sprayed around the intake and hoses with starting fluid and found a leak round cylinder #2. Installed a new gasket today and runs like new.

 

Good deal. It was an intake leak?

 

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yes..thanks again!