ok so first of all i used volvos built in diagonosis hardware for my 91 740turbo and it gives me a code 2-3-2. so i check the intake manifold and find no leaks. i still have yet to get up and in the car to test the 02 sensor, BUT the prob is that when i start the motor it starts fine but the idle jumps up to about 1200 for a few secs then drops back down to 800+ or so. Then when i put it into drive the idle drops down to about 400-500 and almost dies but comes back and idles @ about 750. i notice no real performace drops or lagging. but after a long trip that i returned from yesterday i came home and put the car in park and the idle jumped up to 1200 and stayed there. i sat and watched it for a few mins as i let the turbo finsh cooling down then shut it off. later that night(about 3 hours later) i went out and started the car to just see if it was still doing it and it idle'd @ about 1000 this time where is normally is and has been for these last few weeks.

i am planing on checking the O2 sensor but do not know how to test if its good or not. I am going to install a new fuel filter to see if that could be a prob and while down there i'd like to check the fuel pump but once again don't know how. any help would be very much appreciated

mike

Mike:

I can tell you that I have started to see this issue on my car today after putting in a new fuel pump relay and tightening up the elctrical connections in the relay board. My 85 745t settles around 1000rpms after I start it up now, where it would idle at around 800rpms before. However, after I drive it for a bit I find that the rpms settle back down and will idle at 800 or so again. It moves around a little bit as well, but its always done that in the past. When I first had the problem after starting it in the morning it jumped to around 1100 or so rpms and kind of moved around just above 1000 rpms.

I'm thinking I need to clean the injectors, and that the fuel pump may be having issues, not sure. Also want to check the in-tank fuel pump, but I'll probably leave taht to my mechanic to diagnose. I'm interested in seeing what some of the more knowledgable folks on this board have to say.

-Rick

Mike,

I have similar problem with my 87 760 Turbo. The engine dies on idle. To prevent it from dying, I have to use my both legs (auto tranny), one leg on gas and the other on brake while seating on a stop light. The main fuel pump is also quite too noisy. I've used a fuel injector cleaner but no help. I do believe that my problem is on the fuel injectors needing some good cleaning. Good luck....

well .. i fixed/figured out my prob .... the metal pipe that attaches to the back side of intake manifold (its between the #2-3 cylinders that's opposite of the throttle body) that runs down to some kind of vacuum thing was busted. had a 1/2" by 1/4" hole of metal missing and was severd off of the pipe below it ... any one know what this part is called????? so i can order a new one???????? i used some temp muffler tape to fix it so that i can drive it to shop tomorrow and fix it but i need ot find the part first ... i might head to volvo dealer and have them look @ it and sell me part there and i can drive back to shop to fix. the car runs fine under load its just the idle is CRAP ... so for all who think they checked for vacuum leaks ... CHECK AGAIN