Hi all,

In advance, I do apologize for some erratic english here, since it's not my mothertongue! I do hope I will find the same level of good advices that a get on similar forum, only for my old motorcycle (I own a 1976 Honda CB750K).

Just bought a 1990 Sedan 240DL. The previous owner took care of the car like a prized possession therfore, it's in great shape. Except one thing: it won't run well before the engine warms up and even then, idle is rough. Now, before posting this message, I did read the old postings to see if anything would ring a bell.

The previous owner did warn me about it; his mechanic said it was the idle air control valve (which sounded logical). So, I did change the idle air control valve with a NEW one. The problem is still there. When engine is cold, I have to let the foot on the gas pedal in order to warm up the engine, for 30 seconds or so. But surely in the winter, it won't even start. And, even when warmed up, the idle, judging by the engine's wobble, must be at 650 - 700rpms or so.

Questions:

(1) Is there a simple way to verify if there is some voltage or something like that at the valve's connector? If so, what is the classic troubleshooting method for this?

(2) Is there some sort of "computer" (ECU?) on these cars and if so, could it be related to this problem? If so, what's the simpliest way to find out? Trouble code of some sort? And where would that computer be located?

(3) Anything else I should check ata the same time, besides the oubvious plugs, wires, distributor, air filter, etc.. ? (yes, they are all in good shape)

one thing I noticed: speedometer seems to be working on and off meaning, sometimes the needle and trip meter work, sometimes don't. When the needle "comes back to life", at the same time, the "please change gears arrow" (sorry... don't know the appropriate term for it) lights up. Which indicate some kind of proper computer related analysis and therefore, this computer (or ECU) might be working properly.

Thanks in advance for your responses,

Paul

 

Try cleaning the throttle body and check for vaccum leaks.

The arrow on the dash comes on sometimes when the relay for the overdrive goes bad.Do you push the button on the shifter to turn it off?

 

Hi,

I guess I should have mentioned that the transmission is manual (so I guess that takes care of the overdrive button). I did a few researches on this forum and asked a few questions around. Someone told me that it also cuold be related to tow (or more...) things: temperature sensor and/or oxygen sensor. Most likely to be the temperature sensor, due to it's function to "tell" the ECU wheter the engine is warm or not and to adjust the gas flow accordingly. (I guess: cold, more fuel; warm, les fuel)

I was also told that on these 1990, the ECU doesn't return a code like on the more recent cars, meaning you just can"t "plug in and diagnosis". Is that correct?

If it turns out to be too complex, I guess I'll just take it to a Vovlo mechanic I know; most likeyl, he must have seen this kind of behavior before.

In the meantime, if anyone has an idea, feel free to drop some sound advice my way.

Thanks in advance,

Paul

 

I would still try to clean the throttle body and look for vaccum leaks.

Follow the link to learn how to pull codes.

http://www.troublecodes.net/Volvo/

 

Hi all,

I finally decided to take the car to my volvo mechanic. He ran a whole bunch of tests on the car, which in the end, showed that is was after all the Air Mass Meter that had gone bad. At least, I'm glad to know that every other sensors (temp., O2, etc) are good.

Attached is a picture of the car. I bought it last friday. 1990, with 250 000km on it.

Thanks again for your sound advices, 'hope I'll be able to to the same for some of you!

Regards,

Paul

[IMG]local://upfiles/3209/4E13D1C8229746A9AD0B6E6C68A9367B.jpg[/IMG]

 

Congrats[sm=exactly.gif]