volvo 240 rough idle "need help"

beertownbmw · Post by **beertownbmw** » 29 Jul 2004, 08:29

87 Volvo 240 DL, wagon. Current mileage 222,000

This car is a May manufacture date for that year, the is no unit to take codes on this car, ie map sensor

Current condition:

beertownbmw · Post by **beertownbmw** » 30 Jul 2004, 00:39

in addition to the above checks I checked the Oxygen sensor. I checked voltage when hot from the single lead to ground and got between 0-1 volts. It also correctly responded to a simulated air leak (by opening oilcap and partially pulling out dipstick) the voltage dipped and the restored to stable reading. I also checked the resistivity across the two pole plug in it was 12-13 ohms at hot.

arete · Post by **arete** » 30 Jul 2004, 08:07

Be sure and check the timing and then there is a #9 hex screw that adjusts O2 levels. Don't know how to describe it but it can lean or rich up the mixture. I have a guage which reads the O2 mixture and can adjust it with that screw to keep it correct.

Guest · Post by **Guest** » 30 Jul 2004, 08:27

please tell me location of #9 hex screw you are speaking of. i am not familiar with this. I will check the timing and let you know.

Thank you for your reply.

John Waldron

Volvord · Post by **Volvord** » 30 Jul 2004, 16:49

You have done a good job covering many of th e trouble spots but I would be checking (or re-checking) some of the basics)

1) although you have good spark what is the comdition of the spark plugs, if the center electrode is rounding off they should be replaced.

2) what is the condition of the high tension plug wires? a common cause of rough running is failing plug wires.

3) dirty fuel injectors, even though the idle changes when you disconnected them a leaking injector that is dripping fuel or dirty injector that are not providing an acceptable spray pattern will cause roung running because the fuel will not atomize prior to reaching the cylinder.

4) distributor cap and rotor for condition, cracks, carbon tracking.

5) valve adjustment, although valve clearences usually incraese I have come across several instances where valve clearences have decreased causing rough running.

6) check the adjustment of your throttle position sensor, you should hear a "click" when moving the throttle from the idle position.

If the engine runs well and pulls strong off idle then your timing belt has not skipped, but do remember that timing belt replacement is a regular maintenance item and should be done every 50-60k km.

beertownbmw · Post by **beertownbmw** » 31 Jul 2004, 04:18

Thank you
Checking timing is my next step. And I will let you know the results.

As for Spark/wires/distributor ect. They are all brand new.

Does anyone know a good test for the Fuel Injection Temperature Sensor? I have know this to cause a similar problem, but do not know how to test. Usually a resisitivity test, but do not know required values.

Volvord · Post by **Volvord** » 31 Jul 2004, 09:19

I know I have found a value for the temp sensor i=on the internet but cannot find it right now, try http://www.brickboard.com/FAQ/700-900/E ... mptoms.htm it has a lot of good information.

You may also want to try replacing the knock sensor, when these fail it will play havic with the timing. Mine failed on my 1987 and cause a series of drivability troubles.