Hey all,

Just bought an 87 240. Runs like a tank when it's warmed up, but when it's been sitting in the cold weather all day and i start it up and drive it almost stalls out. I have to let it warm up for at least 5 min before it's ready to roll.

Plugs are getting the right mixture and compression is good. Anyone else have this problem? Any solutions?

I know it's a 30 year old vehicle so it might be expected. Thanks

 

there's a coolant temperature sensor (CTS, also called ECT) which tells the ICU (ignition control unit) and ECU (fuel injection control unit) how warm the engine is, so they know how much fuel and what spark timing to use. its possible this isn't working well, and giving bad information so the ICU and/or ECU think the engine is fully warmed up when its still cold. more often, the CTS fails so it tells the ICU/ECU the engine is dead cold when its warm, so it runs way too rich, but still, stranger things have happened.

this article discusses the CTS and how to test it. its mostly talking about 89+ LH 2.4 cars, but 87 LH 2.2 aren't that different, and I think the differences are clarified somewhere. https://www.volvoclub.org.uk/faq/Eng...ingECTFailures

 

Thank you for the reply Pierce, I'll be looking into this further. Would you clean throttle body and other items as well?

I checked the plugs and they are perfect, so the right mixture is occurring it appears

 

What is the easiest way to change the sensor? I'd like to be able to change it without taking off the the throttle body and stuff, if that is possible.

Most likely will have to bleed the coolant when changed as well right?

Thank you

 

i wouldn't touch it unless you've tested it with a meter and shown it to be grossly way off, and even then, half the time its a wiring problem, not a failed sensor.

its screwed into the head under the intake manifold, its the two-pin sensor, I forget which position its in, there's also the sensor used for the temp gauge on the dashboard, and the antiknock sensor in the same general area, I think the ECT/CTS is the one under the #3 manifold, so its a bear to get to, you either take the whole intake manifold off, or you remove everything from the manifold (throttle, MAF), and the idle air valve...

 

Thank you pierce. I will heed to your advice and not tackle this until I'm sure what the issue is.

 

Also test the o2 sensor. My car started running really badly when it was warming up then running fine when fully warm, turned out to be a totally ruined sensor.

 

easy o2 sensor test... o2 sensor has two connectors, one has two pins, for the heater, the other has one pin with the signal. these connectors are on the firewall near the wiper motor on a 240

disconnect the single pin connector, take a 2" piece of a single strand of some copper wire, wrap one end around the pin, put the connector back together, so the other end sticks out, and wrap this around the + probe of a multimeter, and clip the - probe to a good ground (like the one for the wiper motor). set the meter for DC Volts, with a low range (like 0-1.99V). start the engine, let it idle til it starts to warm up.

if the o2 sensor is working and the engine is in lambda balance, the volt meter should swing between a higher and lower value.. the higher value is something like 0.7-0.9V, while the lower one is like 0.1-0.4V... the voltages aren't important other than low being less than 0.5V and high being above 0.5V

ideally at idle it goes high, low, high, low every few seconds, and the high and low are about the same length of time. if you rev the engine up to like 2000 rpm or whatever, the cycle of high-low should speed up some but at any steady RPM should still be about equal length high as low.