Okay, my cousin's friend came over today and asked me to take a look at his
240 which he purchased only a month ago and been having some engine troubles. It sometimes refuse to start (cranks but won't ignite), other times it starts up fine. And when it's running, sometimes it stalls out for no apparent reason, and the lambdasond light often stays on.Both his 240 and my 740 were '90 models, both with B230F engine and LH2.4 injection system. First thing I tried to do is to recall any diagnostic codes from the OBD. I could only recall the codes from the ignition system (via socket 6) but nothing from the injection system (via socket 2). I tried running functional test and self-test with the injection system (test modes
2 and 3, pressing the button twice and 3 times respectively) and again no response, not even the flashing lights.Next thing I thought of doing was swapping computers, as they're the same year with same engine and injection system, I thought they should be interchangeable. When I plugged my computer to his 240, it started fine and I could also get the OBD test modes for the injection system to respond. When I plugged his computer to my 740, the OBD test modes for the injection system failed to respond again.
Then I tried to start my car, with his computer. The car started, ran for about 2 seconds before the idle speed dropped WAY low and stalled, and I couldn't get my car to start again, despite numerous cranking. He told me this is exactly what happens to his 240 from time to time. At this stage I am fairly certain that whatever engine problem his 240 has, the injection computer is the main culprit. One thing I noticed is that his car is still on the old FI computer, with pink sticker, Bosch code 0 280 000 561 and Made in Germany. My car also came with that computer and I had idle problems about a year ago, although not as bad as his. My mechanic told me that the old computer is prone to failing with age and there's a new updated version with white sticker, Bosch code 0 280 000 951 and Made in Spain, and that's the one I got when I replaced my FI computer.
Anyway, the reason I'm posting all these is because I want to ask you guys if (1) I'm making the right assumption that given both cars are '90 models with B230F and LH2.4, the computers are interchangeable, (2) with the symptoms and diagnostic steps I've taken, is it safe to assume his computer's the main culprit, and (3) if any of you guys also aware of the difference between the old "pink sticker" computer and new "white sticker" computer.
Lastly, the fuel tank pre-pump on my 740 comes on when the ignition is moved to position II (the Bzzzzz sound), but cuts out after 2-3 seconds (assuming engine isn't started), which is normal for my car I believe. On his 240 however the pre-pump stays on as long as his key is left in position II. Is it normal for a 240? Are they designed to stay on or supposed to cut out after 2-3 seconds like my 740? I tried to find the fuel injection relay on the 240 (and made an earlier post enquiring about its location) but still couldn't find it. _________________ Will '90 Volvo 744 GLT (B230F) - daily driver '73 Volvo 164E - Looking for buyer (restore or wrecking)