2002 volvo s60 Do I have a bad engine computer?

[turtlehead]

I'll be checking them this morning.

Along the same lines, I am wondering if anyone knows what the computer is doing the first thirty seconds after starting the engine? If I knew what the programming was looking at it might help me narrow down the problem. It could well be that the cam and crank sensor issue, while still a problem, is not the real reason why the engine is shutting off at the 25 second mark. I've noticed that once the engine stalls, I can't restart it if the key remains in the II position- I have to turn everything off, in effect resetting the computer from scratch.

Thanks again everyone for your help in figuring out this frustrating problem.

[abscate]

I think thats normal key operation on most cars today.

There is a thread in the P80 section about a 30 second shut down problem that might be worth looking for.

Depending on ambient temperature, my P2 takes about 15-30 seconds for the O2 sensor to heat and start sending useful data. The car idles at 1500 rpm until this happens, then drops to 850.

Do you start at 1500, then stall?

[turtlehead]

Abscate:

I checked the 02 sensor yesterday, I don't see any damage to the wiring. I unplugged it and started the engine, with the same result. Stall after about 25 seconds.

In answer to your question, the engine idles at around 8-900 rpms so I wouldn't say it was unusually high.

My thinking at this point, which may be totally wrong, is that (as Doublebug suggested) the engine computer is going through some initial procedures which allow it to run but when it reaches a certain point in its programming it finds something that causes it to shut down. I'm thinking there is some wiring issue, maybe a short somewhere or a bad sensor, that the engine computer doesn't access until the 25 second mark, which is why I was asking for information about the programming sequence.

Is this the right place to be asking that question, or should I try one of the other Volvo forums?

I will go search for the other thread you mentioned, Abscate. Thanks!

[abscate]

How about the same test but unplugging the MAF? Black plug near the air cleaner

I don't think unplugging the O2 sensor is a useful diagnostic fir anything but let the experts chime in on that.

[turtlehead]

My thought about unplugging the 02 sensor was that if the ECU is getting a bad signal, or the 02 harness has a short, then disconnecting the sensor should give me a different result. But you are right, Abscate, I'm not an expert so if someone else knows a better way feel free to give me your input!

I have tried unplugging the MAF, same outcome. My experience with bad MAF's is that they cause the engine to shut down much faster than what I'm experiencing. Plus, my car does run if I unplug the cam sensor, and Vida is giving me a reading on volume of air coming through the intake, which I assume is what the MAF is supposed to measure.

Frustrating, I'm sure it will turn out to be something simple, but I'm pretty well stumped.

I had a 93 850 where I did a manual transmission conversion a couple years ago that suddenly developed a no-start issue- by that I mean it started fine immediately after the conversion, and the issue showed up months later. I discovered that it would start after a shot of starting fluid, so after changing the CMP, MAF, CPS, ECT and finally the ECU with no change, that's actually how I got around for months. Then I found an intact wiring harness from a manual 850 at the local u-pull-it and took a chance. Turns out that was the problem- the 93 850 apparently changed the polarity in the crank sensor between automatics and manual cars. I had tried reversing the polarity (cut and splice) of the crank position sensor wires in my original harness, but it wasn't until I swapped out the whole harness that the issue went away. A simple solution, but it was damned frustrating to chase it down. I still have no idea why the issue didn't appear immediately after the conversion!

I'm going to keep chasing this problem down, hopefully the answer won't take me months to find like it did with the 850.

[Gyllenhammar]

I replaced my top yesterday and got the same problem as You. It started and run 20 s and then died.
In my case it was the camshaft position indicator that did not work. I removed it and found that the
metalpiece mounted on the camshaft was broken. Replaced it and now it works.

[turtlehead]

Jimmy57 mentioned this to me when I first posted about my problem in June, I think the part you are talking about is called a reluctor, it is bolted to the intake cam and it is the rotating part that the cam sensor reads, I think it is a 10mm bolt IIRC. I looked at mine back in June, but that was only to verify that it had the right configuration, as Jimmy57 suggested. I'm certainly going to take another look. I may even have a spare sitting in my garage. I will let you know what I find, and thanks for the suggestion. I still haven't figured out the problem and I've had some other projects to deal with. I will post again and let you know.

[Gyllenhammar]

That is the part that was broken on my S60, difficult to see when it is broken. On mine it was the smallest piece out of 5 increasing pieces. Most likely broke during transportation as I bought my new top on the internet and it came without the plastic cap on it. I had the same 2 fault codes as You, thats how I found Your thread. Have been running a week now without problem...........

[turtlehead]

THAT WAS IT!

When Jimmy57 mentioned it to me earlier, it was in the context of whether I had the correct reluctor installed, and I merely counted the tines to see that I had the right one, I never examined it to see whether all of the tines were intact. It was, in fact, the smallest of the tines that was broken. I installed the spare reluctor I had sitting in my garage, and my car now runs with no cam/crank sensor codes.

I knew it had to be some little, stupid thing that I was overlooking, I've never had a problem like this before, but now we all know just a little bit more about what kind of symptoms are caused by what kind of problem.

Thank you, thank you!