I replaced the AMM that I thought was bad, bu the car still dies right after starting. When the AMM connector is unplugged, the engine stays running. the idle air control motor is fine, throttle position switch was replaced with a good used one a year ago, and there are no missing or cracked vacuum lines or duct hoses. What else should I suspect as the problem? I have a spare ECM, should I try replacing that as well? Thanks, Paul

I have an update: the car finally stays running without having to unplug the AMM. After replacing the AMM and the O2 sensor with no luck, and checking the IAC motor and TPS, I swapped out the ECU as a last resort. When I pulled the old one, it had a little rattle inside, so I guess something must have broken inside. I installed one from my 88 parts car, hooked the battery back up, and it runs! I still need to adjust the TPS to get idle back down to where it should be. I hope this helps someone else, too.

It was hard not to jump in and suggest the obvious - that if you had a spare ECU, to go ahead and swap it. That's what having a spare is all about when it comes to complex parts that can't be verified by the eyeballs. Now, you have a spare AMM - a much more likely failure item.

When we don't do, or can't do methodical troubleshooting, we fall back on suggesting the most likely and frequent reasons for symptoms, in order to swap parts. Your ECU is about the most bulletproof box in RWD electronics, so it definitely does not fall into the "likely" category. That doesn't mean it can't be destroyed.

Now, we gotta know. What fell apart in yours. It is just garbage now, right? So why not pry it open and share the story?
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Art Benstein near Baltimore

If speed counted, rabbits would rule the world.

Wow, thanks so much for the update. Thats something I've been trying to track down for awhile - if one of the failure modes for the ECUs is rough idle, and it seems to not be the case (at least based on what I've found by searching).

The other interesting thing that you note is the high idle, as thats what mine is doing as well, but I havent fixed anything. Not to rain on your success, but I wonder if the solution is somehow a byproduct of a possibly different fuel map in the different ecu thats allowing it to run (and hide that the problem is still there). Not saying that it is, Im just thinking out loud here.

In any event, its progress, and thats good!

Now I just have to find a spare ECU to test mine...

Now I just have to find a spare ECU to test mine...

Still following your story. Does this mean you finally received your spare AMM from Turbo Bricks?

With regard to alternate maps, I like your way of describing the limp home "map" where the LH2.4 ECU decides the O2 sensor can no longer reliably report mixture, or that the AMM is out of range (air makes no sense with RPM). The RWD list has come up with quite a few non-standard ECU failures in the last coupla months.
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Art Benstein near Baltimore

You spend the first two years of their life teaching them to walk and talk. Then you spend the next sixteen telling them to sit down and shut up.

No! I paid him last friday and its been nothing but excuses since then! Im telling him it has to ship today or he can refund the money.

I did some more testing on my car the other night - on a fresh ECU reset, the first code it trips is 113. After driving for awhile, it trips 221 and 232.

Additionally, I don't have a working odometer, so I've never been able to accurately check fuel economy, but I realized that in the past week, I've driven straight to work and home 8 times (4 days x 2 trips), and calculated the mileage via googlemaps. 24.1, 90% highway. No soot, so I can't possibly be running rich.

Anyway, will update when the AMM gets here.

Have you checked the pins in the connector for the AMM? Sometimes they get pushed into the connector and do not make good contact.
Otherwise it is possible you got a bad one.
Dan

Ooh, thats not good news, because Im in the same boat as you, but waiting on my new AMM to come in the mail. I'm at the end of my rope, I have no idea what else it could be.

My thought process is this - the when the AMM is plugged in, the ECU says "Alright, I've got everything I need - AMM, O2 sensor, ECT, crank sensor, etc, now I'm gonna inject fuel according to this map....." and the car stalls.

Without the AMM plugged in, the ECU says "shoot, I can't trust this stuff. Alright, now I'm gonna use THIS map..." and the car runs.

I still think a sensor may be out of range, but pulling the AMM defaults the ECU to a fuel map that doesn't use whatever other sensor is broken.

I still lean towards the problem being a different sensor, such as an O2 sensor or TPS or something, but I suppose it oculd be the ECU.

Good luck, let us know what you find!

Which system does your car have? If it's the LH 2.2, then the O2 Sensor is suspect as well. The AMM reads the signal from the 02 sensor to adjust the air/fuel ratio. You need to check the O2 sensor, and if it checks bad, then replace it, so the AMM can do its job. I routinely check the mixture on mine, and occasionally have to tweak it a touch to keep the fuel economy as high as I have it set.

Do you have a Bentley Bible? Since you are a Florida fan, do you live in Central Florida? I'm in Leesburg, and would be happy to help you with your troubleshooting.

Were you asking me or boatbuilder?

If you were asking me, then if you'd like, we can discuss here: http://www.brickboard.com/RWD/volvo/1362742/220/240/260/280/making_slow_progress_rough_running_still_interested_art.html

so as not to hijack this thread, although they do seem to be quite related.

I am in South Florida, near west palm beach. Leesburg is quite a bit away unless I'm on a trip up to Gainesville, which I don't think I will be for awhile.

I don't have the bentley book, but I do have a haynes.

I haven't replaced the oxygen sensor since I bought the car, so that could be faulty, but would a bad one make the car stall? I would think that the car would run but get poor fuel economy. It could also be the TPS, since it was a used one that was installed last summer. What is an ECT? I'm not familiar with that one. I guess I considered installing my spare ECU because that is a part that I already have and would not have to spend any more money to test it. Thanks, Paul

AMM? MAF? If so then do the checks in the bently. Sounds like you could have a bad new part.

Andrew