Ok, here's the situation. This post is about my friend's 240. He bought in only a few weeks ago, already had a bit of work done to it (fixed a transmission leak, slight alignment adjustment, bit of exhaust work, and a few other things but nothing to do with the engine) and now he's having trouble.

Facts about the car: It's a '91 244, B230F (has the 016 AMM), automatic, factory a/c, no cruise, Canadian car, no EGR, about 260000 km's on it. Nicely optioned, but not extravagant. A nice car.

Last night I followed him to his office to pick up his other car, a '79 wagon with serious running and safety issues, to take it to his apartment and leave it there for the time being. We expected trouble with the wagon (and did have that too), but the sedan started acting up (he was driving): sudden loss of power on highway, will barely idle, and stalls as soon as you touch the gas pedal - even in park. However we found that if you work the gas very very slowly that it will indeed accelerate the engine. But as soon as you let up it goes right down to ~500 rpm and almost dies. We had to get it towed, and decided to take it to my house, in the city, and that I could try to work on it while he out of town on work business. Well I'm not making too much progress.

Basically tonight after work and supper I tried to pull the CEL codes and only got one (from socket 2 only: 1-2-1). I guess that's "faulty signal to/from AMM". So I tried unplugging the amm and started it with no apparent difference in idle quality. Reset the computer, and the cel comes right back on, and nothing gets any better. In fact the exhaust smells very rich (I'm familiar with that smell...). I also ran the diagnostic tests the computer will do and could hear the injectors clicking, then the IAC valve clicking (sounded okay), but the third test the computer tried to run didn't apparently do anything (the light flashed at the same rate as the two successful tests but Icouldn't tell if anyting was happening - does this mean that the radio suppression relay is gone? does this car have one? My '91 740 does, I know that much).

Now it will barely start and it immediately shuts off. I gave up and came inside to make this post. Going to bed right away. Maybe it was the turkey I ate over the past few days.

I have a list of hte usual suspects to try (and yes these are all things I have replaced or checked on my car, the 740. And I don't think many of these standard PM items were ever done on this car in the past (though it was a one-owner car to begin with): flame trap dirty, IAC clogged/dirty, throttle body dirty, broken ignition power stage, faulty ect sensor, faulty knock sensor, faulty amm, faulty crank position sensor, faulty FPR, cracked intake air hose, failed airbox thermostat, faulty in-tank pump, old: plugs, wires, vaccuum lines, air filter, etc.. It also has nasty-looking fuses with cruddy connections. What I'm saying is the standard maintenance things probably have never been done.

Now I can do most of these things, or show him how to do them or help him (that would be preferred) but I'm hoping the gurus in Volvo Valhalla can just point us in the right direction in terms of where to start. I don't feel comfortable just starting to replace things willy-nilly (been through that with my car - had it two years almost and have only driven in 1000 km's.....) and this guy isn't terribly mechanically-inclined (though I am), and most of all I just don't have a lot of time to spare anymore right now. I have a million things going on at the moment and this makes it a million plus one. I don't mind helping, and having it parked here for awhile, but in a few days he'll need to drive anyway so it has to get fixed one way or another.

My first thought is the AMM. I think I have a spare one lying around (the one from my 740). Should I try it? I know there was a big thread not too long ago where the guy had a faulty AMM and Art had a series of tests to try. I haven't tried those yet. Regardless, all those standard PM things need to be done. Especiallly before we leave for Portland next month... (for IPD garage sale. will be about a 4500 km trip.). I could also dig up my can of Deox-it and try cleaning the electrical connection.

Thanking you in advance,

Mathew
--
1991 740 automatic, sedan, B230F Burgundy/Tan Leather

Your description matches those a failed AMM, of course when you unplug a bad AMM the engine will continue to run bad. You list a long list of maintenance items to perform. I would try to diagnose and fix the basic problem first. There is always a danger when you perform a lot of maintenance that a second problem is created. Then there are 2 things to diagnose at once and that can be a challange. Get it back to where it was before the failure, then do the preventive maintenance.
--
David Hunter

Hello,


You said that the disconnection of the AMM yielded no change in driveability, this almost vindicates the sensor. I would trust the computer on this one. Have you checked the integrity of the harness? Pull the computer interface and run down the AMM pins with the continuity tester.

I also believe that the computer may have flaked.


Goatman

Mathew
It is the AMM and the only definitive test is to swap it in and see if it works. Everything you described happens in the limp home mode from a failed or disconnected AMM.
Dan

I second the motion. when you swap it, disconnect the aluminium hose from the exhaust manifold heater to the air box. when you find it is the AMM (Rusty at RPR) for another plus a themostat for the Air Box, or just leave the heater hose disconnected until the winter.

Thanks guys, this all helps. I was reluctant to start doing all that stuff til I at least had an idea of where to start. I will try the amm first. However I do acknowledge the one reply where the poster said it's not the amm since unplugging it changed nothing. Man I really hope it's not the wiring to/from the amm. And that it's not the computer.

So here's my plan:
1. Disconnect the heat stove hose to the airbox.
2. Remove old amm and try the one I have on hand.
3. If it works then he drives it home, with instructions to order a new amm. If not, then ??? Start probing pins maybe.

I'll try it tonight and report back. Thanks.

If the AMM has failed the problems you describe will occur whether the AMM is plugged in or not. You can try some electrical contact cleaner on the connector and cross your fingers.
Dan

The 240 in question belongs to me! The problem was the AMM. Mathew replaced it with a spare and also disconnected the aluminum heater hose, and thankfully she's back up and running. I'm going to order a new AMM and other parts which as Mathew suggested, are looong overdue on this car!

I just wanted to say a big thanks for everyones input and off course to Mathew for offering to keep the car at his place for a few days while I was out of town, and take the time to look at it; seriously, he is waay in over his head at the minute with his own 740, so I really appreciate it!

It didn't work out to bad, luckily. The worst feeling about owning Volvos is having two, and both being out of action at the same time!!

Here's a few pictures of my '91;
http://s41.photobucket.com/albums/e279/thisismyminiadventure/1991_volvo_240/

Yep it just turned out to be the amm. Good thing I had that spare lying around. Worth it to buy them from the junkyard when the 016's appear. Anyway thanks again to those who replied - it was a huge time-saver in that we didn't have to go through every other part on the car only to find the amm was the problem.

That was a relief.
--
1991 740 automatic, sedan, B230F Burgundy/Tan Leather