My 88 245 has been running poorly as of late. It will not hold an idle when it is cold, and the engine power surges and drops out as it is driven. In the last couple weeks the car has has its good days and bad days as I have tried to diagnose the problem. I drive the car 100 miles a day, and today as I prepared to return home, the car would barely run/start/idle. After poking around the engine compartment for the um-teenth time, I pulled the connector harness to the AMM, and the engine ran much better(it would idle)..I limped home. The car has had recent tune(plugs, rotor, cap, fuel filter...) and ran fine until one afternoon about a month ago
Questions:
1.Can I be fairly certain that the AMM is shot.
2.aside from finding one at a salvage yard, where is a good place to find one(fast) Partsbin has one for 170$ or so...other prices are much higher.

Thanks,

Steve in Minnesota

Steve, Before you change the AMM, check the connector pins on the cord and the AMM for corrosion. If nothing looks obvious snap the plug on and off of the AMM several times and see if it runs any better. If not the AMM is most likely toast.
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Bruce S. near D.C.

This is something I posted a while ago about a similar problem I had. Hope it helps:

I have a 93 which had the same problem, plus a part throtle miss at cruise. I've developed a kind of check list
approach that I'll share. From my investigation, an idle problem can come from four possible sources: (1)
vacuum leaks,(2)ignition/electrical problems,(3)fuel delivery problems, and (4) sensors/ECU/AMM problems. I
solved my problem through the process of elimination by checking the four areas in the above order, which
starts from easiest and/or cheapest to hardest and most expensive. I first checked for vacuum leaks. Pay
particular attention to the intake manifold and the molded hose from the flame trap to the breather box, below
the intake manifold, and the lines to and from the idle air controller (IAC). While you're at it, check the hard
plastic lines going from the intake manifold to the charcoal cannister below the right front fender. Mine were
bad, but this didn't solve the problem. I used both the soapy water method and the propane method. Don't use

chemicals which could damage the O2 sensor. I then checked the ignition, and did the same thing you did
(plugs wires, rotor, cap), plus I cleaned with electrical contact cleaner (CRC from parts store) all the electrical

connections and applied dielectrical grease (but NOT on the 02 sensor connections). Also, check for proper
grounds, especially on the fuel rail, and check the large-amp fuses on the + battery terminal. Sometimes
these fuses can become burned, but still not blow. Next, I checked the various sensors. The first one was the

engine coolant temperature sensor (ECT), which is next to the knock sensor under the intake manifold. You
can suspend it in a bath of water and check the resistance to see if it is in spec. However, make sure you get

the chart that's correct for your car. I believe the one in Bentley is for the earlier, blue-headed ECT. Mine
turned out to be out of spec, but this didn't solve the problem. I also checked the throttle switch as per the
Bentley procedure and adjusted it, just to be sure. A lot of folks recommend cleaning the IAC and I did this
(even swapped in a new one), but that didn't help me. If you suspect a bad one, there's a neat trick that was
posted here to test it by swapping a gate valve and adjusting it for a constant idle. I next checked the fuel
delivery system by checking the running and residual fuel pressure as per the Bentley procedure. I also
removed the injectors and cleaned them using the Ponte method of using a battery charger, backup light
bulb, and compressor, but be careful this is dangerous. I cleaned the throttle body and used a new gasket
(also a good time to check the operation of the throttle switch). Lastly, as everything checked out I swapped
in a rebuilt AMM and cured the problem. From what I've read, these usually fail in a no-start mode, but mine
must've been the exception. When I think back on it, my problem was intermittant, so maybe this was a give
away. My 93 still has a slightly rough idle when warming up, but having a working thermostatically controlled
flapper valve seems to help (I differ on this with most others). Pls post how you eventually find your cure.

Check the IAC.... I'm fixing to drop a NEW AMM in from FCP Groton $310, from what I read rebuilt aren't reliable....FWIW
--
Breadman '83 244GL 220K

Hi Steve,

I once replaced my AMM with one from a yard. It lasted very shortly and then died again. If I'd do it again, I'd just buy a new one. But I didn't do extensive testing on it either. I pulled the old at the yard, installed it onsite, and decided it worked. Not very intellegent of me! So take note: I'm as far from being a mechanically inclined as perhaps possible.

Well it does sound like an AMM gone bad, I recently went through a very similar problem with on of my 86 245's and after a lot of head scratching and knuckle busting discovered that the dime store cap and rotor I had bought only lasted about a month (but hey i saved 5 bucks)replaced them again with higher quality parts and all seems well. 2 weeks now and not so much as a miss. If you decide to replace the amm i'd at least consider a used one unless you are 100% sure yours is bad.I picked up one at a local yard for $10 bucks and there is almost always a couple on ebay. the haynes manual has a description for checking them as well but i still can't figure out what they are talking about.
Good luck hope this helps
Bret
--
rust free in west Texas

It sounds like the AMM . There are some resistance and voltage tests in the Bosch , Bentley and Volvo Problem Solver manuals ( none of which I have ) Maybe somesone will post them here . BTW - A couple of years ago I bought a rebuilt 007 AMM for about $ 175.00 from one of the big chain supermarket type auto parts stores with a "Limited Lifetime" warranty which held up fine for the remaining 2 years I own the car .

If the car starts and runs with the AMM disconnected but not with it connected, the AMM is likely shot. (Don't plug or unplug the AMM with the engine running) At least that was the symptom on my '88 when its AMM quit. It just wouldn't run after sitting for a weekend. Fortunately I could swap in the AMM from my '86 and then the car ran fine. I bought a new Bosch AMM rather than a rebuilt since I've read so many negative comments on rebuilt AMM's. Actually, I don't think there is much repair possible to the AMM except maybe for the platinum wires since th electronics is potted. I got my AMM on the internet, might have been The Parts Bin but I forget now. Anyway the car runs fine now.