Well my check engine light light has been on for a few days. The codes led me to possible AMM problems but my car would start and run fine.Finally today after a few starts and shut downs it would not restart. Remembering something I read here on the board about disconnecting the AMM[car off],I tried it and the car started right up. Drove it home ⎠ miles] no problem.I am waiting for another AMM [used] to come it a few days.Can I drive the car without the AMM in the mean time,need to take the kids to school.Any advice.TIA
Nelson

You're OK, but performance will be minimal. The car runs at a richer setting when in "limp home" mode with no AMM signal.

Since the computer defaults to a 'full-rich' mixture, you're dumping in a lot more gas than is needed to keep the engine running. This can cause carbon deposits to build up in the cylinders and also in the cat. If too much carbon accumulates in the cylinders, it can lead to a detonation problem where the superheated carbon detonates the gas/fuel mixture before the spark plug fires.

Carbon buildup in the cat is not good. It restricts exhaust flow and if there's too much unburned fuel passing through it, you can actually melt the ceramic core. If the core melts, then you'll have a big obstruction and your only option will be to replace the cat.

If you can use/borrow another car while waiting for your AMM to arrive, by all means do it. I wouldn't drive more than a couple miles with the AMM disconnected, just long enough to get it home and only if I'm less than 10 miles away.

FYI, in a box in my wagon, I keep the following items:
1. Spare Main Relay.
2. Spare AMM.
3. Spare Fuel Pressure Regulator.
4. Spare Timing belt.
5. A couple of open end wrenches and screwdrivers.

So far in the last year, I've used 2 Main Relays, 1 AMM, and 1 Fuel Pressure Regulator (all were replaced on the road with used parts, typical 'down' time was 30 seconds to 5 minutes). By planning ahead and spending $50 at the pick-n-pull parts yard, I've been able to keep my car on the road during several otherwise debilitating situations. I'm an Eagle Scout and I like to be prepared for just about any reasonable situation. Most people probably don't need to carry a Timing Belt with them, but I keep one with me in case it should fail while I'm driving through a mountain chain and there's no place to get one for +100 miles.

God bless,
Fitz Fitzgerald.
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'87 Blue 245, NA 225K

Yea but Fitz how can you change a timing belt on a mountain road ,in the dark,with "a couple open ended wrenches and screwdrivers"?
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philvo

Well Phil, using the bubble gum, coat hanger, swiss army knife, and duct tape in my glove box, -and since my middle name is Macgyver...

Seriously, I keep a timing belt & tensioner with me so as to prevent being stuck in the middle of nowhere at a mechanics garage for ## days while he orders the part via slow boat from Brazil. Since it's not practical to bring every tool that I own on every trip, I only bring the ones that are most likely to help me in the most common Volvo breakdowns (Relay, AMM, FPR, T-Belt & Tensioner). If the timing belt does snap, you can be back on the road in a few hours once you locate a mechanic with the tools. (either borrow the tools or pay to have the work done) On any long trip, I'll typically bring a full set of sockets and some misc nuts and bolts too.

At somepoint when I head out to Glacier National Park, I might bring the necessary tools with me for a timing belt change, but we'll cross that road when we get there. For now, the big parts have to stay home. -like the spare Flux Capacitor and Hyperdrives. If something major breaks, I'll have to be content to use the sub-light engine (B230F).

God bless, and watch for overhead wires when landing on a highway.
Fitz Fitzgerald.
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'87 Blue 245, NA 225K

About four years ago my wife and two kids were returning from Seattle to our home in Vancouver Washington. The timing belt on my wife's 1986 745T snapped. It had only 45,xxx miles on it. My wife called me from her cell phone and told me the car had broken down. I drove to the Gee Creek rest area and picked them up. It took less than a minute to diagnose the broken timing belt. We drove home (about 45 minute trip), and I got my tools, spare timing belt, PVC rain gear (yes, it was winter), a Coleman lantern, and a flashlight.

Sue and the kids held the lantern and flashlight while I worked in the winter rain. I changed the timing belt in one hour and ten minutes from start work to running engine. I have never done the job that fast in my garage. I was motivated to work fast under the miserable conditions.
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john

My problem is I do not have access to another car.My everyday commute with the kids in tow is about 25 miles round trip.I should have the AMM by friday,I hope.I am not driving too hard [ for obvious reasons] but still need to take the car out everyday.Thanks
Nelson

You won't hurt the car at all, but it won't run well.

I carry a spare used AMM in each car, along with a spare distributor I haven't had to use an AMM on the road yet, but it is nice to be prepared. Used AMM prices run all over. I have bought our spares when I didn't need them, and have not paid over $20 for one. AMMs are worth much more when you are desparate.
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john