I apologize if I'm not posting according to all of the rules. I'm new to this forum (joined today) and am desperate to fix my car. I have almost $1500 in parts in it and it's still acting up.

I have a 1986 4-speed manual with overdrive 740 GLE. I've used the Volvo Maintenance FAQ for the past couple months trying to diagnose the problem. I recently spent $100 on an inspection at the volvo dealership. Head mechanic with 24 years experience couldn't figure out the problem.

I've replaced the MAF sensor, ignition coil, both fuel pumps and filters, ECT sensor, spark plug wires, spark plugs, rebuilt the distributor and replaced the crank pickup, fuel pump relay, ignition control module, and cleaned the grounds on the intake manifold and battery harness to frame... maybe some other things I'm forgetting. I've ordered a new ECU and o2 sensor, so I will see how those work this weekend.
The mechanic said the fuel pressure is fine and the fuel pressure regulator is in good condition. IACV works -- if you unplug it the engine rpms change a lot.

The symptoms have changed since I replaced the MAF. Before, they were intermittent, or only when the car had warmed up and been driven for 20 or 30 minutes at operating temp. Now, the car dies if I take it past 2k or so rpm and let it drop to idle. Every time I push the clutch while rolling in a gear, even as low as idle rpms, it dies. On a cold start, it will idle fine for a few seconds, then rev up a little and fluctuate then die. Normal operating temp idle is very rich and smells like gasoline and has a misfire. Any throttle or letting off the throttle causes the car to jolt like it's going to or from 0 fuel or air.

A couple days ago the radio fuse blew and the door bell for the key in ignition started ringing while driving down the road. I replaced the radio fuse and the ringing went away. The ringing came back today and the fuse blew.

Are these problems associated with the harness shorting in a few places or is it something else? Any help would be greatly appreciated. I'd like to keep the car and get it functioning as it only has 137k original miles, but I need a reliable car.

So I replaced the engine harness, computer, and cleaned injectors. One was pretty fouled up and having trouble spraying, but they're all good now.
Car acts a lot better now, but it still has trouble on a cold start. It will idle up to like 1800 or 2000 then go down to 800 or 1000 and idle a little rough, then go up again then die. I have to hold the throttle to keep it alive until it's warmed up. Once it's warmed up, it idles at 900-1000. I've tried adjusting the fine adjustment knob but it doesn't seem to have much of an effect on the idle. I checked for vacuum leaks but can't find any.

If I feather the throttle on a flat patch of road and just barely keep car maintaining speed, it sometimes jerks or rocks back and forth indefinitely like I'm pushing and letting off gas abruptly.
When I'm rolling to a stop and push the clutch, it drops to 100-300 RPM and nearly dies.

Any idea what this could be? I'm wondering if the TPS is bad. It drives great otherwise.

You need to read through the FAQs on how to adjust the idle. Turning the knob without everything done properly won't do you any good.

http://www.brickboard.com/FAQ/700-900/EnginePerformanceSymptoms.htm#PoorPerformanceIdleSurgeandHuntDirtyThrottleBody
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I think disintegrated harness is a likely cause. With low miles like it has, I wouldn't think harness issues, but 1987 is last year of Volvo's easy to degrade wiring material.

Tell us more about the MAF/AMM. These cars are picky about them, and someone on Turbobricks received an AMM from the Volvo dealer, a genuine part, that was a China design (and made) and did not work properly; there are some ebay versions that don't work well either, I speak from personal experience. So new MAF could be causing problems too.

I feel your pain about elusive problems. I'm trying to find out why I'm consistently losing 2-3 mpg in City and Highway without success. I've replaced many many parts. It may also be my harness as I have a 1986 Turbo automatic.
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The original Bosch maf that came with the car seemed to work well enough but when the car got hot it would start to buck and jerk violently and die every time I'd push the clutch and let it drop to idle. If I unplugged it, the idle would smooth out and run perfect until I pushed the throttle. Idling with the OEM maf was very rough and would shake the car. You could tell when it got hot enough because you could smell fuel inside the cabin and the throttle would be a drain on the car until a certain point then jolt forward.

I swapped that out with a remanufactured Bosch maf from auto zone. The symptoms changed and the car no longer bucked. It did start consistently dying no matter what temperature the engine was and the idle was extremely rich and had a misfire.
I tried adjusting the mixture screw buy it didn't seem to have an effect. Thinking I'd messed with the factory settings and would never be able to get it right again, I swapped it with another remanufactured Bosch MAF from autozone.

I bought a MAF from Autozone a few years ago that was made by Cardone. It held up well at that time it was only $117, recently I replaced it with a Python brand remanufacturer.

What kind of spark plugs were installed? Platinum tip plugs don't work well these engines. Standard and iridium tips work well, but much written about platinum giving people problems.

You may be down to testing circuits for ECT, MAF, and O2 sensor. Trying to find bad wiring.
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I'm honestly not sure what kind of spark plugs were installed but I don't think I would've spent much on them. ECU came in yesterday and the harness should be here in the next couple days. I'll see about wrapping the wires in electrical tape or something to add a little more protection in case the new one deteriorates. I'm hoping this will fix all the problems.

I think when it dies there is a short somewhere,,,because vovolos forget to rust away &die,,best to just rerap the the wires,,,seek out all vacuum leaks,,,,most mechanics don't have the time to concentrate on finding the actual source of the problem,,,either they are lazy ,too busy,,or dumb

If you have the bad engine harness, it normally can be seen on top of intake manifold the injector ground wires. The insulation will be crumbling. The "dinging" going down the road is usually telling you your dome light/interior lights are burnt out or shorting. Check all your connectors, the pins both male/female have been know to back out and making poor contact.
Have you cleaned your ICV and throttle body? After cleaning, confirming the throttle position switch, etc. Do you have the large black plastic knob on your throttle? So mechanics masked issues by fooling with it instead of doing the actual adjustments.
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The injector ground wires were exposed all the way into the harness. I wrapped them in electrical tape a while back thinking it would help.

Thank you for explaining the dinging. I was thinking the ignition was going out. While driving today I checked the fuses and the Heater Fan 30 amp fuse was melted into the plasic tray. Fuel prepump and radio fuses were also burnt out. I replaced the prepump and that fixed the main pump whining.

Mechanic cleaned the throttle body when he inspected it. ICV seemed to be functioning fine -- I unplugged it and it changed the idle immediately. I'll try cleaning it when I have time this weekend.
Yes there is a plastic knob on the throttle. I've turned it a few times back and forth to see if it would affect idle but it didn't do much. The car runs so bad at this point I don't think it would help.

I ordered an engine harness a few moments ago.

Yes the harness can cause lots of issues. You could only see the obvious problems. Inside the harness is probably worse. Look in the FAQs about setting the base idle on the 2.2 ignition. The ICV has to be grounded out to set the idle. The throtle position sensor should click the minute you move it off the idle position. All this is covered in the faqs. Take your time replacing the harness.
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