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My 84 245 (B23F motor) has been very hard to start early in the morning. Cranks for a long time before turning over, and then runs rough for several miles.
On days when I don't start it until afternoon (it's been sunny and warm here every afternoon), it starts right up and runs perfectly.
Any ideas as to what's wrong? AMM is my first thought, but how could I test it?
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>AMM is my first thought, but how could I test it?
Easiest way to gauge the AMM's contribution to no starts is to try starting with the AMM unplugged. Don't plug or unplug with ignition on. If it starts, cold, without the AMM connected, and idles much better than with, consider replacing the AMM.
I like the other replies too, such as the morning condensation and sticky IAC.
--
Art Benstein near Baltimore
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I had this same problem with an 88 240. Every morning it would crank and crank before starting. In the afternoon it fired up immediately.
I checked the fuel system over and over and could not find any problem. Then I replaced the plug wires and distributor. Bingo, the car started first crank.
I can only assume there was a small amount of moisture/condensation and it somehow disrupted/weakened the spark.
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Thanks for recommending this - it's the simplest, so I figured I'd try it before investigating the suggestions in other posts.
I've had brand new Bosch cap, rotor, and plugs sitting here in a box waiting for me to get around to installing them. Old ones had 26k+ miles on them. Put the new stuff in today, and am glad I did. Old cap was beat up inside. Plugs looked lousy. Rotor looked...tired.
Motor is running nice now, but don't know if this has fixed my cold start problem. Pretty serious cold front is supposed to come through tonight, I think --- I'm looking forward to trying to start the car up tomorrow morning. But even it starts hard, I'm still glad I replaced this other stuff. It was way overdue.
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posted by
someone claiming to be JimL
on
Wed Sep 29 03:12 CST 2004 [ RELATED]
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Does yours have an Idle Air Control valve - silver cylinder thingie located below the intake manifold? Sounds like it is either inoperable or the coolant temperature sensor that signals the computer to open the IAC is faulty.
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posted by
someone claiming to be Mike
on
Tue Sep 28 20:56 CST 2004 [ RELATED]
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I would first check the cold start injector and thermo-time switch. Remove the injector, aim it toward a glass container, crank the engine, and check for the presence of a spray pattern for 5-12 seconds. If it doesn't spray, check the wiring and the thermo-time switch, located on the cylinder head behind intake manifold #4. When I had my head gasket replaced, my Volvo had trouble with cold starts in the AM. I did the above and found that the thermo-time switch wasn't connected!
A previous posting today discussed testing the resistance of sensors in hot water. You may want to try that or just check voltage output to the cold start injector.
Next, look at your control pressure regulator, if your car has one. I had a cold start problem for a year until I changed my control pressure regulator. it has started fine ever since.
Finally, this is not very likely, but check your battery's charge. Presumably, where you live is cold and you're starting the car early in the AM.
I doubt your AMM is faulty. Bentley's manual describes how to check the AMM with a volt meter.
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Bentley's is the bible for Volvo's. However, you can check out an AMM and everything will look good, but performance is still bad. I work as an an engineer and was fortunate to speak with a Bosch engineer several years ago. I too have an '84 Brick. What Bentley's and everything doesn't tell you is there is active circuitry inside the AMM. Everything can look good by both voltage and resistance checks, but your car still runs like -you know what. You can repair all possible sources of air lear leaks without success. The reason is AMM has active circuitry which isn't accessable. I didn't believe it when the Bosch man said to replace the AMM, but I did. For the last 5 years, my car runs just as good as it did 20 years ago when I picked it up from the factory in Gothenberg. Good luck.
Oh, also be sure the idle motor isn't gummed up. It's not really a motor, but it is a prime suspect.
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Bentley's is the bible for Volvo's. However, you can check out an AMM and everything will look good, but performance is still bad. I work as an an engineer and was fortunate to speak with a Bosch engineer several years ago. I too have an '84 Brick. What Bentley's and everything doesn't tell you is there is active circuitry inside the AMM. Everything can look good by both voltage and resistance checks, but your car still runs like -you know what. You can repair all possible sources of air lear leaks without success. The reason is AMM has active circuitry which isn't accessable. I didn't believe it when the Bosch man said to replace the AMM, but I did. For the last 5 years, my car runs just as good as it did 20 years ago when I picked it up from the factory in Gothenberg. Good luck.
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What you write is so true. The AMM checks provided by Volvo's tech manual writer and passed along through Bentley and Haynes are unfortunately inconclusive, almost useless. The reason the circuitry on the AMM can't be reached is the bulk of it lies on a ceramic substrate surface mount hybrid.
Interesting to me, was finding the -002 (metal version used in LH2.0 83-84) has one important circuit element accessible off the hybrid-- its offset adjustment. All of the -002 failures I've examined fell below the minimum (enriching) output needed to fall into the range compensated by the mixture pot. Same with the few -007 models I've examined. But for a technician, the -002, with its offset reachable on the thru-hole circuit board, is salvageable, and can be re-biased with an external resistor. I was disappointed to find the -007 and -016 have no such place to work with.
A better characterization of good and bad AMMs could be made by observing the output voltage with the motor not running. This may not qualify the unit over the entire range of fuel needs (gain) but all the failures I've seen are baseline (offset) shifts. They are just too lean to allow the car to idle.
--
Art Benstein near Baltimore
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