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hi sages- think i have solved my rough running and misfire especially when cold or damp. replaced dist.cap and rotor with echlin napa parts. looked to be good quality. couldnt find bosch which is what were on the 92 240. old parts seemed very old . terminals inside and on rotor were worn , burned and somewhat corroded. motor instantly ran better and miss was gone. car has 221k. in using the old rope and weight trick to remove the stuck rotor, i pulled the ears off it. had to tap off the remainder with a cold chisel . put permatex anti seize lube on the shaft so next time rotor isnt stuck. in examining the fragments of the old rotor i noticed there was a coil of wire buried inside the top of the rotor between the end and center terminals. it was covered with a black plastigoop. never saw that in a rotor before. figure it must be a resistor which gives a step up to the voltage or current given to the plug, like a capacitive discharge function. not sure why that would be needed since the bougicord plug wires are resistance wire and should do the same thing. am i right. also- when i got the rotor off, i slid off the plastic cover on the lower distributor, expecting to see a reluctor and magetic pulse swiching unit, but there was nothing but an empty tub. is the coil charged and discharged directly through the ecu by a different kind of switching? thought volvo used a system similar to ford and chrysler. thanks tons for the education. oldduke
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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You're not up-to-date with your '92. Ever since about '89 or '90, the ECU gets it's signal about crankshaft position from a crankshaft position sensor that sits on top of the bell housing and monitors the flywheel.
There's nothing left in the distributor, no weights or springs or diaphragms to adjust timing versus rpm or engine manifold pressure. The ECU does all that according to a algorhythm stored in its memory.
The only thing the distributor does is "distributes" the spark energy to the spark plugs -- i.e., the rotor and cap are the only working parts left inside.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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The ignition is triggered by the crankshaft position sensor above the flywheel. I believe the 240 from '89 and on had this.
--
1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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so budcold if i understand you correctly- the crankshaft position sensor triggers the coil(turns the coil on and off) and replaces the function of the old ignition points which was replaced by the ford/chrysler reluctor and magnetic pulse in the distributor. any thoughts on that little wire coil in the rotor? thanks oldduke
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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You're on the right track, but it's a little more involved. Still basically a 3-step process to get running, as spelled out below.
Not sure about the rotor resistor or whatever.
Art Benstein would know.
Start-Run Sequence Bosch LH2.4 FI and Bosch EZK 116 Ignition
1) During starter cranking, the Crank Position Sensor sends timing pulses to Ignition Control Unit (ICU).
2-a) The ICU uses these CPS pulses to trigger the Power Stage (aka Ignition Amplifier), which initiates spark from the coil. [like the old points used to do]
2-b) At the same time, The ICU also propagates the pulses to the FI ECU, to allow FI operation (no ICU pulses means no fuel operation).
3-a) The Fuel Injection (System)* relay (previously energized at Key On) powers the AMM, IAC, ECU, Injectors, and Fuel (pump) relay coil + side.
* The System relay is in the white case with the Fuel relay.
* NOTE that on 700/900 cars with the square pump relay, the RSRelay becomes the "System" relay as described above.
3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel relay by grounding the relay coil (– side) to run the fuel pumps.
When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.
Determining whether or not there is spark at the plugs (2a) — and whether or not the plugs are getting gas (3b) — makes a good no-start "starting" point.
• On the '85-'93 240, jumpering the LEFT side contacts of fuses 4 and 6 will bypass both the 25A blade fuse (or fuse #6 on '91-'93) and Fuel relay — and will power up both pumps immediately.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Can the CPS system be replaced with the older ignition system?
--
1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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The resistor is for radio interference suppression. By memory, it is 1000 ohms. I replaced one on a stranded 83 244 to get it running. The resistor was open, and I guess the ignition system wasn't strong enough to jump the gap. Lucky for me the stranded daughter was visiting her friend, a 5-minute walk from home. Found the problem using an ohmmeter.
--
Art Benstein near Baltimore
"I am" is reportedly the shortest sentence in the English language. Could it be that "I do" is the longest sentence?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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If I'm not mistaken, IPD was selling a special rotor without internal resistance for those who wanted more spark energy. I'm not sure what application there was (there are different rotor sizes, and not sure what size their special rotor came in).
[I hope I'm right. I'm in the process of packing up/boxing most things in my house for an eventual move, and I've boxed my old catalogs. If I'm wrong, my apologies.]
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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thats interesting art- radio suppression(static)- thought modern cars generally used resistor wire and/or a condenser wired to one of the side terminals on the coil to do that. would its use on the rotor also up the current to the plugs? thanks oldduke ps- are you still fooling with maytag A108s?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Modern cars? You can't hardly identify the coil in modern cars. More like coils plural. But tripping further back in time, to the days of Marconi, you'd find the physics that led to the first radio transmissions. The spark "rung" a piece of solid wire, like a bell.
If the wire was a good conductor, especially on its outer surface, it worked better, or rang louder. If it was a poor conductor (a resistor) it didn't. So the ideal radio suppression (suppressing the tendency for the secondary ignition to become a radio transmitter) is to make the entire circuit from stuff that is very resistant to high frequency AC -- eliminating as much of the "good conductor" as possible: resistor plugs, resistor wires, and a resistor rotor.
If you apply Ohm's law to the current that creates the arc, you'll see that these resistances are minute with respect to the voltages needed to ignite fuel/air mixtures, but solid wires and non-resistor ignition components sell on that basis more than their real advantage -- less to go wrong.
Speaking of less to go wrong... the old Maytag (singular), no, I'm not still fooling around with it. That's the beauty of the beast -- it needs no fooling around. Just using it. Same with the Volvos. Just driving them.
--
Art Benstein near Baltimore
We childproofed our homes, but they are still getting in.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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hi art- thanks for your knowledge and insight. surprised you havent tinkered lately with the A108. only 3 bullet proof designs left- the 240, A108 and the slant six car if you can find one. only have one worry on the A108 which has been running since new in may 77. mechanic told me only thing that will kill it dead is if the transmission goes. said no parts or rebuilds available. what do you think. will it soon be curtains for my 108? thanks tons oldduke
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