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| 5 wire ecm https://slantsix.org/forum/viewtopic.php?t=56109 |
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| Author: | dano126 [ Wed Sep 03, 2014 6:58 am ] |
| Post subject: | 5 wire ecm |
having trouble starting my new 225 1976 slant six in my 1952 dodge panel. Every thing is hooked up. The engine cranks but doesn't turn over. Checked gas. I replaced the four plug ballast resistor. "The blackyellow wire which goes to the negative post on the coil for sum reason is hot (10.0 volts) when I hook it to the coil, the voltage drops at the coil from 10.0 to 4.50. So basically I'm not getting spark from the coil to the distributor. |
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| Author: | nm9stheham [ Thu Sep 04, 2014 11:29 am ] |
| Post subject: | |
I assume when you say 'hot' you mean 'has voltage' rather than thermally hot? Has the engine just been rebuilt? Let's assume that everything was timed right for now.... Clean up the grounds thoroughly under the ECM and make sure there are good clean bolts and start washers to lock them to the chassis. Check the reluctor gap in the distributor for the right gap; I believe that is .008". Check the 2 lead distributor connector for being clean and having good contacts, and also check the connector to the ECM for the same; the round sockets in the ECM connector in particular can get spread open and lose contact. To see if you have any spark fromt he coil while cranking, put a screwdriver disconnect the high voltage spark wire from the distributor cap and position it so that it is about 1/4" from the engine block or bare part of the valve cover. The spark when cranking should jump at least 1/4" in open air with a strong, blue spark. Measure the voltage at the + terminal of the coil when the key is in RUN, and then measure it again at the coil + when cranking and let us know what you see. Then put your voltmeter on the coil - while cranking and see if it varies up and down raipdly. Put the voltmeter on a higher voltage scale as there can be a strong 'kick-up' in the voltage at the coil - if it is being triggered by the ECM. And avoid doding a lot of cranking if the cam is new....it needs oil ASAP. |
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| Author: | dano126 [ Thu Sep 04, 2014 3:47 pm ] |
| Post subject: | |
Thanks. I now have a new 4 wire ecm. The neg coil wire is now reading 1 volt. Which is better?. Is it normal for the coil to read 12 volts with neg wire disconnected and 4.50 connected ? Key is on " run ". Im not giving up. Ill post some pics. |
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| Author: | WagonsRcool [ Sun Sep 07, 2014 4:32 pm ] |
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Quote: Is it normal for the coil to read 12 volts with neg wire disconnected
Yes, you're reading system voltage on an open circuit, which only tells you that you have some continuity thru the ballast & the coil. About 1V is normal at the coil (-) with the key ON , engine OFF & everything connected. 4.5V shows that there was something wrong- bad connection at the ignition module ("ecu") or module mount/ ground point- or the module was bad. See my new post on Chrysler EI. |
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| Author: | dano126 [ Mon Sep 08, 2014 2:52 pm ] |
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Thanks fpr the help. No success yet. So I have scraped and cleaned grounding points (engine block, ecm mounting points), I have check the gap, and I am not getting a spark jump from coil wire to valve cover when I crank the engine. Voltage readings at coil wire going to distributor are : 20.50 with key on, and 150 to 50 to stopping at around 16 while cranking engine. Ive tried starter fluid, there is gas squirting in the carb. Could the distributor be 180 degress off ? The engine came at TDC from the engine builder, so he said. We stabbed the dist. right away before connecting the trans. Running out of options ? Rewire ? |
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| Author: | dano126 [ Mon Sep 08, 2014 6:01 pm ] |
| Post subject: | |
Im tracing spark with a screwdriver. No spark at spark plug. Getting spark at the coil wire(orangey/red color). So I guess Ill check the gap again. |
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| Author: | WagonsRcool [ Mon Sep 08, 2014 8:30 pm ] |
| Post subject: | |
Quote: Voltage readings at coil wire going to distributor are : 20.50 with key on, and 150 to 50 to stopping at around 16
Ehh?? What wire are you checking? The only "wire" I can think of going from the coil to the distributor is the high voltage lead?? If you used your DVOM to check that you may have damaged the meterYou should get a spark tester like Thexton # 458 (about $25- amazon)- it has an adjustable gap that lets you quantify how strong or weak your coil output is. You connect it to a plug wire or coil output lead, attach the ground clip to something metal on the engine, & set the gap. Your coil should fire across a minimum 3/8"(up to 1/2") gap while cranking. If it's very weak, one of the first things I'd check is whether your wires are connected correctly to the coil. The wire from the ballast resistor (brown) must go to the + terminal, while the "ecu" wire (black yellow) goes to the - terminal. |
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