So I don't know whats going on anymore. 65' Valiant with 225 Slant 6 ran great three days ago with points in it, would take half a crank to fire up. Now I got a 5 pin blue box ECU (By HiRev7500) with accompanied two wire distributor. Installed it, and I have an impossible time firing it up when its cold out, once its warm it will fire in a few cranks. Now, the accelerator pump squirts fuel great and the choke closes to about 1/8". Spark plugs are brand new NGK ZFR5N gapped at .045" with metal gasket removed. Coil is the original, but has 1.6 Ω across it so doesn't seem bad. Plug wires are 7mm and only a few months old. I pulled the cap and rotor outta the working points distributor and put it on the new one. With the cap removed I can grab the vacuum advance tube (Carb end) and suck on it and watch the advance plate move in the distributor, then release pressure and watch it snap back. I'm getting 12.39 Volts (Same as battery) at the "hot" side of the ballast resistor, and about 9 Volts on the other end. I've checked continuity through the whole wire harness and getting continuity through everything. I checked the the ECU was grounded right and double checked that I was getting continuity through pin#5 to ground (I was). When the car was running with new system, I set timing to 8 degrees BTDC with vacuum advance tube plugged on distributor end. I also rechecked the valve lash when the motor got warm with the new system (.022 Exhaust & .012 Intake). The slant has good compression and a nice, new, fast starter motor. Now I can not get the thing to fire up when it gets cold. I spent 20 minutes spinning it and it only caught for just a second. Yes I know, I should have done the GM HEI instead of this probably Chinese crap, but still. Any ideas cause I'm near the end of my rope with this?
Cant start when cold after installing Electronic Ignition
- Thread starter Travis G.
- Start date
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TrailBeast
AKA Mopars4us on Youtube
First check the gap to be about .008 on the distributor pickup coil and see if that fixes it.
Then check your cranking voltage to the coil positive. (cranking voltage not just ignition being on)
You know about the two ignition circuits?
Ign1 and ign2
I didn't see any mention that you put the four pin ballast resistor in for the five pin module. One side is for the coil and the other side is for the control module.
DustyEd
Well-Known Member
I thought the Hi-Rev 7500 ECUs were 4 pin ( the green*red tracer wire is not used) which use the 2 pin ballast? But like Garret said, if it is 5 pin, it needs the 4 pin ballast resistor.
If it ran great before and all you changed were electrical items, I tend to think the problem lies there. Are the new spark plugs in the same range as the old ones?
If it ran great before and all you changed were electrical items, I tend to think the problem lies there. Are the new spark plugs in the same range as the old ones?
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scott657
Well-Known Member
I have the Jegs 7500 4pin the fifth wire (green with red tracer I believe ) is not used. came with single ballast resistor 1 OHM
First, if it ran great, why mess with it? Points ignition runs every bit as good as electronic as long as everything is in good working order.
That said, cold start problems when not fuel related usually are related to ignition timing being retarded or spark plugs that are bad. I would also check the ECU plug issue as already described.
That said, cold start problems when not fuel related usually are related to ignition timing being retarded or spark plugs that are bad. I would also check the ECU plug issue as already described.
DustyEd
Well-Known Member
Do you know what the ignition advance was before changing the distributor? If you do, try to match it. You may want to recheck carb air/fuel ratio if you have changed the original timing.
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Sounds like it doesn't have spark when cranking. But it has 12v to the ballast and 8 out. It is either wired wrong or the box is bad. I just has a car doing it . When warm it would fire when leaving off the key. The box was bad.
dano
Evil Handy Man
Define cold? I've had issues below Zero but not in then 40*F and up. If you put a battery booster on does it start easier when cold?
67Dart273
Well-Known Member
THAT IS NOT a 5 pin box for starters
Check the following while cranking USING THE KEY. you MUST run these tests USING THE KEY.
Clip a meter on the coil plus. Double check coil voltage in "run" Should be about 6--10 or so. Now crank the engine, read the meter, should read "same as battery" and above 10.5V or higher. Run same test with meter clipped to battery, the two readings should be very close to each other
Now "rig" a test spark gap using a SOLID coil wire. You can even use low voltage wire, just keep it "clear" of objects. Use a plug, a test gap, or hold a screwdriver with a test clip. AGAIN use the KEY to crank. Spark should be even and rhythmic, and at least 3/8" more typically 1/2" or more, nice hot snappy spark.
ROTOR PHASE. There are occasional cases where the pickup/ reluctor polarity gets reversed, and this moves the spark timing rotor--to cap--contact relationship. Does the engine run smoothly at all RPM and start good when warm? In other words does it run OK? if not check out pickup polarity and rotor phase. Google it
You likely have, but check coil wire and plug wires are OK and that cap/ rotor is in good shape. Clean, dry, check rotor for spark "punch through"
You can not assume a coil is good by resistance readings. There are several things that go wrong with coils that simply cannot be easily tested, with basic instruments. If there is ANY doubt, and or your tests (above) showed suspicious results, replace the coil
If you have a good hot (cranking) spark, if it's in time, if the plugs are in good shape and it has compression, then it's not an ignition problem
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67Dart273
Well-Known Member
Found this on the Jeg's site which tells me this is a 4 pin box.........
- Plugs into all Mopar OEM, JEGS, and Mopar Performance wiring harnesses, whether the harness or vehicle was designed for 4 or 5-pin Ignition Control Units. No modifications required.
- Use with ballast resister. Works with 2-Pin or 4-Pin ballast resistors. Use without ballast resistor will destroy the Ignition Control Unit.
- Use with OEM or OEM-Spec (oil filled) ignition coil. E-Frame coils are also acceptable. High Performance Coil 555-40105 is also recommended. Coils made for C-D ignitions (MSD, etc) may destroy the Ignition Control Unit. Coil Primary resistance should be no lower than 1.4O
- Pre-startup test (recommended for vehicles that has experienced Ignition Control Failure). Connect a voltmeter between the coil positive (+) and a good ground. Turn ignition key to "run" position. Voltmeter should read between 7.0 and 9.0 volts. If higher turn ignition key off immediately and check ballast resister (resistance - too low 0.5O minimum, 1.0O recommended for most street applications), ballast wiring, shorted coil, ignition switch wiring, etc.
I have seen ecu's get funky when cold and when they get a bit warmer they are fine. Hit the ecu with a hair dryer for a minute and see if it fires up if so......
pishta
I know I'm right....
Id get back into distributor and double check .008 gap with brass feeler cold. Maybe you got "pool shrinkage" somewhere. Disregard any later videos on that link...
Far out guys, thank you for all the info! Yes you right, 5 pin ECU, 4th pin (Green wire with red tracer) is unused. So I also have just a 2 pin ballast resistor. I will start double checking thing when I get home, this stupid virus has me running around the state right now. I think I have a spare/new Accel SuperStock Coil Part# 8140 laying around the house somewhere I can also test with and possibly a spare set of plug wires. When I say cold, I mean about 60*F, so not that cold. I will also double check the airgap is still at .008", never thought about the brass gauge experiencing "shrinkage". I will also try hitting the ECU with a blow dryer and see if that does anything. That interesting what Oldmanmopar said, because it did seem to fire as I was releasing the key from the start to run position. But like I said, when I get home I will run tests and update you guys, thanks again!
Make sure the box has a really good ground to the body. Scrape some paint or use a star washer with some bite.
Ok so this dang virus put the ol' Valiant on hold for a while. But finally home and having time to work on it again. Here is where I am now. After using a spark tester and my phone camera to see results. The problem was that it wouldn't have any spark while cranking, but once the key was released out of start position I would get some spark. I went out and got a new ecu box and when I installed it I make sure there was definitely a very strong ground going to it. I also replaced wires with 8mm and coil with known working Accel Super Stock. Used cap and rotor out of the point system that work just fine. Double checked air gap at .008 (no "pool shrinkage"). I still have the same problem. No spark while cranking and spark on the key release. I did get it fired up once on the key release and it idled and reved up just fine (Should be noted that with point system it would idle at 700 rpm and now with electronic ign it idle at 1000 rpm with o carb adjustment, so i'm getting more bang for my buck). I put a voltmeter on + of coil and got 8.3 volt while key is in run position and 9.4 volt while cranking. Then put voltmeter on battery and got 10.9 volt while cranking, so I have a 1.5 volt drop. Doesn't seem like that much but could be my problem. The only things I could think of at this point are a bad 1 ohm ballast resistor or poor battery ground cable. Going to get a new battery cable this evening. If anyone else has anymore suggestion or comments feel free to leave me something.
67Dart273
Well-Known Member
Don't get all excited about "5 pin". I doubt VERY much anyone is going to find a new 5 pin module. The fact that a box has 5 physical pins does not make it a 5 pin
67Dart273
Well-Known Member
Simple, you made a simple wiring mistake. There are two ignition power sources that appear under th ehood, IGN1 and IGN2. IGN1 is "run" and is hot ONLY in run, it goes dead in "start." This wire is often dark blue but not every year
The second is IGN2, usually brown, and is ONLY hot during "start" It's job origininally was to bypass the coil resistor in start, and provide nice hot full battery voltage to the coil+ during "start." That wire is likely not connected
If you don't have a manual, go to MYMopar and download a free service manual, as well as one of the aftermarket wiring diagrams, which are less detailed, but sometimes easier to follow.
67Dart273
Well-Known Member
WHAT GOES in and out of the ignition switch in a Mopar:
1...BIG RED, unfused power into switch
2...BIG BLACK, unfused ACC switched power to the fuse panel. "Hot" in "run" and "accessory"
3...IGN1, usually dark blue......"Ignition run" hot ONLY in run, powers ignition, alternator field and regulator, electric choke if used, and a couple of smog doo dads some years
4...IGN2, usually brown, hot ONLY in "start" feeds to coil+ side of ignition resistor. IF YOU DO NOT have an ignition resistor, it must be jumpered to IGN1 such as MSD or HEI
5..."Start" almost always yellow, feeds to starter relay to operate starter
1...BIG RED, unfused power into switch
2...BIG BLACK, unfused ACC switched power to the fuse panel. "Hot" in "run" and "accessory"
3...IGN1, usually dark blue......"Ignition run" hot ONLY in run, powers ignition, alternator field and regulator, electric choke if used, and a couple of smog doo dads some years
4...IGN2, usually brown, hot ONLY in "start" feeds to coil+ side of ignition resistor. IF YOU DO NOT have an ignition resistor, it must be jumpered to IGN1 such as MSD or HEI
5..."Start" almost always yellow, feeds to starter relay to operate starter
To everything 67Dart273 just shared.Thanks for all the info 67Dart273, but like I stated on a previous post, I misspoke when I said I had a 5 pin. Yes it physically has 5 pins, but for this unit only 4 pins are used and only requires a 2 pin ballast resistor.
67Dart273
Well-Known Member
^^And on that note, to make this a bit simpler "I HOPE" the coil and resistor wiring is UNCHANGED between breaker points and Mopar electronic. Example, "if it dies" you can unplug the box, stab a breaker point distro in there and hook the dist. wire to the coil neg and go down the road.
When cranking the engine, current flows to the coil without going through the ballast resistor.
So the voltage difference from 10.9 to 9.4 is either in the wiring or the ground.
ECU should be wired like this, except 63 won't have a fusible link and some other minor differneces. During start, power to the coil goes through the Ignition 2 wire.
Power to the ECU does the same, but then goes through the 1/2 ohm resistor.
Power for ECU is the wire at the top of the pentagon. Source from the ignition-run circuit. Use a piggy back terminal for a neat and good connection. I assume that's what you did but just checking.
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If the vacuum advance on the distributor was plugged, but the hose was open, then the engine was probably running at higher rpm.
The initial timing must be set at the specified rpm.
If its too far off, then it can makes starting more difficult.
So there's another possibility. Hard to know if its what happened but figured I'd mention it.
I usually remove the vacuum advance hose at the distributor and stick a golf tee in it.
With the slant, might be slightly easier to pull the hose at the carburetor and put a cap on the carburetor port. Either way will work.
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