SOLVED -- (Emergency -- Car stuck on side of road, need help please.)

[8v-of-fury]

Driving to work today, the ignition completely went away. The engine died and i coasted to the side of the road.

There was only spark leaving the coil when you'd be on your way off the key. Nearing the off position the engine would kick over almost every time. But only whatever cylinder was near on the rotor.

The ballast is seeing battery voltage, on both sides with the connector off the ECM. And 7v with the ecm connected. Giving the coil 12v on the + didnt make it start. Changing the coil with a new one on the road didnt make it start. All things still left the kickback when coming off the key.

Ballast ohms out right
Dizzy pickup ohms out right
Ecm is getting power on RUN, and should be on crank when i gave the coil + 12v from battery post.

I also gave the distributor a verified ground just in case. The ecm also has a good ground and been given a secondary one. Tried it with a booster pack on it too to verify crank speed and system voltage.

Oddly enough it stalled 3 tmes this morning while cruising, and the first two times i did nothing but regained spark out of the blue..

I am leaving it for a few hours on the road, but need things to check/try for when i go back in 2 hours.

Thanks so much guys.. appreciate it.

 

[8v-of-fury]

Newer electronic conversion, wires, coil, plugs.

Its an 88 with an aftermarket orange box/ proform (summit) distributor.

 

[Joe12459]

It sounds like the ECM is not getting power on crank. Even though you give the coil direct power, the ECM might not be getting power during crank, or the ECM itself might be bad.

 

[8v-of-fury]

Which pin of the ecm connector do i need to check when on START? Can i check with the plug off the ecm, or do i need t splice in to the harness?

I just figured by me giving coil + 12v the circuitry would reverse the 12v to where it needed to be.

Ecm could very well be bad, what test can i use to verify this?

 

[Aspen500]

99% of the time if there's only spark during crank, it's the ECU. The "run" ciruit fails internally.

 

[Joe12459]

Pin #1, the lt. blue wire with the yellow trace should be hot during start and run. In the run position, it gets power directly from the ignition switch. In the start position, the power comes from the coil + and backfeeds through the ballast resistor into pin # 1. try putting power straight to pin 1 and see if it starts.

 

[BudW]

ECM is normally considered to be the Lean Burn/ESC/SCC computer.
ECU is normally considered to be the 4 or 5 pin Electronic Control Unit (sometimes is orange).
I know it’s splitting hairs but when I first read your post, I was thinking Lean Burn.

Attached is diagnostic information from my ’77 FSM – that might help.
Note: this is for the double ballast resistor version. Pay no attention to the “start circuit” portion of ballast resistor – for you don’t have that.

The most likely causes are (in order that I normally see):
Pickup coil
Ballast Resistor
ECU
Wiring harness (short, open, rodent used for food, etc.)
BudW

 

[8v-of-fury]

Aspen500, it would not start at all. It would give an ignition kick on a single cylinder just as you were letting off the key from a tried crank.

Thankyou Joe for your speedy replies! it helped me out in the time of need.

BudW, ECM/ECU both a computer although thats why i made my second post to allieve confusion lolll.

Wanna know what i found? Changed my coil back and rechecked all voltages and what not.. starts up fine. I rush to get it down the road to my work on my lunch. It stalls once on the way but thankfully fired back up...

I get to work, pop the hood and give things a wiggle. ECU connector wiggle killed the engine. Get the lady to turn the key, crank crank cranki wiggle the pug she fires right up.

Its not the connection of plug to ecu, but harness to plug.. i must now find a way to remedy this problem it would seem.

 

[7T8 Custom]

Mopar Performance Electronic Ignition Wire Harness

 

[8v-of-fury]

I am going to be putting a GM HEI module and 12v coil in the Chrysler tomorrow morning, as it will be time before I can get that harness. In the end this will round out the ignition system to a more robust/available one that runs on full voltage.

 

[Aspen500]

Some may give you a hard time for that but,,,,,the HEI style ignition works good with a lot less wiring. I've got a DUI in my car. It's the one where a Chrysler distributor has an HEI module mounted on the outside of it. Works like a champ.

 

[Joe12459]

Some purists would probably have an issue with the fact that you did the ECU conversion to begin with, but that's just their opinion. While the orange box is a fine ignition for a daily driver, the parts are less readily available these days. and the ballast resistor is a weak link. The HEI conversion makes sense, is a simple conversion, and functions just as well while using readily available parts.

 

[8v-of-fury]

Couldn't find a GM module local for under $90 being that it was Sunday.. so that was a no go this morning lol. However, I did happen to find my other Chry Co. ECU in the garage that I bought a long time ago for another ride and never used it. It is probably also a china brand, but it is silver and the connections in the plug were a bit bigger and thus tighter.

I had it narrowed to the connection in the china wiring harness so yesterday i lobed that end off and just use straight bullet connectors but the problem persisted when the connectors were wiggled. Could not get a solid connection happening there at all.

Today I crushed the bullets a bit to make sure they fit tight and also swapped in the Silver ECU. It even seems to start better, I wonder.. is that silver box much different than the summit brand proform orange box I was running for the last 3 years?

 

[8v-of-fury]

I am running 15* initial, 14* vacuum for a total of 43* by 2200. It seems to do very well with these numbers.

 

[Joe12459]

The way I understand it, the difference in the orange box is that it supports higher RPM operation than the stock box.

 

[slant6billy]

I'm running an MP orange box for the last few months in lieu of the silver box. Took the car out tonight just after dinner and it stalled at a light. Not that it had not done it before, but I am switching to the silver box since the orange box was used to break a motor in and then it was sold to me. I'm just not seeing the gain the silver box had. also going back to my Edelbrock set up vice the Holley. I run with 6 spare ballest, 3 Voltage regulators, spare coil and a bunch of fuses. Just what is needed to get back home.

 

[BudW]

The GM HEI Module and Chrysler ECU work on the same exact principle.
Chrysler reduces the amount of voltage going to ignition coil on purpose – to increase ignition coil life.

You can remove the ballast resistor (or get a different resistance resistor) and you will get more voltage to spark plugs and a hotter spark – at a greatly reduced ignition coil life.

A trick a racer friend of mine had. He drove his car to track. Once there, he bypassed his resistor and got better ET’s, but then re-installed the resistor to get back home. He also took spare coils for sometimes the coil would not make it the ¼ mile, before burning up.

By the way – for any car – do not touch the ignition coil after or during engine running. It will give you a very bad burn!

Chrysler ignition coils are not meant to run at 12 volts – even though they say so on the print/stamp on side of them.


Tip: be sure not to waste any of the heat compound for the GM HEI Module. Those modules will die from excessive heat, if none or not enough heat compound is used.


Note: I purchased – but not yet installed, a Rev-N-Nator ICU (http://thertgarage.com/products.html ), some time back. They recommended a replacement ignition coil (which I also purchased) – which I suspect may, by itself, help with the less than 12 volts issue. No measurements made on it yet (its vacuum packed and put away, for now) to compare to a normal Chrysler ignition coil.

Note: I wish Chrysler called there ECU (Electronic Control Unit), an ICU (Ignition Control Unit) instead, for it would have made my life a lot easier.
BudW

 

[8v-of-fury]

I am on my phone at work, so this short reply is only a reflection of that. Not to disregard my appreciation for your very well worded and informative posts BudW!

I had always read that the voltage stepdown was to keep the ECU alive longer..

 

[kkritsilas]

From by background in electronics, it is most likely to save the drive transistor(s) more than it is the coil. The driver transistor (s) are the ones that send the voltage pulses to the ignition coil. It/they are probably not rated to drive the current at full voltage to the coil. That is why there is a ballast resistor; it limits the amount of current that the coil is trying to pull out of the ECU. You don't need a ballast resistor if the coil resistance is high enough (non factory spec.), because the coil itself will not try to pull so much current that the drive transistor(s) will have a long life. It comes down to how much current (=impedance/resistance) the coil is presenting to the drive transistor(s) vs. how much current the transistor(s) can reliably provide long term.

I haven't seen the schematics of the Chrysler ECU, but I suspect that the big transistor on the outside of the ECU is the drive transistor. I don't know if there are any others inside the unit. It could also be that they are using another kind of semiconductor, like an SCR or a triac but I suspect it is a transistor (or a few) with a snubber network.