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Sunday that system failed, luckily in the driveway before I left to run an errand . I got it going again (I THINK, haven't driven it far yet) but, not before replacing both the module and coil.
The engine was running and then it just quite and wouldn't restart. In the process of troubleshooting it started blowing the 15A fuse protecting the ignition circuit. I replaced the coil first since I already had one, no dice. Then scrambled to get a replacement module at the auto part store. Checked to make sure it was still dead.. Installed the module and she fired right up. So, I decided to put the old coil back on... dead again. Put, the new coil back on.. it lives!
So, from what I can tell one component failed and killed the other. I'm guessing the coil since it was super hot when I first touched it.
Both the failed and replacement coils are Motorcraft DG470.
I compared the resistance of the two. The resistance of my meter leads was about .3 or .4 ohms.
As you can see they have different readings. But without specs I wouldn't know if it was good or not based on ohm readings alone. From what I can tell acceptable ranges vary greatly for hei coils depending on their intended application or whether their stock/oem vs high performance/aftermarket.
On the bad coil wouldn't the primary basically short out the module? From what I understand this shouldn't be higher than .5 ohms, higher will lower output power.
And there's like a 380? Ohms different between the secondaries. Not sure what that means.
The failed module was a NAPA TP45 and was replaced with a BWD CBE4 from Oreily since my local NAPA was already closed for the day.
I'm concerned about the quality of CBE4 as I've read the TP45 is one of the better aftermarket modules and is comparable to the GM 990 (high performance series module). It has circuits for variable dwell and current limiting which cheaper modules do not implement. Out of curiosity I'm thinking about writing BWD concerning this matter but, ultimately I'll probably switch back to the TP45.
I'm still wondering why my coil failed (if that's what caused this). I went with an OEM coil instead of aftermarket in hopes of better quality and reliability.
Wonder if it was a lemon or maybe the way I've mounted these device is negativity affecting their lifespan? (Pictures in my other thread linked above)
Anyway, I lucked out this time. You see I never got around to purchasing a spare coil and module after I did this conversion. The coil I had was intended for my second hei conversion and I had no spare module. I'll fix that for sure!
Well, I turned my bad coil and module in on warranty. I already got the replacement module from napa. Still waiting for the coil.
The truck didn't seem to run as well as I recall with the CBE4 module,so I swapped it out for the TP45. That seemed to fix that.
When I first switched over to hei, I immediate noticed a rapid tick/buzzing sound as the engine idled. I assume I'm hearing the e-coil fire or arcing in the distributor. That noise was quieter with the CBE4. So, I'm guessing the TP45 must produce hotter spark? I don't know.
At least now I have a spare coil and module on onboard.
I carry a ECU and a Ballast with me.... Now that I have had one in the truck as a spare. I've never had to use it....lol
Murph's law I guess...
Glad you got your back up and running.... Keep us posted...
It's been awhile so I decided to provide an update on this.
When I first did this conversion, I couldn't get the system to last a year without the coil or module or both failing.
Basically it boiled down to my choice of coil. The buzzing sound I heard... that was the coil. I assume what was happening is the coil would fail and usually would take the hei module with it.
So, I avoid coils that buzz. I'm currently use Delphi Part#: GN10183. It's for the same vehicle applications the DG470 was for but, there must be something different. I haven't had a failure since.
Something else I learned that will kill this system pretty quick (well potentially any electronically switched ignition) is an open circuit on the secondary side.
If you need to check for a misfire do a power balance test using vacuum hose and (incandescent) test lamp.
Mopar has a fine ignition system, I couldn't find a reason to put a HEI on anything but a GM and even then I'd go with a MSD if it was a performance aplacation.
Only one way to find out.. keep driving. If it does continue to be an issue I can always switch back. I still have all the original components and left the wiring harness intact.
I'll be honest, I did this conversion for no other reason other than that I wanted to and I could. Having previously done alternator swaps and being pleased with the results I wanted to see what this modification had to offer.
When I came across the write up over at slantsix forum I was in intrigued and wanted to give it a try.
At the time I felt there was a slight improvement in startup and idling. If anything else, this mod took care of a minor detail with my Fitech installation (during my engine rebuild) a head of time. The Fitech has a white wire that requires full battery voltage during cranking and running. Since the hei doesn't use a ballast resistor. The ignition crank (ballast bypass) and runs wires where jumped together. If that wasn't the case I'm sure I could have figured out something using a push button or diode or something, but it was nice it was already done.
Haha! You called it RacerHog. I suffered another ignition system failure last Saturday. This happening a month after me waiting a year to give this setup the green light sounds about right.. lol
Alright so here's the story.
I had been cruising around town and decided to stop at the local Dollar General, I parked, went inside and when I went to leave the truck wouldn't start. Using my Fitech handheld showed no tach RPM reading while cranking. Confirming with a test light across battery positive and coil negative produced no "blinky blinky" while cranking. I swapped out the module and the truck fired right up and I drove straight home. The truck wasn't running too good but, I'll reveal the reason for that a little later. It was only because I was already parked and the weather was nice I took the time to diagnose the problem otherwise, I would have gone straight for the module.
Once I got home I decided to do additionally research on the hei ignition system. I needed to find out if my conversion was at fault or if genuine hei setups were having similar issues. Here is what I found...
I found a post here over at the chevelles forum by Dave Ray aka IgnitionMan. Dave Ray seems to be well known for his "small body HEI" conversions. In this post Dave talks about hei style coils being prone to causing premature module failure due to the heat their exposed to on top of the distributor cap. This heat causes the coil insulation to break down and results in internal shorting of the windings which kills the module in the process. Plus, I'm sure the module being mounted inside distributor doesn't help either. This same post mentions there are kits available to convert coil-on-cap setups to remote coil. Because of the above mentioned problem Dave recommends the use of an oil filled coil (specifically the NAPA IC12) as they are better at dissipating heat compared to their epoxy insulated counterparts.
Alright, so this is definitely a problem that no doubt some chevy owners are having to deal with... but it doesn't explain the problems my conversion has been having. My e-coil is remotely mounted to the firewall with a custom made bracket. My module is mounted remotely to an aluminum plate customized to fit in the stock ICM location on the inner driver side fender. Real thermal paste was used between the module and the plate... not dielectric grease. Both coil and module are powered by a relay with a custom made harness to eliminate excessive voltage drop. It doesn't get much better than this..
So, I move on in my search. Next stop the Twilight Zo... I mean the hei module.
Back when I was doing the initial research for the hei conversion I had heard there were concerns about the quality of hei modules being made these days as pretty much all of them are made overseas now. The biggest problem with these "off shore" modules are that they have omitted circuits for example, current and dwell control. Apparently these circuits are necessary to protect low-resistant coils during low speed engine operation. Which I can agree with since most of my ignition failures have always been at idle. Some people will go out of their way to salvage older genuine module from junkyard vehicles.. I'm not one of them. Plus, the bone yards around me don't take too kindly to people trying to walk their yards for parts.
So, what now? Supposedly, running a coil with a high primary resistance will help take the stress off the module. A low ohm coil (0.5 ohms) can pull as much as 6 amps. A regular oil filled coil (1.5 ohms) will still fire at 25kV but at a reduced current of 3 amps. I got this data from a post by "GMC Bubba" over at the jalopyjournal forums.
So, where am I now? I selected an oil filled coil to switch to. In this case I went with the slantsix guide recommendation which is the UC16 by Standard. It's a pretty blue that matches my plug wires and reads "12V USE WITH ELECTRONIC IGNITION". This coil seems to be used on later Chrysler products from 1979 to 1993. I previously never considered running this style of coil with hei as it seemed to defeat the purpose but, after being made aware of these issues I may not have a choice if I wish to keep this system. I've been running this coil for a week now and the truck doesn't run any better or worse than it did before. I'm going to see how this goes for now. I'll clean up the wiring later when I have time. I'll keep you posted.
Oh I nearly forgot. I mentioned at the beginning that the truck ran bad after I swapped the module in the parking lot. Well, It also still ran bad after I switched to the UC16 coil. It turns out that was my fault and I learned something about my Fitech setup.
The module bracket I made also has a condenser mounted to it with the wire connected to pin B (key hot) of the module. My backup module also have it's own bracket but, there is no condenser. My brackets also have a ground wire that allows me to quickly change them out without unbolting anything. So, in an emergency they can literally hang by the wires. After several hours, I found out that the Fitech system doesn't care for this at all. It will set a fault code P0335 "RPM noise". I found out my module bracket has to be bolted to the truck and the condenser connected or the code will set and engine will miss under acceleration/throttle up. I wanted to share this because I found this discovery funny. Back with the carburetor, the truck didn't care either way. In fact, the only reason I added it was to help reduce noise in my stock radio.. which it didn't do. Not having that cap would have made for a pretty rough first time Fitech experience. So, I'm not sure if this would happen with the mopar electronic ignition or not but, I do believe some mopar vehicles have those filter caps installed by the coil. As a tip, it may worth checking if it's still hooked up, working or add one if your having trouble with rpm noise on a fuel-only Fitech setup.
Oh one more thing. Supposedly, another circuit that was omitted from the hei modules was a timer that shut it down if the key was left on with the engine off. This is also a module killer. Normally this wouldn't be a problem for me but, I leave the key on a lot when playing with the Fitech settings.
I hope someone finds this post most enlightening...
Mopar has a fine ignition system, I couldn't find a reason to put a HEI on anything but a GM and even then I'd go with a MSD if it was a performance aplacation.
Thanks For the Info and taking up the fight...
Also, Did you step up to the 8MM Suppression plug wire set? That may help the noise issue. Or the Firecore? I think i seen a write-up on those over on For-a-bodys only FBO???? Have not used them myself... I Been using Accel Super Stock Wires for a long time.
Yes, I did indeed switch to 8mm wires. I got a set from Summit Racing which I'm sure is far from the best, but 8mm none the less.
I do find it interesting how the numerous articles available online about this ignition swap, talk it up likes it's the best thing ever but, if you peek over the fence it couldn't be further from the truth... For example:
getting tough to find quality modules these days. carrying a spare with the tools to change it out is a really good idea.
So, I don't know. Maybe this swap used to be more viable years ago.
As for my conversion I'm going to wait and see how long it last this time with a different coil. I still kinda suspect it will fail anyway but, if this does greatly reduce it's failure rate I'll go ahead and keep it since I already have it in place.
The one thing I do like about the hei and my remaining motivation for wanting to keep it is the fact the module is powered by one wire instead of two wires for crank and run, which simplifies wiring for my Fitech and relay control of the ignition system.
However, if this convenience comes at the price of reduced reliability I'll switch back to the stock ignition. I'm more than capable of making the mopar ignition work with my efi.. I just don't want to.
If nothing else this thread will help provided a good reason to others why not to switch to hei (which I feel is lacking in search engine results). I mean.. it works fine when it's working... If your cool with replacing coils and modules annually. Because thats pretty much been my experience with it.
I am curious how long it will last this round. I probably won't known until a year from now but, the summer heat may speed things up as well. I believe all my failures up until now have been in the summer, never winter. I'll keep you posted.
I'm not sure I understand. From what I understand a typical charging system voltage is between 13.5 - 14.5 volts.
Prior to efi I ran a 63A SI10 but, switched to a 140A SI retrofit from Summit (SUM-810344) about a month ago. The 63 amp could no longer keep up and could only manage to maintain a voltage of about 13 during cruise and voltage would slowly start to drop to 12 while idling for extended amounts of time.
Although now that I think about it, that may have been hard on the module. I've heard under-powering can be just as damaging as over-powering when it comes to electronic circuitry.
I do have an aftermarket voltage gauge installed. It measures available voltage at pin 87 of the relay that powers the coil and module.
New Personal High Score: ~968 days (2 years, 7 months, 24 days) before failure.
So, it seems making an aftermarket hei module drive a 1.5 ohm coil instead of a 0.5 ohm coil will increase service life and while this is a large improvement from the previous annual failures it still isn’t great.
For comparison, I replaced the ICM on my other dodge truck with an aftermarket mopar unit sometime in August of 2018 ( 4 years, 5 months or 1616 days ago) as part of a tune up. Still working fine. The original unit still works too but, it was leaking potting material. I still keep it onboard as a spare.
I carry a spare hei module so I don’t get stranded but, I’m thinking about returning to the stock mopar ignition.
Besides reliability , I would like to clean up my wiring at some point and getting rid of the hei would help with that. It seems I’m always making changes so it makes it hard to commit to one thing so I can rewrap my wiring harness.
However, I could run one more long term test... I haven’t decided yet. (46330)
I managed to get my hands on a genuine 990 hei module from an old distributor I found laying around. So, I now have this module in service for the time being.
Other thoughts:
FiTech has put out a tech video that claims their systems can’t get a clean tach signal from ignition systems that utilize a ballast resistor. I will be curious to test if this is true as I am skeptical.
I find the similarities between the Big Three electronic ignitions system interesting. They all seemed to be triggered by a variable reluctance sensor (aka 2 wire magnetic pickup). Which explained why you can find guides for converting a ford or mopar to a hei igniter. The boxes all understand the same “language” input wise. The main difference between hei and the other two systems is the lack of a ballast resistor or resistor wire. I can’t prove it but, I personally believe this is the reason the gm module is failure prone or at least it’s various aftermarket incarnations.
I also find it interesting that one of the selling point for switching to hei is elimination of the ballast resistor however, I have never had on fail and even if it does you don’t even need any tools to diagnose it. Does the engine only fire when cranking? Boom done. Carry a spare.
In the end I think I understand now why I see so many MSD boxes at the car shows...
Im not sure if it is heat that kills them or voltage spike.... All i can say is, I have gotten good ones, and i have gotten bad ones..
One of the orange boxes i had worked vwry well with an allison ignition coil and worked for about 12 years without issue...
everything else is kind of hit and miss....
I totally get it. You never now what your going to get. It could last a month or be fine and last years...
Here's a short story.
Years back when this truck still belonged to my employer. It once had an issue where it would suddenly die after running for about 15 minutes and wouldn't restart for a couple hours. The repair shop would reproduce the issue and find there was no spark. They would replace the ICM and the truck would jump back to life. We would get the truck back and the issue would soon return. Well, after about 2 ICMs it was discovered that the truck had a faulty voltage regulator. It was causing the ICMs to overheat and shutdown or plain die and never come back. That is the only time (so far) I've seen a mopar-style ignition box fail.
Yes, They don't like much over 15.0 Volts for very long... Or the large swing from Low to High... And we have all had those charging issues..
Good info you have given....
After one week of testing with the stock mopar ignition box, I fully committed to switching back by removing the hei module and its supporting hardware.
This conversion has been quite a learning experience. I'll know what the deal is, if I ever have to troubleshoot a 1974 to 1990 GM product that no longer has its OEM module. In fact, if I was ever to get an older Chevy (I own a 94 Astro 4.3L w/ TBI), I would seriously consider trying to convert it to a Ford or Mopar ignition. I think it could be done since all three systems use a VR (variable reliance) sensor as the input. I think the trick piece would be either a "small cap" distributor OR a "remote coil cap" as these would allow use of a non-hei coil. The advantage here would be even if a ignition module or ballast resistor failed, the repairs could easily be made without having to mess with the distributor, thermal compound grease, etc... The parts also have the potential to be cheaper and more readily available compared to a high-end aftermarket system. Of course, the parts have to be reliable with a decent service life for that to be true... this was my primary issue with the hei module. The oem module I acquired may have lasted for years but, that's a treasure hunt which I found unacceptable for such an important component of the ignition system.
Lastly, As I suspected my efi has no issue getting a usable tach signal from the stock ignition system. It doesn't even need the radio noise condenser unlike with the hei but, I kept it anyway. The reason I wasn't 100% sure if it would work is because FiTech put out a tech video about 2 years ago that stated ballasted ignition systems will not work. I personally believe the real reason is to upsale consumers having issues to CDI or ecu timing control rather than diagnosing their real issue but, that's another story.
Now I need to order a few spare ICMs and ballast resistors.
The hei module does have the advantage of using blade connectors, so a harness can be built in a pinch... but it's looks aren't easy on the eyes.
With so many great aftermarket ignition systems available now days I can’t imagine trying to adapt an OEM system. Why would you want to hack something together?
Besides the reasons previously stated I have no reason other than I could and wanted to. Just my way of exploring the hobby... I'm simply sharing the results of what I learned.
Without a doubt my hei setup looked like a hack job, that was the other reason I got rid of it. I would have tried to find away to make it look better if it would have worked. A ford or mopar box would probably be easier to make look good in a swap since you can get a proper wiring harness for them but, a ready-to-run style distributor is the only right way to put (4-pin module) HEI on something not a Chevy. However, for a stock non performance vehicle I personally wouldn't even do that for hei. I question the reliability of all aftermarket hei modules at this point.
I understand an aftermarket ignition box wired for magnetic pickup trigger (thus bypassing the module) is the proper way to get out of this hei mess on a GM product. That's the one thing this experiment made clear. You can't depend on a car using a module from the auto part store.
I can understand your reasoning I guess I’m not at the point of doing things for kicks and giggles, I have a hard enough time doing things that need to be done.
06-11-2018, 07:15 PM
