Issue with crane cams hi-6 cd ignition

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pjc360

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I have been having a strange issue that I finally narrowed down to being ignition related some how.
At first I thought it was a drivetrain issue on my 91 w150 4x4 truck.
The issue I was having was a horrible vibration that came on at 2500 rpm.
I figured out the vibration showed up at 2500 rpm in every gear, and then realized it was showing up in nuetral and park as well.
I decided to hold the throttle at 2500 in nuetral and listen really close and I've determined it's a really bad miss fire.
It starts sputtering and popping out the exhaust, I checked my spark plugs and they are good, ohmed my plug wires, they check out, checked resistance on my ignition coil, it checks out.
I have noticed when I'm holding the throttle at 2500 rpm and it's in the middle of it's Miss firing fit the little red light on the crane ignition box is going in and out, getting brighter and then dimmer and brighter then dimmer.
And the box it's self gets awfully warm to the touch while this is happening.
I'm pretty confident whatever is causing the miss fire is inside that ignition box somewhere.
My first thoughts are, could the rev limiter be malfunctioning, glitching in and out at 2500 rpm?
Or could a bad ground to the ignition box cause something like this?
I'm wondering if there is anyone else that has encountered an issue like this with a cd ignition box, and if so what did you end up doing to fix it.
Distributor is a brand new firecore 50 with less then 100 miles run time on it, plug wires are Taylor thundervolt 8.2mm wires, coil is a crane cams lx91 e-core style coil.
Distributor cap and rotor are brand new.
Pick up coil checks out reisistance wise.
This is just really strange.
 
I had a similar problem and it was the coil, returned the coil and box, they added more epoxy and sent them back to me. shortly problem returned, replaced coil with an msd
 
Marcohotrod said:
I had a similar problem and it was the coil, returned the coil and box, they added more epoxy and sent them back to me. shortly problem returned, replaced coil with an msd
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Was your coil testing out fine resistance wise and still having the issue?
Cause my coil is testing within the specs that it should.
 
So a little update, I ran a 10 gauge ground wire directly from the negative battery post to the crane ignition box and it didn't do anything.
Still Miss firing pretty badly.
 
IIRC, multi-spark only happens until 3000 RPM then its just a longer duration spark. make sure your yellow/white (retard) wire is taped off. try new coil.
 
pishta said:
IIRC, multi-spark only happens until 3000 RPM then its just a longer duration spark. make sure your yellow/white (retard) wire is taped off. try new coil.
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Yellow and white is the stage input wire the (rev limiter) brown and white is retard wire and it is taped off.
I'm thinking coil as well, but what's throwing me off is how it's testing fine when I check the primary and secondary resistance with my multimeter.
and it's also strange that the coil would only be affecting a couple cylinders, wouldn't it be affecting all the cylinders, it sounds like it's missing on one or two cylinders but not all 8.
 
Anyone got a part number to a cheap 12 volt parts store coil that I could just hook up real quick to eliminate wether or not it is my coil causing the issue?
 
pjc360 said:
Yellow and white is the stage input wire the (rev limiter) brown and white is retard wire and it is taped off.
I'm thinking coil as well, but what's throwing me off is how it's testing fine when I check the primary and secondary resistance with my multimeter.
and it's also strange that the coil would only be affecting a couple cylinders, wouldn't it be affecting all the cylinders, it sounds like it's missing on one or two cylinders but not all 8.
Click to expand...
One can ohm out fine and it's the rise time between firing that lacks. can't recover quick enough
 
coils can also have internal shorting/breakdown at higher RPM's. Is your rev limiter dial up past 25? a cheaper alternative would be to buy/borrow a 5 pin ECU and wire it up.

PS>> does it do it with the vacuum advance disconnected?
 
Yes, I too am wondering what it does at some higher rpm than say 2800 or 3200.
You can put your timing lite on each wire and watch the strobe action; that might tell you if it is a particular cylinder or all, etc.
 
It still misses at above 2500 rpm it just seems like it takes longer for the Miss to come around once your above 2500 if that makes any sense.
And yes the rev limiter is set at 6k
 
pjc360 said:
It still misses at above 2500 rpm it just seems like it takes longer for the Miss to come around once your above 2500 if that makes any sense.
And yes the rev limiter is set at 6k
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I've seen many rev limiters have issues. You may have it set at 6k but it may be screwing you. Can you bypass the rev limiter?
 
yellow rose said:
I've seen many rev limiters have issues. You may have it set at 6k but it may be screwing you. Can you bypass the rev limiter?
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Yes I can dis-connect the rev limiter by taking the 12v lead away from the rev limiter wire.
I'm going to try that tonight, I'm also wanting to a try a cheap temporary parts store coil, is there any particular coil I should ask for? Or wil any 12v ignition coil suffice in a quick little test.
Just want to hook it up and bring the engine up to 2500 rpm to see if the Miss firing stops.
 
Cheaper it is, to disconnect the rev-limiter. If the engine continues to rev past 2500, say to 4500, and does so under load, then it's hardly likely to be the coil.
I have seen it be the plugs tho. Some coils cannot spark more than .028 gaps, some can spark .080s or even .100. Sometimes the timing is too far advanced for the fuel, and detonation cracks the insulators. Then it does exactly what yours is doing.
 
reason I asked about the vacuum advance was that possibly the mechanical advance plate (if it is in transition at 2500 rpm) is altering the pickup clearance?
 
pishta said:
reason I asked about the vacuum advance was that possibly the mechanical advance plate (if it is in transition at 2500 rpm) is altering the pickup clearance?
Click to expand...

I could see wondering that with a stock mopar distributor that I didn't know much about.
But this is a brand new firecore 50 unit wit less then 50 miles on it.
When I pulled this distributor out of the box I checked the reluctor teeth gap at rest and I hooked my mighty vac to it and applied 30hg of vaccum pulling the vaccum arm all the way over and held it there while I went around each tooth and checked the clearence and each one was dead in at .008.
Some of the boots on my spark plug wires are cracked, and this issue got even worse when I tried to remove some of the plug wires to check on cylinder 7 and cylinder 8's spark plugs since they were the ones that looked to not be sparking as hot as the others the last time I pulled all the plugs to check on them.
Anyways i broke a couple of the plug wires trying to get them off this last time to check on the plugs and i put them back together the best I could and that's when the problem got even worse.
So I'm ordering a new set of plug wires and a new coil this morning and paying a little more for 2 day shipping to have them here by the weekend.
I'll start with the new plug wires first, if it's still acting up I'll put the new coil on it, if it's still acting up with the new coil and new plug wires then I'll ether make an appointment with a shop that has some equiptment to track down what's going on like a spark analyzer and ollithiscope or I'll go to Napa and buy an Msd digital 6 cd ignition box that they have there and wire that sob in and see what happens.
Just not sure if it will make me mad
Enough to go and drop 250 bucks down on a new ignition box, cause if it turns
Out not be ignition related at all then I'm stuck with 2 coils and 2 cd ignition boxes, not that I would have all that hard of a time selling one of the boxes and coils but I wouldn't get what I paid for them.
So I guess we'll see how this falls
Into place, I'm hoping to discover what it is without spending too much money.
I need new plug wires anyways, I broke a few of them and some of the boots are cracked and they are 3 years old too boot.
So I'm basically buying a coil not knowing if I need it or not, if the plug wires solve it, and i don't have to install the coil to try it I can return the coil.
 
sounds like you checked the reluctor gap 6 ways to sunday! 60Kv is alot of juice to try and contain with a cracked boot. May have been 'leaking' to ground. you may have been able to see the arcing at night. Buddy had an issue and we looked at the motor in a dark garage and saw the coil wire arcing and 2 plug wires arcing to the header.
 
I wanted to give everyone an update to what the issue was.
I figured out the problem was rotor phasing in the firecore distributor that I had purchased at Mancini racing.
Rick from firecore took real good care of me and sent me a new distributor right away and I installed it and checked the rotor phasing and it was much closer to the cap terminal.
So now the Miss firing is gone and the vibration that came from the miss fire is gone.
I realized it was a rotor phasing issue because when I un-hooked the vacuum advance I noticed the issue was gone.
Soon as I hooked the vacuum advance back up the issue would appear again.
So the vaccum advance was pulling on the advance plate ccw which was pulling the rotor away from the cap terminal causing the miss fire.
 
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