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Re: Back with rough spot around 2500 rpm [Re: RapidRobert] #2417685
12/13/17 12:01 AM
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Originally Posted By RapidRobert
I would think, but the compression rings could be adequate & the oil rings can still be bad. First we gotta resolve the blinking light potential.

So where do I go from here? Should I buy a couple valve springs and put them inn on cylinder 8!and see if that fixes it?

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2417708
12/13/17 12:41 AM
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I would put a clean plug in #8 & see if the light blinks differently on #8 than on the rest of em & if so we might swap some plug wires & see if the intermittent blinking follows the wire (that is on #8 now). I wouldn't buy a valve spring right now.


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Re: Back with rough spot around 2500 rpm [Re: RapidRobert] #2417720
12/13/17 01:12 AM
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Originally Posted By RapidRobert
I would put a clean plug in #8 & see if the light blinks differently on #8 than on the rest of em & if so we might swap some plug wires & see if the intermittent blinking follows the wire (that is on #8 now). I wouldn't buy a valve spring right now.


Ok the only issue is I don’t have a shop and my truck is on the side of the road and it would enrage the entire neighborhood if I sat out there Reving the engine.
My neighbor already hates my truck says it’s too loud.
My main thought on that is I have tried multiple plugs on cylinder 8 and the result is always the same the number 8 plug always ends up semi fuel fouled and smelling like fuel.
These are brand new plug wires with less then 100 miles on them, same with the coil and same with the distributor.
The only part of the ignition that hasn’t been replaced and isn’t brand new is the crane cd ignition box.
This issue has been present for a long time and at first I thought it was a vibration from drivetrain then realized that wasn’t the case because of how it’s rpm dependent.
Then I buy new plugs and wires and a new distributor and a new coil all at once and that doesn’t make a difference.
I’m just so annoyed with running in circles with this thing and never pin pointing exactly what the issue is.
It’s been driving me insane.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2417766
12/13/17 02:22 AM
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I will go back thru everything & see if anything jumps out at me.


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Re: Back with rough spot around 2500 rpm [Re: pjc360] #2418092
12/13/17 06:44 PM
12/13/17 06:44 PM
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Originally Posted By pjc360
Originally Posted By RapidRobert
I would think, but the compression rings could be adequate & the oil rings can still be bad. First we gotta resolve the blinking light potential.

So where do I go from here? Should I buy a couple valve springs and put them inn on cylinder 8!and see if that fixes it?


Change the springs, they aren't that expensive.

What is the timing at 2500 rpm?


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Re: Back with rough spot around 2500 rpm [Re: pjc360] #2418253
12/14/17 12:20 AM
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so I was thinking today and I remembered awhile back a few months ago I was sitting in neutral and held the throttle at 2500 rpm where the missing starts and I remember my crane ignition box was getting pretty warm to the touch.
And the red light on the box was flickering rapidly at 2500 rpm.
I also know that I have gone through an un-usual amount of pick up coils with this crane ignition box.
Before I purchased this firecore distributor I was running a Mopar unit that was customized and set up by Don at fbo systems.
I went through 2 or 3 pick up coils on the distributor from don.
They would last like 6-9 months and then all a sudden they would just die.
Then another time a couple years ago I had a Premium borg Warner distributor cap on my distributor from don and the coil button on the inside of the distributor cap melted away completely.
That crane box is the only thing I haven’t tried replacing.
It just never occurred to me that it could be causing this issue but now I’m kind of wondering if I got a bad box.
I bought it from a whole saler on eBay and they said it was brand new and it was still packaged Ike it was brand new when I got it, and I got a really good price on it.
Is there any tests I can do to determine if the box is the cause of this missfire?
I don’t have the factory ignition module and wiring anymore otherwise I’d just wire that back up and see what it did.
I’ve triple checked the polarity of the pick up coil wiring I know that’s correct.
I’ve ohmed the new plug wires they all check out at 50 ohms per foot.
I’ve ohmed the coil out it checks out.
Pick up coil checks out on the ohm test.
That basically leaves that crane ignition box.
I’m going to try the timing light on the other cylinders while bringing up the rpm to see if the miss fire shows up on other cylinders or if it’s just strictly cylinder 8.
I got off work an hour and a half late and it’s already too late to be outside reving the engine and testing the other cylinders with the light.
That might have to wait till this weekend.
But if I can get off work at a decent time before the weekend I’m going to try it out and see what happens.
The only thing that’s throwing me off is how number 8s plug always looks like it’s struggling to fire compared to the others, of it was the ignition box you’d think it wouldn’t be affecting just one cylinder.
But we’ll find out when I get the light on the other 7 cylinders and bring the rpm up to where it starts missing

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2419648
12/16/17 10:58 PM
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So I did some more testing tonight and I found out that this missfire that occurs around 2000-2500 rpm is not just limited to one cylinder.
It’s happening on all 8 cylinders.
I hooked the timing light up to every cylinder and brought the rpms up to 2500 rpm and I could see the break in the light on every cylinder at 2500 rpm.
I checked the timing at 2500 rpm with vacuum advance and it’s at 43 degrees at 2500 with vacuum advance.
Without vacuum advance it’s at 33 degrees at 2500 rpm.
So based on what I found tonight my current thought is the crane ignition box has something wrong with it internally.
I talked to a tech tonight about this issue and he agreed that since the miss is showing up on all 8 cylinders it sounds like the ignition box or the pick up coil in the distributor.
I explained to him that this issue was present with my previous distributor and that o bought a brand new firecore distributor and the issue is still there.
He said based on the fact that you have replaced everything else in the ignition system it sounds like the box.
Cause I told him the coil is brand new and that made no difference, the plug wires are brand new that didn’t make a difference, plugs are brand new.
And cap and rotor are also brand new a lot with distributor.
Vacuum stays steady at 20hg while idling, when I hold throttle at 2500 the vacuum gauge kind of oscillates a little bit but not by much maybe 1/2 an hg.
I’m not seeing anything on the vacuum gauge to indicate major problems and compression test revealed 155psi on all 8 cylinders while warm.
He asked if I have noticed anything strange with the crane box now or ever since I got it and I told him how it’s always made a pretty loud buzzing sound.
He said Heaney heard some boxes that are quiet and some that buzz so he doesn’t know if that is something to consider or not.
Since there is no way of testing a cd ignition box that I am aware of I was thinking about pulling the box out and taking it apart and seeing if I can see anything un-usual with the wiring and transistors.
Any burned wires or burned area’s.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2419796
12/17/17 12:32 PM
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I wish you were nearby as we could put a spare OE MP ign on it & see if it straightens out. The box IS beginning to look guilty.


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Re: Back with rough spot around 2500 rpm [Re: RapidRobert] #2419903
12/17/17 04:18 PM
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Originally Posted By RapidRobert
I wish you were nearby as we could put a spare OE MP ign on it & see if it straightens out. The box IS beginning to look guilty.


Well I used to have a the factory Mopar wiring harness and a chrome Mopar ignition box and a canister oil filled coil.
But now the harness is all hacked up, I still have the chrome box, and I don’t have a coil or a ballast anymore, I don’t know what happened to them.
I moved a couple years back and I suspect it’s probly all buried in my storage unit somewhere.
I could just go buy an msd digital 6 box for a couple hundred bucks at my local Oreilly auto parts store, it would be super easy to wire inn since I already have a cd ignition box wired inn and all the wiring is there for a cd ignition.
I just hate spending money on things without knowing without a doubht that what I’m replacing is the cause of the problem.
But everything at this point seems to be point at the crane box.
Specially when you consider I went through an un-usual amount of pick up coils in my previous Mopar distributor.
I always thought that was strange, I went through 3 pick up coils in about 10k miles and I think whatever issue this crane box has is what was wiping those pick up coils out.
And when you also consider the box gets kind of warm to the touch when you hold the throttle at 2500 and it starts missing and the red led light on the box starts flickering while the throttle is held at 2500 and it’s missing.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420030
12/17/17 09:37 PM
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I’m going to turn thenrev limiter all the way up tonight and see if the missfiring moves uonhigher in the rpm, if it does then I’ll be convinced it’s the rev limiter malfunctioning inside the box.
I’ve said it before that it almost feels like it’s bouncing off a rev limiter just not quite as harsh as I would expect it to be but then again that could be because it’s not totall kicking inn but it kind of is.
I just don’t know, I do know if I end up replacing the ignition box and it fixed the issue I’m going to send this box inn to fast who boughtnout cranes ignition line and ask them to diagnose the problem and if it isn’t too severe of an issue I’ll have them repair it and send it back that way I’d have a spare box in case I ever run into this kind of thing again.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420032
12/17/17 09:42 PM
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i've got an msd streetfire on my truck and haven't had any problems. pretty sure they were only $100 when i bought it. seems to be 150-ish now...

https://www.msdperformance.com/products/ignitions/street_fire_cd_ignition/parts/5520

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420048
12/17/17 10:31 PM
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you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01

Re: Back with rough spot around 2500 rpm [Re: Tom Fox] #2420080
12/17/17 11:28 PM
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Originally Posted By Tom Fox
you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01


I thought if you set the rev limiter to 0 the engine won’t start?

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420156
12/18/17 01:44 AM
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Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420357
12/18/17 03:16 PM
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Originally Posted By pjc360
Originally Posted By Tom Fox
you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01


I thought if you set the rev limiter to 0 the engine won’t start?


is this for your ignition box?
http://www.cranecams.com/uploads/instructions/9000-6000c.pdf

00 disables rev limiter, 01 disables multispark AND rev limiter...

Re: Back with rough spot around 2500 rpm [Re: krautrock] #2420418
12/18/17 05:10 PM
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Originally Posted By krautrock
Originally Posted By pjc360
Originally Posted By Tom Fox
you can disable the rev limiter all together by setting your rotary switches to 00. also if you want to disable the multi spark & rev limiter, you set them to 01


I thought if you set the rev limiter to 0 the engine won’t start?


is this for your ignition box?
http://www.cranecams.com/uploads/instructions/9000-6000c.pdf

00 disables rev limiter, 01 disables multispark AND rev limiter...


Yes I still have the instructions and I have went over the wiring multiple times.
Pick up coil wires are wired correctly, the purple crane wire goes to orange positive on distributor and green crane wire goes to black negative wire on pick up coil.
The yellow rev limiter wire is wired directly to battery positive.
The main power wire on crane box is 10 gauge wire going straight to battery positive and the negative main wire on crane box goes directly to negative battery terminal.
Coil wires are correct.
Thin red wire is going to it’s own switched 12v toggle switch to power the box on and off.
I have pick up coil wires routed as far away from the other wires as I can.
Rev limiter is set at 6k rpm on both dials.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2420776
12/19/17 02:21 AM
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have you tried bypassing the toggle switch and going direct for a test?


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Re: Back with rough spot around 2500 rpm [Re: rhad] #2421149
12/19/17 10:04 PM
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Originally Posted By rhad
have you tried bypassing the toggle switch and going direct for a test?


Going direct to what? Since this truck was efi before I got it and I put a carbed engine in it I’ve always used a toggle switch to power my ignitions, first with the factory Mopar electronic ignition and now with this crane ignition box.
Could powering the cd box off of a toggle switch be an issue or cause an issue?
It’s a 50 amp toggle switch that turns the box on and off.
I didn’t know what else to use to power the box on and off.

Re: Back with rough spot around 2500 rpm [Re: pjc360] #2421254
12/20/17 12:58 AM
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if it's like an MSD it should have a low current turn on lead that should be a switched 12v source.
the thicker red wire should be wired through a fuse to basically the battery.

still doubt any of that is going to give you a miss only after 2500rpm. and especially be worse when it's colder...

Re: Back with rough spot around 2500 rpm [Re: krautrock] #2421258
12/20/17 01:10 AM
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Originally Posted By krautrock
if it's like an MSD it should have a low current turn on lead that should be a switched 12v source.
the thicker red wire should be wired through a fuse to basically the battery.

still doubt any of that is going to give you a miss only after 2500rpm. and especially be worse when it's colder...



Ya it’s exactly like an msd, the thin red wire is a switched 12v wire.
I have that going to a 50 amp toggle switch.
The big main power wire is going directly to positive terminal on battery and the big ground is going directly too negative battery terminal.
Coil wires are correct, pick up coil wires are correct.
It’s just strange whatever it is, I would be confident it was the ignition box at this point except for the fact that the issue seems to get better when I take away the vacuum advance.
That’s what led me to rotor phasing a few months back.
But I have checked rotor phasing with my current firecore distributor with and without vacuum advance and it looks good.
So that’s the only thing that has me a little baffled.
I’m still leaning towards the ignition box, I just wish there was a quick and easy way to test the box before spending the money on another one.

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