Slight Miss

[289]

Hi
My 89 5.0 has a slight miss under no load condition. It is fine as soon as I push the gas, but it kinda bucks alittle under a constant speed and under 2k rpm.
I have a steeda 19 cam 1.72 rockers and intake, and a crane ignition, I don't know why this is happening. I have new wires and I have closed the gap on my spark plugs to .039. It also seems to be random some days it runs fine others is sucks. Please let help me out with this one I'm guessing maybe a sensor but I don't know.
Thanks

[Dark_5.0]

I would start with the coil.

[289]

Can you tell me why you say the coil thanks

[289]

I have just changed out my msd coil with a lx 92 crane coil which matches up with my crane ignition box and I am still getting major jerking and missing under no load situtations. Its really pissin me off I don't understand I thought that an ignition system helped
not hindered
I don't have this prob when I go to the stock ignition
Please someone give me insights
Thanks

[jimberg]

Check your timing with the new ignition and then check it with the stock ignition. If they're the same, check your codes. If you don't have any codes, try resetting your computer. Check for vacuum leaks. What kind of wires did you get? Are they installed so that the wires (especially 5 and 6) have plenty of separation? How's your cap and rotor looking? Did you gap the plugs to .039" because of the problem or is that just something you did when you installed everything else?

[289]

Yes I gapped the plugs to .039 because i was seeing sparking from my boots to the top of my plugs after I did that if fixed that problem.
Why do 5 and 6 need separation do they cross fire???
The wires I have are taylor solid core with no resistor low resistance
Thanks

[jimberg]

Your wires are your poblem. You should not use solid core wires with a Crane ignition. It says that specifically in their installation instructions. Get yourself a set of MSD 8.5 mm Superconductor wires and that should fix your problem. Regap your spark plugs to .054" while you are swapping out the wires.

Yes, 5 and 6 can crossfire and that is likely happening with the wires you are using.

[jimberg]

Just to be clear. Crane tells you not to use solid core wires because of RF issues effecting the box. If you see arcing from the boots to the top of the plugs, there's clearly something wrong with the wires you are using. Did you remember to use dielectric grease to coat the inside of your boots?

I like the MSD wires because they have really long boots that are shapable so you can position them away from the headers. They have a real low resistance and are spiral core so there is low RF coming from them.

[289]

I guess all I can say is DOH
I was afraid of that I know these wire make a crap load of RF because I can't even use my AM radio.
So do you think its just the RF thats screwin it up, do you think i might have damaged something usein these type wires.
Thanks for your input

[jimberg]

Hopefully you haven't damaged anything. My guess is that the wires are crossfiring or arcing against the headers. RF interference in the computer would just cause temporary, intermittent problems. Get those MSD wires and see if the problem goes away. Regardless of the outcome, you know that those wires are wrong.

I still have RF issues on AM, but there are some stations that I can listen to without any problems. Part of the problem is that I have a fiberglass hood and that's not really good at containing RF. I usually only hear interference when I'm far away from the station.

[PKRWUD]

Good call, Jim!

[289]

Well your advice helped I don't have the missing prob at no load I went to msd super conductor 8.5's, but I am still having a blip running up from 30mph in 2nd
then I it basically turns on and off in like high 3rd or always 4th at like 4.5k
I can lideraly seem my tachs ( I have 2) both go down amost to zero and back up again. Like it is turning off for a second. I don't think its a loose connection cause it is consistent around upper 3rd or 4kto 5k in 4th gear
I do have a crane box (older) and crane coil that is new.
Please give me any insight to this prob Thanks

[jimberg]

Bypass your Crane box and see if you still have the problem. If you don't, we know the problem is in the ignition box. If not, we have to come up with some other tests.

I had an old Crane HI-6 box go out on me before. But that was after my car sat for 3 years. My box just wouldn't work all together, no misfiring or anything.

-When's the last time u changed your fuel filter?
-Why are your plugs gapped at .039? Stock is .054. If you have an after market ignition you can actually open up the gap to .060. But I'd at least run the stock gap for a 5.0.
-Are you running platinum plugs? I'm not a 100% sure why this has happened...but in the past I've seen numerous posts on people having intermittent sputtering problems after installing high dollar platinum plugs. If you do have platinum plugs...loose them. Regular Autolite or NGK plugs will do just fine.

[289]

well I tried stock ignition and it did the same thing first it blew a 10amp fuse I have inline with the ignition line powering the coil. So i was crazy and put a 20amp in well it fried something in my distrib cause I tried putting the crane ign which I know works and then another ignition mod and nothing so for some reason when I shift gears let off the gas and get back on it cuts out and shorts somewhere cause it blew the fuse then the distributor. So my next question is how can I eliminate the computer from my distributor I just want to go to the old style vacum or mechanical,which msd distributor is good for an 89 5.0
thanks