Ad Radar
Facebook Click here to find out more!

need help identifying a (miss)

Mopar Muscle
1 |  2 |  Next   | Last 
Item Posts    Sort Order

need help identifying a (miss)

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/20/12
04:26 PM

I have the 300 hp crate 360 magnum in a 1991 dodge short bed 4x4 truck and i have a little miss that i can not for the life of me figure out where its coming from or whats causing it.
The truck originally had a tbi 318 but i tore out the fuel injection and ran a 4 barrell carb and old school mopar ecu ignition. I am running a 4 pin wells ignition module and i have a 10 gauge ground wire coming from behind the wells ignition module to the engine block. I am running a crane cams lx91 ignition wich can be used on cd and inductive ignition systems. I have a mopar distributer that i bought brand new about 3 months ago from Don at fbo systems, he curved and phased it on his distributer machine. My initial timing is set at 14 degrees and my total timing is set at 32 degrees and i am running 91 octane fuel. I have a 1 ohm 2 prong wells ballast resistor. My ignition switch took a crap on me so i am powering my ignition thru a 50 amp toggle switch, i am also powering the lights to my oil and tempature gauge off of the 50 amp toggle switch that powers my ignition.
I thought about running my toggle switch off of a 4 prong relay, but the manager of the parts department at my local dodge dealership told me that the 50 amp toggle switch would be more then enough to power my ignition. I had read that if you dont have a high enough amp rated toggle switch and you run the ignition off of it that it could cause a (miss)
Now the other day i found that the spark plug in the number 5 cylinder was not firing anymore, the plugs i am running are ngk v-powers gapped at .035. The plugs dont even have 1000 miles on them, so i thought it was odd the number 5 plug haad just up and stopped working, but with further re-search i have learned that ngk's will up and fail alot. So i replaced the number 5 cylinder plug and the miss appeared to be gone but i noticed it again last night when it was idling. the engine was cold and had not been ran in a few hours, and i started it up and i heard the miss thru the exhaust while at an idle.
I do not know what is causing this, distributer is brand new curved and phased, my cap and rotor are brand new, rotor is a standard blue streak rotor cap is a cra quest gold cap with copper inserts, made by wells. My ignition module is brand new and it is grounded to the engine. My altenator is brand new and it is wired up correctly and i have a brand new wells voltage regulator and i also have the voltage regulator grounded to the engine.
when i first got my new distributer from don at fbo systems he told me to set the initial timing at 16 degrees wich would have made the total timing land at 34 degrees and then he told me to hook the vaccum advance up to manifold vaccum. He had the vaccum advance set to add 14 degrees of timing at 18 inches of vaccum. My engine makes 18 inches of vaccum at idle. So i did this and it was thudding out the exhaust pretty bad, i called don and he said i needed to richen up my idle air mixture screws on my carburetor. My carburetor is the edelbrock performer 600cfm manual choke carb. So i tried that and no matter how i adjsted the idle air mixture screws the thudding out the exhaust while at an idle never went away. So i called him back and asked about running the vaccum advance off of the ported source and he about tore me a new ass hole for saying that. He dont agree with running the vaccum advance off of the ported source. So i turned my initial timing down to 14 degrees wich landed my total at 32 degrees. Then i turned down the vaccum can to where it was adding 10 degrees o timing at 18 inches of vaccum instead of adding 14 degrees of timing at 18 inches of vaccum. Then i adjusted my idle air mixture screws to the highest vaccum reading on my vaccum gauge.
My engine seemed to like it this way, 14 initial and another 10 degrees from the vaccum advance at an idle so it was sitting at 24 degrees at an idle with the vaccum advance on manifold vaccum. But then a couple weeks later i started to notice the thudding out the exhaust again... So i decided screw running the vaccum advance off of manifold vaccum, and i re-adjusted my vaccum advance can to add 12 degrees of timing at 18 inches of vaccum and i put it on the ported vaccum source.
And ever since i changed the dead plug on the number 5 cylinder it has been running pretty good. But then last night when the engine was cold i noticed that thudding sound out the exhaust again!!!
I'm just hoping someone here might have some answers for me, or might have some things for me to check to make absolute sure there is nothing wrong with my ignition set up. And i was hoping somone here could tell me why my engine was thudding out the exhaust while at an idle with 14 degrees of initial timing and another 10 degrees of timing from the vaccum advance with the vaccum advance hooked up to manifold vaccum. I mean where should my vaccum advance be ran from? ported or manifold? and if it should be ran off of manifold why wont it idle clean on manifold vaccum?  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 08/20/12
06:11 PM

a few things...

are the #5 and #7 spark plug wires separated by more than an inch...  this is an issue in a LOT of motors causing inductive cross firing..  where the magnetic field created in the corona around the spark plug wire induces a high voltage spark in the wire next to it..  in the 5/7 case... it fires the #7, 90 degrees early... burning off a lot of fuel. causing it to run lean and melt the piston usually...

something more likely..  pull the cap... flip it over... look at the pattern of the arcing the tip of the rotor leaves on all 8 terminal ends located inside the cap...    the burn marks should be on the CENTER of the terminal.. half way to the tip...

they should NOT Be at the top of the cap....  if they are..  you have found an issue i ran across about 10 years ago..  i went as far as calling the blue streak trouble shooting line..... sent the offending cap and rotor  back to the parts store where they were supposed to forward it back to standard ignition.. standard called me later.. ask me where the cap was...   the parts store thought i was crazy and tossed it out..   i actually think.. that the tip on the rotor was installed/riveted on backwards... as the ROUND side was out.. instead of the flat square end i would normally expect...

you do have to understand that when the high voltage spark is created in the coil secondary...  it comes down the coil wire... has to jump the gap between the tip of the rotor and the cap terminal.. run all the way down the spark plug wire to jump another gap at the spark plug...  flow through the heads.. and eventually work its way back to the ignition module mounting bolts...

please stop by your local parts store.. invest the 6 bucks in the HELP brand 15" braided ground strap... hook the 3/8 hole end to the back of the head.. after you have scraped the paint off..  use a flanged bolt.. or a lock washer...  put the other end under one of the ignition module mounting bolts.. this will greatly shorten the distance the high voltage spark has to travel to make a complete circuit...

lastly.. invest in a new reluctor..    if your reluctor has a single chipped tooth.. you will have a misfire..  if its rusty.. or been sand blasted..  it just won't retain as much magnetic field as it should... they are cheep and they do go bad...

lastly.. when you are looking inside the cap... are the wear marks evenly across the inside cap terminals.. or all to one side.. if so.. replace the reluctor.. and put it on with the PIN in the other slot...   one slot for big block apps.. one slot for small block apps..  i forgot which.. i don't know why i cannot recall.. there are arrows to show the rotation of the shaft.. and the pin goes on that side...  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/20/12
08:57 PM

my reluctor is brand new, the distributer is brand new and everything in the distributer is brand new. but i did follow your instructions that you had gave another person on this web site as to checking for bad grounds. I set my volt meter on dc scale and checked the volts between the positive and negative battery terminals with the engine running and the headlights on you had said you should see 14.1 to 14.6 volts, well mine read 12.5 to 12.6. I also checked between the negative battery terminal and the engine block, you had said you should see 0.04 volts, mine read 0.01 volts, i then checked between the negative battery post and the body, you had said you should see 0.02 volts, mine read 0.00.
I also checked between the positive battery terminal and the altenator output stud with the engine running and the headlights on and you had said you should see 0.5 or 1/2 volt, mine read 0.665 volts to 0.700 volts.
But you had said to the other guy on this web site to set his meter on 20 volts dc scale, my meter wont allow me to set it on 20 volts dc scale, i just have dc scale or ac scale or ohms and a couple other settings. It's a craftsman meter that i got from sears. But i'm wondering with the numbers i have given you if you can detect some bad grounding issues? and i am just wondering if these gound issues can cause an ignition miss?
I do have my wells ecu ignition module grounded from the back of the mounting bolt to the engine block. And i also have my wells voltage regulator grounded to the engine block as well.
My ignition is ran thru a 50 amp toggle switch, and i am also powering th lights for my oil and tempature gauge off the same toggle switch thats powering my ignition? is there any way a 50 amp toggle switch could not handle powering the ignition and the lights to 2 small gauges? just wondering if i have too much of a load on my toggle switch? and if its possible its causing a miss? i would hope a 50 amp toggle swith could handle powering the lights to 2 small gauges and my igntion module.  

69_340_GTS 69_340_GTS
Enthusiast | Posts: 535 | Joined: 06/09
Posted: 08/21/12
04:10 AM

I'd never run  vacuum advance off a non-ported source. You wind up with way too much timing at low RPM & especially at idle.

A 50 amp switch is more than enough.  Check all the connections though.

Does the engine miss under power?

You do realize that you will probably never have a butter-smooth idle on this motor, given the cam that is in it.

Plug wires is a real good place to start looking, IMHO.  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 08/21/12
07:18 AM

first... i am taking that you also installed a chrysler electronic voltage regulator..  i don't like the low output..

can you measure the voltage from the output terminal to the case of the alternator...

since you have bypassed almost everything else....   do you have an amp meter in the dash?? or a volt meter??

you might want to run a 10 gauge wire in addition to the stock harness...  from the alternator output terminal to the positive battery...

you have several choices.. and i will have to look up a wiring diagram ..  this shorten the path the output voltage the alternator puts out to get to the battery..

here is the diagram of the 73 ignition and charging system.  since the power and logic modules controlled the alternator charging am taking that you must have installed some kind of voltage regulator...

Mopar Electronic Ignition Diagram

the DASHED wire does not exist on yours.. the aqua colored wire does not exist.  as the blue wire has voltage at run and cranking positions.. sorry.. i don't have one drawn up for the 4 pin module..

the 0.00 volt reading between the negative post and the body is probably because of the additional ground wires.. or the fact that your truck does not seem to be charging anywhere near where it should be....

here is the complete voltage drop test...

VOLTAGE Drop Testing

were you able to pull the cap and look up inside at the burn marks on the 8 cap terminals?? where the arc from the end of the  rotor is supposed to jump to the middle of the machined area of the cap terminal???

look at the bottom of the reluctor... notice the alignment pins are not 180 degrees apart..  if the reluctor is on with the pin in the wrong slot.. when the coil fires.  the rotor will NOT be pointing directly at the cap terminals.. making it jump a HUGE gap...   the burn marks on the inside cap terminals will be off to one side... not even across the entire machined surface...

how about checking the resistance of the wires...    1,000 ohms per inch max..   its a shame that your meter is auto ranging.. is there a push button that moves the decimal point around...  can you post or PM the craftsman part number.. so i can download a manual to see if it can be manually set...  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/21/12
01:05 PM

wayne, i do have a voltage regulator. It is made by wells. i have a 8 gauage wire going from the altenator out put wire to the starter selanoid i believe is what its called. I can run another wire from the altenator out put post to the positive battery post if you think that would help. My spark plug wires have 450 ohms of resistance per foot. I just measured them. They are borg warner select 7mm supermag wires.
My voltage regulator is wired up correctly. I have triple checked that a thousand times in the past, but i did keep frying the borg warner select voltage regulators... they would only last about a month, but this last time i decided to buy a wells voltage regulator and it has been working fine for the last 3 or 4 months.
I do have a voltmeter inside the dash of the pick up truck. And my meter says Craftsman autoranging multimeter 82139. And i took the cap off of the distributer and the burn marks appear to be even to me. I was thinking about ordering a rotor from napa, echlin makes a performance rotor that has a longer rotor segment then stock and i have been told it really helps with arching inside the cap. The part number to the echlin distributer rotor i am talking about is ech-mo3000  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/21/12
02:35 PM

wayne, i dont know how possible this is, but somone had mentioned to me that it is very possible i need to run a step or 2 colder spark plug, and that the heat range of my current spark plug very well could be causing the thudding out the exhaust while the engine is at an idle.
Again i dont know if this could be causing a problem or not? i do run premium 91 octane fuel, the compression ratio is 9:0.1 and it is a magnum engine, i dont know what the heat range of my plugs are, but the plugs i am running are ngk v-power spark plugs part number zfr5 11 i belive. i dont know if that is a stock heat range or not.  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/21/12
03:36 PM

wayne, i also bought a roll of 10 gauge wire, so if running another wire from the altenator out put stud to the postive battery terminal will help then i can do that.
But i do have an 8 gauge wire going from altenator output stud to the starter selanoid i belive.  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/21/12
03:40 PM

And i just figured out my craftsman meter does have a range button on it wich does move the decimal around.  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/21/12
08:06 PM

come on boys, i need help figuring this out, sould i take the 8 guage wire i got running from the altenator output stud to the starter selanoid off of the starter selanoid and put it directly on the positive battery terminal?  

yvdz yvdz
User | Posts: 118 | Joined: 12/08
Posted: 08/23/12
12:45 PM

I am actually having the same problem with my '73 Dart. [360 engine] It is misfiring sometimes, even though all parts are basically new.  Plugs [NGK] look clear, brand new MSD 8.5mm wires, cap & rotor looks perfect. I posted a problem last year about this car. It had been sitting in storage and I fired it up, it ran for about 30 seconds, then died. I ended up replacing the ballast resistor & module.
It ran fine, then later it started to run rough and wanted to stall sometimes. That second [OEM] module came out of a '74 Imperial I had still laying around. [It had the orange box before] I installed a new module, the next cold start after that was great, like it never did before. However, a week later it was the same problem all over again: misfiring & rough idling. Once fully warmed up it smooths out for the most part. It is sort of ok to deal with in the summer but in the winter this thing is a nightmare to wake-up. I have installed a ground strap from the module to the engine block, another strap from the inner fender to the right cyl.head.
This didn't seem to make any difference. Do I still have to keep the no 5 & 7 wires apart when using 8.5mm wires?  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 08/23/12
05:59 PM

can you run my 4 part test again...

after the first part to verify the amount of charge on the system....

engine off. headlights on for one minute then off..  
12.65 is a fully charged battery
12.45 is a 3/4 charged battery
12.25 is a 1/2 charged battery

you need to have more than 12.5 volts to get an accurate reading of the alternator output and ability of the charging system..

now that you have charged the battery on a charger for an hour at 10 amps to bring it up to close to full voltage after you remove the surface charge again..

run the 4 part test again..

engine running headlights on..

1.    battery neg post to battery positive post.. not the cables the POSTS... 14.1 to 14.8 is expected...

1._______________ resullts

you may have to do test 2 3 and 4 twice.. if you get less than a volt.. but it displays 0.00.. change the decimal to give you 2 volts DC .. so you can read millivolts..

2. battery negative POST to the engine block  0.04 volts is expected...  

2._______________ results

3. battery negative post to the body.. try at the firewall.. or the inner fender.. 0.02 volts is expected..

3.________________ results

4.  engine block to the body.. same places you checked at test 3.. inner fender and firewall...

4._________________ results..

i don't know why your charging voltage was so low....

let me explain the voltage drop test... if you get 0.04 or 0.02.. thats GOOD.. as you are actually measuring the slight resistance of the copper wire as the electrons are FLOWING through the wire and being used someplace.. not just static..

if you can get the charging system voltage up to 14.1 to 14.6 or so volts where it should be...
run the rest of the test...

you can also if the alternator is putting out the voltage.. measure from the alternator output terminal to the battery positive post..  i think you posted that above... i will have to go back and look...

this test takes under 5 minutes..  i can do them in a minute if the hood is open.. so i am trying not to have you spend a lot of time...

i am just trying to figure out why the charging voltage is so low...

say.. how is the battery in the volt meter??? that has caught me a few times.. when it was going dead.. the meter readings were all over the place...

this forum is having some maintenance tonight.. 8/23/12

i am going to pm you .. so you may have to wait till tomorrow to get it .. you have 2 hours from this post...  

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 08/23/12
06:16 PM

the  0.700 MV voltage drop is kinda excessive.. in my opinion.. the whole charging system voltage might be trying to pass through your toggle switch...

thats 7/10th of a volt...

you can always remove the direct cable you are adding between the alternator output and the positive battery...

as for the THUDDING noise...
do you have stock exhaust manifolds..   do you have factory cats.. with a precat... i have had those rattle so hard.. my cousin took his dodge van motor out and brought it to be to rebuild.. and it made the same noise after restarting...  i did not hear the noise.. as he was doing the work..  he actually brought the whole van to my shop to have it checked..  but he got there really early in the morning and stripped the heads and the oil pan off..  he was ready for me to pull the rods and pistons when i got there at 8am..  everything was perfect.. when we started it.. it made the hammering noise.. and let me tell you .. it was LOUD.. and on hard acceleration and when you snap the throttle closed...  another tech who just dropped in.. grabbed a hammer.. climbed under and pounded on the cat case slightly..  noise gone..  the steel wool that surrounds the monolith was burned out.. so the monolith was bouncing around.. he tightened the hold by the housing and it stopped bouncing around..   sounded like the biggest meanest rod knock you ever heard.. but it was not a rod.. ..

if you have stock exhaust.. how is the heat riser valve?

do you have some plastic pliers to pull the wires out of the distributer cap one at a time to find out which cylinder is actually making the noise..  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/24/12
11:21 PM

i dont have plastic plyers... And my exhaust is not stock. I am running hedman hedders into true dual exhaust, my exhaust pipe however is too small. It had a fairly new dual exhaust set up on the truck when i bought it, so i just bolted my hedders to it. My exhaust pipe is only 2 inch exhaust pipe. I normally like to run 2 1/4 or 2 1/2. But currently it has 2 inch exhaust pipe on it with an h pipe right before the 24 inch glass packs.
Maybe my voltage is getting stuck in my toggle switch? i have a 50 amp toggle switch tied into the ignition side of the ballast resistor. My key still starts the truck and my key still powers the starter and powers my heater. My engine wont fire unless the toggle switch is turned on and then once running i can turn the key off but it wont shut off untill i flip the toggle switch off.
With my engine running and with the headlights on and my heater on high between positive and negative battery terminal with my meter set on vdc and it reads mv in the corner of the screen i get a reading of 12.60. with my engine running lights on heater on high and measuering on vdc with it reading mv on the screen i checked between the positive battery post and the alternator output post and it read 12.90.
Between the negative battery terminl and engine block it read 0.003 to 0.004 and between the negative battery terminal and the body it read 0.002.
I also checked between the neagtive battery post and the blue field wire connector on the back of the alternator, that read 11.65. Then i checked between the positive battery post and the blue field wire coonection at the back of the alternator and it ranged from 248.6 to 258.0.
I had these numbers written down from when i did all the testing the first time.
I dont have a way of charging my battery because i do not have a battery charger. My alternator is a 55 amp napa reman alternator and my battery is a car quest 84month battery with 800cca. I have a ground wire running from neagtive battery terminal to the body and from negative battery post to the frame and from negative battery post to the engine block. I also have a 10 gauge wire running from one of the mounting bolts from voltage regulator to the engine block and a 10 gauge ground wire running from one of my ecu mounting bolts to the engine block as well.
So i should be good and grounded. And i was wrong about my alternator output wire being 8 gauge it is only a 10 gauage wire, would it help if i went to an 8 gauge wire? Also is it possible this 55 amp alternator is just not big enough to power everything at an idle and then it does fine once i start driving? becaue that was suggested to me by a mechanic friend of mine. He said i should have at least a 78 amp alternator. Anyways i hope something can be figured out with them numbers i posted.  

pjc360 pjc360
New User | Posts: 39 | Joined: 01/12
Posted: 08/24/12
11:25 PM

another question i forgot to ask, what heat range of spark plug should i be running? my compression ratio is 9:0.1 i run 91 octane premium fuel my initial timing is set at 14 degrees and my total timing is set at 32 degrees. And i am also 4000 feet above sea level. I am currently running ngk v-power plugs the zfr5f11's. It was suggested to me i try a 1 step colder spark plug since magnum engines typically like colder plugs and since i am running 91 octane fuel and since i have a fairly high initial timing setting?  

1 |  2 |  Next   | Last