I have a misfire

[sam z]

I have a misfire that I didn't have before paint. Trying to track it down.
I'll give the fastest version I can here and chime in with suggestions:
1. Didn't miss before paint.
2. It has electronic ignition with orange box
3. Went to visit mechanic today, ruled it electrical but - Wires, cap, and rotor are all determined
to be "ok" and do not need replacement.
4. Said I have slight amount of play in distributor, but this is not an overnight issue, so to blame
the miss on this might be a stretch (hard to imagine this being an all-of-the-sudden problem).
5. When engine was installed, there was an issue getting the orange box properly grounded.
Eventually, it was determined after not having spark that it was the cause.

I've consulted my old mopar engines guide. Under high speed misfire it says:
-Loose connection or poor ground
-Spark plugs in poor condition
-Faulty plug wires (ruled out for the present time, see above)
-Low battery voltage

Ok, any advice beyond this simple list please chime in. Thanks.

 

[ACME A12]

Red paint. Should have gone with B5 Blue...back to the paint shop... :basketcase:

 

[ACME A12]

I have a misfire that I didn't have before paint. Trying to track it down.
I'll give the fastest version I can here and chime in with suggestions:
1. Didn't miss before paint.
2. It has electronic ignition with orange box
3. Went to visit mechanic today, ruled it electrical but - Wires, cap, and rotor are all determined
to be "ok" and do not need replacement.
4. Said I have slight amount of play in distributor, but this is not an overnight issue, so to blame
the miss on this might be a stretch (hard to imagine this being an all-of-the-sudden problem).
5. When engine was installed, there was an issue getting the orange box properly grounded.
Eventually, it was determined after not having spark that it was the cause.

I've consulted my old mopar engines guide. Under high speed misfire it says:
-Loose connection or poor ground
-Spark plugs in poor condition
-Faulty plug wires (ruled out for the present time, see above)
-Low battery voltage

Ok, any advice beyond this simple list please chime in. Thanks.

If wires, cap, and rotor are all good as stated...then suggest that you double check to ensure a proper ground for the box since you have fresh paint and no miss prior to visiting the body shop. Also check the plugs; maybe one has just gone deep six and it has nothing to do with going to the body shop. Just its time. Report back and we'll keep working down the list.

 

[sam z]

There is only one bolt securing the box to the firewall, there should be two. It was moved, and there is
no hole drilled for the lower bolt, hence it secured in one place.

 

[SomeCarGuy]

This is part of the reason that I ALWAYS run a dedicated ground to the ECU. Always.

Orange box is a POS anyway. You can shoot a self tapper in there and run a ground, but it will still be an orange box. Can't change the spots on that leopard.

 

[george68hemirr]

i am with ray....grounds

 

[moparchris]

Another thing to consider is that there has been a lot of dirt and dust rolling around your car during the paint process and maybe something is awry in the carb. Basically when you get something like this its best to start with the basics.

 

[sam z]

Secured the orange box / scraped paint / fastened properly - misfire not corrected. Checked battery
as well and it's fine.

Going to inspect all the plugs now.

 

[mac]

check the air gap on the dist. :cents: (with a non magnetic feeler gauge)

 

[sam z]

Checked the plugs this morning - two were basically hand tightened, but other than that they
were ok, the gap was good.

Mac - the gap in the distributor was checked this afternoon and it was correct. Checked MP performance
guide on the specs.

This sucks, my gut feeling says something is loose somewhere or a bad ground, I just can
find it.

AND, I don't think this is causing the problem, but who knows. The grounds on the car are misplaced
right now. Neg from battery is going to back of power steering resevoir, not the front of the block.
That location has a broken bolt, and it was grounded to the PS location prior to paint. HOWEVER, the
installer took the short wire that is supposed to be from rear of block to firewall, and instead put it
on back of PS resevoir (with the other) and ran it to the fender underneath the battery tray. This
can't be good.

 

[SomeCarGuy]

It would be worth making sure the car has good grounds. He may have ran it there and not made sure it was a clean area.

You could run a wire from the bat to the ECU to make sure it has good ground.

The pickup in the distributor may be junk???

Make sure he didn't monkey with the plug wires while he was at it. Look at 5 and 7 for sure. Look for a missing vaccum cap. Sometimes cars in a shop will get cabbaged for small stuff to get another car out of there.

 

[SomeCarGuy]

Oh and I still say the orange box might be the problem. They suck.

 

[sam z]

Why 5 and 7 in particular?

Bought some new wires. Going to go enjoy the experience of putting them on. It can't hurt. :brickwall:

 

[SomeCarGuy]

18436572

Easy to cross up, fire really cose, but will miss.

 

[A31PKG]

When you say mis-fire, is it a random rough-running type of thing, or an actual rythmic miss? Is it popping through the exhaust or carb? You could have a bad ground or poor connection somewhere for sure. Since you say it was running fine before, and all that was basically changed was paint, then definitely confirm a good ground path for all things electrical. Otherwise - as already mentioned - the firing order is a good place to start. 18436572, counter clock-wise rotation, with (from front to back) 1357 on drivers side, and 2468 on passenger side. Also, depending on how long the car sat in paint jail (I love that term-learned it here BTW) it is possible that a lifter has collapsed (bled down) and needs some time to pump up. I've never been a big fan of those orange boxes either. Although if it was internally bad, it would not likely pick on just one cylinder, the distributor could though, but why all of a sudden? Hmmm.... Just throwing some ideas out there....

 

[sam z]

Keep with it guys....thanks.
I would presume its not a lifter based on your reasoning. I drove the car to the shop in late April after 5 or 6 months of storage and it was ok. It was in paint jail for less time, between three and four months.

I was at my mechanic's shop last night and this morning. Based on his observations and tests he is convinced it's
something electrical, like just about everybody has stated.

I just changed the plug wires, I figured it couldn't hurt. Didn't start the car. I just got burned out and I'll get back at it tomorrow. They were the the type that you cut, crimp, and fit so it took awhile. Passenger side was a pain.

I'm with a lot of you guys thinking its a ground or a piss poor connection somewhere after being painted. Checking, re-routing, and adding some grounds is on the agenda for tomorrow.

 

[SomeCarGuy]

Did you use fuel stablizer while it was parked?

 

[sam z]

No on the fuel stablizer, but I've run around a tank of new gas threw it since pulling it out of storage, getting it home, etc.

 

[sam z]

Ok...think its cured. The wires. I think a few of you guys eluded to it. A little puzzled how my mechanic eliminated that
as a possibility. :loco:
Anyway, took it around the block a few minutes ago and it ran pretty good. Jumped on it a little too and it ran hard so I think I'm out of the woods.

If I have to open this thread again with crap news I'll be pissed.

Have a good weekend. Hopefully I will now.

 

[A31PKG]

Glad it worked out! I prefer the universal black 7mm plug wire sets myself. The pre-terminated kits always seem to have one or two that are too long or too short. The O.E. sets are better, but cost more $. With the universal sets, you can make them all the right length so they fit the engine. It is a bit time consuming, but at least you get the satisfaction of knowing it was done right, and it looks good too! You could also use a black magic marker to cover any lettering if desired.