Not in my case.....1998 Chrysler Sebring Vert with a 3.0l V6.......run awesome everywhere but light load on the interstate, and the miss was so intermittent, it made it extremely difficult to diagnose. Brand new set of NGK's out of the box.....and one insulator had a fine crack in it. Changed the plug and problem gone. This was like 15 years ago but it burns in my mind.....we had a Snap On red brick on it....drove it around for hours over the course of four days.....pure hell.

Jebby

 

That's what I would normally think also but you never know. Just tossing it out there in case he has tried everything else.

 

I put headers and real dual exhaust on my 75 back when it was only 3 years old. Got rid of the pellet catalytic converter and the single exhaust. Even put low restriction mufflers on it like magnaflows. The power went up a lot.

But it ran so lean it would surge at cruise! When the weather changed and it got a little colder and the air a little denser it would miss like mad at cruise. I wound up learning how to change jets & rods in a Q-Jet. Did it twice a year after that, spring & fall. I kept it as lean as possible and it got 20mpg hwy. A bunch of years ago. with 3.08s. 4spd.

 

Well.....replaced the plugs and plug wires and still have the issue. Cap, rotor and points appear to be new. Still not sure if it is electrical or gas starvation. Going to check timing next and maybe a carb rebuild. Car has sat for at least 5 years with the PO starting it occasionally. Here are the pics of the plugs....couple look really lean and couple look rich....give me your thoughs.

Thanks in advance.

 

18436572. 1-4-6-7 pretty clean. 5-3-8-2 dirty. one pri way richer or leaner than the other. carb time.

 

With the sheen and a slight glare off of the upper threaded area, I would suspect oil residue deposit and not fuel. Gas evaporates so fast that you would have to be quick with the camera. You sure that's not oil?

Anyway, I am trying to match two cylinders / two wet plugs with two ports of the cyl head. What I am getting at is, a faulty Intake gasket. Not a leak at the top side of the gasket, nor the sides, but rather the bottom. If the bottom of the gasket leaks, oil vapors from the lifter valley show up on plugs looking just like yours.
And introduces a vacuum leak that is invisible to see. (= erratic idle).
# 5 & # 7 look really dark and are side-by-side ports, just for example.

 

I have a quadrajet 17057213 awp...worth rebuilding it or replacing...if replacing, what would be suitable?

 

From your first post I got that this engine ran fine until your mods.

that being the case I think the focus needs to be on what was effected by those mods first before we go chasing down non existent problems.

IE, jetting/fuel delivery. If that means a carb rebuild I guess you could do that. But if the carb was running fine before the mods then the only thing that has changed here is flow through the engine and that is where the focus should be IMO.

 

Reelav8r...I agree with you....however, I'm not sure if this issue was there before or after...The car is new to me and have only driven it about 25 miles total. I've been sorting out a few things that the PO/his mechanic did. The car wasn't kicking down when it was pushed, so I adjusted the kickdown switch and that worked but didn't drive it that much after. The car idles perfect, i do get a little hesitation taking off from a stop tho.

For the record, this is a driver car with mods....will never be a original example.

List of issue/fixes that have been done at this point
1. Kick down switch adjustment
2. longer wheel studs on the rear....studs were too short and only grabbing about 3 threads on lugs...and only 4 lugs on the rear
3. replaces rear passenger caliper
4. Headers and side pipes w/muffler inserts
5. removed the smog pump equipment
6. new plugs and plug wires
7. new bulbs in the dash
8. repaired power antenna
9. converted r12-134 via ez chill kit....actually work.
10. properly mounted 1982 seats that PO installed
11. replace fan relay and a/c relay
12. install a vented gas cap (wondering if it should be none vented)
13. replaced passenger head light bezel
14. replaced the head light switch
15. replaced 3 fuses
16. repaired/adjusted passenger door handle
17. installed a new coil

Thanks again guys!

 

lean mixture here too. Could be your accelerator pump.

this carb is not the easiest to rebuild and tune properly. If you want to rebuild he carb by just replacing worn components that is fairly straight forward.
if you really want to understand the qjet get this book.

 

Coil? Can you put the old one back on?

 

We have bingo.
(Place bet now).

 

The gas cap should be a non vented. You still have a evap system or should unless someone removed it. The Q-Jet has a tiny paper filter element in the carbs inlet. I have seen cars that ran and idled fine but had a loss of power at highway speeds by dirty filters. Fuel pressure is a concern and should be checked. The Q-jet isn't hard to rebuild. Check out this article from Super Chevrolet on the Corvette EVAP system.

http://www.superchevy.com/how-to/add...or-ecs-repairs

 

Thanks guys...I'll check out all suggestions.

 

Turns out it was the fuel pump. Running good now.