Ignition/carb question.

6Stang7

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Jun 1, 2003

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Livermore, CA

Mar 23, 2004

#1

• Mar 23, 2004

• #1

I notice that when I lay into the throttle, it just doesn't feel right. She'll pick up, but I would expect more with a T-5 and 4.11's. It feels like there is a delay and that she's not pulling that hard. When I hit the next gear and lay into the throttle she will kinda bog down and then studder a little while the rpm's pick up. When I pull a plug wire off while she is idleing, the idle doesn't seem to change at all, and I can here a spark jumping somewhere. When I hook a new plug up to the wire I pulled off and grounded it, I will get a nice blue spark, it's just it will not fire every now and then. What really bothers me though is the idle not changing when I pull a plug off. What gives here? Carb problems? Ignition problems? Both?

Also, about 3 days ago at work I did a little tire roasting, and after I let off the car was idling at 1200-1500 rpm's. I was able to back the idle screw out all the way, and pull back as hard as I could on the throttle linkage and the idle still didn't drop down. I shut her off, put the idle screw back in, and started her up and the idle dropped back down. What gives with this?

 

68_stanger

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Nov 21, 2003

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Petoskey, MI

Mar 23, 2004

#2

• Mar 23, 2004

• #2

Well, my guess is gonna be carb tuning, is causing the doggieness. But How does it rev when it nuetral? Any doggieness/coughing? Popping? Have you verified spark at each cylinder? If you can verify spark at each cylinder it will be the carb needs adjusted.

 

6Stang7

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Jun 1, 2003

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Mar 23, 2004

#3

• Mar 23, 2004

• #3

It revs fine in nuetral. I haven't tested all the cylinders, but what really bugs me here is the intermitent non-firing of the spark. I am hoppeing that my ground wasn't good.

 

dodgestang

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Dec 15, 2003

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Cecil County, MD

Mar 23, 2004

#4

• Mar 23, 2004

• #4

6Stang7 said:

It revs fine in nuetral. I haven't tested all the cylinders, but what really bugs me here is the intermitent non-firing of the spark. I am hoppeing that my ground wasn't good.

Click to expand...

Bogs down when you give it gas.......fuel dump......non-firing plug....fouled from fuel dump....

Put in new plugs and tune the carb.

 

68GEETEE

5 Year Member

Nov 21, 2003

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Texas, USA

Mar 23, 2004

#5

• Mar 23, 2004

• #5

I was gonna say that if she delays responding with a quick throttle, you may need to adjust your vacuum advance to come on sooner, assuming you are running a stock distributor. Also check for a possible vacuum leak somewhere.

 

F

fastcoupe68

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Mar 10, 2004

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nj

Mar 23, 2004

#6

• Mar 23, 2004

• #6

I agree it sounds like a possible vacum leak

 

6Stang7

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Mar 23, 2004

#7

• Mar 23, 2004

• #7

dodgestang said:

Bogs down when you give it gas.......fuel dump......non-firing plug....fouled from fuel dump....

Put in new plugs and tune the carb.

Click to expand...

The intermiten non-firing was with a spark-tester (looks like spark plug with a clamp on it).

 

6Stang7

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Mar 23, 2004

#8

• Mar 23, 2004

• #8

I don't think it's a vacuum leak, as she revs up fine in neutral. Som times after so hard acceleration and I go into neutral and give her a rev, it will stumble once then rev fine.

 

D

D.Hearne

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Sep 29, 2000

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south louisiana

Mar 23, 2004

#9

• Mar 23, 2004

• #9

What ignition setup are you using? Points? Electronic? Are the plugs and wires new?

 

6Stang7

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Mar 23, 2004

#10

• Mar 23, 2004

• #10

The ignition is a pertronix solid state and the plug wires are new MSD. the plugs have about 2.5k on them.

 

dodgestang

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Dec 15, 2003

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Cecil County, MD

Mar 23, 2004

#11

• Mar 23, 2004

• #11

6Stang7 said:

The intermiten non-firing was with a spark-tester (looks like spark plug with a clamp on it).

Click to expand...

My bad...I must have misread....when did you put the petronix in? Can you swap the points back in for diagnosticss? You still will have to deal with fouled plugs if they aren't firing anyway

 

6Stang7

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Mar 23, 2004

#12

• Mar 23, 2004

• #12

I put it in about 7 months ago and I never had a problem with it. What I am wondering though, is that the idle didn't change when i poppped the plug wire off; however, I did get spark when using the tester. So either the plug don't work, or I am not getting fuel there. When I open the throttle up a lot I can see fuel spary out both primary jets, so that means fuel has gotta be gettin to the cylinder, right?

 

6Stang7

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Mar 24, 2004

#13

• Mar 24, 2004

• #13

Also, I noticed that on the new little gauge cluster I installed, the volt gauge bounces back and forth between 14-16 volts at idle and when I am drivng it runs right at 15. Isn't that too much?

 

D

D.Hearne

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Sep 29, 2000

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south louisiana

Mar 24, 2004

#14

• Mar 24, 2004

• #14

Yea, that's too much. 13 is normal. If you notice the acid boiling out of the battery's top, is also a good indicator of the voltage being too high. Change your plugs, but remember to inspect each of the old ones as you remove them.What about the cap, and rotor, what kind of shape are they in?

 

2nd Mustang

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Feb 24, 2002

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Southern California

Mar 24, 2004

#15

• Mar 24, 2004

• #15

14 volts at idle is good, 15 volts at speed is a little high, 13 volts with no other load on electrical system is borderline low. I had MSD wires which didn't last a year, and I don't drive my Stang very much. You might want to check the distributor cap and rotor. I once had a cheap cap that couldn't handle the MSD6A power. It literally blew the top off the cap when I jumped on it in first gear.

 

J

jesserose17

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Aug 21, 2003

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Southern CA

Mar 24, 2004

#16

• Mar 24, 2004

• #16

Just pop the hood and observe the engine running at night, with all lights off. So, that way, if you see any sparks flying, replace that offening part - wires, coil or cap...

Also, did you bypass the coil resistance when you installed Pertronix? I believe it works better if it gets full 12V input to coil. Check your timing - 10-12 degrees BTDC for stock cam, 14-16 BTDC for mild performance cam. Ensure your vacuum advance is properly working.

If that doesn't help, it's probably time to clean & tune that carb.

 

6Stang7

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Jun 1, 2003

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Livermore, CA

Mar 24, 2004

#17

• Mar 24, 2004

• #17

I found out that the plug wire for cylinder 8 was bad, so I fixed it and I can notice a little difference when I pull the wire off that cylinder. I notice now that she is having problems idleing on her own after she has sat for 5 hours or more. Carb issues?