Part Throttle Weak Performance

[bobfake]

Hi all,

Follow up to my posting in the Fuel and Air Systems Forum. As mentioned over there, new carb solved the issue of no squirter action. I'll dive into that carb and figure that out later.

My immediate issue is that the car starts, idles and drives (383, 4 speed), but at partial throttle it is very weak and feels like it is suffering an ignition issue. 1st gear seem OK, but I think the low gearing is hiding the issue. Immediately after shifting into 2nd, 3rd gear and 4th gear, it is just plain sluggish.
What I have done to troubleshoot/correct:

1) Vacuum Leak - none found
2) Float Levels - dribbles out of sight hole when bumping the car
3) Plug wires - all seem to be OK. Less than 1000 miles on them
4) Firing Order - OK
5) Distributor cap and rotor - seem to be fine. Less than 1000 miles on them (Distributor is a freshly rebuilt unit) NOTE: this is a converted Chrysler electronic ignition from who knows when. (See Pic)
6) Timing - ~12 degrees initial and advances as expected with increased RPM. Set with vacuum advance disconnected and plugged. I do not have a timing tape so I don't know total timing.
7) Replaced the coil with a brand new Accel Super Stock unit. (removed the Pertronix Flamethrower coil)
8) Ballast resistor - key in ON position is 5.3v in and 8.75v out.
9) Cleaned and regapped the plugs - less than 1000 miles on them. A couple were fouled.

Any assistance is greatly appreciated. Trying to resolve to go to Carlisle this week and can't drive it 400+ miles in this condition...

Thanks,
Bob

 

[RJRENTON]

Hi all,

Follow up to my posting in the Fuel and Air Systems Forum. As mentioned over there, new carb solved the issue of no squirter action. I'll dive into that carb and figure that out later.

My immediate issue is that the car starts, idles and drives (383, 4 speed), but at partial throttle it is very weak and feels like it is suffering an ignition issue. 1st gear seem OK, but I think the low gearing is hiding the issue. Immediately after shifting into 2nd, 3rd gear and 4th gear, it is just plain sluggish.
What I have done to troubleshoot/correct:

1) Vacuum Leak - none found
2) Float Levels - dribbles out of sight hole when bumping the car
3) Plug wires - all seem to be OK. Less than 1000 miles on them
4) Firing Order - OK
5) Distributor cap and rotor - seem to be fine. Less than 1000 miles on them (Distributor is a freshly rebuilt unit) NOTE: this is a converted Chrysler electronic ignition from who knows when. (See Pic)
6) Timing - ~12 degrees initial and advances as expected with increased RPM. Set with vacuum advance disconnected and plugged. I do not have a timing tape so I don't know total timing.
7) Replaced the coil with a brand new Accel Super Stock unit. (removed the Pertronix Flamethrower coil)
8) Ballast resistor - key in ON position is 5.3v in and 8.75v out.
9) Cleaned and regapped the plugs - less than 1000 miles on them. A couple were fouled.

Any assistance is greatly appreciated. Trying to resolve to go to Carlisle this week and can't drive it 400+ miles in this condition...

Thanks,
Bob
View attachment 1690886

To be a little sarcastic about your situation, but you are the 12,745th person to mix match ignition system components and complain about poor performance.
Looking at your pixs, the ballast resistor is an old 4 prong type. You cannot increase voltage thru the ballast resistor....your point #8. The pix shows what appears to be an origional ECU. It is possible that your point #7 replacing a Pertronix coil with an Accel coil accomplishes nothing....WHY did you do this; what was the reasoning? Why not use an origional coil and corresponding ballast resistor ? The aftermarket ECUs have a poor longevity with mix matched components. Just ask Ray of @Hallifax.com on this site. Indiscriminate components substitution yields trouble.....ranging ftom: no start, poor operation, missing and lack of top end power. The usual explanation is: "an unknown author in a magazine" or a "buddy without any real knowledge" says: all in search of "blazing new horsepower", "faster starting", "better MPG".
The electronics in the ECU are sensitive and must be operated within limits governed by the use of compatible components......talk with Ray @HALLIFAXHOPS ......he'll set you straight.
IMO.....reinstall the ORIGIONAL MOPAR components......
BOB RENTON

 

[bobfake]

To be a little sarcastic about your situation, but you are the 12,745th person to mix match ignition system components and complain about poor performance.
Looking at your pixs, the ballast resistor is an old 4 prong type. You cannot increase voltage thru the ballast resistor....your point #8. The pix shows what appears to be an origional ECU. It is possible that your point #7 replacing a Pertronix coil with an Accel coil accomplishes nothing....WHY did you do this; what was the reasoning? Why not use an origional coil and corresponding ballast resistor ? The aftermarket ECUs have a poor longevity with mix matched components. Just ask Ray of @Hallifax.com on this site. Indiscriminate components substitution yields trouble.....ranging ftom: no start, poor operation, missing and lack of top end power. The usual explanation is: "an unknown author in a magazine" or a "buddy without any real knowledge" says: all in search of "blazing new horsepower", "faster starting", "better MPG".
The electronics in the ECU are sensitive and must be operated within limits governed by the use of compatible components......talk with Ray @HALLIFAXHOPS ......he'll set you straight.
IMO.....reinstall the ORIGIONAL MOPAR components......
BOB RENTON

Bob - thanks for the feedback. I wish I knew the story behind this car, but I've only had it less than 2 years and all of the "upgrades" to electronic ignition, etc were done prior to my ownership. I'm just trying to get it back running strong so I can drive it.

So - to address some of your comments - let me give it a whirl...

1) Cannot increase voltage through ballast resistor...makes sense, but this is the way it has been since I bought it and it was running fine. Even though I haven't touched the ballast resistor, could the wiring simply be reversed?

2) Original ECU...I don't know. It's a MOPAR 1246 unit. Again - what was on when I purchased the car.

3) I changed the coil simply to eliminate that as a possible issue.

@HALIFAXHOPS...Can I call you to discuss sometime soon?

 

[RJRENTON]

Bob - thanks for the feedback. I wish I knew the story behind this car, but I've only had it less than 2 years and all of the "upgrades" to electronic ignition, etc were done prior to my ownership. I'm just trying to get it back running strong so I can drive it.

So - to address some of your comments - let me give it a whirl...

1) Cannot increase voltage through ballast resistor...makes sense, but this is the way it has been since I bought it and it was running fine. Even though I haven't touched the ballast resistor, could the wiring simply be reversed?

2) Original ECU...I don't know. It's a MOPAR 1246 unit. Again - what was on when I purchased the car.

3) I changed the coil simply to eliminate that as a possible issue.

@HALIFAXHOPS...Can I call you to discuss sometime soon?

1. The ballast resistor limits the current the ECU switches. The transistor on the ECUs case switches the primary current to the coil.
2. If the coil requires more current by design the ECU will ultimately fail....no start/run condition.
3, if the ballast resistor is wrong, more resistance = lower coil power, poor performance ; low resistance = more coil power but possible ECU damage over time.
4. I'm a proponent of origionality. Since its a part time car, why not go back to points/condenser system, 0.5 ohm ballast resistor and MOPAR coil and get rid of someone else's headaches.......
You don't say what year car/engine/transmission you have, Do you have the Factory Shop Manual (FSM) ....It has wiring diagrams, parts used, adjustment procedures, etc.....it's an invaluable tool....available on line free of charge......go to the link, down load your car.....it's a big file.....save or print......1000+ pages

www.mymopar.com/service-manuals/

BOB RENTON

 

[bobfake]

1. The ballast resistor limits the current the ECU switches. The transistor on the ECUs case switches the primary current to the coil.
2. If the coil requires more current by design the ECU will ultimately fail....no start/run condition.
3, if the ballast resistor is wrong, more resistance = lower coil power, poor performance ; low resistance = more coil power but possible ECU damage over time.
4. I'm a proponent of origionality. Since its a part time car, why not go back to points/condenser system, 0.5 ohm ballast resistor and MOPAR coil and get rid of someone else's headaches.......
You don't say what year car/engine/transmission you have, Do you have the Factory Shop Manual (FSM) ....It has wiring diagrams, parts used, adjustment procedures, etc.....it's an invaluable tool....available on line free of charge......go to the link, down load your car.....it's a big file.....save or print......1000+ pages

www.mymopar.com/service-manuals/

BOB RENTON

Thansks Bob - I have the FSM. It's a 1968 383 in a Super Bee with an A833 4 speed.

I'm ashamed to admit...I went back over everything again...F'ing (pardon my french) #3 plug wire was off. I would have bet a months salary that I absolutely made sure those plug wires were on properly yesterday when I did the plugs. I have no idea why that one came off, but I can now smoke the tires off the thing...

I really apologize for taking up your folks time with this idiotic issue.....Bob