WHAT'S LIMITING MY POWER?!?!

All the symptoms point to one bank being out.

There wont be any popping/banging if there is no ignition at all, or no fuel on one bank. There will be a strong smell of fuel if there is fuel but no ignition.

You can disable one bank in turn and see if the engine stays the same or doesnt run at all. Exactly how you disable a bank I am not sure without knowing the ignition system. On a 2-coil system you would simply disconnect the coil primary. Some ignition systems dont like simply unplugging the plug leads or HT lead.

You mentioned going on drives. This is not very advisable with a major fault condition of this type present.

 

IF it's the alternator, it could be a connection issue in the charging system, not an actual alternator capacity problem. I'd personally call carbs/intake an extremely low probability as a cause UNLESS the accelerator linkage has gone totally awry and is not opening the butterflies correctly. If they were only opening say, 1/3 of the way, you'd have the described problem.

It'll be interesting to hear what the cause is once you discover it. Good Luck!

 

Previous mechanic that worked on my car wired new 12v supply to coils direct from battery due to only getting 8v at coils using factory wiring loom. This was not enough voltage to keep the Pertronix ignition happy. Seems like the alternator would be a closer source.

 

Post a pic of the connectors at the DFU's they have a specific way to be wired so that they fire. There's also the issues of proper ignition sequencing for waste spark on these flat crank engines.

And yes the DFU's pull a healthy amount of amperage to run, IIRC it's ~9.5Amps at peak load. That requires that they get a direct battery connection for power, using any part of the stock harness is going to cause issues and make it harder diagnose faults. clean new grounds and +B harness is a must.

The alternator should not have any problem supplying the needed amps to run the DFU's as long as the charging system is up to spec. I've only run into problems when updating the 3x8's to full EFI and then when the cooling fans kick on with AC running it can start to load more then the alternator can supply, toss in a hot summer night with the lights on and the battery will start to drain down unless the alternator has a min rating of 100amps.

You may indeed have a bank out, as to why???

 

Invest the money in having a competent tech look at your car, someone local F-car guys recommend. John.

 

Yes.
Does the '79 have the two cat system? If so, the unburnt fuel will be feeding a cold cat (assuming the bank NEVER fires) and not be very exciting, but I would expect fuel to be coming out of the exhaust pipe in short order.

From cold run the engine for 15 seconds. Turn it off and feel the front and rear header. I bet one will be a little warm and one stone cold.

Just for grins you could look into the back side of the cam covers and see if all of the pulleys are spinning when running.

The engine will run just fine on battery power for a long time. I'd leave the alternator alone for now.

 

DFU #2 is wired wrong per the schematics I have on hand. I'll grab my cheat sheet in a couple mins and update. Not sure about the plug wire order.

 

Justin, I'm referring to the yellow plug. DFU #1 is correct:
DFU#1 pinout
A = white
B = Red
C = Black
D = Red/White +12v

DFU#2 pinout
A = Black
B = Red
C = -
D = Red/White +12v

As to the spark plug wire layout. DFU's coil pack closest to yellow plug is coil A, the next one is coil B. So for DFU #1 it's coil A, and B and for DFU #2 it's A2 & B2.

A = cyl's 1&4
B = cyl's 3&2

A2 = cyl's 5&8
B2 = cyl's 6&7

 

I had to go look at the XDi manual, seems that they now have both DFU's wired the same. wasn't always that way. I used to pinout the harness because the schematic and harness didn't always match up.

If you haven't go here and download the manual for the XDi and read thru it, it provides schematics and layouts. Product Manuals | Electromotive

The yellow plug is layed out so that A is for coil A, B is coil B and C is coil C, since there is only 2 coils per pack there is no wire needed for C in the plug. D is the power supply wire.

So a miss-wire will only result in the firing order being all jumbled up.

Also the coil pack needs to have the ground-wire go direct to the chassis. That's the black wire under the allen screw, can't tell where that wire goes to.

 

You could try unplugging one of the yellow connectors and see if it makes any difference. Then plug it back in and unplug the other one and see if it makes any difference.

That way you can determine if you have a whole bank out as opposed to maybe 2 cylinders only (eg a coil has failed).

If a whole bank is out you can look at the firing order which will of course depend on not only the pinning of the yellow plug but also on the HT lead ordering. So you can map this out and check if its correct. Its not possible to see from the pictures what the firing order is, as the HT leads cant be followed.

 

How does the car idle? (Without a heavy electrical load)

A carb car will barely idle and struggle to stay running with a bank out.

 

You must feel the force to gain more power. Review Episode IV.

 

I've been following your progress in this post and the other one involving the timing. You mentioned you did not have a lot of time to diagnose and work on this. Bottom line this is a diagnostic problem and a step by step approach must be utilized. Make a plan and do not deviate from it halfway through.


Either drop the car off and have someone make it right or study how this system works, check what you have and then check each system.

Its either electricity, air or fuel.

Electricity

1. XDI install-Read the manual and info I sent you. There is a status light on the control unit. Watch it as the car starts. I suspect if the XDI install is making the car start and run it is working, however, the firing order can be wrong. Make a diagram using the reference material and cross check it with your engine.

2. Check the ground and +12V connections. You may have to pull the wheel and take out the inner wheel liner.

3. Definitively determine if you have spark on every lead and on both banks. Remember that this is a wast-spark system and the spark plug fires two times for each stroke. Unless the spark plug wire firing order is incorrect, this should not be a problem. Check the insert I sent in the other timing post.

Air

Check air filter and the old mufflers on the car. You mentioned it has no cats now. Crazy thought, but check the passenger side air inlet, plastic tube and airbox throat to see if there is an obstruction. People have been known to put towels or cloth in the air intake to minimize the gas smell after the car is shut off and put in a garage-you never know.

You could also have a vacuum leak, but that involves a whole other set of diagnostic procedures. I also suspect that unless it was severe, the car would still start and run.

Fuel

You know you now have new gas. Could have the old gas "varnished" up a a fine fuel screen? There is a fine mesh filter inside the tank right before the fuel outlet pipe. It can easily get clogged or rip or clogged. Its accessible by taking the nut off from the bottom of the driver's tank. Not the first thing I would check, but it can slow down fuel flow in extreme situations.

Each carb has a fine mesh copper screen/filter that keeps dirt out of the bowl. Were those 4 screens/filters cleaned or replaced?

I mentioned this in an earlier post check the fuel path:fuel pump, fuel filter, hoses, screen filters and jets. Even though your carbs were rebuilt, dirt still could have entered the system during reassembly.


I think the problem lies in the fuel system, but only a diagnostic approach to rule out the integrity of each system will reveal the actual problem.

Be patient, I know you want to drive the car and have it perform properly, as we all do, but many of these cars have been neglected and it takes a while to get things right. Look at it this way, it took years of neglect to get the car this screwed up, you are not going to get it "un-screwed up" in a week. Take your time, be patient and in the end you will have saved yet another 308 from being just marginal to driving like it should when it was in its prime.

Once you get it running well, consider replacing the rubber bushings in the control arms, sway bars and end links, shocks ends, and steering rack mounting. Have the steering rack rebuilt. The end result is great. These cars were special in their day, yet very few are that way now. It up to you to bring it back and reap the rewards. Patience, money and a good mechanics or reference guide are key. Hang in there. The XDI system will get sorted out and soon it will buzz up to 7500 RPM and put a smile on your face.

 

That wiring looks correct for both plugs. Look at the PDF file I sent you that has the wiring diagram and the firing order and check your car, page 5.

 

All 5 of those steps are the perfect procedure for any Ferrari owner in your situation