Lean Burn / SCC trouble...

  • Thread starter Deleted member 1959
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D

Deleted member 1959

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Hi Guys

I just purchased a 1979 LeBaron for Summer use here in Denmark and joined your forum.

The 318 engine has the dreaded Lean burn system with the SCC computer.
I am having trouble with the engine cutting out about the time when the thermostat opens.
It has happened about 5 times over the last two weeks on short trips, but it´s not consistent, and it can happen also when the car is warm and idling: I testet it today and the engine cut out twice over a period of 30 seconds when it reached running temp.
There is no sputtering; it just cuts out like if you turn the key.
I have checked all the vacuum hoses and wires and can´t see anything wrong.
I guess you guys over there must have a lot of experience with this system, so are there some quick things to check before I move on to tossing out the whole system and replace it with a conversion kit ?
I read the Lean Burn Conversion 101 thread, but the article dates back from 1995, so I guess today the solution could be a different one ?
I love the car, and I don´t care what it costs - just want it up and running again and being as reliable as possible !

Best Regards
Claus Jensen

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89.Fifth

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Welcome Claus! Thanks for joining! Gorgeous car you have there, I hope you hold on to it for a long time.

It might not be the lean burn acting up. The LB/SCC is always given a bad rap but honestly these cars have so many bandaid systems for emissions that there's usually a dozen other causes for the problems. There are many things that can cause what you're describing when the car warms up. Could be the ignition coil, ignition wires, EGR, ballast resistor, fuel bowls evaporating, etc etc.

I would start with disconnecting the EGR valve when cold and see if the problem repeats on warmup. There are temperature sensors that open up EGR on warmup but if some portion of it is malfunctioning it can cause stalling. If that doesn't seem to do it then reconnect EGR and test the ignition coil. You should also test the ballast resistor. You're in Denmark so I'm not sure which is cheaper for you to replace first. Both of those are known to fail with heat/overheating.
 
D

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-Thanks :) No doubt I will hold on to it. It drives really comfortable (when it drives) and it´s very rare over here.
I will go on with the testing tomorrow. It´s 7:30 PM here, so no more testing today.
I´m not good with electronics, but I do have multimeter. Can you tell me how to test the ignition coil and the ballast resistor with it ?
 

Master M

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Hello, You could also be having an issue with the magnetic pick up in the distributor. Don't you be blaming that Lean Burn spark computer just yet !!!
That is a very nice car you have.
 
D

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Thanks for the suggestions - I will carry on with the testing today.
 
D

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It starts right up again after it cuts out, so I guess the spark needed is present.
What can I test by putting the choke on ?
I am testing all parts of the system by the Haynes manual, but have not found any faults so far.
 

Dr Lebaron

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No hard cranking or petal pumping after it cuts out and fires right up?
Then never mind the choke thing then.

Clogged fuel filter/fuel line?
Pin hole in fuel line?
Right where it goes from the frame rail into the engine compartment always fails.

What kind of gas is there in Denmark?
I love my 93 octane non ethanol myself.
 
D

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I have checked the fuel filter and the lines around it for leaks, but it´s ok. It will be changed anyway once I start ordering parts.
I didn´t check it for internal clogging, but I have no reason to suspect the flow being obstructed since it starts and runs fine, and can even drive for about 10 km before the cut-out comes.
The problem seem to coincide with the engine being up to temperature and the thermostat opening, regardsless of whether it is driving or standing still in idle.

We get 92 and 95 octane unleaded with max 5% ethanol. In Sweden they can add up to 15%, and the cars that can run on it gets a 25% discount on the price/liter.

Nice car ! I originally looked for a Chevy caprice but the lines on the LeBaron are just so harmonic and the little boattail is just a great design.
Are your LeBarons still running with the Lean Burn systems on ?
 

Dr Lebaron

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I had a few Mopars that would stall just as it was warming up.
But in my case it cranked but wouldn't just restart.
I would reach for the white toggle on the carb, turn on the choke and it would start.
 

BudW

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The Lean Burn computer (SCC) system is a decent system for the most part, and don’t give most people many problems.
Most problems are unrelated, but the finger gets pointed to the LB/SCC.

The ignition coil and distributor pickup coil are the two more common electrical issues, with the pickup coil being more problematic.
Fuel system is the next issue – but what you are describing doesn’t sound like fuel.

If problem is intermittent and dies occasionally – that will be a fun problem to chase down. One can’t condemn a part being bad, until you get catch it in the act. If car restarts right afterwards – that will be a hard one to catch.
BudW
 

lowbudget

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That sounds like the 85 Fifth Ave. I just picked up last summer. That is the reason I got it for $500.00. I just swapped it to reg. Chrysler ignition, non feedback carb and it fixed the problem. After you get left on the side of the highway twice with 2 different vehicles the conversion is a no brainer. Once was a distributor run pick up as the start pick up had already failed in an 85 P/U and the other was the computer in a 85 Fifth. The pick up I knew was going so I had a Direct Connection kit coming and the 85 Fifth I put a new computer in it and started collecting parts. Now the conversion is the first thing I do to a vehicle if it needs it or not. I figure there is a reason there was detailed instructions for de-lean burning a car in the Direct Connection kit.

Where is the coil located? I always take a heat gun/blow dryer to them to see if the heat is causing them to shut down. It only takes a few minutes and it is free! Good luck!
 

BudW

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I “believe” all ’80 through ’89 FMJ’s ignition coils are located on the passenger side rear corner of engine compartment, just above the frame rail.
20160829_140132a.jpg

I used two red arrows, sense part was dirty/oily when picture was taken and it's kinda hard to see – but both arrows point to same item (ign coil).

NOTE: Do not touch an ignition coil during or shortly after engine turn off! It will be hot – too hot to touch! 150’ F or hotter (my guess – not measured one to find out).

There is also a small chance of a (voltage) shock.



To the original poster – without a positive pin-point test to say what the problem is, you will only be tossing parts at it – which is both time consuming and expensive.

That said, if car restarts right after it dies – which It does occasionally, will make pin-point tests very difficult, if not impossible, to do.

Sense Chrysler parts are not on every street corner, there (I’m assuming), I think I would consider EITHER performing a Lean Burn changeover – or at least get the parts on hand for a possible future project (Lean Burn changeover).
Sometimes having the replacement option on hand, will keep troubles away . . .
BudW
 
D

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Hi guys

So I did some more fault finding and changed the negative battery-to-earth cable since it was hanging on by 1/3 of the original wires.
BUT I suspect the real villain was the ignition coil which was leaking oil, and also sits in a (I´ve heard) bad place lying down on the intake manifold.
Now a new one is installed on the firewall; the gas filter, spark plug wires, distributor cap and rotor are also new. Changed a few more vacuum hoses too, just to be safe.
I just ran it for 2 x 20 km without any breakdowns, so I hope it was the coil.

It does not run all that smooth though, but I suspect this is down to an old carb and some badly needed adjustments.

I once had a 67 Toronado which had trouble staring when warm. I changed its 4-bbl Rochester to an identical NOS - never had any trouble since. I am thinking I might as well do the same on the LeBaron.

It has a 2-bbl Holley carb 4095918, which I would like to change to a NOS of the same type. Or maybe there are better alternatives out there that also will be a straight swap ?
 
D

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A small question: on the side of the vacuum amplifier is this pipe sticking out - see picture.
Is this supposed to be open, blocked or connected to something ? I can´t see any loose tubing anywhere.

Vacuum amplifier_LI.jpg
 

BudW

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I don’t know that there is a problem with the ignition coil laying on it's side or being mounted on the intake manifold – other than it gets in the way during repairs, at times.

The ignition coil is oil filled (for cooling), and does run way too hot to touch (don’t touch it when engine is running or shortly afterwards, or it will fry your finger!). If coil has been dropped, or cracked, then it can leak oil. The oil helps transfer heat and as an insulator. A cracked coil will work but - will start to arc or spark jump internally over time, before it dies.

1980, Chrysler moved the Ignition Coil to the passenger side inner fender/firewall corner on FMJ’s.
I thought it was because technicians kept complaining of the coil being in the way all of the time – but honestly – I don’t know why.


Vacuum amplifier_LIa.jpg

The “missing vacuum hose” is not what you think it is.
That is the “vacuum exit” for an electric solenoid. The Lean Burn/SCC controls the EGR valve on your car, and in this case, that solenoid is what the Lean Burn uses to turn EGR on/off. What appears to be a vacuum hose nipple is actually where an approximately ½" x ½" (13mm) square piece of open-cell gray foam is, to use as a mini air filter. The foam is nice to have but is not required. If Lean Burn/SCC is removed, then that solenoid will be disabled (as well as EGR) so it won’t matter anymore.
My opinion – don’t worry about it.


Your Holley carburetor is correct for your car, Holley 2280 Model Number (will be stamped on it somewhere) is R8448A – which is correct for 1979 318 with Lean Burn/SCC in 49 states B, F, M and R bodies. It is not a computer controlled carburetor – but does have a throttle position sensor and/or idle switch located on passenger side of carburetor (Lean Burn/SCC input(s)). You may have more luck looking for the model number (R8448A) than the Chrysler part number (4095918) – which I’m surprised the sticker is still there.

NOS carburetors are out there – if you look hard enough. I would recommend getting a carburetor kit, a new float (if black plastic) and a new choke pull off – and either rebuild it yourself or take to a carburetor shop for rebuild (I would assume there are shops there who do that).

What kind of fuel do you have available there (octane and ethanol content)?
BudW
 
D

Deleted member 1959

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Hi Bud
Thanks for a very informative reply. :)
I am considering getting a rebuilt carb from Rockauto since they have the 2280 in stock and I dont have much experience rebuilding one.
I will get a piece of foam for the solenoid if thats all thats missing.
About the fuel: we get 92 and 95 octane with 5% ethanol. Shell also has 99 oct for those who wants to pay 15 cent more pr liter ;)
 

BudW

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The low compression 318 you have – you will be fine with 92 octane fuel.


Before ordering a reman assembly, please read this https://www.forfmjbodiesonly.com/classicmopar/threads/carter-bbd-w-idle-enrichment-egr-dump.6415/#post-71848 Last half of Post # 8.

FMJ cars were not made to or meant to use anything but 100% gasoline/petrol. At least 5% is better than 10% or 15% that we sometimes get.

It takes about 10-20% more Ethanol to burn, than it does gasoline. Today’s automobiles can compensate for the additional fuel usage, ours cannot (even the Lean Burn computer controlled carbureted ones cannot compensate for that much of a difference) – so your car will always be running on the lean side, a couple of percentage points. That can and will effect drivability, a bit (poor idle, lack of power, etc.).

The second thing is Ethanol eats away at rubber and plastic floats (and metal, long term). I’m fairly sure (but not 100%) there are brass floats that will fit the Holley 2280 (it comes normally with a black plastic float). That would fix the float problem. Replacing the rubber fuel hoses with newer Fuel Injection hoses should fix the other concern.

I have the choice to purchase 100% gasoline (at a higher price) and my cars run pretty well with it. When I have to purchase 10% Ethanol – I can tell the difference right away. I doubt my wife can or an average person can, though.

Short-term, running Ethanol will not hurt anything.
Mid-term, Ethanol, will eat plastic and rubber components up and not allow engine to run at 100%.
Long-term, Ethanol will corrode metals.

If I had to run Ethanol all of the time – I might be tempted to add a fuel shut off valve to carburetor (like my lawnmower) and turn off the fuel to carburetor and let engine die from carburetor bowl being empty. On restart, open the fuel shut-off valve and restart (but it will take a few extra cranks for fuel to refill carburetor bowl).

That said, 5% is a whole lot better than 10% or 15% - so your effects will be lessoned some.
BudW
 
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