Grumpy Lean Burn. sputtering and clicking on a 1988 Plymouth Gran Fury.

Engines, Exhaust and Fuel Systems

  1. IndieDippy

    IndieDippy Member

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    Hi. while I'm not new to M body cars i am new to driving them. i have a 1988 Gran Fury with bad lean burn problems. some days the car runs like a charm while today the car acted up all the way home. the car makes a clicking sound at idle that can usually be cured by some revving though i don't like having to rev while someone is in front of me. today the clicking was constant. I've been told that the clicking is the lean burn computer freaking out. the car also has a habit of bucking me back and forth on rare occasions and today it was sputtering out of control. the car was vibrating and sounded like an old pickup truck. it cut of every time i came to a stop especially annoying while trying to park. thing is it worked fine while on the way to where i was going but the problem seemed to arise after i peeled out of a parking lot to avoid a collision with an oncoming speeding car. i have checked my fluids and they seem fine. one thing i have found that doesn't seem right is the choke was sitting wide open while the car was cold. any help with my situation would be greatly appreciated.

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  2. Darth-Car

    Darth-Car Well-Known Member

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    It still amazes me that folks are so quick to blame the Spark Control computer. There has not been a Lean Burn car made since the 70's. The only thing that the two systems have in common is the fact that there is a magic computer box on the side of the air cleaner. The innards of that box are totally different comparing a Lean Burn System to a Spark Control Computer system.

    There are many cars out there that are successfully running around with the Spark Control Computer systems. Yours being an 88 should be no exception. :)

    So where does the problem really come from? It could be a heat related issue. Neither of these systems likes to be hot. On the Spark Control Computer systems they had an actual quilted foil insulation pad on the bottom on the outside of the plastic housing. Check to see if that is still there, or has it been removed, or has time and fluid contact caused it to disintegrate? There are lots of wires that connect to the Spark Control system, check them out for good connection at both ends, and make sure that they have not shorted along their path with worn insulation. Vacuum for the system to work correctly is crucial too. You should have a vacuum diagram under the hood. Vacuum lines may look good, but if they are cracked can flex while driving, causing a vacuum leak that can cause all types of trouble. Inspect the lines thoroughly. Some folks will exercise a vacuum line, and while wiggling it around spray it down with carb cleaner. If the engine surges, or dies during this test you may have found your leak.

    I have never heard of a Spark Control computer clicking during operation; especially so that you could hear it in the cabin. Perhaps you have a bad spark plug wire, or distributor cap? Fire up the car at night in the dark with the hood open. You might see quite the light show pointing to your true problem. Good Luck :)
     
  3. AJ/FormS

    AJ/FormS Well-Known Member

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    The clicking could also just be the PCV valve. It may be responding to a vacuum leak, which could even be a split PCV hose.
     
  4. IndieDippy

    IndieDippy Member

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    let her run for a while at night. saw no sparks but could hear a click or two but the car was behaving at the time.. after letting the car sit for an hour or two it took me back and forth to work no problems, shes quite the bipolar car. she does seem to want to shut off after idling with no revs. i'll try and catch her when shes acting up if i can. from what i've seen the wires seem fine. it looks like it might need a new air filter and the choke is still sitting wide open when cold. my lean burn hypothesis is going off what the previous owner told me and different things i've heard online. i definitely think my problem is rooted in my carburetor.
     
  5. Darth-Car

    Darth-Car Well-Known Member

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    Oh those things you have heard on-line. :D We all know everything on the internet is true. NOT!

    That carb could be a contributor to your problem. First check your choke pull off thermostat and make sure that it is moving freely. In the old days you could adjust the unit which could affect the pull off time. Late model units like yours are factory set, and you can not change the pull of time. It works better this way with the computer. There is a choke pull off thermostat wire. make sure it is connected, and not shorting anywhere. That could mess up the operation of that unit big time.

    There is no mixture adjustment on the carb. It is handled electronically by the carb. There can be one,. or two wiring connectors on the front base of the carb, and they connect back to your friendly computer. So yes the computer controls your spark, and your carb.

    Depending on the mileage, and the type of fuel that has been run through the car you may very well need a good carb rebuild. Find a good, old time carb shop, and let them rebuild it for you. If they tell you you need to ditch the Lean Burn, which we know you don't have. :) then hit the door, because they are Brand X guys, and could not fix a MOPAR if their life depended on it. These electronic carbs can be rebuilt, and will function well if you get a guy doing the work who understands the concept of an electronic assisted carb.
     
  6. BudW

    BudW Moderator Staff Member

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    There is a lot to unpack here.
    I have the tendency to call any engine computer system for any FMJ (or B, R or C body) “Lean Burn” – even though Chrysler only used that term the first couple of years. For whatever reason, “Lean Burn” has been burned into my brain.

    My experience is the computer system gets blamed for most problems but rarely is it the source of problems. I would say it is the source of less than 5% of problems that people blame on it. All the other 95%+ problems are normal non-computerized car problems (fuel, ignition, compression, etc.).

    Now with that said, your clicking problem and intermittent problem might point that direction.

    Automotive choke thermostats (the bimetallic spring portion) does wear out and will eventually stick in a mid-position after 10-15 years. On the shelf, they will last a long time, but the constant heat cycles (0 to 220’ and back/forth) and rust just does them in after time. I recommend changing the choke thermostat on any Chrysler carbureted vehicle (first) that is having drivability problems and if existing choke age is not known (or is over 10 years old, or older). Included with that is to make sure the choke heater circuit is hooked up and working and choke pull off is hooked up and working. It doesn’t matter if carburetor was made by Carter, Holley or Rochester (Q-Jet).

    There is a lot of items that can make a clicking noise on your car. Only one that can injure a person is the ignition system and even then, you will inflect more pain from jumping/jerking away than what the high voltage ignition system can do to you. Touching something that is hot is a different matter, so I do recommend getting some gloves first, even cheap jersey gloves.
    Areas I know that can click is:
    - Starter relay (only when key is in “start” mode)
    - Cruise servo (only when car is moving 30 MPH or higher and cruise is engaged)
    - Wiper motor and/or wiper delay (when wipers are on – unless something is wrong with wipers).
    - A/C clutch relay or other compressor related switches under hood that controls A/C compressor operation.
    - The carburetor mixture control (MC) solenoid. This part is always in motion up/down and its noise can be a buzz, a rumble, a click, a stutter or several various other noises. Mostly the MC solenoid is not that apparent unless air cleaner is off, and you are working close by it – but sometimes it can be on the noisy side. Off to the front passenger side corner of carburetor is a 6-wire black plugin. Unplug that connector when engine is on (or unplug then turn engine on), can confirm the MC solenoid as being noisy. Just don’t leave it unplugged.
    - On the firewall, there are two vacuum solenoids side by side (white circle, below). One turns the EGR valve on/off. The other solenoid (ASRV). This solenoid controls the switching valve for the A.I.R. pump (by the P/S pump). The A.I.R. pump sends air all the time but depending on temp of engine. The air is sent to exhaust manifolds or sent downstream to the rear catalytic converter. The firewall mounted solenoid or the A.I.R. pump mounted switching valve (yellow circle, below) can both make noise, sometimes – but unless there is a good-sized vacuum leak, they are either on or off.
    88 AHBm.jpg
    - The PCV valve came make noise, sense that part is constantly moving – but generally not audible.
    - A short in wiring harness can affect some electrical solenoids – making a click noise.
    - Nonelectrical items can make noise as well, like a bad water pump bearing, idler pulley bearing and so forth.


    Something to keep in mind. The Feedback carburetors have about 10% adjustability (5% movement to lean side and 5% towards rich side) so they have some flexibility to them – when using 100% gasoline. 10% Ethanol came out after our cars were made. Not only is the alcohol harmful to many metal/rubber components of our car – it also uses about 10% more fuel. On a properly running car using 5% Ethanol, you would be right on the border of carburetors limit to adjust the fuel ratio. A 10% Ethanol is not in that limit and will make car run, well like (insert a 4-letter word here). Please avoid using 10% Ethanol in our cars – or get carburetor re-jetted to use 10% Ethanol (but then don’t use any 100% gasoline). Personally, I think you are just better off with 100% gasoline.
    BudW
     
  7. IndieDippy

    IndieDippy Member

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    luckily after changing my air filter and being a bit more gentle with the car (I'm a young guy so i was whipping it) the problems i had that day have not happened again. the clicking which is more of a mix between a "click" and a "clink" only appears every now and then and goes away with a good rev. the car is treating me well for now its just that this one drive where it was sputtering and what not really scared me. hopefully that won't happen again. oh and by the way i put 87 gasoline in the car. been putting 87 in these cars for years and they haven't freaked out beyond normal old car stuff.
     
  8. kkritsilas

    kkritsilas Well-Known Member

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    If the car doesn't have a ton of carbon /coking build up in the combustion chambers, 87 octane is fine. Stay away from ethanol, if possible.
     
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  9. XfbodyX

    XfbodyX Well-Known Member

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    A good vid on the whole lean burn system.


     
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  10. Ele115

    Ele115 Well-Known Member

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    Very few cars need Hi-Test. Cars with carburetors will not tolerate low quality "blends" though. You can expect gas gauge failures and carburetor drama. Same for Boats, bikes and mowers. The stuff at the marina is pricey but has never let me down. They let you fill cans, but not a car.

    As stated, watch for carbon. My one 440 Fury had a cracked exhaust manifold when I got it, and when I removed it 3 of the exhaust passages were about 90% plugged with very hard carbon. The EGR passage was too. I cleaned all intake and exhaust passages for a whole weekend and that cured a number of issues, which if the car had been equipped with ESC or Mean Burn, I probably would have done the conversion and had the thing still run bad when I was done.
     
  11. XfbodyX

    XfbodyX Well-Known Member

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    This would be the cats azz to find one of these.
     
  12. Aspen500

    Aspen500 Well-Known Member

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    Not sure if you guys have it "up north" but look for ethanol free 87. We have it at about 1/2 the stations around here.

    I remember seeing one of those testers "back in the day", at the Ford dealership in the mid '80's, of all places. Never had a reason to use it, not even sure if it worked anymore. They had gotten it for trade ins and even regular customers with Mopars. Not a clue where it ever ended up. Probably in the scrap bin most likely.

    Watching that video reminds me of high school with the scratched film and warbled audio. All it needs is to have is the clatter of the film projector and a film break and then a 5 minute delay while the teacher splices it back together, lol.
     
  13. XfbodyX

    XfbodyX Well-Known Member

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    Wheres my scotch tape?
     
  14. IndieDippy

    IndieDippy Member

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    I'll keep a look out for ethanol free gas. in my area we only really have corporate gas stations (bp, sunoco,711,shell,highs,royal farms) many of the independent ones went abandoned long ago here. car only got grumpy on me once in the past few days. it cut off as i was shifting into reverse twice. i opened up the hood. let it run for a little bit and it didn't act up once going home and when i left later in the day. i think what she really needs is some clean air. perhaps i should clean the carb, maybe move my license plate though i don't think its blocking air to bad.
     
  15. SixBanger

    SixBanger Well-Known Member

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    Maybe vapor lock related by ethanol bend fuel and hot enginebay temp
     
  16. Ele115

    Ele115 Well-Known Member

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    I have compiled a comprehensive list of the benefits of blending corn into our gasoline:
     
  17. BudW

    BudW Moderator Staff Member

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    That list is exhaustive (sic) and gives an compelling reason to use E10 or E85 ( . . . or not).
    BudW
     
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