Symptons of Lean Burn Failure ???

gporeilly

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I know a ton of stuff has been written here about removing the Lean Burn but my question is more about the SYMPTONS experienced if the Lean Burn is in fact acting up.
For the most part my 5th runs like a dream and just purrs down the road....BUT every now and then it starts to "buck" or "hestitate" ranging from a few seconds to minutes... then its gone as fast as it came. This problem has been extremly irritating and proving very difficult to diagnose as it happens so sporadically. Usually happens when there is a small strain put on the engine such as heavy traffic with lots of stop/go action, or going up a hill. With that being said, it could very well happen even while cruising on the highway at a steady speed. Taking foot off the gas helps to stop the bucking. Can happen once in a week or almost every day for a couple of days. Weather does not appear to affect it.
Friends have offered various possible causes with the most pausable being that the Lean Burn is going off kilter and not igniting the exhaust gas fumes correctly ?? The car has never stalled but sometimes when it is acting up and the car is turned off it has dieseled on the rare occasion. Just guzzles gas when it acts up and I swear I can actually watch the gas hand move......
Do these symptons indicate that this is the start of my Lean Burn giving up the ghost ??
I am fortunate in that I have acess to the conversion kit to elimate the Lean Burn system, as well as a qualified mechanic. BUT of course I need to be confident that the Lean Burn is the problem for sure before I take the drastic step before conversion.
I have changed plugs, wires, EGR, and various sensors.....all to no avail. I am not mechanically inclined by any stretch of the imagination. Is it possible something simple has been overlooked and could remedy my woes ??

Any and all input from our esteemed members would be greatly appreciated to hopefuuly resolve this very fustrating and aggravating problem which seems to be happening more frequently.

Eagerly awaiting your responses......
 

ramenth

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The fact that it's dieseling tells me that the timing is off. That it doesn't do it all the time tells me it's not a mechanical issue, it's a timing control issue.

Intermittent issues are the hardest to diagnose, but getting back to what it does when it does it:

You say it bucks. I get what you're saying by this, but a little diagnosis done by you, can go a long way. Next time it does it, pull over if you can, and power brake it. Does it feel like an ignition break up? In other words, does it feel like a misfire gone mad? At what RPM range, if any? Does it just stumble and fall on it's face?

As for overlooking something simple... how are the spark plug wires routed? Nice and clean, no overlaps? The wires are good and separated, away from touching metal?

You changed plugs, wires, etc, what about cap and button? Are they free of carbon and corrosion?

Personally, since you say you have access to the parts and someone competent to put 'em on for you, I'd drop the Lean Burn anyway, problems or not. You'll like it better.
 

gporeilly

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Robert,

Thanks for the prompt response. Is the timing control monitored by the Lean Burn system ?? It has only dieseled a few times but it was only when it was acting up. I forgot to mention that idle is very rough as well when acting up. Excuse my ignorance...but does power brake mean to hold brake while giving it some gas ?? The guys here don't think the timing is off as the problem is sporatic and if was timing would be like it all the time in their humble opinion.

I appreciate any advice you can offer and more than willing to try anything you can suggest. Pretty sure the rotor and cap were replaced but the timing was never adjusted as when she runs fine she runs great.
 

jasperjacko

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sounds like a problem I had on an 83 doba. there is 2 pick-up coils in the distrib., a start and a run, could the run coil be going out?
 

tim berry

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I'll go with what jasperjacko said if you want to try another distributor I have a good one I'll give you just pay for postage
 

ramenth

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Robert,

Thanks for the prompt response. Is the timing control monitored by the Lean Burn system ?? It has only dieseled a few times but it was only when it was acting up. I forgot to mention that idle is very rough as well when acting up. Excuse my ignorance...but does power brake mean to hold brake while giving it some gas ?? The guys here don't think the timing is off as the problem is sporatic and if was timing would be like it all the time in their humble opinion.

I appreciate any advice you can offer and more than willing to try anything you can suggest. Pretty sure the rotor and cap were replaced but the timing was never adjusted as when she runs fine she runs great.

And you're guys would be right. Mechanical timing issue, like the distributor being out of time, the timing set going, or a cam issue, it would be happening all the time.

Yes, power braking means holding the brake, in gear, and revving the engine. If you can do this when it's acting up and then post up what it's doing, and roughly at what RPM range it'll help narrow down some diagnostics.

sounds like a problem I had on an 83 doba. there is 2 pick-up coils in the distrib., a start and a run, could the run coil be going out?

Could be. One of the reasons I've asked for more diagnosis on his end and posting up the results.

If it gets worse then it really raise it's ugly little head. Turn the key into the start position it won't crank until you let go and falls back into the run position is usually indicative of a bad start coil. A bad run coil can give the symptoms as it starts breaking down.

At that point, since he says he has the parts and someone to do the conversion for him, it's a good time to go ahead and eliminate the LB.
 

jasperjacko

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I think a new pickup costs 15-20 $ I had this prob. years ago. I paid 2 different "ase" certified mechanics (parts changers) who replaced cap, rotor, plug wires, plugs,fuel and air filters, egr, and still wasn't fixed. Decided to bite the bullet and take to a dodge dealer (expert???) to get it fixed "right". 2 days later they still couldn't figure it out, but recommended replacing all the above parts because they wern't "mopar replacement parts". I said " no, I don't think so". When I went to get the car, they said I owed $120 for labor. I said WHAT LABOR?!, they said test drive and "diagnostics". I said "WHAT DIAGNOSTICS, YOU HAVN'T DIAGNOSED AANNNYYTHING!!!" They refused to give me my keys until I paid . I reluctantly did, and said "kind of like Arnold", I'll be bock ! lol.

I limped it to the library, spent 10 min. in a chiltons man. and figured out the problem.....run mode pickup. I went to the parts store, bought a $12 (non-mopar) part, and had the car running smoothly in another 30 minutes!!

I drove back to the dealer, told them what I did, what it costs, and debated why I, a non educated dope, should have to pay their "educated" dopes. The million dollar answer? My car was too old (15 yrs) and I shouldn't expect anyone to know how to fix it....ARE YOU KIDDING ME!!!!
PS: That dealership is no longer in buisiness!
 
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Greg55_99

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Back in my day (mid 70's) when the Lean Burn started giving people problems, we go to a boneyard and pick up an electronic ignition distributor (non-lean burn), contol box, ballast resister, four barrel intake from a 340 (not hard to find back then) and a Carter AFB carb. Swapped all of that onto a Lean Burn 360. Got rid of the computer. Run like a champ. Bob's your uncle....

Greg
 

gporeilly

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Thanks guys for all the helpful comments...keep 'em coming.

Will take the car for a run today and try the power brake trial and get back with the results. The kit for the conversion will cost me approx $230 including the wiring harness which I thought wasn't bad. Would be FANTASTIC to find something simple with your help to avert the conversion. The car only has approx 37K original miles and I was thinking too damm soon for the Lean Burn to give out, but then I know any part especially electronic can give out at any time. Definately have to check out the distributer a bit further per your helpful advice. In a way I would like to keep the car 100% stock but even though I could have much more serious problems, it is so damm fustrating. ..perfect one minute...acts up...perfect again....acts up....

Oh, a couple of times it was bucking so badly I pulled off the road and turned off the ignition...waited a couple of minutes while I cussed under my breath and out loud....started the car and everything was OK. This is only hit or miss..sometimes it worked for a couple of minutes and problem started again, and other times could run all day with no problem.

Tim, thanks for your very generous offer and I will PM you with details after I take her for a run.

Again guys, appreciate you taking the time to respond.
 

bremereric

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If you go the route of replacing it look into the MSD ready to run distibutor. That's what I did on my M body and it was a simple two wire hook up.
 

gporeilly

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Just got back from having a new pickup coil installed....never solved the problem unfortunately but worth the time and cost to eliminate the possibility. Car ran like a champ for awhile and got me all excited then bam right back to same...acted up for a few minutes then perfect again. While it was acting up a little {much worse at other times} I pulled off to the side and did the power brake. Nothing to report there...just reved up as normal.

Everything has pretty well been eliminated and finally starting to give in that the conversion to remove the Lean Burn is the only route to take.

In the meanwhile, keep those opinions coming. Thanks again to all for their comments.
 

jasperjacko

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It may just be the "flux capacitor" someone said...
 

Jack Meoff

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Engage!
Picard2379-1.jpg


Picard2379-1.jpg
 

gporeilly

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My 5th really acted up today per my posting of bucking/dieselling/etc....pulled off the road per recomendation and power braked to rev engine. .... extremly rough/missing/etc. Pulled back on road and was fine again as if nothing happened. Soooo agravating I have finally resolved to the Lean Burn removal conversion unless someone can suggest something else.
 

gporeilly

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....and the saga continues.....after searching for a garage that still has an old Lean Burn Analayzer for almost 2 years I unexpectly found one yesterday that has one in storage. They are going to dig it out and hopefully they can take a scan of my car late next week. Car worked perfectly yesterday until I headed home from the garage and then acted up again for a few minutes. Seems like ok when cold and then problem when heats up with strain from stopping and going in traffic. Of course no point to scan on analayzer unless acting up so I have to leave the car there for a few days. Still grasping at straws here....

One thing that confuses me on the lean burn elimination is that the detailed online insturctions I have say nothing about replacing the carb but when I read comments from other sources it seems as if the carb does have to be replaced while others make no reference to it. The auto store here that quoted me a price on the conversion parts said nothing about a replacement carb.

Anyone care to clarify for me.

Thanks again guys.
 
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