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Discussion Starter · #1 ·
My 302 is Dieseling

Hey all,
I have been stocking the boards for awhile now and thought this would be the best place to find help. I have been a Chevy man all my life but have switched up to Ford trucks recently. I bought an 89 Bronco 302 4X4 eddie Bauer edition for next to nothing a couple of months ago. When I drove it I heard spark knock under load at low rpms and just figured plugs and wires would fix it. Well i was wrong and need some thoughts on the matter. I was able to get most of out with the fixes listed below. The truck has 180k on it. I have replaced the plugs, wires, rotor, cap, air filter, fuel filter, and had the timing set at a dealership (timing markers were gone). Thanks for any help I can get all.
 

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aka: kemicalburns
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What was the timing set at by the dealer. should be at 10*btdc. might try a higher octane gas to. now with that many miles on the motor the timing chain could be stretched a bit and not allowing correct timing. did the ford dealer have any suggestions?

What kinda plugs did you use , you might need a cooler plug also make sure your wires are not to crossed up. also check for vacum leaks and drop by an auto parts store and have them pull some codes
 

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Discussion Starter · #3 ·
Yea the timing was set by the dealer. They had it in there replacing a water pump that went bad when my father was driving it (So I didn't get a chance to ask them anything). I didn't even think about the timing chain...hmmm. Is that a known issue for higher mileage 302s? I may go pick up a code scanner this weekend as I don't like other people working on my cars. I used some AC delco platinum fancy plugs (stock heat) because they didn't have my tr55s in stock. I run only 92+ octaine in my vehicles. I have been all through the wires and vacuum tubes. Does it matter where on the dist. cap the wires lay? I guess I could check the intake for leaks. I was trying not to tear into the motor for awhile but it looks like it might be time for a cam and some headers...hehe. Thanks for the info... Anyone else have any thoughts?
 

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aka: kemicalburns
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that motor has a lot of miles on it. so putting cam and headers on it would be a waste of time and money. save a little more and have the motor rebuilt or buy a longblock to replace it. You may need a valve job to that could cause the issues as well.

late
 

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the other guys have listed all the things to check. 180K and you're "not ready" to tear the engine open? It's time for go fast parts ;)

Oh, you put down the wrong term in your title. ;)
"My 302 is Deiseling (sp)" emans your engine won't shut off when you turn the key off.
 

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Actually, "dieseling" is another word for "knocking" & "preigniting". They're all caused by a lean condition, poor timing, or high combustion chamber temps. The chain sounds likely, but so are the fuel pumps and spark plug wire routing. High-octane gas can also cause it, and your Ford dealer should have mentioned it since it's on all their service CDs. Try running regular - it's better (according to Ford) and more cost-effective (according to the EPA).

 

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Discussion Starter · #8 ·
Steve83 said:
Actually, "dieseling" is another word for "knocking" & "preigniting". They're all caused by a lean condition, poor timing, or high combustion chamber temps. The chain sounds likely, but so are the fuel pumps and spark plug wire routing. High-octane gas can also cause it, and your Ford dealer should have mentioned it since it's on all their service CDs. Try running regular - it's better (according to Ford) and more cost-effective (according to the EPA).

Sweet I didn't see that pic under my hood. Really high octane can cause detonation? I was under the impression that because it burns slower it reduces detonation...(I am just a weekend warrior though not a mechanic) The spark knock (dieseling) is very light and only happens briefly unless I am heading up hill. I think the order of wires on the distributor are wrong and I most definetly have a ton of carbon to clean out (Seafoam time). Hell yes I am ready for mods! Sadly I want to get into the 11s with my camaro next season so it gets priority right now. I am trying to get a 351 right now though to do as my first mod.. :rockon . Thanks all for the info and it is good to see the board back up.
 

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Discussion Starter · #9 ·
I rerouted the wires on the distributor cap and ran a bottle of seafoam through the old girl and no more noise. Now if it would just move as fast as it sounds...haha. Thanks all for the advice.

BTW that diagram is for 5.8s and newer 5.0s mine is an 89 302.
 

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aka: kemicalburns
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so what do you think fixed your problem, was it the wires or the seafoam. I have a low rpm ping that i cant seem to fix. im tempted to try this seafoam what do you think?
 

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Discussion Starter · #11 ·
kemicalburns said:
so what do you think fixed your problem, was it the wires or the seafoam. I have a low rpm ping that i cant seem to fix. im tempted to try this seafoam what do you think?
Yea I broke the rules...haha. I should have done one thing at a time to see what works. Imho if you have a high mileage motor there is bound to be at least some if not alot of carbon buildup in the heads so go for it. The bottle is only 7.00 at napa. Do this treatment outside as the truck will spew out black smoke and lots of it. You should also make sure your wires are routed correctly and are well seperated from plug to cap. So far that is all I know about ford 302s...hehe. I hope it helps you out.
 
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