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Discussion Starter #1
Ive replaced spark plugs, wires, cap, rotor, maf, fuel filter, fuel pump, spider harness, coil, heads fully rebuilt, new cam, timing chain and gears, all new gaskets complete motor kit. Im thinking lifters or a ecm. The misfire is always there sometimes worse then others.
 

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You mentioned the spider harness but what about the spider upgrade itself with fuel regulator? Has that also been done? Do you have a lifter ticking and that is why you are thinking about replacing the lifters? Seems like you have thrown alot of parts at this problem and it may be time to have it professionally diagnosed.
 

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Discussion Starter #3
Its a brand new spider harness with the fuel reg on the back. I replaced the heads do to a 30% loss on cylinder 1 during a leak down test. When i pulled the motor i tried to pull a couple of the lifters and i couldn't get them out without possible damage to them. So i left them in.
 

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Discussion Starter #4
Im thinking lifters cause theres a little tick i have but mainly thinking the possibilty i have a worn out lifter not pulling its weight causing the misfire.
 

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Are you getting any codes? Checked for possible vacuum leaks? With a vacuum gauge? When you say random, is it all over the place or one or 2 cylinders? You said you "pulled the motor", for what? The lifters should have come right out unless they're coated with varnish. If you have a bad lifter the miss would only be on that cylinder. Have you tried pulling one plug wire at a time to see which cylinder? Could also be a worn cam on one lobe if it is only one cylinder. A scanner will tell you the misfire counts on each cylinder.
 

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Discussion Starter #6
Code is the p0300 random misfire. Ive done the pull one wire off at a time and see if it changes and they all drop one by one. When the truck is running it runs good but has a stumble/misfire when idling then will finally though a p0300. I pulled the to do the oil pan gasket and replace the rear main seal. I just replaced the cam and timing chain and gears have less then 15 miles on them.
 

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A P0300 would suggest it's not a bad cam or lifter since it's not one cylinder. If it were cylinder #1, for example, you'd get P0301.
Those 300's can be hard to find.
Next things I'd try are cam and crank position sensors. If they're going bad it can alter the spark and injector timing.
Problem with crank sensor is it requires a CKP relearn after install and that requires a bi-directional scanner like a Tech2. Or pay your local dealer $50-150 for 5 minutes work. You connect the Tech2, find the CKP relearn page and press start. Rev the engine a couple times and then remove the scanner.
What brand cap and wires did you use? 4.3's a finicky about anything other than ACDelco OEM.
 

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Discussion Starter #8
Do i have to take it to the dealer after replacing the crank sensor or would a top of the line snap on or autel be able to do that.
 

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8/31/1897 - 4/29/2004
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Reading these always hurts my brain.
Y’all don’t have any pull a parts or u pull it’s?

a 4.3l is a $100 engine all day long. Why would anyone go through all that when you can buy an entire running engine for $100? Or a blazer for $500-1000. take it’s engine,and put it in your truck...fixed it! lol
 

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Reading these always hurts my brain.
Y’all don’t have any pull a parts or u pull it’s?

a 4.3l is a $100 engine all day long. Why would anyone go through all that when you can buy an entire running engine for $100? Or a blazer for $500-1000. take it’s engine,and put it in your truck...fixed it! lol
Don't know about your area, but up in the PacNW, pick & pulls are pretty proud of their parts....you pay...or don't play.
 

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Discussion Starter #14
I have 2 pick and pulls in my state and my problem with a junk yard motor is i know nothing about the motor. It could be good or have other problems.
 

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I just had a thought. Have you checked the distributor shaft for excessive play due to the bushings being worn out? If the distributor shaft is moving around in the housing that will really mess with the timing on an engine.
 

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8/31/1897 - 4/29/2004
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9,159 Posts
I have 2 pick and pulls in my state and my problem with a junk yard motor is i know nothing about the motor. It could be good or have other problems.
it’s just a simple mechine once the ignition system,and fuel delivery is taken out of the picture. I buy engines,and all kinds of miscellaneous parts from pull a part regularly. I’ve dealt with enough bad engines to know a bad engine before I hear it run.

look for crashed trucks,or trucks with scratches on the roof from roll over..they ran before they got totaled. I’ll peak under a valve cover,and pull the plugs out..looks good I pull the engine,and take it home. If I notice anything when I’m resealing it? I’ll just take it back...r&i a S10 engine only takes a couple hours...


















 

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8/31/1897 - 4/29/2004
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9,159 Posts
Lol! I must be on pornhub too much,because that post had an alternate meaning...haha haha

I’ve already put 45,000 miles on that engine of unknown mileage,history,and condition. any time you buy any used vehicle you really don’t know what you’re getting. using that as an excuse buying a used engine is comical at best. at the wrecking yard you don’t get into trouble taking things apart to discover mechanical condition...most people won’t let you peak inside their engine to tell if they’re telling the truth about maintenance and condition. If you’re capable of doing cylinder head replacement? you should be knowledgeable enough to look inside an engine,and tell if it’s good or not. I’ve seen people spinning engines with electric impacts,and compression testers screwed into the spark plug holes in the wrecking yard...they take it next level,but they obviously know what they’re doing.

Funny thing is I didn’t even use a hoist on that engine. I flipped it straight into the wheel barrel. I was there maybe an hour and a half. When I rolled it to the counter the guy was like wtf?!?!
 

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Ive replaced spark plugs, wires, cap, rotor, maf, fuel filter, fuel pump, spider harness, coil, heads fully rebuilt, new cam, timing chain and gears, all new gaskets complete motor kit. Im thinking lifters or a ecm. The misfire is always there sometimes worse then others.
The old random misfire gremlim. Had this same problem with my 97 and 98 4.3L base model pickups. Like you I threw part after part and $ after $ at it. Nearly bald from pulling my hair out I tried what a friend tried on a 4.3L powered full size Chevy p/u, I bought and installed a new distributor.


Problem solved!
 
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