MY TRUCK HAS BEEN SITTING 6 MONTHS AND HAVE HAD TWO MECHANICS TRY TO FIX THIS RANDOM MISFIRE I WATCHED YOUR VIDEO YESTERDAY BOUGHT A DISTRIBUTOR CAP AND FOR THE FIRST TIME I HAVE NO CHECK ENGINE LIGHT ON 😂😂😂. THANKS FOR THE INFORMATION YOU WILL ALWAYS BE A LEGEND TO ME
I fought this battle for years, new cap and it would run great, for about 3 months. I did the following fix and it's now going on 2 years without a fault. Check your distributor rotor for UP and DOWN movement. The cams on these engines will wear the distributor teeth enough the rotor will move up and down and therefore jump/miss contacts.
Wow! Wish I found this video sooner. I'm just winding up a major resurrection, of my son's 2000 Jimmy 4D SLE (mine now). All new brake lines, new fuel sending unit, new fuel filter (could hardly blow through the old one - the new one, is as easy as breathing), replaced radiator (a bitch to get reinstalled - the lower lines), and then got to the heart of the problem, a persistent miss in #6. Same route, bought a used, upgraded MPFI. Cap looked a bit worn, so replaced cap and rotor. Just pulling plugs now. The 3 I've gotten out so far, are all under gaped at .035 to .040. Hope to get it launched by Saturday, and praying that everything works!
MY 1989 S10 Blazer was misfiring. Checked the wiring and found on sparkplug boot toasty... Replaced Cap rotor plugs. Ran ok for a few Months then stated misfiring again. Changed out air filter. Started running ok,but just for a few days... seems like it's running lean. so cleaned out the Throtle body, cleaned out EGR valve. It still worked great no need to replace and changed Map senser and pcv ... Running good again but still has a little shake... after seeing this video, will invest in a really good distributer Cap. Hope that takes care of the problem.... forgot to mention I also changed out all the vacuum lines...If anyone knows anything else I can change out,would appreciate it...
I can concur to this video, my 2003 Blazer Xtreme (Non-EGR 4.3L Vortec) had a rough/low idle and a misfire. I had previously did the full tune up: Spark plugs and wires, distributor rotor and cap, fuel filter, fuel pump (had gone out shortly after buying the Blazer), and oil change. When the running rough condition got worse I replaced the spider injectors having smelled a strong fuel smell in the intake knowing it was the fuel pressure regulator leaking, still ran rough and missed. I then took the distributor cap off and sanded the contacts and reinstalled, still ran rough and missed. I then turned to youtube and came across this video, I knew I'd previously installed a cheap distributor cap so I went and got an Accel distributor cap and rotor, the Blazer now runs perfectly smooth with no issues. I really appreciate your video, it helped me out a ton!
I recommend using AC/Delco parts for fuel & electrical parts. Only problems with cheap parts, been working on GM vehicle's for 40 years. Trust me the few extra bucks is worth it.
Had "no start" issues with my 03 s10, 4.3l. Replaced bad looking ignition coil wire. Also replaced the other wires as they came in a pack. Worked a day. Then no start. Put in a new ignition coil- worked but hesitated badly when revving in neutral. Popping, backfiring or something. Saw your video and said shoot I'll try cap and rotor. They were replaced only a year ago (they were Ac delco parts and looked almost new -8,000 miles). Anyway, put new ac delco cap and rotor on and seems to have fixed the problem. I've taken it out in the rain and a few wet days and hammered on it. Runs stronger than before. Thanks for sharing your video
I was having the same issues with my 2001 blazer and was getting extremely frustrated... I took your advice and replaced the cap and boom! Good as new. Thanks for posting this!
You're welcome. Did your old cap also look perfect like mine did? I've always been under the impression bad caps get all worn and pitted but maybe not.
Yes! No obvious wear... when I took it off I got discouraged because I felt like there was nothing wrong with it. But I was wrong. It obviously was bad.
Look what I just found out why " Moisture " in the Distributor Cap! I made a Video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zWHvMYCItkE.html
my 2000 Silverado has a 4.3L and my cap was tied with 2 zip ties and it looked pretty bad I changed everything spark plugs + wire cap and rotor and I still have the miss fire???? any help
I hear you brother, I'm currently in the same boat and I've narrowed it down to the cap and rotor. parts just got here today but I can't wait to install it with my old man. father /son project with a couple beers
You just resolved a big problem I have had for 2 years and 2 caps and rotors, both from Advance without a fix. Saw this and this time I went to Auto Zone for a different manufactured cap and it was an immediate success. Thanks so much.
Thank you for sharing this video about fixing your Blazer I had the same problem with my Jimmy and after I watched your video went and bought a distributor cap bang fixed thanks buddy
Thank you for posting this video, my 1998 Isuzu hombre started missing and throwing the p0300 code. When I cleared the code I got a p0301 code then after clearing it again I got a p0302 code, then another p0300 code. I saw your video and replaced my 4 month old cap with a new one and it solved my problem. Thanks again, just because the part is fairly new don't rule it out
Give you guys something else to check, chased the 300 code for months it includes such a wide range of parts, multiple parts changed on my 2004 Astro 4.3,checked fuel pressure,vacuum,compression,shorted wiring/replaced spider injector, distributor,rotor,cap,plugs(4.3 doesn't like iridium)wires,coil,maf and map,idle solenoid,vapor purge solenoid and probably forgot a couple things,all along it was the crankshaft sensor,not faulty,but the screw that holds it in the "plastic"timing cover was stripped so the sensor was loose and vibrated around not keeping the 030" airgap it needs,put in a helicoil to fix the threads,my buddy relearned the sensor with his snapon scanner and done,$2.00 thread repair and a buddy!
Thanks for posting this. Quite often it’s the simplest things that are the most confounding. I just picked up a 2000 blazer today. It won’t start. The guy I bought it from took the heads off but didn’t adjust the valves on reassembly. I hope that’s the reason.
Just wanted to add here that on my 97 c1500, I've been chewing through rotors and caps from autozone on warranty for the past 3 years and when this problem showed up, I would replace them both and be good for a while. I have since put in a cheap aluminum distributor (the cap and rotor on those cheap distributors are absolutely awful so just throw them away and use your delco) and my horizontal slop (when turning the rotor) decreased significantly to about 1/4 of the original distributor and I have not had a p0300 dtc show up SINCE. Plus, the cap has actual fine threaded screws now instead of those t15/t20 screws for plastic, big plus. Start by buying new DELCO plugs, DELCO plug wires, and DELCO cap and rotor. test your coil as they generally will NOT be bad and then buy a new one if you want to. Usually a new cap and rotor would last about 6 months, this last time, they lasted a week. My symptoms for misfire was at 1500-1600 rpm, 40-45 mph, and accelerating and decelerating at 70 mph. At all these listed, I would have awful throttle response and engine hesitated so much you could feel it in the transmission! So a few months ago I did the distributor. It doesnt have to be stressful and only takes about 30 minutes. Immediately I could tell there was an incredible difference. Truck had no hesitation at all anymore. Ridiculously smooth idle, ridiculously powerful lower end. It felt like a new truck. I would like to point out I had already replaced the fuel pump and changed from CFI to MFI a few years back when dealing with a intake gasket leak. If you keep chewing through caps and rotors like I did for 3 years and have probably 3/8 to 1/2 inch (1 to 1.3 cm) of rotor movement horizontally, just buy a distributor already, not a stock plastic distributor but an aluminum one. Good luck with your misfire fellow gmt400 guys. P0300 absolutely sucks to diagnose but you'll eventually get there. Edit: reason for posting this now was I noticed my maintenance log was behind and I was updating it. I definitely understand the frustration of not knowing the ending to a thread on a forum post and the like so this is closure and may help at least somebody out. Give it a shot. I used a $50 distributor off amazon. Others online have sworn by this solution too. Look into it at least. I'd replaced every ignition component before this and I'm mad I did. Had a similar issue with a hard pull to the right and replaced the entire front end and suspension trying to fix it. turns out I did not replace the entire system, I had forgot to replace the tie rod adjusting sleeves and they were slipping threads on the tie rod allowing it to fall out of place. Think about everything you've replaced in a system then think if you've missed anything. FSM does NOT say much about p0300 so if you want to buy an fsm just for that (like I had) I'm telling you, it is NOT worth it.
I had a P0305 code = Cylinder #5 misfire. I replaced the #5 spark Plug and wire for $9. This solved my issue. 2001 GMC Jimmy 4.3 V6 "W" code 142,725 miles
My 2003 GMC Sonoma had a P0300 for year until I found a video describing the symptoms and he said to test the points in the cap for continuity (there should be none/no jumping from one to another). 2 & 4 were crossing! I had just installed a new dizzy that day! It was the last thing I thought of! I’m now on my 4th Dizzy. This last one one of the screws was “missing” from the rotor. I found it just sitting underneath. It had backed out and popped off. The other one was so corroded that it sheered off “for me.” 😁 😡 Had to take the whole assembly out, carefully drill it out (after I had tried to make a slot for a screwdriver but no room to get leverage) and reinstall with a new and cheap one. I read a comment on here to use AC Delco
I have an 2000 S10 4.3 that was running rough and one morning, out of the blue, just would not fire up. Chevy guy at work said cap and rotor but don't buy the cheap one or in 2 to 3 years it'll be time to change it again. Replaced cap and rotor and yes it was time, lots of corrosion/fuzz on the contacts, and she fired up. Fast forward 2 years later and it wouldn't start. New cap and rotor and she fired up. Somebody posted a few comments below that the 4.3 does not like aftermarket parts and I think their right. Aluminium contacts on mine looked slightly "frosted" and it kinda looks like yours do too. Nothing beats copper. Next time, maybe.
I agree I had that same problem with a brand new cap it was a cheap Chinese it was all I could get at the time and it ran like crap I noticed it during routine maintenance so I put my old cap back on ran fine until I was able to buy AC Delco now I keep a spare AC Delco cap rotor and spark plugs they fit perfectly in the glove compartment
Juuuuuust Changed the rotor, (palindrome), ha ha ha, anyway, '96 Blaze, 152k, $700, ran fairly well before anything was done to it. Had a skip in number one, and a slight dry noise so I change out the water pump, fixed that. Changed out plugs. Same diagnostic. Change out rotor and cap. With cheapest one they had. I wanted to buy the more expensive one but my mechanic friend said they wear out about the same time, no matter which one you get. Still intermittent skip. I guess I'll buy the more expensive cap tomorrow. I will keep my fingers crossed... hope it's not the spider array. Thanks great Vid Truth.
The dis. cap in the V6 4.3 is NOTORIOUS for failing. Most recommend AC Delco and nothing else. But whatever works for you. What I did was replace the all plastic distributor (the whole unit) with an all aluminum one - simple pop & drop. $100. For me that made a HUGE difference. Plastic under stress and heat will eventually ALWAYS fail.
It doesn't matter which cap you buy, they all will eventually start crossfiring. I've gone through 4. I started with the oem then bought the expensive one. Last two I got cheap from rockauto. They all lasted about the same time
When the fuel pressure bled off, I don't think he clamped off the fuel line/lines to see which direction the bleed off was. Mine right now is bleeding pressure off in the direction of the fuel pump. Holds pressure after clamping that fuel line off in front of the fuel filter.
I have a 2003 GMC Jimmy with a 4.3L. It has a low rpm misfire and runs a little rough at idle. I’ve done a tuneup with new plugs, plug wires and distributor. I replaced the intake gasket. I did a compression check all good. I replaced the spider injectors three times in one month. Still have a misfire at idle.
I have a 97 GMC Sonoma, same motor. I have to change the router and cab once a year because of the same problem. Have a brother with the same vehicle as you he too has to change the cap and rotor every year.
On my 2000 express 4.3 the distributor sensor was intermittent and replacing it fixed the problem. 35.00 after i replaced the EGR Plugs Wires Cap. Just saying its worth changing before the cost gets away from you.
you mean the cam position sensor that's inside the distributor? I replaced that a couple years before I made this video. Cam sensor will almost always throw a code though.
I have a 96 chevy s10... I changed the air filter, the spider, fuel injectors and even took off the bed n changed the fuel pump. I'm hoping it's something as simple as the distributor cap. But so my question... when you say ur blazer ran shitty... what do u mean? I didn't look but do you have a video of it? So my s10 has been repeatedly backfiring as u accelerate, rough idle, smells like gas, doesn't accelerate when I step on the gas... doesn't stall out but just about sounds like it's going to and it's throwing the same codes that you mentioned... I appreciate any feedback thanks!
So I replaced my cap on my 4.3 and I started getting misfires within like 2000 miles, it was a brand new AC Delco, and the contacts were starting to get pretty nasty, I believe it’s because the plug wires are such high resistance all the electricity is zapping the contacts in the cap, I should have replace my plug wires when I replace my cap, this is a 200,000 mile motor and I’m sure the plug wires were never changed
I'm having a really bad distributor problems that are causing a misfire similar to that on my 1955 Ford Customline that has a 1967 Ford 390 cubic inch Fe engine. I'm not sure what to do
we have a 2005 gmc jimmy that we have had since 2021, it just started misfiring, so we started with the plugs. we changed only 5 out of the 6 plugs, and it already doesn't misfire quite as much as it used to, we had the same error code come up(p0300)
it's nice when a car just totally quits running. Seems easier to fix. A friend had a 95 dodge shadow. It had a problem I can't remember now, but it ran really bad. I raised the hood. It made so much noise. All kinds of noise and it was bucking and chucking... I told him, a normal car would just quit with all this going on and we could find the problem.
Yeah, don't buy anything from RockAuto. I tried them and the several items I bought there were junk. I have a misfire right now too. Fuel pressure is okay, but I have a severely melted harness by the exhaust manifold, so I'm going to start by replacing that.
I own an 01 Blazer 4.3 v6. Same issue. I have learned there is a more expensive, better made cap and rotor that is sold on the aftermarket sites. I might have to invest in one.
Yeah some people tune these 4.3's so there's a ton of good aftermarket stuff. I think the stock AC Delco one should be good enough since my truck had the original cap when I bought it and it lasted 155k miles. Where I went wrong is buying China junk.
My 98 Jimmy runs perfect while driving, but soon as I come to a stop and sitting there idling, holding brakes, it starts to fluctuate the rpms, and sometimes dies. Any suggestions?!
Same thing here! I did everything you did except I changed the fuel pump as well,all the sensors! And $800 dollars in parts later it was a $30 dollar distributor cap, So 3 months after I fixed the problem the distributor cap went bad again . Must be a shotty design
GOOD FOR YOU! IF YOU HAD A MULTIMETER YOU CAN OHM THE 2 CYLINDERS THAT WERE MISFIRING AND THERE'D BE RESISTANCE INSTEAD OF BEING OL (OPEN LINE) COMMON ISSUE. AND ALWAYS USE OEM IF YOU CAN AFFORD THEM.
My 2001 Chevy van had the same problem, the distributor cap would crap out about once a year, I switched to a cap with brass contacts, last cap I had to put in it.
Boy I wish that was my problem. But I have a brand new cap and rotor on and still runs like crap or idles like crap. Checked all the same things you did and more. Even took it to a Chevy dealers and one one can dine the problem.
Yea even the ac Delco caps are junk. Ya gotta get something like a accel from summit racing or something super high quality. Because those wires run through the plastic so close together they end up finding any imperfection to arc through. But that's only part of my problem.
Did your Blazer have trouble with start up do to the P0300 code? im running P0300 P0175 and P1870 codes-- i changed the spark plug wires and plugs... new pump filter, my next step was regulator but wanted to ask if that cap problem was giving you start up issues?
It started pretty good but just ran terrible the whole time. If youve got that p0175 it could be a leaking spider injector. Very common problem on these trucks.
i had the same thing i had a bad coil and finally fix it all of it the upstream sencer was bad it caused the misfire running to lean bs change the two sencer often i was surprised after replacing half the dam motor ......
I hope this is my issue as well. I have replaced the entire dist about 4 months ago when the rotor snapped and the truck stopped. Had the engine checked nothing bent. Truck ran great after i replaced the dist but three months after started suddenly misfiring hard at a stop light and died. I have since replaced fuel filter plugs wires and spider assembly. Made my mistake by buying a new dist from autozone. Still under warranty so I am going to get the cap replaced that came with the dist and see if that helps. Great video btw.
Alex's Bikes and Motors yep exactly that. I have gone through damn near everything so I am going to try and replace my cap and rotor plugs and wires and see if it was something simple that my untrained eye didnt think about.
Lol just bought new spark plugs and was juuuust about to pull the trigger on a new spider injector set up. 🙃 going to buy a distributor cap tomorrow and solve this once and for all.
A lot of times its not the cap it’s just moisture in the cap if you spray it down with carb cleaner or anything with alcohol base and wipe it dry it works too saves a lot of money
They are known for the cap looking fine and being bad I had the same problem with my Silverado with the 4.3 about 6 months ago and a GM tech said it’s one of the most common problems with them.
Damn I've done the cap earlier with no luck. About to do the whole distributor. The altnator has went bad twice also. Not sure if related. Chasing so many problems :(
Alternator and misfire probably aren't related at all. if the distributor itself is bad you'll have some sort of spark, the timing will just be out. First thing to do if you haven't yet is to check the diagnostic codes. They'll tell you a lot.
RANDOM MISFIRE FIGHT FOR MONTHS.....MINE ON MY 2001 GMC SONOMA WAS THE ORIGINAL COIL....( GONE BAD ) THE WAY YOU CAN TELL IS THE COIL IS RIVETED ON TO THE BRACKET...... ( WHICH MEANS IT'S ORIGINAL) BEING MINE WAS 2001 ..IT'S 19 YEARS OLD SO I REPLACED IT WITH ONE FROM THE JUNKYARD THAT LOOKED NEW AND WAS BOLTED ON ...WHICH MEANS SOMEBODY REPLACED IT.. AS SOON AS I PUT IT ON MISFIRE WAS GONE..... RUNS PERFECT ....HOPE THIS HELPS SOMEONE OUT THERE ....IT'S AT LEAST IT'S A CHEAP TRY ..
if it happens again i'll probably replace the whole distributor. I made a video before this where i took the distributor out and checked for play at the gear and i didn't seem too bad. Not new but also not that bad
@@alexsbikesandmotors I had to pull my distributor, after shearing off the #@$%! cheap screw, that came with my cheap ebay new cap. Checked it, as per some other video, and it seemed alright, but will keep an eye on it. Thx.
A hairline Crack in the distributor. First time it took me awhile to sort out. Second time, I knew what it was. Mine was on a 70s jeep. No vehicle is immune to this.
I may have the same problem... my 2001 also put out po300 and mass air codes... even crank sensor po335... i did replace the cap with a cheap chinese ebay one.... maybe i need to pay big bucks for autozone one... This thing went for running like crap to total no power un driveable shit... i want to drive it into a tree but its does not have enough balls to destroy it... was yours running like total shit??? thanks
Im looking for one of these truck in good shape...almost impossible to find 2 wheel drive with the 4.3 engine 2 door automatic preferably...id gold on to. this truck...these are very desirable little trucks..
Question I see when you lift your back glass up the panel is broken where the screw was. Mine is stuck close how did you get your window/hatch to open?
Ok fellows got a 92 vortec4.3 Jimmy that I just Dk...misfiring hard starting...pops sometimes..idels high..cuts off when sudden stops and smells like it's flooding sometimes...any suggestions??
There’s a chance that it’ll need another cap soon I worked on a 4.3 safari van that went through like 3 distributor caps in less than 2 months until I finally replaced the whole distributor it hasn’t had the problem ever since
Hi. I am working on a 97' Blazer 4.3 for a friend of mine. It was so difficult to get it to run, but once it ran, it drove perfectly. It would stop every now and then, but no more than that. Anyway... I figured I would replace the distributor cap and rotor. Just by looking at the old cap and rotor, it looked like a new cap and rotor would do wonders. Changed it out with AC Delco parts, and it fired right up on the first crank. Then we took it out for a test drive, and suddenly after 1-2 miles it started breaking up and misfiring really bad. Any suggestions? Should I try another distributor cap and rotor?
Is the check engine light on? the first thing I would do is check for codes. Also I would bet the cap and rotor are fine. There's no way a cap and rotor could fail in 2 miles unless it was installed wrong. Next thing I would do is pressure test the fuel system to rule it out. Connect gauge to port on back of motor, turn ignition on 3 secs, pressure should build to around 60psi and stay above 50 for a couple minutes at least. If you lose pressure then the spider injector needs replacing (very common on this motor and feels like an ignition misfire). If it passes this test and you've got no codes then it's probably ignition. From there I would check every part of the ign system starting at plugs (all 6) and working back to the dist. You're really shooting in the dark without pulling the codes first though. These are complicated trucks and they love to run like crap.
The check engine light is not on actually... First time wrenching on a car this "new", so I dont have a OBD scanner actually. Ordered one now though...Ok, sounds good. I just wanted to ask some people with more experience with these trucks than me. Thank you so much for helping me out, I really appreciate that! :)
My 97 blazer has a sizzling sound coming from the brake pedal. The pedal is also hard to push and hesitate to pull off what could be my problem. Please someone
my blazer doesn't have a tach so I don't know but it ran so bad I couldn't get it to 50mph. Once it started misfiring I drove it home at like 20mph and didn't drive it again till I fixed it. Since you replaced all that stuff on your truck I would do a compression test to make sure you don't have a dead cylinder. Also what codes do you have?
Had the same issue with my 02 xtreme 4.3. Watched a video guy said it only happens on days when dew point is high. I had the same issue so I replaced the cap and it fired right up. Then a few days later it happened again. So it's a shitty factory design with no rubber gasket around the bottom of the cap. So of course moisture builds up and causes a miss fire. Weeeeeeeee
What exactly was the the symptoms you where experiencing. I have the same code on my 99 silverado. I changed the plugs and wires so far and the motor still has a hesitation at 2000 rpm. If i drive in first gear and keep the engine at 2000 rpm the truck will buck pretty bad but i put the peddle to the floor it will run fine after i get passed the 2 to 3000 rpm range. Does this sound similar to the problem you were having?
I just watched your other video and noticed that you removed the wires from the cap in your other video and it ran worse but in this video you said it ran better. Do you think its because you had replaced the spider injection before this video?
No, the spider injector had nothing to do with the misfire at all. Motor ran exactly the same afterwards. I did another pressure test and the new one held pressure, so the old spider was definitely leaking, just not bad enough to affect how it ran. First thing I would do after visually checking for spark is a fuel pressure test. Connect gauge to test port, turn ignition on 3 sec then off. Fuel pressure will: A. Get to around 60psi and hold around 50-60psi for several minutes (this means the spider is fine) or B. Fuel pressure will climb to 60psi and then drop to zero immediately (this means the spider is leaking). If you dont have a test gauge they're pretty cheap like $15 or $20
Describe when and how much did you have the misfire I have a misfire and can't figer it out. It only does it when warmed up to temperature. and only when driving.
So it was misfiring while idling before? My S10 is starting to misfire just a little bit when the engine is warmed up. I know I have a vacuum leak so I'm going to fix that first and see then.
it was misfiring the whole time at any engine speed. Sounded terrible and barely ran. I got another video on here that I made before I fixed it and I talk about the misfire in more detail.
@@alexsbikesandmotors Thank you for sharing. Mine only misses a little bit and runs great so I'm assuming it's something else. Definitely will keep an eye on the Cap though!
On a 2001 Chevy S10 pickup doing plugs wires and cap have you ever heard of you have to reset the computer please comment back in let me know or is it just caught in dry you do the plugs the wires in the cap and you keep it movin need to know thank you
You do not have to reset the computer after changing plugs and wires. Resetting the computer doesn't do anything except erase the codes that set off the check engine light. It won't affect how the engine runs.
@@alexsbikesandmotors But did he have to race it so much that the stuff in the Converter was coming out the tailpipe does he have to race it that much please comment back thank you
