Jimmy, if you have a good quality scanner tool such as an Autel unit or equivalent, that would tell you real quick during a real time test(engine running)which cylinder is misfiring and how many times. It would also read fuel injector pulse width, and maybe you have an injector tip not spraying as well as the others and goes away when warm. Thanks and keep us posted, Jimmy!
Hey jimmy, I can only echo mm_in_Havasu’s comments other than, if someone was going to make a copy of item I don’t think they would leave out three little dots, I would be more inclined to think that the oem manufacturing process just doesn’t require them anymore.
For what it’s worth: Anytime you do a compression check you should do a leak down check too. You already have the plugs out. The vehicles I work on I have seen good compression but high leak down (30% or more).
Do a simple check of spraying brake cleaner around any intake gasket, Throttle body gasket, injectors, EGR and EGR tube as well as any vacuum lines. If there is a surge in the idle in any spot, then you know you have a leak. Good luck Jimmy
@1RoadGarage Be careful with that! Break clean trunks to Fosgeen gas when it hits something over 300 degrees so be careful. Fosgeen is deadly and there no cure. That's why it should never be used to clean part being welded. Look it up.
Make sure all wires in the fuel injector connectors are tight and not loose with the harness. Take a multimeter and check the resistance in each of them as well as the coils to rule out any resistance issues. You can check the resistance lf the incectors themselves too. Try running some incector cleaner thru the system. Could always sipe down the throttle body and spray the maf with some cleaner to make sure those are clean.
Try cleaning your Mass Air Flow Sensor, and Do a fuel injection cleaning and a throttle body cleaning you probably have minimal deposits on an exhaust valve and it can't/won't seal 100% and that could be your rough idle. Have a great day and wish you all the best.
That sparkplug tester is pretty cool. The front two cylinders being slightly down on compression would have me looking at head gasket. I would do a leak down test on those cylinders. If one was down on compression it could be valve related but because its two a joining cylinders i think head gasket.
Man o man. I hope it’s not the head gasket. Are there any other signs that would rule that out? Truck drives perfectly fine. No smoke out the tail pipe. Oil seems normal.
@@1RoadGarage open Radiator cap while engine is cold led it get to temp thermostat opens and then look for bubbles this is one way to check fir head gasket or get a head gasket testing kit combustion tester
Ugly thought. On that engine you need to remove the throttle body and intake manifold to get the valve cover/cylinder head. It adds quite a bit of time to the job.
Well... When you do discover what the issue is, That'll be one to help others. Case in point, I first started watching when you did your 1st steering bearing video! That was a big help.
Hey Jimmy! Love the content! I'm not sure if you have tried it yet but, I know these GM I6 engines are notorious for this issue. The throttle body gets dirty and sticks slightly from what i recall.. as its a drive by wire system it doesn't have a iac motor to take care of idle air.. its definitely worth a shot imo! On the bright side those plugs definitely needed replacement so not a waste of time lol
Jimmy, with a 20 year old vehicle, there are a lot of things which could be causing a rough idle. Since you have replaced the plugs and found no improvement, I would suggest looking at the fuel and air side of the equation. Is the MAF sensor dirty or faulty? The AIT sensor? The coolant temp sensor? Are your fuel injectors dirty? You mentioned that you replaced the fuel pump already. What about the fuel filter? Possibly a vacuum leak somewhere? Rubber hoses age over time and with a 20 year old car it's likely you have a worn out vacuum hose somewhere. But hey, we love watching your videos so keep on wrenching!
ive chased that very problem for years on every make since efi became the induction system of all manufactures and it always ends up being a injector with some trash in it , id change the injector for that cylinder or make up jumper rig to trigger it and backflush it
Boy Jimmy, I feel your pain. I chased a rough idle for months on my '97 Suburban. I see a couple of good suggestions below. As much as you don't want to find out bad news like a head gasket leaking, it's better to find out now than later going down the road at 80! I've been a 1Road fanboy since way back (Cali days), so I really want to know what you find. Can't wait to see what's next.
I would check them to lower compression cylinders do head gasket test for combustion gas in the coolant and even check to see if it had blow by it running and oil cap off you might have a fouled Fuel injector causing less fuel to a specific cylinder Jimmy 12:00 @1road
I will be buying a spark plug checker tonight. Try a little dielectric grease on the end of the boot when you reinstall them, it will be helpful for removal.
Check the engine mounts. But I’m thinking the throttle body is dirty. Other thing is the intake manifold bolts might be loose. Check for torque. Lastly using brakleen look for a vaccum leak. Remember, no codes tells you it’s not a sensor, misfire etc.
Good video. The tel tale for me was that #4 spark plug. with that residue on it tells me that there is soomething getting into the cylinder that shouldn't be there. Check for coolant or oil getting into the cylinder. If there is something getting in that shouldn't, it may show up on your O2 readings. That is, of there is enough contamination. Just an educated guess. I hate to see you just keep throwing parts at it. Good luck.
Your bad plug had particulate on it, which you noted in the old footage. That is most likely due to oil getting past a valve seal. The oil is atomized in the combustion chamber and that is why you have the particulate on the spark plug rather than a wet plug. Maybe that bit of oil is mucking with your air fuel ratio and causing the slight stumbling.
I've read all the comments through Sept 5, 2023, and I have a similar issue with my Cylinder #1 misfiring randomly, with NO CODES. On my Ford V8 Triton, roller followers go out. They allow the valves to move via a wheel. They pop out of position or freeze/break. I have just opened up my cylinder to examine, and so far no luck. Roller follower looks good. So, we may both have a similar issue, because this cylinder has so much water leakage crustations (like your spark plug) but mine is on the spark plug port, and the buildup is so bad, I can't even get to the spark plug nut area, and I can't remove the spark plug, until I dig/scrape off all the calcium crust. You may also have an internal water leak into the cylinder. Only a Leak Down test will prove it out for both of us....
Disconnect and cap off vacuum ports on the intake manifold including ones going to throttle body. Had a evap purge valve give me the same issue once, found it by eliminating any possible leak point.
I just diagnosed a 16 grand cherokee for a misfire. Plug was ashy just like that #4 plug. It misfired only on cold start and somewhat at idle. Pulled spark plug and checked chamber after it ran for a bit and cooled off. Stuck a bore scope in cyl 3 and found coolant sitting on top of the piston
Have you checked the engine mounts?Try putting in nuetral and see if vibration goes away.The mounts are filled with oil and may show signs of leaking.The passenger side usually goes first being next to the exhaust manifold. You can have youre lovely wife assist in starting it while you film it,then watch in slow mo.If the jolt on initial start get worse with colder temperatures its probably the mounts.Dont forget to check the transmission mount also and buy factory GM mounts. Good luck I hate a rough idle also.
Love your channel Jimmy, just found it and subscribed recently. I've found lots of helpful information for my '97 Chevy K1500. Btw, which video address your final solution to the steering shaft in your '95? I saw the problem you had with the Borgeson shaft and your comment on another channel regarding the Cunningham Machine shaft (which I just ordered). Did you end up going this route and how did it work out if so? I'm sorry I haven't watched all your front end rebuild vids yet which probably address this... my bad!
It happened to me once in my 2014 gmc Sierra After 125k miles I checked everything it was okay I asked many of my friends and all of them told me to adjust the idie because after 125k and 9 years some sensors are not reading right it was 500 rpm when I was parking . My turner guy adjusts the idle in my truck and it runs fine sens then . I hope this helps you Keep the good work
I would look at the intake manifold gasket or the valve cover gasket based of cyl 4 plug covered in fluid. they deteriorate with age and heat since vehicle is from 05. i am going through a similar prob with my 96 gmt. do the ETHER test and see if it revs up around the mating points of the head/valves/motor/intake to get a better idea of where to go, and the plug is not the exact issue but cyld 4 is deff issue. most likely intake/valve cover gasket.
with a compression test like that i'd be doing a leakdown for sure. Also did you inspect the IAC valve? I think this engine must have something similar. i'm an outboard mechanic and any idle issues i always check that IAC 1st.
Just because you swapped all the coils out dosent rule them out you could have got What us mechanics call out of the box bad parts NEW Never Ever Works They could of bren faulty coils out of the brand new Box Jimmy @1Road
I would look at Fuel injectors.. Try some techron fuel additive, it might help and it definitely wont hurt. Not the same beast. but I had a 2012 Cadillac SRX w/150K miles that had very rough idle, thought it was the spark plugs, which they were baked, but ended up it was a fuel injector. Replace one, you might as well replace all of them. Clogged fuel injectors show with a lifetime of cheap Costco gas and the like.
With the engine running, use a laser thermometer & measure the temp of the exhaust manifold @ the cylinder head. The one which is substantially cooler is misfiring. !
these engines are solid but they have a bunch of common issues. Check variable valve timing solenoid, if it does it on a cold start its most likely not that though. also check water pump pulley for side to side play by applying pressure with your hands to the fan. I have seen the water pump bearings go bad to the point the fan wobbles around causing vibration.
So I read through most of the comments on here and nobody has suggested a clogged cat yet. I see you have a video (which I haven't watched lol) about the cooling system so I assume you changed the thermostat housing already, and besides this is a 2005 and the stuck thermostat-->clogged cat issues are more likely to happen on 1st gen gmt360s. So basically what happens is the thermostat sticks open which causes the computer to continue running the engine rich trying to get it up to normal operating temp. Normal temp for these are about 200-210. Wouldn't hurt to check your temp gauge cause there are reports of around 160 when the stuck thermostat thing happens so it can go unnoticed. Sometimes you can get a code too but not always! This could be the source of your fouled up spark plugs and potentially could cause catalytic converter gremlins for you in the future! Hope something in this word spaghetti helps you out!
You should try maybe replacing the idle air control valve. It could possibly be the source or part of the problem at least. And if it’s not it’s a super cheap and easy part to replace so at least you’ll know that’ll be another thing you can rule out. Only thing is you would probably be running a code if it were stuck open or closed or dirty or somethin, so maybe not it.
If your fuel trims look good you know for a fact it's not a vacuum leak. Plug a code reader in and check the timing. Does this vehicle have a timing belt or timing chain? Might have something to do with the timing of cams etc...
@@1RoadGarage Well for one you need a better code reader. And two that live data didn't show ignition timing information. Those fuel trims looked ok to me but it better to have a code reader produce a graph of the live data or show additional items (like timing ignition)
Did you you ever change the cam phaser Solenoid, for the variable valve timing? They don’t cost to much and aren’t hard to change. It caused my Trailblazer to misfire when it went bad.
G'afternoon Jimmy 🤠. Could the issue be an off idle stumble from the idle speed being a skosh too low?. My 98 Chevy Blazer had a very similar issue. It turns out the idle speed was too low and it was causing it to stumble while idling and just off idle until the rpm's picked up and it went away. I turned up the factory idle adjustment screw and even was it maxed out I couldn't get it to idle above 700 RPM. I pulled the idle adjustment screw out of the throttle body, and held the throttle open with one hand while I threaded the adjustment screw in so it was facing the opposite direction and gave the idle set screw more adjustment. I said it so it idles about 950 RPM in park and 750 - 800 rpm in gear. It solved my off idle stumble hesitation issue and now it runs great. I hope this helps my friend 🤠 ..
@@1RoadGarage it's all good Jimmy 😇 . Just remember, when it comes to engines not everything can be controlled electronically. My Blazer has the 4.3L fuel injected Vortech that's electronically-controlled. However there are still some things that have Factory settings like the initial timing, throttle blade angle and the idle speed screw that need to be set by hand so the electronics have something to go off of 😋 ..
Something that's good practice when changing your spark plugs is putting a little antiseize compound on the threads. Especially if it's an aluminum head. It'll prevent any galling if you have to replace them again. In any case, nice work Jimmy!! 👍
Hey thanks, yes that would make sense right? A while back I did some research about that and found a few videos from one of which was a spark plug manufacturer that was talking about how the chrome on a spark plug is actually the lubricant. Said that the only time to use anti-seize is when the threads are bare steel.
Yes watch South Main Auto on you tube .He has a GMC terrain that has the same problem you have.Engine missing and no check engine light on.The fix was to install a new timing chain kit from GM.
Have a friend with a2011 corvette he’s had to change multiple plugs because they go bad just sitting. His car has less than 10,000 miles. Bet he’s changed 6 of the 8. Drive your cars people
For as often as you change spark plugs, every 100K miles, and only buying 6 - don't be cheap! Get them from the dealer or auto part store. Way too many counterfeits out there.
I know. I’ve heard about the mounts but this is more than that. The vehicle will also sometimes stall or almost stall. Rough idle but smooth driving and idle is sometimes smoother than others.
@@1RoadGarage50psi when it's running normally? Or when it's messing up? Might need to get a fuel pressure gauge with a long hose and monitor it while you're driving
Fk acdelco plugs, in my opnion ngk is the best, and i have said it a couple of time now, dump a bottle of seafoam TRANSTUNE, yes transtune in your gas tank when its low, add high octane fuel and drive on highway for atleast 3 hours at 100km/hr speed continuously and then change your engine oil. Ffs just give it a shot.
Only use the plugs that the manufacturer recommends. Nothing else. Same for plug wires, cap, rotor....I never buy any igniton parts online. Only from the dealer, even though its more expensive.
