Misfire caused by a vacuum leak 

I really want to say thank You, I have been looking for this vacuum leak for a really long time. Changed my throttle body, injectors,spark plugs,coils, upper intake gasket,and a few other things. Really wanted to find it myself and not deal with a shop, and watched many many vids and thought to myself, I guess it’s compression BUT when I saw your video, I immediately did what you said and it was my lower intake gasket and changed it .It is running so smooth and I felt a relief come over me. Thank GOD for you!!!!!!!!!!!

I know man, for sure I miss our "daily bread" in the morning. Still haven't found someone as dedicated to share in the word with me. God Bless, talk soon

Thanks for the great info! This is exactly an issue I have been having. DTCs occasionally tripped due to cylinder 1 misfires on 98 Saturn SL1. I wish I would have watched your video prior to buying new plugs, wires, coil, and injector over the course of a year. I also checked the compression just before buying the injector and it was fine. After the injector didn't fix it I opened my ears to hear a hiss. I then found an intake leak right by cylinder 1 using carb cleaner. It looks like water would be a safer way to go, that's what I will use next time. I am going to consider your purchasing your book. Well done.

I really love the content man I've been binge watching you since I found your channel it's really refreshing to see somebody truly confirm a problem and not just replace on a hunch you've taught me a lot of things. I was also very pleased to find out you were a man of God. God bless I wish you and your family the best.

Scanner danner, you're a professional. I learned a lot from you. Keep up the up the good work. BRAVO ZULU.

Unfortunately for the car owner this is true. There simply is not enough good technicians in my field and WAY to many parts changers.

In 35yrs as a tech I have never used water to find an intake leak..I have used oil,brake cleaner, carb cleaner smoke test etc..I can see water is a safer viable option..Thanks for sharing,

Danner was my instructor. Hell of a guy, passionate smart and great to learn from. I'm no longer in the field and still watch his videos. Keeps me interested in diagnostics and sharp on what he taught me. Tell me my man don't look JUST like Karl Hagelin

Best car troubleshooting video for any car or problem that I've ever seen. Thanks. You saved me lots of money with my Neon.

I still come back and watch your teaching videos because you are so fucking thorough, detailed and fastidious. You ALWAYS prove your theory. Thank you! Truth told though, when I fix things, sometimes I just accept a good result and move on without being certain.

i love the smoke. smoke is great for confirming your repair. i hate come backs and charging twice for what could have been spotted on the first visit

Thanks so much for the video. I have an '03 Dodge Dakota 3.9 ltr with over 300,000 kms on it. Long story short the fuel pump had to be changed. Just after the pump was changed I had a misfire on #5 cylinder code. Have changed out plugs, cap, rotor. Checked operation of injector using a stethoscope...all injectors were humming away. Did a compression test today and have some wonky numbers from that but that's another story. Bottom line will do the water check on the #5 and see what comes of it. Again...thanks for the video. Cheers.

Thank you so much. I've been looking for all of the information in this video on how to troubleshoot this without throwing parts at my truck.

Piece of cake on that engine. Whole different story on my 3.0L V-6. Great video. Thanks.

PRODIGY Sir ScannerDanner From the start to finish loved it tutorial great video amazing footage thank you very much. Take care and have a great day PRODIGY Sir ScannerDanner From Nick Ayivor from London England UK 🇬🇧

It is a great "pinpoint" test. Propane will give you an area, but the water shows exactly where. Thanks for the comment

Wish I saw this video before installing new plug, coil plug, maf sensor on my 08 Lexus ls460. I ended up doing a smoke test this morning and found smoke leaking from my intake manifold. Well at least I'll know I have done a somewhat tune up on my car and I guess I'll change all my gasket to be on the safe side. I'm no mechanic but RU-vid, Google, and forums help me out a lot

I don't know what to say, but you are the best boss sir👍

Ty... awesome info... I like the great tip using spray bottle with water... vs flammable liquid sprays.. I've seen so many cars catch on fire with techs using brake clean.... so dangerous..

Scanner danner, you're the man. Intake manifold gasket leak will trigger a misfire.

this is a great video, very helpful for us non mechanics. I've got a 99 civic with a miss fire under load and this may or may not help me but it is nice to have another diagnostic tool to track down the problem. thank you I'll be subscribing to you channel for more information. keep doing what you're doing.

Helpful. Others suggest spraying brake cleaner at the leak to listen if the engine will run better, due to the extra fuel. I do believe that making the engine run worse would be easier and more conclusive. Thumbs up for sure!

I don't remember who showed me that test, but it is a great test. Especially when you don't have a smoke machine. Thanks for the comment

As others said, I never tried water for leak testing but it looks like a great idea. I think this would work better than propane. Gonna try it now on a problem child car that won't idle too well. Thanks for sharing.

Never had an issue with that. I understand your concern though, just be careful if you decide to use a garden hose. No danger with a squirt bottle.

I've also used the techniques you've demoed for finding vacuum leaks, and in addition have a stethoscope I modified with several different interchangeable open end probes; made of various tubing scraps. It's far from perfect, but allows me to listen closely around most anything I can see, and some I can't. Running along gasket lines, there is no doubt when a leak is found. Some are dramatic. It's also great for quickly finding dead/shut off injectors, exhaust leaks, and more.

SD we love you bro. You are one of the best technician I ever know

Good Video, Found you through Eric The Car Guy. Happy i did, good info and easy to understand. Thank you for posting

Thank you! That was the plan, I am trying to combine book material with case studies. I think it helps.

Great video Paul. It's amazing what a simple thing like water can do, oh and a little common sense and knowledge.

Appreciate you bro, this may be my issue on my 03 forester. Grateful for your input time in this video.

I know, you can hear her in a lot of my videos. Brings back memories, doesn't it bro.

That is correct and you will get shocked if you don't give it somewhere to go. It will choose you as the path.

I have a story, which is a puzzle for me and probably for many who reads it. I went to Firestone on Northway Hwy to do alignment and State Inspection. The car is old, and basically it is my toy-car to practice on auto DIY projects. 2001 Saturn SL2. The car was running maybe not the best, but normally, my main concern was alignment, bcs I did a lot of suspension work on the front, and my husband observing how I move parts around came to the conclusion that the car will never run again. At Firestone they couldn't do alignment, bcs they needed a special tool (for the rear), which they didn't have and advised me to go to a dealership to do a proper alignment. To my amazement they said that the current alignment on the car was pretty good, gave me a print, which proved it. I assume, the alignment was good, bcs I counted turns on outer tie rod very accurately. They said that the battery didn't pass the test (car was sitting for a long time), but passed the safety standards, so I need to make 50 mi on it and come back. I went back home, and on the way I noticed that the car started to shake slightly at one red light. When I came home the engine was shaking like crazy. I switched it off, took Actron, but before diagnostic decided to start it again and listen once more what the engine does. The car started vibrating vigorously, the arrow of the rpm jumping from 400 to 1200 and back all the time, then after a loud sound ("bum!") died. There was a small puddle on the ground from the transmission fluid. Actron gave P0404 code, which is emission code, so I decided to clean a Throttle Body, what I did, but there were not much changes. Next morning car died again on idling, when I warmed it up. Now in addition to P0404 it gave a code for the Powertrain Module (Engine computer). I started the car again and without any waiting in Idle went to the Toyota dealership, they did some work on alignment, but also didn't have that tool for the rear of the car, and advised one GM dealer. I suspected bad fuel, so I added like 1/2 tank to make it full, poured good engine cleaner, car started to run a bit better, but still vibrating at stops (though at 800 rpm already). No more leak fm transmission. In that condition (car was still vibrating on lights) I went to Jupiter Chevrolet Dealership, where they did the front alignment perfectly, some rear, but not toe (again no tool for that job on the rear). When I started to drive I immediately noticed that the car runs perfectly well, no rattling, vibration, you could sit like hour in Idle, it runs very smoothly and good. I went back to thank and ask, what it was, what did he do, but the mechanic gone for the day. So my question for the puzzle is: what can be done to the car that it develops a vibration on lights, and see how, not immediately after I left the Firestone, but after about 5 miles of driving? And what the mechanic at Chevrolet Dealership did, that the car runs with no problems now, very smoothly and quietly. Later he said that nothing was done besides an alignment, and he never opened a hood. Thank you for the great film.

Thank you. I teach at Rosedale Technical Institute in Pittsburgh, PA.

Thanks for taking the time to make this video... very good technicians are hard to find & your vid helps me get started on pinpointing the similar problem for my 2002 nissan quest

thank you for commenting and your kind words

Thank You for this upload. This video was awesome. You're a really good teacher.

I think my original comment got erased or something idk,thank u for this video i will DEFINITELY be back on here after trying this.ive got a spray bottle,now i just need a prayer

Excellent demonstration, thank you. 🙂

Very good development of the theme and accurate explanation !!!

on a map (speed density ) engine you can have normal trim numbers with a vacuum leak.

It is helpful for me,I have my idea for DIY about misfire,thanks.

not necessarily intake gasket, I had a time when the injector o-ring was torn in half and was missing the other half, was causing misfires like crazy.

Po302 on my 2006 Subaru sti with 150,000 miles. Runs fine. Swapped plugs, ignition coil next is injector swap then leakdown test

Nice nice. Lovin' the vids dan,got my mind goin' :) Especially the 30 min one on the crankshaft fluctuation sensor.

Scanner Danner is the man !!!!!

i would have never guessed to check that on my srt. im going to do that test tomorrow and if that's the problem im going to be shocked. I have spent well over 1000$ fixing stuff that could be wrong.

Great test, safe and simple.

Thought you said it passed the smoke test? Don't worry about the open loop fault, the PCM will do this if it cannot compensate for the condition. Do the water test as you said.

I saw the thumbnail and was like "is that a Chrysler" I knew because I have a neon and that's the only car I know with an engine that looks like that

Steam cleaning while checking for air leak. 2 for the price of 1. Great test Paul.

Yes it only misfires when it’s cold! Replaced the dang coil pack and fuel injector when all I needed was a gasket

learn something new everyday! thanks, keep the vids coming!

Great information and examples.

Sweet man, it probably worked like a charm didn't it? It is a great pinpoint test for sure.

I'm so glad I found the channel. Your knowledge is incredible. Thanks for posting these videos!! Keep them coming :)

It would have, but I didn't check it. I was focusing on showing the water test.

I like the voice and accent of this guy

Love this videos. Keep up the good work. Looking for more information on intake temperature sensors and the effect they have on fuel delivery

👍 super helpful as always! Thank you!

Excellent tip/trick! Much safer than the carb/brake cleaner method,especially around my suspected leaky EGR tube!

Bravo very good ill try this my car msf c1

Good shit. Thanks for sharing Paul. I'm following along in your book.

Fantastic !! Well done as usual.

Thank you my friend!

Propane/butane, either one is fine. I only suggest a vapor over a liquid (carb or brake clean), simply due to the fire hazard. A vapor if it ignites will quickly go out where as a liquid will keep burning. Either way you must be super careful as you can still catch the car on fire, or worse yet your garage.

Ok I see what you're saying. I had perceived your issue here based on what I experienced with a Chevy for 9.5 years..had it to three "good" shops and they just threw parts at it and one day I just happened onto the problem myself. But by then I was pretty much done with it. It was a gutless pig V6 that really got no better mileage than a V8. If it had been the light duty RWD it would have been fine but mine weighed 673 pounds more and it was like driving an 88 Chevy Beretta with 90 HP all over again. Back then I was only pitted against JD popping John's, tortoises, and old donkey's. I do not miss either of those vehicles.

I think you just diagnosed my issue on my 1995 mustang 3.8l it has a lean o2 sensor reading on only one bank, bogs when cold, and has a low idle. I am going to try this soon. Will let you know the outcome. BUT when first driving, it will begin to bog and WITHOUT changing the throttle position (still under load) the car begins to accelerate back up and run normally. All in the course of maybe 2-3 seconds.

Thank you I will remember that it will be quite helpful for that vehicle and that engine thank you.

Hey Dan, I gotta tell ya, your the man dude. Awesome videos. I'm guessing your from the burg somewhere. I'm from Steubenville. Keep up the good work and....keep on scanning

Great video! I always learn something useful with your vids. Keep them coming!

ScannerDanner, notice how those spark plug wires were improperly routed through those spark plug boots. Aw man.. the guy that did the tune up in the past :D And is that a dodge neon? Nevermind. Interesting video again.

I have the same car 97 2.0 liter sohc neon. I get intermittent cylinder 3 misfires when accelerating to highway speeds. I'm thinking I should swap wires and plugs because, the compression tested good plus i've rotated the injector positions and seen no difference. Plus I noticed minor corrosion in the inside of the wire to coil boot. Don't think they've ever been changed Has 160k miles on it. Also have to do a complete set of motor mounts and replace the egr system and tube in the future.

Great instruction and video! Thank you!

Beautiful. Simple and effective.

Excellent video I have 1nrfe dvvti Low rpm lack of power need to press gas more and sound from exhaust gogogo No rough idle No codes No engine light No white smoke 39mpg atm Change spark plugs air filter cleaned throttle body inside out Any recommendations Its an electronic throttle body can drive 70mph at 3500rpm but lots of noise

As far as i know there are about 10 factors to an engine misfire just to mention the main ones are Vaccum line leaks,Bad Spark plug(s) wire(s),bag ignition coil( pack ) or dirty (carb) fuel injectors.

that a nice unique teat ,I'll try to use it in the school

I’m having the same issue but with cylinder number 4 I was spraying some carb cleaner around the gasket to see any change and the car died before I could finish listening to the RPMs, gonna try this trick out when I got time, just replaced all my wires and plugs and ignition coil brand new. Same issue so I believe I have a gasket problem but won’t jump gun just yet

Hey! Scanner! another well done informative work of art!~ after watching your vids, and your answering of all the different car questions you get here! I've come to the conclusion any car can pretty much be repaired if the mechanic working on the vehicle has thorough knowledge of how a car works~ and that a lot of shops including dealers don't have the experinence or the knowlwdge. so they tell you they can't find anything wrong! or a dealer just wants you to buy one of thier new cars!..LOL!

Just a random story for anyone reading....one time I had a Ford Taurus come in that barely ran, it ran really rough, and no power at all, barely pulled up on the drive on lift at the shop I was working at ay the time. Got lucky in the first thing I checked was spark. ...it had the waste spark set up with one big coil pack that housed three different coils. ...and on two of the towers (one coil)there was no spark at all. So I had the boss order a coil pack, installed it real quick and the car ran a thousand times better now that it was running on 6 cylinders instead of 4. Well I talked the customer into getting a bit of a "tune up"to go along with that repair. Plugs, wires, Air filter and oil change just for good measure. And it was a good thing I did, and that they agreed to it. ...the air filter was really dirty,plugs were black AND wet, BUT THE REAL KICKER is that when I pulled the oil Drain plug, SO MUCH GASOLINE POURED out of the oil pan, it was crazy, it poured out for almost ten seconds strong flow before the oil started to drain out behind it. ...it was crazy. ...just where those two cylinders had a dead miss and all that fuel wasn't being burned, alot of it washed the cylinder walls down and seeped through the rings and into the crank case. ...if they would have NOT bought oil change etc that engine probably wouldn't have survived much longer. ..they said they had been driving it like that for a while out of necessity for waiting until they had enough money to bring it in. Not sure how they made it that long. That was the first time I had ever seen something THAT extreme from an ignition missfire. Pretty crazy. Because you know that the oil pickup/pump had to have been pumping straight gasoline all through the engine.(probably the cleanest oil galleries and bearings in a high mileage taurus in the world at that point after that lol the gas had to have cleaned any carbon build up or sludge or varnish it came it contact with i would think) Not sure how much damage it acquired in that time as far as cylinder wall damage for lack of lubrication and also oil pump damage from pumping super lowviscosity gasoline or bearing damage, , all I know is after the coil pack, plugs, wires, oil change and air filter i test drove it for about 10 to 15 minutes and it ran great, no knocking or any weird noises at all. And it rangood for a longtime after that, theycame in for regular oil changes after that for a while, for all I know they are still driving that old taurus. Lol. THEY WERE EXTREMELY LUCKY I'd say. They were so happy and extatic that the bill was pretty cheap considering how bad it was running they thought it was gonna be a major problem, but it left out of there a totally different running car than when they pulled it, made me feel good too Because I could tell they didn't have much money to spare and REALLY needed that car to get back and forth for Their family. Kinda makes me think that God was looking out for them. Has anyone else ever pulled a drain plug and got straight gasoline or anything else, like coolant or anything, and then the engine still ran good an gold afterwards???? Every time I ever seen contaminated oil ,not even anywhere close to that bad, the engine started to knock.....I would've like to disassemble that thing just to see what kind of impact that had pumping gas through the oil system, my guess would be super clean, but extremely accelerated wear. ....

Wow great video. I'm running on a problem as well with an 03 neon myself. Had a p0301 come on it wouldn't act up in cold start though more when it was fully warmed up. Even at idle it wasn't as much as a concern only happened when I would accelerate. The engine would bog down badly loss of power and then the p0171 came on as well. I noticed my fuel trims go way high when I would accelerate my engine and would bog down. But as soon as I came back and to park the idle was normal and the fuel trims came down again. But only starts to rough idle when I have in drive. I'm assuming that the 301 is cylinder one meaning that problem is in that area and the 171 meaning it's a air and fuel mixture that is incorrect. Which leads me to think one or the other. Fuel injector which u had swapped but no light has come one yet. And two the intake manifold on cylinder one and this video is leading me to believe I may have just that. Also I was wondering is the fuel pressure at idle normal for a neon to be 6-9 psi. I know the fuel pressure at max is around 50psi. But I never do see what the pressure is at idle anywhere. And I get that in my scanner. And also this fuel pump is Brand New from AutoZone it's a Delphi fuel pump

Doing a 2012 Explorer right now. Another shop did the timing chain set now has a steady rpm cruise random, comes and goes misfire and vibration. Doing this on weekend for a friend.

Sad part of engines didn’t have all this computer stuff and sensors it would probably run right

You're a brave man grabbing that spark plug wire like that LOL

Great video ScannerDanner. Subscribed to your channel. Need to pick your brain a bit. I have a 05 Neon SRT-4. Started to get a P0301 3 months ago. Vehicle only has 17k miles on it now. Its not my daily driver. Bigger aftermarket turbo, custom fuel system (pump injectors return line) custom tune etc etc. So far I swapped plug wires.. 1 & 3. After I cleared the code. It came back on. Still P0301. I swapped 1&2 spark plugs still got P0301. I boost leak tested the vehicle and usually if the intake manifold gasket is leaking it will HISS or scream at you. Car has an aftermarket Hondata plastic intake manifold gasket. So I doubt that is it. So recently I went a step further. I took the fuel rail off and my RC 750cc injectors off and had a somewhat local shop flow test and clean them. He said they were fine and had no issues holding pressure and were perfect. So I bought a compression tester and crossed my fingers. all 4 cylinders were 120. (cold motor) So I put everything back together and put a new set of plugs in there just because. Haven't started the car up yet to drive it around. Should I test the coil pack even though it is only 17k miles? Car has an aftermarket small battery from Odyssey with just 330CCA. I noticed I started to get the P0301 when it was cold out. Could the such a small battery cause the code since it is not given enough volts to the car? Car runs and drives fine. and goes WOT fine with no miss at all. Seems to just miss a tiny tiny bit on cold starts. What say you?

maybe this is what is going on with a Trailblazer we are working on...it keeps says air/fuel metering, and we replaced the o2 sensor, and it didn't change anything

I have a P0300, P0301, P0303, P0305 all bank 1 misfire. Could a vacuum leak be the issue?

How do you feel about using a can of carb or intake cleaner and spraying around the gasket to listen to idle raising?

Third attempt, the shop writes down "no problem found".

I believe the intake leak would lean it out . Would the fuel trim numbers start to go rich ?

Thanks Russ!

@scannerdanner update: on 2003 sable v6 duratec, i cleaned Maf, upon start up it went closed loop, stft wher still high average 32 on both banks.. after about 30 sec of running it back to missing at idle and open loop.. I do hear some hissing at back of intake to congested to tell tho, so I'm going to try the oL warter in the bottle trick now..

People talking about the water spray. What you think it happens when it rains and you run over a big paddle of water and steam come out of your motor? You keep going or you stop and park freaking out?

anytime, thank you!

Great video man. Are these kind of leaks more common in engines that have overheated at some point?

Hey scanner danner i have a 07 avalanche with 5.3 with misfire. I did a dod delete and took afm out of pcm. P0300 comes up frequently. Had p0101 pop up for a little but but is a new map sensor. I replaced pvc valve and it ran like new but slowly misfire came back then last week took right side valve cover off and ran it and misfire went away and ran nice. Put valve cover on and ran like a champ for a couple miles then slowly developed a p0101 then p0300. Im lost.

I wouldn't recommend spraying water onto the engine or around electrical connectors. you can use carb cleaner and it's safe on gaskets and connectors. it will also either idle the engine higher or cause it to shudder.

Sorry I can't help with that. Every car is different. You'll need to look it up. Go to Mitchell1 DIY auto repair and pay for a day pass for parts/labor and diagrams. Basically everything that you will need to do the job. It is cheep too, it is like $10 for 5 days or something like that. Just bill it to your customer when your done.