Misfire from a sticking fuel injector (no fuel misfire)

A common problem on these second generation GM fuel injectors. (Multec 2) They would mechanically stick closed and cause an intermittent misfire. I cannot tell you how many of these I have run across, where the customer already replaced all of the ignition components in an attempt to fix the misfire. There are multiple ways to identify a no fuel misfire. In this video we will cover a few of them. In the related videos posted lower on the page, I will cover more.
Symptoms
- intermittent misfire
- check engine light (P0300)
Fix
- clean or replace sticking fuel injector
Tests shown
- injector sound test
- secondary ignition waveform of a no fuel misfire
- injector voltage waveform showing a missing pintle hump
- misfire counters on a scan tool
Tools used
- Scan tool
- Lab scope
- Secondary capacitive pick-up
- Back-probing pin
Related videos
- How to test a fuel injector (open winding case study) Nissan
• How to test a fuel inj...
- How to identify injector flow problems (Toyota 1.8L) part 1
• How to identify inject...
- How to identify injector flow problems (Toyota 1.8L) part 2
• How to identify inject...
- Secondary Ignition Waveforms (common faults)
• Secondary Ignition Wav...
- Identifying type of misfire using tailpipe emissions
• Misfire troubleshootin...
Playlist
- (Chapters 17, 18 and 19) Fuel Injector Testing
• (Chapters 17, 18 and 1...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[@mike-yp1uk]

Hi paul, just want to give you a big thanks. Since joining your channel things have changed in my career. I used to be a frustrated parts changer. Diagnostics were to much for me. After buying your book and doing all your free videos i joined your premium channel for two years drilling this stuff into my head as i do to this day. I want to thank you now i am opening my own father and son garage. A&M auto service and sales. You opened my eyes to the world of diagnostics. Everyday i must study or i lose my edge but you explain in great detail and thats what made it stick. Thanks again for all your efforts. You are a great instructor.

[@ScannerDanner]

This is so awesome to hear. Makes everything I do have real value to me. Thank you so much Mike!

[@felixarmendariz7964]

Scanner danner is an Einstein at his work.... the smallest detail to be great. Makes work more effective.more productive. It equals to more profit.

[@mamoudbah6558]

Man you are too good You know what, you are the best teacher i have ever seen

[@ScannerDanner]

Oh man, thank you so much. Glad your here

[@mamoudbah6558]

Thanks a lot man

[@mamoudbah6558]

I will like to get in touch with you

[@jaimecarbone6580]

This a dynamite video, the instructor gets an A, his analysis of the problem it's so easily explained by him, Thank youI just learned a lot in a just 12 miunutes video.

[@keithsrepairinc1608]

This injector test worked perfectly. Found P0307 code on a 2001 Silverado 5.3L set because of #7 injector stuck--no pintle hump. Your test videos help us all to learn more. Making better mechanics every day!

[@lanceair151]

I can certainly vouch for the Chevron Techron in terms of unclogging fuel injectors. I recently repaired a 98 Toyota Avalon that had sat for ten years. The fuel tank and pump assembly was completely rusted, but old fuel was still in the lines up through the injector rails keeping moisture out and the rest of the system from corroding. After replacing the tank, fuel pump, filter, blowing the lines, and adding fresh gas, the engine would not start. Adding a bit of fuel in the intake proved the engine would fire right up, so I definitely had gummed up injectors. I added a bottle of Techron to about 4 gallons of good fuel and cycled the key a few times to push the mix into the fuel rail, then cracked the line open to drain the rail and repeated that draining/filling process two more times to push fresh mix into the rail and injectors. I let it sit for 30 minutes and started the vehicle. It went from no start to running on 3 or 4 cylinders. I snapped the throttle a few times, shut it down to sit overnight and when I fired it up the next morning the car ran like a sewing machine. Never had another minute trouble from it.

[@PicassoPete]

Brilliant video. Nice to see the injector waveform normalise after the mechanical tap with the screwdriver.

[@MaicSalazarDiagnostics]

This video guide me in order to fix a Ford E-250 with the same symptom! You are awesome! Thanks again for all your help! Injector 5 misfire! Did all the procedure as you show here! I even got it unstuck! Replace the bad injector, now Van is running like a charm!

[@jonteague7495]

great video, we need more Tech's that will take the time to learn these things about scan tool operation. great job sir!!

[@danielcotayo4357]

I like the scientific approach to solve car's problems using such advanced equipment as you do on your videos. It is a more accurate way to find what is the cause of a malfunction in the system. I really like your videos.

[@muskman55]

Such an incredibly thorough video relevant to any fuel injection system

[@ASEDoc]

Excellent video. I'm an ASE Master Tech L1 diagnostic specialist and watching these videos is like a refresher course. The fact that you're using the Snap On scanner/scope is cool since I have the new Modis Ultra which is similar to your Verus(though I see the Verus may a little faster and more user friendly). Good work man!

[@Crzyfrlss1]

Thanks for posting this. I need to do this test later today and needed a refresher tip, was trained many years ago for lab scope diag. but was never able to put what I learned to use until a recent purchase of a Triton D8

[@mrbibstoo]

Excellent presentation! Very concise and right on track. Thank you for presenting this in such detail. Might I also add that in many cases I have also been able to find a stuck pintle by using a stethoscope and listening for the audible "click" when the pintle closes. Much faster to find than hooking up a scope, just not quite as accurate.

[@marceloromero9012]

Thanks for the video, clear explanation and procedure!

[@Enrique_Osorio]

Thank you for this video and teaching me more about fuel injector waveforms. I gladly edited my most popular video on fuel injector waveforms due to what I learned today.

[@harold6863]

You explain everything so clearly. Thanks so much.

[@SuperGusi1]

your the best teacher by far keep up the good work.

[@ScannerDanner]

Thanks man!

[@svenvos3971]

Real nice explanation of this diagnostic procedure.

[@RandallFlaggNY]

One of the best videos I've ever seen on YT.

[@ausmartin1]

Excellent informative video on the Ecotech, here in Australia most are fitted with Bosch Injectors and way less problems, but like anything with age etc. anything will fail.

[@ScannerDanner]

great compliment, thank you so much!

[@chriscarshunting]

Very nice. Great knowledge. Thanks for taking the time to share...

[@ScannerDanner]

Will do, stay tuned and thanks

[@ScannerDanner]

@juanstrongman If you like these videos you would also like my book. Check out my website listed on my Channel page or search Auto Computers Troubleshooting (I cannot post a link here for some reason)

[@Willyconrad]

Excelent video and explanation. That’s the way to teaching

[@alkhashtee]

It is really nice tools and great job. Thank you so much for these details

[@batinhbngo]

thank you for sharing your knowledge. Good explanation. Please share more.

[@michaelr6205]

Great stuff as always from Paul!

[@Joe_1971]

Great video Paul...i learned something valuable.!!!

[@richardballinger517]

Brilliant video, good explanation of what your seeing on the scope, could have done with this video last week. My motorcycle didn't seem to be firing on #3 cylinder. I used my portable scope (electronics engineer) to test this that and the other on a fuel injected bike for the first time.

[@tiztiz5839]

12 years later from your video Paul, i just had this happened this to me exactly chevy 3.1 all i had was. p0300 but what it was cilinder 3 injector stuck closed after days of unexperieced diagnosis i remembered your video , i smacked the injector fixed in two seconds , i am gonna try injector cleaners will see if it stays running

[@ScannerDanner]

BG 44K Fuel system cleaner was the fix for this one from what I remember? Thanks!

[@tiztiz5839]

@@ScannerDanner will try , stay strong paul.

[@ScannerDanner]

Yes, that is also an acceptable method, however noises transfer and you can hear injector clicking from the injector next to the one in test, especially with the sensitivity a stethoscope provides. This is why I will use a long screwdriver for the sound test as it is more muffled.

[@ziadabdelmuti9547]

Great video thanks for the useful information

[@ScannerDanner]

SIA 2000 and it is made by snap-on for the Vantage Pro and Verus. There are other adapters that are less expensive that you can view single cylinder events, but this thing is awesome for parade type waveforms of all the cylinders.

[@jasaircraft]

awesome vid and tools!

[@amorozzo70]

wow,you are the man.great video

[@ScannerDanner]

im ok with that. thanks for asking Merry Christmas

[@juanstrongman]

another great vid! you should put these on a DVD I would buy it!

[@cheese7837]

excellent video

[@robertfloresjr8837]

Great job!

[@danielraymadden]

Dan good video to the point.

[@liviudaniel5082]

great video i like it ,nice explication!help a lot !

[@cfauvel]

OMG that was awesome....I want to go back to school !!!

[@rrmech11]

Nice job

[@trublue2319]

Nice and fast good for us techs who use the snap on knowledge is power

[@ScannerDanner]

any scope you can do this with

[@ViewThis.]

Wow! This was more interesting than a million dollar block buster movie.

[@allpromechanic1218]

the best videos on YT

[@jeremycaraballo3494]

Great video

[@ScannerDanner]

@MrToolean sure. it uses a high resolution crank sensor. one that has enough signals on it to allow the pcm to monitor acceleration rates of the crankshaft between cylinder firing events. a frequency increase =the cylinder fired. a frequency decrease = misfire

[@ScannerDanner]

What was done as part of the "tune up"?

[@tinohernandez7370]

nice job bro

[@ScannerDanner]

@CoolasIce2 I have never seen a stuck open injector other than when the control wire is shorted to ground, causing a constant magnetic field. I think the fuel pressure behind the injector pintle would force it to close, maybe that's why.

[@justynbumpus1070]

thanks for this video! awesome!!!!

[@hamiddaily]

Really nice

[@JS-ri2rx]

Excellent thank you

[@ScannerDanner]

@500hpsi Yes, you would have. I attempted to show that too but I was getting too much interference with my amp probe at the time.

[@train4905]

Superb sir.superb

[@MrToolean]

Just recently found this channel, and I LOVE it! Dumb question, when you say that misfire's are calculated off of crankshaft speed, how does that work? Can you explain a little more about how the ECU calculates that? Thanks!

[@miltonscornertobylove5068]

Aweson video. Every shop needs a verus lol

[@jeremycopsey5992]

you sir are awesome

[@ScannerDanner]

You re-uploaded my videos, which is basically stealing money out of my pocket! I gave you permission to link my video NOT recopy them and make them your own with completely different web links. I have taken action against you for this.

[@train4905]

Superb sir.thanku.

[@masksareforwhitepeopleonly4311]

thank you

[@Jursaw]

Freaking intelligent guy! Learned a lot from your videos!

[@mohammedshamy6768]

thanks Master

[@DavidGutierrez-zi4dy]

THANKS!

[@felixarmendariz7964]

Smart man bro.💯

[@vincebauer4777]

nice video

[@narutouzumaki6534]

very useful G

[@Darkshadow7081]

very interesting

[@MrNerdyOne]

good stuff

[@mustafaqays8]

Thanks for this helpful video. How can the ECM detect the misfile ? Is it mentioned in the book ?

[@scientist100]

Thank you for the redirect. It helps to see these waveforms. What would it look if the injector was clogged or if the fuel pump pressure is not enough to open the injector? I need to go back to basics from your book for sure and get to see the waveforms as I get more hands on on bad signals that I'm not 100% certain if they have a certain characteristic.

[@ScannerDanner]

A lean misfire on a secondary waveform will look like this stuck closed fuel injector. Whether that lean condition is from a vacuum leak on one cylinder, a restricted injector, or low fuel pressure. Obviously a low fuel psi condition would result in ALL of the cylinders looking like this. Check out chapter 1 for some examples of secondary ignition misfires. I have some lean condition examples in there as well. Thank you!

[@ScannerDanner]

Stuck open would result in the same pattern (no pintle hump). However the symptoms would be drastically different. Check out my video on "Stuck open fuel injector". This one wasn't stuck open mechanically but was electrically shorted to ground so the waveform would be completely different, but check out how it ran!

[@partyboyvinny]

very cool

[@ScannerDannerPremium]

No, as long as the winding and power and ground are good. Pintle hump location on the ramp is also variable and differs with each injector. IT is something that you would compare to other injectors on the same car only.

[@MrBronze90]

God bless you

[@ScannerDanner]

@JohnxWaynexGacy If you mean what they should look like, the answer is yes. Did you watch my injector driver designs video? It is a classroom lecture on injector waveforms directly out of my book. This video is just some of the injector material that is there. I have a complete section on injector testing too.

[@CHewYue]

pretty interesting to see that the scanner stores previous data of previous misfires per cylinder

[@holbanology]

Hi Paul, first off all thank you very much for you amazing lessons. Have a quick question. Its there possibity to read secundary field from ignition coil pack type?

[@12mak]

with a HT extension lead and a clamp pickup or a paddle type COP pickup

[@masksareforwhitepeopleonly4311]

Hey Dan, good video do solenoids lose their magnetic strength over time causing slow pintle response, and can this be seen as pintle hump placement on the ramp i think i heard this in one of your videos thanks DT

[@tomywoo4671]

It's cool to see how a stuck injector would show up on a scope

[@robertmccully2792]

Great video. If you have feed back for all injectors capability and the tool to read them. Wish i had a newer vehical and the latest snapon tool.

[@Theview24]

Paul, do you recommend any exhaust tail pipe analyzers?

[@irvingcarbajal1433]

What does this injector problem do to fuel trims? Btw, thanks for your videos, they are awesome 👌

[@oscarrojas4281]

You the man

[@JD-526]

When you use an amp clamp on a fuel injector as you mentioned in this vedio, do you hook to a specific wire or can I just clamp the entire loom to the individual injector. I watched this video 3 times before I picked up on that. Thanks Mr danner. You are a great teacher. I need to go premium.

[@ScannerDanner]

You won't be disappointed my friend. Thank you!

[@mikalf1]

can this testing be done with a regular oscilloscope or do you need a special tool like your verus and the settings that come with it

[@edgarcastaneda9086]

Sr. Danner could we expect the same hump if the injector was stuck open? thanks for sharing your knowledge with all the youtube community, greetings from the border

[@edwinsandoval1130]

hi mr danner where you got that tool for the secondary ignations you are the best I keep learning more from you videos tanks

[@ScannerDanner]

+edwin sandoval there are many different ones out there. www.aeswave.com/COP-probe-p9335.html www.aeswave.com/COP-Secondary-Paddle-Lead-Capacitive-p9151.html www.aeswave.com/15-inch-WyzeProbe-for-Secondary-Ignition-and-COP-p8764.html

[@edwinsandoval1130]

Tank you so much sir

[@mariocorona6836]

I know u mentioned chevrons techrons inj cleaner, What do u think about Lucas injector cleaner?

[@arctican7483]

GOLD!

[@CoolasIce2]

Good info. What would you say the percentage is of stuck OPEN injectors vs stuck CLOSED? Maybe 80 % open vs 20 % closed?

[@cernalegacy]

How did the fuel trims look with this kind of problem? Thanks great vid.

[@cernalegacy]

I have a constant misfire in cylinder 1 and cylinder 3 the values go up to 98 and my bank one fuel trim long-term hits two Max 25 and a shirt term hits is Max at 50 at first I thought it was a vacuum but I cannot find it even with a smoke machine so now I'm thinking it's a bad Vortec injector spider thingy come across this recently

[@thesetruths1404]

Hi I have a 2007 Liberty 3.7L V6, 117,000 miles. Owned it since 67,000 miles. It operated perfectly for the first 30,000 miles and then it started getting a #1 Cyl misfire code P0301. It also seldomly gets a #1 cyl fuel injector circuit open P0201. It must be a very mild fault as the misfire freeze frame data shows it always happens at less than 350 rpm and when cleared it comes back immediately at next startup, cold or hot. So it seems to only happen once on startup as its moving up to regular idle speed. The miss isnt noticeable when driving or idling. Its getting 15.5 mpg fuel mileage. Doesnt burn oil. Doesnt smoke. Has great power. I've changed plugs and coils but no difference. Cleaned air intake, air filter, and ran cleaner through system. I've cleaned and inspected the injector plug and all wires but no difference. Dry / wet compression test of #1, 3 and 5 cylinders all read good: 160 / 175 psi. I'm wondering if there's a mild wire defect for that injector, or just a flakey connection somewhere. Has anyone tried to use a new set of compatible gauge wires and run them to a place closer to the injector control? I can't see where the wires go though. I'm not sure if I should just live with this, or troubleshoot it more. I don’t care about the engine light as we don't have emission requirements. Now that I know the compression is good, I'm not so worried about it. Any suggestions of what to do next? Thanks!

Great

[@dreamer2355]

Another question. Without using a lab scope, could you also attempt a fuel injector leak down test using a fuel pressure gauge and a manual device to activate the injector such as supplying 12v to the injector after disconnecting the injector wiring connector ?

[@lifeInProgress_8020]

@ScannerDanner can you by chance do a video on capturing a bad injector on low amp. probe. A good one would dirty injector that is causing a lean condition. also what is your option on amp probing starter for testing purposes? would it be accurate for diagnosing a failing starter? thanks

[@DAQUAN88]

What is the name of the Secondary Igniton adapter you are using and where did you get it at?