Diagnosing Toyota Prius With Fuel Leak & Cylinder One Misfire

[@TStheDeplorable]

Because you willingly put up a video where you did not have the absolute answer at the end, we all got to learn a lot from the guys in the comments who deal with this problem regularly. It seems that vehicle may have a failed head gasket leaking coolant into #1. THIS is how we all learn! Thanks!

[@crasher88]

a true professional there! you undid Toyota coil connectors with out braking them

[@rexberttechnica6702]

A tip for you. When working on a toyota hybrid that you want to keep running, you can put in maintenance mode. Foot off the brake, press start button twice, step on accelerator twice, shift to neutral, accelerator twice, shift to park, accelerator twice. Then foot on brake and press the start button. The engine will run continuously.

[@rmacuil5]

I'll just get pastor mike to lend me a hand 😂

[@dilanmedina2565]

He did put it in maintenence mode around 20:01 he says it

[@StrongerThanBigfoot]

Prius sucker cheat code for infinity run

[@MsFireboy2]

Thanks for posting.

[@jacobstowe2]

True statement.

[@NathanMerrill-r5w]

As several others have commented you most like have a bad head gasket. my quess it that blip on the spark fire line is coolant entering the cylinder. Allow the car to sit overnight. Remove radiator car, if it is still under pressure you have a problem. Pressurize the cooling system and use a borescope in cylinder 1 to inspect for coolant leak. thanks for your videos!

[@jianbinchen2881]

90% is bad head gasket. i see alot 10 to15 prius doint that.

[@jianbinchen2881]

if missfire only at high speed is intake egr pot clogged

[@mandytuning]

You alright on everything except a blown gasket will not keep pressure overnight. A blown gasket will bleed the pressure to the cylinder with engine off .

[@baja-automotive]

I chased something weird like this before. 2018 Crosstrek with 120k miles (came in for misfire/rough idle) and factory plugs, you could gap check these plugs with a trash can lid. Anyhow I still had a roughness count on one cylinder. Scoping the ignition coil (coil on plug) i was having some weirdness happening like your Prius. I swapped the coil, and the problem did not follow. I scoped the coil plug wires and found no problems. So i pulled the plug back out and inspected the plug hole and piston with a bore scope. I discovered the plug seat/treads were trashed with corrosion. I ran a cleaning brush from a rifle kit through the spark hole and put it back together; problem gone.

[@bobnevala5218]

WOW!!! You just can't make this stuff up! Thank-you for commenting!

[@keithbrown7406]

Interesting. I have the same issue on the burn line diagnosing a misfire. Swapped coils and plugs but stayed with the cylinder. It's clearly a extremely fast change in resistance but I have not been able to figure it out. Also looked with borescope and there is some light oxidation on the aluminium seat with the thread looking dirty. Will try cleaning and retest. Could be a poor ground path you have identified.

[@bobnevala5218]

So many great comments on this one! Customers just have no understanding as to how the slightest little thing can cause a problem. Unfortunately, it can make a customer think that you don't know what you are doing. Thank-you for doing this and all the videos that you do Sir!!!

[@davidmoss9471]

One of my favourite channels Sherwood. Hopefully TST are making the Big Event virtual like last year for those of us outside the US

[@marlinyoung1606]

I would say the ecop is probably getting a magnetic field from the solenoid on top of the valve cover right by cylinder 1 causing what you’re seeing

[@sherwoodcooke7766]

Yep, I think you are correct. I'll check it on one of our Prius's tomorrow to verify. Thanks!

[@FACTSAutomotive219]

Ignition is ever changing too. Depending on the design access and tools used there is a lot of interpretation. It is another tool in the arsenal to funnel our path. And trying to think on the fly while doing vids is not easy. Well done Sir

[@VILSONDUSEVIC]

These engines are known for EGR issues and head gasket leaks (coolant leak into cylinder).

[@gwrider2146]

Yep, a rough cold start can indicate coolant seepage into the cylinder from sitting, especially if it smooths out after running a minute or so.

[@VILSONDUSEVIC]

@@gwrider2146 Yeah, putting the cooling system under pressure and checking inside the chamber with the camera would be helpful.

[@kevincampbell8298]

Was learning tune with the old Sun scope back in 82-3. It was valuable back then. More goodies today

[@jasoneyes01]

Nice find. Leaking fuel in the engine bay is a serious fire hazard. I would never chance parts on any fuel system as in go to the dealer for the part. GREAT fix, great call, on not replacing the oring. I was thinking the discolored ring on the spark plug was a corona ring from spark leaking past the boot.

[@midwestrustwarrior]

The o ring probably pinched when a dealer tech put it back on dry. We would always unplug that line there when doing a fuel injector cleaning service.

[@herbertdelph8386]

GREAT videos Sir here in French Guyana i relay your pratices on Heavy duty machnes to another level and winning,Thank you Sir.

[@DJ-tn7vj]

Hi thanks for the tips mr Sherwood. I see that you are still rocking with the first ecops, i had those as well but traded them in for the revised version. Will definitely get some of that alien tape. The 3m tape doesn't stick well due to the heat under the hood.

[@ousmanesarr7287]

hey man what happened with your channel? all videos??

[@EvzenKovar-i5p]

I own a ‘12. Mine has been doing that cold start “running rough” observation Sherwood describes since it was brand new. I was really ticked off about that when it was new but the car has 125K on it and still going. I have a ‘17 Ford Transit work rig that does the exact same thing at cold start up. Also been driving that from new. The 3rd Gen Prius absolutely slurps engine oil out of the PCV valve(there will be a pool of engine oil under the throttle body). On the intake manifold, right before the intake ports, slurped PCV oil and EGR gases mix and clog the 4 intake manifold EGR ports. As cylinder 1 is furthest away from where the EGR gases enter the manifold, often its EGR port is least constricted by this sludge. Cylinder 1 then absorbs a bunch of the EGR gases, that should be going into 4,3, and 2, in addition to its own allocation. Internet chatter about 3rd Gen Prius is awash in complaints of misfire on cylinder 1. It is also where the head gasket blows most commonly. If you own a 3rd Gen I’d recommend an oil catch can. Also, subtract .2-.4 quarts of engine oil from the 4.4 capacity Toyota says it takes to have the crankcase full. Also learn how to clean the EGR cooler, valve and manifold ports.

[@david600R]

Thank you for these teaching videos. I love these!

[@AAB371]

Good job Sherwood. I agree, it's important not to over think things. I've been guilty of this also

[@shakeelsss]

Always great educational content no matter what.

[@mandytuning]

Differential pressure transducer at radiator and other channel at coil 1 to check head gasket.

[@E85_STI]

That must be the return line since it didn’t have pressure when you removed it and it’s not gushing fuel it’s dribbling down. I use a blue paper towel that’s new and use it to check for moisture on the repair area to see if the leak is gone.

[@midwestrustwarrior]

It's the feed. Toyotas have used return less systems for 20 years

[@mjkuwp94]

There is a strong chance the misfire came from a leaking head gasket at Cylinder 1 - coolant into the cylinder. Look inside each cylinder with a camera and #1 may look like it has been steam-cleaned while the others appear normal. This is a known and common problem with gen 3 Prius in the earlier years at least. my 2013 Prius head gasket failed around 180k and of course it started with more mild symptoms before progressing. It may stumble at a stop sign or on cold-start so that is what the driver will notice.

[@thekeeneygarage]

great video. I'd be curious to see relative compression and injector waveforms to see if #1 injector pattern looked different than the rest.

[@dxxxm231]

Relative compression test is not possible on this vehicle. There is no starter to “crank” the vehicle

[@thekeeneygarage]

@@dxxxm231 right on, didn't think about that

[@michaelmounts1269]

I have a gen 4 prius…same symptoms…always smell gas in cold startup. dealership cant find problem…no gas in oil..still under warranty …so for now just documenting it…

[@DuaneDonaldson]

Most every techs problem, they refuse to follow their own set of rules, which means they dont follow a set of known good rules that they have created for themselves when they get in a hurry. There is no need to be in a hurry, you can discount the time if you feel bad. If you dont create a checklist of how to do every little task, then you are only shooting yourself in the foot, if you dont know how to use your equipment to it fullest potential then you are wasting your own time and why should a customer pay for time that you messed up. If you watch Bernie on his 8 channel scope, there is a math setup to monitor the CKP to see if there is a misfire for some unknown reason or is it like you think, a glitch on #1 that does not actually affect the RPM. You still have not tested incyl mechaincal nor fuel injection balance test. Your narrow and wide burn time tends to show fuel delivery to me, narrow is lean and wide is rich but can be within limits, need to look at O2 and fuel trims now that you have new plugs. Thank you for the case study, I still feel that an old school set of spark plug wires slipped in between the coil and the plug with an indective pickup is still the way to monitor seconday spark, I dont trust these COP attachments at all unless it a requirement if the intake needs to be pulled otherwise, cheers.

[@riceburner4747]

Great job. I'm 71, so I'm a bit older than u, but appreciate your attention to details. I own a gen 4 Prius, so I am STILL learning. I wonder if cylinder is carboned being spark plug wasn't firing properly & will take an "Italian tune up" to correct itself? Your son does great camera work. And thanks for making sure we SEE what you are explaining. I wished you told us what ft lbs your are torquing. 👍 PS I forgot to ask, so fuel line isn't high pressurized. I had to jump terminals/or pull fuse on my 97 Camry to work on fuel line. I don't remember exactly.

[@saiautorepairs]

Another great video. Make me want to buy the Escope and the e scan for my shop

[@paulgilliland2992]

Yes can you do tutorial on the Uscope? I bought one and haven’t been able to generate a PWM signal.

[@RyanRansom]

AES Wave has some great usage and setup videos for the uscope on their channel.

[@randywilliams5337]

Since the scope still was a little funny on cylinder 1 and someone had not reconnected the fuel clip properly, maybe something got into the fuel line and ended up in the injector. Might that have caused a bad spray pattern that showed up on the scope? I was waiting to you to check pattern on a couple injectors..

[@charlesabura472]

Just for the heck of it, i would have tried to see what the #1 injector is doing.

[@henrytav]

Great content! Since I was there, I would run a compression test on cylinders #1 and #3 and compare them, just out of curiosity.

[@GNX157]

What is the mileage? Maybe we are seeing the beginnings of a ICE valve needing adjustment, as in too tight of a clearance? Some engines wear like that, they (valves) get tight as they gain mileage.

[@MrOctNot]

The noisy signaled overlayed on the red trace in the deep capture was very suspicious and could lead to why cylinder one is misfiring. Perhaps corrosion creep between pins at the ecu or two wires where insulation has rubbed thin and touching together somewhere in the harness. That "overlayed" signal looked familiar. Hmmm. Just thinking out loud. I enjoy this channel and admire your work ethics. By the way, my mother-in-law gave me a role of alien tape in my stocking for Christmas. Now I know what to do with it.

[@frankv6263]

Love your videos! This might come unrelated or "out of left field" but how cold does it get in your location? I see Sherwood Jr working in a winter jacket... 🤔 Asking from a fellow Northern American up on On/Qc border in Canada

[@theroyaltyautoservice]

You’ll laugh at this one but we are in south Ga! Sometimes it gets in the 20s but it is really humid and can feel colder than it says. However, for you that’s nothing! Thanks for watching!

[@markgalentine6724]

Where did you get you c.o.p. pick ups. I looked on the internet and couldn't find them. Thank you. Really enjoy your videos.

[@martinboucaud679]

Great job my friend I love it.thank you

[@sheerwillsurvival2064]

Carbon deposits on valves ? In cylinder 1

[@ysitrim88]

Another great video!

[@spilledcoffee-gt1qj]

The small black ridge on the end of the fuel one is not normal it’s due to someone putting the connector on crooked and causing the coating to get pushed back

[@christianmiles6532]

Do a cylinder leak test after cool down, could have a coolant leak and may need a new head.

[@Thursby_Car_Sales]

Great content! Thanks

[@paulmeglasson1919]

Did you stick your camera down cyl 1? If you did, did it steam up? Your engine coolant looked a little low. It’s probably a blown head gasket! So common it’s scary.

[@ousmanesarr7287]

Hi . That issue you was seing on the coil one funky firing line is due to the vvt solenoid interference. As far as the problem on this car am 98% sure its a leaking headgasket.

[@ousmanesarr7287]

To comfirm headgasket on this. Engine stone cold .pulse sensor on radiator unplug all coil crank for 5 seconds( thru ev system ofcourse around 600rpm) or. Pressurized cooling system wait 5 to 10mn .borescope in cylinder 1 . Boom Baby coolant drips coming down

[@TracyCorbett]

​@@ousmanesarr7287Yes indeed. That's exactly how I do it. Standard exhaust gas in coolant test and sometimes compression tests give false negatives on these.

[@ryan.mullen]

Where are the ecop’s from?

[@mikesabin8568]

Does running the prius in maintenance mode wear down the battery?

[@VILSONDUSEVIC]

No, the MG1 is spinning with the ICE so the battery is being charged.

[@gustavomartinez324]

No it’s used diagnostics will not wear battery down

[@dxxxm231]

This vehicle most likely has a blown head gasket. Cylinder 1 typically is the culprit cylinder. Will only miss on cold start typically.

[@VndNvwYvvSvv]

How does that cause a fuel issue though?

[@TStheDeplorable]

@@VndNvwYvvSvv Coolant in the cylinder affects the firing of the plug?

[@dxxxm231]

@@VndNvwYvvSvvfuel leak and misfire are unrelated. Vehicles can exhibit multiple issues at one time.

[@whaablatif5445]

what yall doing on the lambo?

[@theroyaltyautoservice]

A lot. 😢

[@ScottPuopolo]

How did you enter maintenance mode?

[@fun4u2bwith100]

What holster do you have for your light?

[@rickmaberry8761]

Thank you

[@johngraham1875]

Nice video guys.

[@mrblonde2013]

If you are going to swap coils, also swap plugs. Eg: swap coil 1 to 3 AND swap plug 1 to 2. Misfire usually stays or moves.

[@TracyCorbett]

Yes, that's exactly what he did :)

[@hitran1913]

he doing a ekg for the car

[@tylerwilliams3868]

dont say youre gonna add a tool to the description and then you don't... come on man