The Trainer #66 - Tackling Misfire DTCs

[@MotorAgeMagazine]

FYI everyone! Pete stated that the use of fuel trim was only valid on MAF systems. The impact on fuel trims caused by lack of fuel will be seen on MAP systems as well. Just be sure to check the LOOP PID and make sure the system was in Closed Loop when the data was recorded.

[@geofschwer1625]

Pete, I’m a average guy who likes to service my own vehicles, but unfortunately I don’t know from anything about electrical circuits. That was, until I accidentally ran across your MotorAge tutorials. Wow, what a fantastic collection of information on all sorts of things electrical! Your videos have really opened my eyes about how to diagnose and troubleshoot problems in a circuit, so thanks to you and to MotorAge for making them available to us.

[@MotorAgeMagazine]

Thanks! I'm glad you found them helpful. Be sure to subscribe so you won't miss all the new stuff we're working on!

[@jeffhesse8415]

Nice job Pete. Very useful information on fuel trim info in freeze frame data. Thanks for your time with these videos.

[@paulajones3856]

Wow. Nice to have someone presenting excellent material in a logical and professional manner. Superb job!!

[@MotorAgeMagazine]

Thanks! We try...

[@70289121]

Oh hey Mister, you are an awesome amazing teacher. You are helping me learn how to use my obdll scanner to it's full potential. I have the dreaded P0300 code on my 2000 Nissan 3.3L V6. I have a fuel issue on bank 2. I only know that thanks to YOU! Thank you so much for all you do!!!

[@technomage6736]

This is a fantastic channel! Very helpful. Thank you so much for sharing! 👌

[@MotorAgeMagazine]

Thank you!

[@grizzy909]

What is there's no MAF & the misfire is in 1 cylinder only? I did a Compression Test on a Acura MDX 3.7 L V6 & it showed all cylinders were @ 230 psi while #5 is at 125 psi, I put a teaspoon of oil in there & it didn't bring the number any higher on cylinder #5 What's my problem?

[@sollykhan2385]

The Best on vehicle testing, AWESOME, PETE, thanks man, BLESS 😇👍

[@falconmotorsports8323]

I just found out misfires stored with no codes..Had an avalanche that wouldn’t go into overdrive hooked up the scan tools thousands of misfires on multiple cylinders

[@Etheo1ify]

Thanks, Pete- This was very useful.

[@MotorAgeMagazine]

Glad it was helpful!

[@psdaengr911]

How about a misfire caused by a cam position sensor's reluctor wheel losing its field or shifting on the camshaft? That can cause a misfire on hard acceleration at any speed, or be erratic and intermitent when the electrical grounds to ECM and/or sensors are losing integrity. Very hard to find using codes and scan tools, and the quality of the multiple grounds is rarely measured by car techs.

[@MustangGuru]

My car is boosted (supercharged ) and I found my misfire to be spark plug blow out under load. Changed to colder plugs and narrowed the gap to .028. All is better.

[@kevinstonerock3158]

It probably isn’t something that happens very often but I have a misfire that’s set while cranking when I look at the freeze frame data. It’s usually below 200 rpm. The engine is usually cold and I would think it should be in open loop which wouldn’t normally give the full range of information for fuel trims, etc. The misfire only specifies one cylinder. I wonder how often something like this happens over a month or years time.

[@MotorAgeMagazine]

Could be a mechanical issue, like a sticking valve.

[@kccodex8931]

Do I need to reset the ECM after replacing a fuel injector on my 2000 lincoln town car?

[@MotorAgeMagazine]

You may find it helpful to reset the KAM memory if you are repairing a fuel trim code.

[@kccodex8931]

@@MotorAgeMagazine Thanks, I'll give it a shot.

[@charlesgould8436]

Do you think it is possible to make an 8cyl. engine that as it dies the computer compensates so it runs like a 3cyl.?

[@mikechiodetti6737]

Like you said Pete, ruling out what's NOT the problem under the misfire conditions comes first and sometimes you have to think outside the box for the answer. When you were showing the waveform that has the spark, fuel injection and the compression. What or who has a breakdown of the positions in the compression part of the wave form. How does that compression wave relate to spark and injection timing? I'm not 100% familiar with that part of the total waveform.

[@MotorAgeMagazine]

Not sure what question you're asking but if you want to know/learn more about the in-cylinder compression test, watch this: ubmadvanstar.hs-sites.com/watch-pressure-acquisition-analysis-from-inside-out

[@samr.m.7709]

Excellent video Pete. Looking forward to the event this summer in Chicago

[@ajseuol1864]

What about unmetered air? I recently had a 03 Maxima with DTC P 0300 and P0301. Someone had just renewed all the ignition coils and spark plugs. The Mis was felt right at startup and got worse as the engine warmed up. Compression was 180 lb in all cylinders and fuel trim was 25 on both Banks. The problem turned out to be two cracks on the outermost Runners of the plenum.

[@MotorAgeMagazine]

Good call! Consider what you're sharing. If only two cylinders were getting extra air, those two were running leaner than the other two.

[@marcricker2570]

Greetings, you always have great information that is on topic and informative. I've got a 1998 Avalon, MAF system, and I'm randomly getting p0300, p0301, p0303, p0305 under load (2500rpm). STFT B1 -20%, STFT B2 +/- 7% during the event. I can feel it but doesn't always give me a MIL light. I'm thinking a bad signal wire or ground wire for bank1, where would you look?

[@MotorAgeMagazine]

What is the LTFT for both banks? Are these numbers from the Freeze Frame data for the misfire DTCs?

[@clarkgarber5495]

Converter.

[@adr.X]

Excellent video, very informative. I'm getting P2097 Post catalist fuel trim system to rich Bank 1 and P2177-system to lean off idle and missfire codes P0300 P0301 P0302 and P0303, on a 2006 Ford Mondeo 1.8 Sci petrol. Can you give me some adivce on how can i interpret these codes? Also my battery doesn't charge more than 12 volts with AC and consumers on, and all lights flicker. Can it be the alternator the cause of the error codes? Thank you

[@MotorAgeMagazine]

The very first thing I'd do is check the condition of the battery ground cables. Watch this: kzbin.info/www/bejne/p5XEgIafiMh4q5o

[@neilray8416]

Great instruction, Thank you!

[@cqmacht4513]

Getting a P0420 code on 99 ford windstar how can i use the graph to diagnosis. this .New to using graphs not working on cars

[@MotorAgeMagazine]

Try watching this: studio.kzbin.infoQ6XUcAFcCiU/

[@robertferrara4529]

How would you find a sticky injector? thanks.

[@MotorAgeMagazine]

I can think of a couple of ways. The hardest is one that sticks intermittently but modern DSOs and their accessories can help. First, use a pressure transducer like the WPS500 in the fuel rail and monitor the pressure drops. A sticking injector will drop more pressure than a normal one. If you don't have a pressure transducer, monitor the current flow across all of the injectors and look for the pintle humps to vary on the suspect injector. You could use a second channel as a reference and monitor all the current patterns at the same time. Hope this helps!

[@SixMonthsIn]

So, how would I begin to diagnose a P0316 code which is set but the MIL lamp is not lit? Is a bad CKP sensor the likely culprit? I believe that the check valve in in the fuel pump module is bad and leaking fuel back into the tank. The FRP immediately drops to 0 when the engine is shut off and at KOEO the fuel pressure leaks down about 1 kPa per second. This could indicate a leaking injector but it seems like a misfire would occur and a DTC set for whatever cylinder was leaking. I notice that this occurs on warm starts. Immediately starting the engine seem starved of few for a few seconds and then recover, hence my theory about the fuel pump check valve.

[@MotorAgeMagazine]

I tend to think, based on what you told me, that there is a leaking injector causing the misfire. The code is for a misfire on initial start-up, and fuel pooling on the piston could certainly cause that. What year is your car?

[@SixMonthsIn]

@@MotorAgeMagazine 2007 F350 6.8L with 197k miles. I have never had the injectors cleaned or replaced. If this is the case, then should I be worried about vapor lock?

[@MotorAgeMagazine]

@@SixMonthsIn No, I don't think so. Do you have a scan tool that is capable of accessing Mode 6 data?

[@SixMonthsIn]

@@MotorAgeMagazine I do. But, I have checked it before and the misfires are all 0 counts on all 10 cylinders. I'll check again. I have replaced all of the spark plugs and all of the coils at about 120k miles so it is almost time to do them again. I've never replaced an injector before. Is it difficult?

[@MotorAgeMagazine]

@@SixMonthsIn I've never done the injectors on the V-10 but it shouldn't be overly difficult. At least its not a diesel or a GDI engine!

[@101numlock]

Keep the training coming ! Really appreciate it !

[@j.r.3330]

Great job and good information.

[@psicopatalucifer]

Excellent video Sr.!

[@petehenderson]

How bout them damn hemi motors p0301 misfire. B4 pulling ur hair out check ur cylinder deactivation solenoids. They love to get stuck. U should include this

[@brucewiles4130]

VERY GOOD JOB SIR ON EXPLAINING,, THAT HELP ME IS NOW I NO WHY OXY CENSOR CODE IN ECM AND THAT PART MITE NOT BE BAD BECAUSE LESS SPARK IN PISTON EVER WHICH ONE SENDS RAW FUEL OUT EX.MAKING OXY SET A CODE PEOPLE REPLACE OXY CENSOR AND NO HELP.. UT OLE WRONG. AM I RIGHT SIR..THANK YOU.

[@MotorAgeMagazine]

Hey Bruce! Trying to follow your comment and it sounds like your asking about an oxygen sensor related DTC. There are several that involve the health of the oxygen sensors, and there are different types of sensors. To properly diagnosis any of them, the first step is to understand why the ECM failed the test and what it tested for. Hope this helps.

[@brucewiles4130]

yes sir,,,think you.......i now have retired and use to work on auto stuff but i try to understand as much as i can..enjoy watching your show,,,sometimes i miss it lol..

[@misaaccooper]

So if an ignition events is weak or fails and you pump a bunch of unburnt fuel and air into the exhaust you'll see a lean condition and single digit + STTRIM??. Would this not present a upstream RICH condition at the time of FREEZE FRAME snap shot. Also, an injector can hang open and dump fuel in the cylinder causing a rich condition. Not just quit working all together shorting fuel to that bank.

[@MotorAgeMagazine]

If a cylinder misfires due to ignition, the ratio of air/fuel is still lambda. The two will burn in the exhaust with maybe some O2 left over. Trims will vary very little as a result and the O2 sensor will see a "lean" condition. If an injector is leaking fuel or failing to close, it is adding fuel over and above lambda - the definition of a "rich" condition, even if the mixture burns in the combustion chamber as it's supposed to. If it misfires due to the overly rich condition, there will be fuel left over after the burn in the exhaust. Hope this helps!

[@7minnow]

GREAT Job!

[@exmotorsports]

New Subscriber. Love your video's..Really appreciate you sharing your wisdom. I too would like to see a live cast of your conference. Is it possible? Thanks

[@MotorAgeMagazine]

Our NACE Automechanika training event will be hosting over 100 sessions over 3 days. This is one event to make in person! Here's more: kzbin.info/www/bejne/hqKXfKiQaNGHqqM

[@hubercats]

Excellent!

[@billyr9840]

Nice !

[@rockynix7731]

Each cylinder will be delivering 12.2.5 pounds of fuel ....

[@NCPDFSB]

wish i could make the event... live cast?

[@MotorAgeMagazine]

Our NACE Automechanika training event will be hosting over 100 sessions over 3 days. This is one event to make in person! Here's more: kzbin.info/www/bejne/hqKXfKiQaNGHqqM

[@NCPDFSB]

thanks pete, always enjoy your videos

[@ShawnErroneous]

Hopefully you dont have the random p0300 code.ah fuck me godammit.

[@chrisczarnik3439]

Very useful advice. From 🇦🇺🦘🦘🦘🦘🦘