In-depth look into p0300

[DILLIGAF]

Actually everyone should bump the idle to 750 - 800

 

[Burla]

great dyi cam thread

If you are concerned about lifters and mis fire, I don't think there is much chance the lifter is causing the mis fire. Even if the roller fell off you still have lifter body hitting cam lobe, which case you would have metal in oil and tick. My thought for what it is worth, if you are gonna change lifters, mise well consider cam with that. Everything said, it still is the most likely culprit, worn cam lob. We have seen that is most of these cases, where the mis fire happens more when warm then cold. If you have tried everything you can and lifters is last move, think about the cam too.

4 gens number one issue = worn cam lobs.

 

[blackbetty14]

I find it very odd that your cam is not the problem. Seems you have done everything I would have looked at. I thought fuel for a hot sec but realized you moved the injectors and used Noid lights. I think you should still get fuel pressure numbers as that pump is old at 190k and they have no post filter (just a pre filter in the tank) also the injectors should be flowed/cleaned and new filter screens installed. Glad to see you measured the rocker lift to verify the cam lobes as well how did you measure that and how consistent were the numbers?

have you tried pushing a thicker oil? 0w40 or 15w40? At this point I would give it a shot... given the mileage and wear probably it wouldnt hurt anything. I know going from 5w20 to 5w30 mixed with 10w30 helped with lifter tick/bleed down on my 2014 ram hemi. Have you tried anything like seafoam through the intake?

 

[MP9C]

I also agree everyone should bump the idle speed that increased idle speed everyone would gain more top end oil and that would help keep lifters pumped up.

Burla, think about if if the lifters are bleeding off they are not staying pumped up that would essentially shorten the rocker ratio not opening the valves all the way

BlackBetty, I agree on getting pump numbers just because. I just put Lucas in it so see if that would make a difference, I haven’t gone to a thicker oil yet tho I am thinking about it. I also did run a little seafoam through the intake an put a few ounces in the oil for cleaning. If I change the oil again to go to a thicker one I’m thinking about running a flush too just in case that could help those lifters.

Also removing the valve covers and starting it you can look for short stroking, when it’s bad it’s really obvious beyond that you can rotate the engine by hand and measure from the head rocker post to top of each rocker arm with tdc of each cylinder using feeler gauges, micrometers, dial indicator

But more and more I am thinking this is oil / lifter related

 

[Sherman Bird]

I've seen many seasoned professional technicians chase their tails for a "P0300" code. That's such a ubiquitous code in that a loose cat heat shield rattle can and will set P0300 (I've seen that numerous times). Go to mode 6 and find the parameter which shows "Fail" and to which CID moniker it correlates. That's your starting point. Use an inductive probe and measure the primary amperage draw on the coils. Check for the Evap system fails. Make sure the PCV system is properly functional.

You're looking for a needle in a haystack for a legitimate problem which is playing "peek-a-boo" with you. Patience and persistence will get you positive results. If all your Mode 6 data are normal and flag as "OK", then you'll have to do visual and symptom diags.

 

[MisterB]

I have a similar issue, but with #3 cylinder misfire. Plugs changed, coil changed, next step is checking injectors. Frustrating as heck trying figure out what is causing the problem.

 

[MisterB]

The truck runs fine cold, but as soon as it gets too operating Temps and cruising 55 to 60 you get a chugging, sluggish type feel, like it's choking out. Dealership said they couldn't find anything wrong, go figure. So trying too do this on my own and it's not going well.

 

[MP9C]

I will check all my Mode6 again and see if there are any direct faults that I overlooked before or if it’s showing all is normal

MisterB, does yours do the same thing with cold vs warm and stop and go vs express way and stock idle vs 2 footing it to hold it up a little ?

 

[Mister Luck]

When you use a socket with a long ratchet on the crankshaft to rotate an engine the most resistance is from the valve train.
Valve Springs are one of the most temperature centric parts in the internal combustion engine and at 190k I would think you could splurge and get a valve job and while your at it replace some parts in the rest of the valve train.JMO

 

[MP9C]

The truck runs fine cold, but as soon as it gets too operating Temps and cruising 55 to 60 you get a chugging, sluggish type feel, like it's choking out. Dealership said they couldn't find anything wrong, go figure. So trying too do this on my own and it's not going well.

Umm that’s definitely different, I can roll right into mine and it’s balls out it don’t miss a beat.

For you I would check your fuel pressure and check your throttle body and pedal position sensor one of those could have a dead spot in the potentiometer.

 

[MP9C]

Yeah Mister Luck, if it comes down to tearing it down I will be looking everything over, might even load all the springs to see the pressure rating on them to see if they all match up. An at that point lapping the valves at a minimum.

 

[Sherman Bird]

Umm that’s definitely different, I can roll right into mine and it’s balls out it don’t miss a beat.

For you I would check your fuel pressure and check your throttle body and pedal position sensor one of those could have a dead spot in the potentiometer.

A profile waveform analysis of the fuel pump using an oscilloscope will tell you right quick if the fuel pump is on the fritz.

 

[RGC440]

It was not to the extent that you describe, but my Challenger started showing P0300 codes. I did the spark plug change on the cylinders indicated only for it to show different cylinders miss firing. Found on the internet that this could happen with not enough octane. Filled with 91 octane, and added a can of fuel conditioner, No more problems. It might be worth a try since you,re in a very cold climate.

 

[MP9C]

A profile waveform analysis of the fuel pump using an oscilloscope will tell you right quick if the fuel pump is on the fritz.

I agree but I’m going to go on a limb and say most guys don’t have a oscilloscope chilling in there garage. I was just pointing him in a couple directions of things to check to find out if his issue is load related or position related.

 

[greg mayrhofer]

It is possible that you have dirty injectors, use sea foam or alike to clean them, or bad o2 sensors up stream bank 1 , it seemed to work for me and a few others

 

[MP9C]

It is possible that you have dirty injectors, use sea foam or alike to clean them, or bad o2 sensors up stream bank 1 , it seemed to work for me and a few others

MisterB, This comment pertains to you.

 

[Marshall]

A shot in the dark, but what about a poor head gasket between 4 and 6?,
but not leaking to water jacket ?

 

[MisterB]

Umm that’s definitely different, I can roll right into mine and it’s balls out it don’t miss a beat.

For you I would check your fuel pressure and check your throttle body and pedal position sensor one of those could have a dead spot in the potentiometer.

Thx, I'll look into that

 

[MP9C]

A shot in the dark, but what about a poor head gasket between 4 and 6?,
but not leaking to water jacket ?

Possible I suppose but with compression being as high as it is I’m not 100% that would cause the miss but anything is possible. An it seems to go away with a rpm increase so I really am thinking it’s something to do with the lifters collapsing at lower rpm an not opening the valves all the way.

 

[RedSRT4Me]

Not sure if any of you found a fix but for me this is what worked.

Torque the intake manifold bolts using a torque wrench. I used 110 inch lbs in proper sequence. Also torqued my TB as well.

Problem solved for both p0300 and p219B.

Good luck.