08 with odd p0300 code

valingt · Jun 11, 2016

ok so i have a 08 ram 1500 5.7 with 109k miles on it.

what its doing is misfiring at 2000-3000 rpms. it will idle for ever no miss.
will rev up to the limit with no miss. only puts the code out in the right rpm range.

i have done.

new plugs. the right ones. and gaped to the book.
new egr
new cam and crank sensor.
all coils are good.

i can turn it off and right back on and it will run fine with no light on till i get in the rpm range.
it almost acts like the mds comes on sounds that way too but the code is on.
i can get the code in tow and in od off.
shop that i took it to thinks bad valve but i would think that if that was true it would be rough all the time even at idle.
i have not seen anyone have one that idles fine with no miss get a p0300 code. i may be wrong on that but thats what some ppl make it out to be like.
im at a loss here so im hoping you guys can help.

cant seem to find anyone that has had this problem or what they did to fix it.

any help or ideas would be welcome.

thanks

Val

89gtcs · Jun 12, 2016

Another possible culprit could be O2 sensors. I'd recommend having someone troubleshoot with a scan tool though...this won't be an easy "driveway diagnosis"

valingt · Jun 28, 2016

not o2's shop said the vac was all over the place. they where thinking valve spring could this be right? he said that #8 would die first then#7 making #1 and #2 turn off to balance the motor. does that sound right and should i start on #8?

Rlaf75 · Jun 28, 2016

If I'm not mistaken I believe the code P0300 is a "Random Cylinder Misfire". What I would do is clear the code and drive it normally. When the CEL comes back on, check it but DO NOT CLEAR IT. Keep driving it to see if another code appears such as P0301 to P0308. That will indicate which cylinder(s) are misfiring and you can go from there. Also on high end scan tools there's a function that should show recorded and or live misfire data that you can determine from which cylinder you're getting the misfire. Driving it may take some time for it to produce another code but if you clear it then you'll have to start all over again because the computer needs to reset monitors which will take even more time

valingt · Jun 28, 2016

for the most part i cant drive it. if i get into the 2000-3000 rpm range it makes the light come on. i had it give me a p0308 one time but cant get that to come back again. you think i should just start with cylinder 8 and go from there?

Demon-HeMi · Jun 28, 2016

ive had a similar symptom when I blew a head gasket

Rlaf75 · Jun 28, 2016

[URL=http://s1073.photobucket.com/user/rlaf75/media/Screenshot_2016-06-28-19-01-43_zpsrjks3q5y.png.html]

[/URL]

valingt · Jun 29, 2016

i know what the code is thanks but still not helping. there are no air leaks and i don't have a egr problem. the egr and all of the components are new. the shop is saying that #8 is getting 80 misfires before #7 and #8 shuts down then #1 and #2 shut down to balance the motor. oil is clean and coolant is clean and full. fuel pump is putting out 60 psi at all times. was going to pull the valve covers off this weekend but trying to get more info before i do.

Rlaf75 · Jun 29, 2016

Ok good luck

valingt · Jul 4, 2016

ok so not valve springs and not valve seat. going to try coil pack and pcv

dexter · Jul 4, 2016

valingt said:
i know what the code is thanks but still not helping. there are no air leaks and i don't have a egr problem. the egr and all of the components are new. the shop is saying that #8 is getting 80 misfires before #7 and #8 shuts down then #1 and #2 shut down to balance the motor. oil is clean and coolant is clean and full. fuel pump is putting out 60 psi at all times. was going to pull the valve covers off this weekend but trying to get more info before i do.

I had that problem with a 2000 Dakota. It is hard to find the problem.

What worked for me was fuel injector cleaner.

valingt · Jul 7, 2016

ok well its not a valve or valve spring. going to try coil pack and pcv now.

valingt · Jul 9, 2016

ok coil pack on #8 is new and pcv is in. seems to run a little better but still a p0300 code.
im starting to think i may have a bad injector what do yall think? its still not saying what cylinder it is that is dieing first.

jwheeler · Jul 9, 2016

You have put a lot of parts on there that will not cause a misfire. Have you done a compression test?

Sent from my iPhone using Tapatalk

dexter · Jul 9, 2016

valingt said:
ok coil pack on #8 is new and pcv is in. seems to run a little better but still a p0300 code.
im starting to think i may have a bad injector what do yall think? its still not saying what cylinder it is that is dieing first.

I'd try fuel injector cleaners before replacing the injector. Especially if you if you don't have any problems while driving.

valingt · Jul 9, 2016

jwheeler said:
You have put a lot of parts on there that will not cause a misfire. Have you done a compression test?

Sent from my iPhone using Tapatalk

coil pack and spark plugs will cause a misfire last time i looked.

compression test was good.

got injection cleaner in it now not helping much

im starting to think is a electrical problem or a computer problem. you would think someone would have had this problem but i can find one like it.

ok so here it is again

will start and idle with no miss
will rev to 3k + with no miss
if it gets in the 2k-3k range it puts the p0300 code out
i can drive it all day long if i stay under 2k rpms if i go over then code.
it shifts good and all that.
doesn't matter if i have the tow haul or od off or on.

i have new spark plugs in all the stock copper ones.
crank sensor and cam sensor.
egr is new
the one cylinder that poped up one time i have put new coil pack in it.
pcv is new

the mds will kick on and off just fine when driving so i dont think its that but could be wrong.

im in my jeep for now and i really want back in my truck plz more ideas so far so good on the questions.

if need be i can make a vid and show you guys if that would help.

jwheeler · Jul 9, 2016

What were the numbers for the compression test? Sounds like it might be a cam problem. Move the injector to a different cylinder to rule that out though.

Sent from my iPhone using Tapatalk

valingt · Jul 10, 2016

ya thats what im starting to think. this started 6months ago and has been getting worse over time. it started with a stall every now and then and now its at this point. is there a way to tell if it is the cam without taking it all apart? could it be the computer doing this? or would this most likely be a mechanical thing?

thanks for everyones help so far we are getting closer to a answer.

jwheeler · Jul 10, 2016

It is most likely a mechanical thing. If there was a problems with the driver for the coil or the injector, it would happen all the time. I think you could pull the valve cover and measure the amount of lift on the pushrods on number 8 and compare to other cylinders. It sounds like a flat lobe.

Sent from my iPhone using Tapatalk

jwheeler · Jul 12, 2016

It's kinda funny. Just had one in the shop with the same problem today. Idle is perfect but when the rpms come up and it is under a little load it would misfire on number 1. I just put in new plugs so I swapped the coil and injector and it still did it. Pulled the valve cover and cranked it over a few times. You could clearly see the rocker for 1 was barely moving compared to 3. Needs a cam and lifters.

Any update on yours?

Sent from my iPhone using Tapatalk

08 with odd p0300 code

Junior Member

Member

Junior Member

Senior Member

Junior Member

Senior Member

Senior Member

Junior Member

Senior Member

Junior Member

Banned

Junior Member

Junior Member

Senior Member

Banned

Junior Member

Senior Member

Junior Member

Senior Member

Senior Member

Similar threads

Forum statistics

Share this page