po 300 code help

hey guys long time since ive been on but as most know i demodded for awile now till i have time to do front mount .
heres the deal ,ive had to do a crap tonof work to get this thing back to semi stock but i finally have it done and its skipping and throwing a po 300 code [multiple mis or random i forget ].i changed the plugs thinking my tr6s were wrong for it anyway but no help.wires seem to be ok.i guess first wat would cause a po300 ?ive had to ,install a new intank fuel pump ,rewire stock injectors ,rewire maf ,o and a good old transmission again,[thats y i took it off the rd.sick of them lol]i also had to rerun all vacuum lines to factory locations like pvc etc.it been alot .so could any of this stuff be causing my issue?idk like i said maybe just start with po300 and let me know wat that could be .thanks guy ,new site color looks nice .

o ye by the way ,should anything happen when u unplug the maf with it idling ,?cus i did and nothing changed ,not worse or better.i did that because i had to rewire the maf and i had a questionable connection.

lolwth just happened ?the site went from blue back to origanal red and format ,wow .i also should mention that the truck was very hard to start for the first time ,it took ten minutes to pick up the cylinders ,ran on 2 cyl for five minutes.then picked up the others.

hello is everyone mad cus i havent been on.lol

thanks for the help guys ,preciate it .wtf

i was beeing sarcastic ,has anyone here looked at this?i really could use alittle help .i replaced the injectors tonight didnt help any .fuel pres is 62.so wth do i do .com om guys some help here ha?

it can take a week before a reply lol goodluck

I had that code and it was a failed rocker. Check all the rockers and look for a bent pushrod. Mine was absolutely quiet on the valvetrain since the lifter stuck up in the lifter retainer.

interesting u say that redc .hmm.wen i powerbrake it to see if its still sputtering i get alitle poping like a rockers off,not bad but alittle pop wen i give it gas and hold the brake.ill have to try looking at them.but the kicker is wen i parked the truck a year ago almost i dont recall it acting that way ,but i did spike boost real high wen the input shaft broke and i never ran it again,so maybe it happened at the same time and because i never drove it after breaking the input shaft i never knew .thanks ,off the wall but possible.im still open for suggestions guy cus i am broke down until i figure this out.

I want to help...I really do. But I can't figure out what you're typing.

u have to much apart !!. did allen retune for you??? dont u have hptuners??.... could be LOTS of things !!.... I can help figure it out but it takes time.... and NOT on the site

ye casey allen did retune for me ,but i do have to check with him and make sure its all properly set ,wen i called the girl took my info [no offense] and im not so sure its was conveyed 100 percent proper,im just not sure it was awile ago.so i will try to confirm the tune ,but im also gonna pull the valve covers and check the rockers and pushrods ,only because like i said earlier i was spanking it pretty hard and spiked boost at like 17 psi wen i snapped the input shaft and never ran it after that so i could of bent a pr or snapped a rocker.its poss.
i agree i did have too much apart and thats why im having a hard time pinpointing the issue.the prand rocker issue is a long shot but im gonna solve my curiosity and check it out.When i first started it ,it acted like it was running on 2 cyl then picked em up.i knew right away something was wrong,because it shoulda purred like a kitten.
Im almost confused were to start.i did so many things to it to put back together .
fuel pump is at 62psi running so that seems to be fine ,i replaced the injectors and that didnt help.I dont have converters so theyre not clogged.no vaccum leaks .
po300 could be so many things.
I will say if it helps any ,im having a charging issue that i wasnt really worried about right now just figured it was the alternator and i would change when i got it running.that also wasnt an issue when i parked it but i figure no biggie.would not charging cause any issues with misfire?casey what do u mean not on the site.?thanks guys appreciate any input.

Quote:

---

Originally Posted by oleshifty

I want to help...I really do. But I can't figure out what you're typing.

---

do i need an accent?b4 u understand me.? youalll.lol

update.i just pulled the rockers and pushrods and theyre fine.would the charging issue cause this problem?i left the charger on it for a couple days and then i started it and it didnt seems half as bad?ok so i back it up in the yard then excel to go forward and im getting a popping like a bad pr or rocker.as soon as the battery started dying the cel cam on.i got engine not charging then a few mins later the cel came on po 300.it acts like a bent pushrod to me with the exception of the charging issue.the battery sat in it for the last year without beeing charged so it could be the battery causing the charge issue also.thanks for any ideas guys.

is the site even working ?evrytime i get on theyres a new look .now its totally differrent and i cant get to a front page.

well i dont know if im talking to myself or not but ,i changed the alternator and it seems way better now .i took it down the rd a couple times and all that seems to be happening is periodically the cel blinks 4-5 times and then goes out .what does this mean .low end is nasty but 60mph or so is a little sluggish.my concern now is the blinking cel .what could this mean?

update po 300 keeps coming back on .lol wtf .seems liike wen it comes on i start getting rich on the drivers side .idk ,im stumped.

Do you have a smoke machine to test for a vacuum leak in the intake? Have you checked to be sure the fuel pressure regulator isn't leaking into the vacuum port?

i have smoked it and all good .no more regulator red ,its all stock for the fuel system .i did have that happen before and washed out my cylinder.lol.had to change the oil 3 times before it got better.im stumped ,it seems to idle rough wich im hoping is the cam cus it always did .the tune is wearing in still tho ,ive only put less than 20 miles on it cus of this damn code.i cant get it inspected.so i only drive at night ,haha.it hasnt came on in alittle wile now so im hoping no monitors show and tomm morning i can get a sticker put on it so i can get it registered.i only have a 3 inch intake tube on it made of pvc and im wondering if im getting the proper a/f mixture causing it to be rich or lean and throwing the code.hope fully something straightens this out its starting to p me off .maybe the tune requires xxx air and xxx fuel to be spot on.or assumes xxxair and allen adjust xx fuel for that air .i definately go rich at idle after awile .

I saw one post stating it ran really rough at first for a while and you were having issues with it running rough. Did you put old injectors in it that sat for a while or are you still using the injectors you had with the FI? If old injectors, they may be sticking. If FI injectors, did you update the tune for the larger injectors?

i put the stock injectors in ,then i took the ones out of my escy in it and the same deal .i do wonder if allen tuned for stock inj or tuned the 60s that were in it bn unaware i was putting stock in.seems to be loading up at idle and then sure enough the cel po300 comes on.i really wonder if my intake tube is too small ,and not giving enough air at idle or not mixing right wen i slow down and stop at a red light .im stumped.im sure its the smallest of things.

alright for now ,does anyone know if allen shuts off the monitors in the tune or not ?seems like it ,wen i clear my cel i go right to the monitors and it says no monitors showing ,wich is great for now that means i can get inspected.but usually u have to do a drive cycle on it and by the time i drive 40 miles or so the lights back on.the truck is running ok but skips alittle at idle and kicks the code wen i sit at a red light ,it really doesnt bother me.so do we know this?thanks.

hellooo?

i'm not at the shop, but i'll check it tomorrow. if the truck had 60lb inj in it and was tuned for stockers, and vice versa, the truck wouldn't even run, so that's not an issue.
a p0300 is a misfire code as you know, a physical misfire, one that you can feel, is not usually tune related. an actual misfire you can "feel" and get to happen at a brake stall, is a misfire.
which means, a plug is bad/cracked (which is doubt), a fault plug wire (start it up at night and see if you can see a spark on the plug wire), an intermittant short or open on the injector wires, or it could be a coil or wire to the coil.
a tune isn't going to help with a misfire, an actual misfire is caused by something on the engine, the tune or pcm does not cause a misfire, the pcm will detect a misfire and let you know there is a misfire.

you mentioned it drives ok, then not, then good, then bad, check the wiring.

if the truck is misfiring at idle (which is kind of hard to tell sometimes), sometimes you can measure the heat on the header (if you have headers) and determine which runner is cold.
a manifold is alittle hard to do.

wiggle wires, if it comes and goes, that's a start.

you changed so much, so go over everything and triple check all the wiring.

if the truck is running, the tune is fine, especially since you said it ran good at once or occasionally, which indicates a wiring issue.

good luck,
allen

hey ,thanks allen .i dont mean to be a fingerpointer at all,i just dont know what else to do .ive had a doubt all along if i wired the inj properly or not but ive color coded all them five times and theyre fine,i think lol some of the colors are faded.but im sure they lay were theyre supposed too..but thats not saying that theyres a loose connection inside the shrink tube ,correct?i changed the plugs,changed the injectors also.by the way ,went from 60s to stock,fyi.i definately feel it at a stop with foot on brake,and i can feel it get worse wen i sit at a light for along time just before the cel comes on.like i said im just not sure .the boots on a couple of my wires do rest on the header but no melting going on.new wires also.changed coils with another set ihad .my only concern in the tune was air fuel mixture maybe causing lean or rich condition that may be telling pcm to add or take away fuel causing misfire,just guessing.when you say check wiring what wiring speciffically would i check for concern.were you talking plug wires or like inj wires ,coil,grounds etc?you mentioned all but quoted [check wiring],lol i got lost.lol. so bassiccally if i find a cold tube then its that cylinder i should run through.my worry is its random multiple misfire.so it wouldnt always be cold and ide have to find it by .coincidence ,right?if this helps today i got a po174 cel that said lean on bank 2.watcha think of that?and bank 2 is pass side right .ide really appreciate youre help bud ,and thanks for responding because i wasnt getting many .lol.and do not think i was fingerpointing cus like i said im just out of thoughts.and just dont know.take care .

ttt

ttt

hmmmmmm,hmmmmm .lol

hey, none taken, just wanted to make sure that a misfire is caused by something wrong with wiring or mechanical. if the a/f ratio is off, that's because the pcm is doing so because of a sensor, the pcm will only do what's it told to. if there is a false lean condition due to a bad o2 sensor, it'll add fuel until the issue is resolved, causing a rich condition, just as example.
did you start it up at night and see if you can see any spark across the header from a wire?
if a cylinder isn't firing, it will be colder, so check that, go ahead and grab each one after it's at normal operating temperature, haha.

ya, there could be an open on the connections you made for the injector clips.
if the pcm set a P0174, that's a lean condition, caused by a bad o2 sensor or vacuum leak, or a bad maf. that would be the side to check for cold cylinders, the ltrim value on that side/bank is probably +25, so there could be an issue on that side.

it's too hard to go over all the wiring, but each wire needs to be ohm'd out to ensure connection.
but all the wiring needs to be gone over that deals with coils and injectors.
test each A side of the injector (that's the hot side) make sure power is there.
the other side, B , make sure there is connection to the pcm be ohm'n each wire.
swap your coils if you have a spare set.

that's a start, that should keep you busy, because it's a pita to do.

thanks bud gonna do it all today,haha.gonna try.ill keep u posted,thank you.

ok so far no luck ive changed maf ,plug wires,plugs.no go .i put denso platinums in and gapped them at 40.sound right?now on the inj wires.wich is a + on each ?looks like if im not mistaken the ground is the one with the black stripe on each one ,is that correct?im gonna try to stick a regular test light in each pos to make sure theyres power cus i dont have an ohm meter ,will that be ok just to check for power?this is getting costly just for a stupid code that could be so many things.

ok update lol .changed coils ,no help.lol wth.checked all inj plugs for power with test ligh and they all had power.sprayed all over the motor with cleaner and couldnt find any vaccuum leake.no plug wires glowing in the dark.im stumped.im thinking about putting the factory air box and intake tube on to see what happens.o 1 more thing how should the pvc work or how do you know if ones bad.whe i put my finger over it it sucks it in.shot in the dark but not sure how the pvc is supposed to function.if you pull it off or leave on u know.whats the deal with them cus it seemed like it ran better with my finger over it.thanks .

pcv valve for some odd reason helped it run better but no go.im about out of ideas .is there anything internal thatll cause a random multiple mis ?po300.i get 2 po300s at a time everytime it does it.wen the a/c is on and im drivin ,i can feel it like a spark plug hitting and missing.now im getting aggravated.i also put a new tps sensor and air box and intake and maf off the esky.im losing it here now.shot in the dark here but my tranny guy said if i hook up my speed sensors wrong ill throw a code ,would this be a code it would throw?idk,just sayin.

whatever happened to gassguzzler ?he was good at this stuff.

hey guys im reading all over and some people are saying any cam just about will throw a po300 code .is this true.and that the misfire perameters need tro be set higher.im not feeling it alot and i feel it could be the cam.its just alittle shaky in gear at idle,wen it pops the code.i do feel it alittle more with a/c on.like a bad plug.but i could be looking too hard.ya know .some are saying that low idle will cause it.turn up the idle 500 rpm could fix it?it does do it wen the idle comes down.aaaalllleen what do ya think bud?

allen did u take the weekend off?were r u ?lol .

come oooooooooooon.jeeesh i have to drive this thing ,man.could aaaaanyone help me here .with the tune questions or about the cam throwing the code .or turning up the misfire perameters.what about a crankshaft sensor,or camshaft sensor?idk i just want this POS to run normal this is exactly y i demodded so i didnt have to work on it all the time.i ready to smash it in a tree if it doesnt get fixed.im stumped and dont know what to do.when it idles to long the code comes on as soon as the idle gets low after 5 mins .so i dont know if its losing the cylinder and lowereing idle or what im soooooo sick of this.and cant get any answers,ive tried and tried on my own.

My 96 used to do the same thing at idle after so long with ZZ4 cam, it ran great but after idling so long it would set the same code at idle, so if it runs fine just turn off the code, if don't ou need to see what cylinders are showing a misfire with a scan tool and go from there. I also showed this code on my 01 pu after putting in my LS1 I copied over all the fuel tables for a LS1 and flashed my computer, except for the MAF which was used the orignal off my truck. Code 300 would always come up around 80 mph, so after looking at info on scanner I decided that program was lean so I used the program off the camaro as far as programming go, it was to rich according to scanner at low speed so I blended it in program on the MAF tables and no more code 300, trims are closer now and no codes, hopr this helps.

BB

BB

you're gonna have to ohm out the wires to ensure there is connectivity. ohm each wire at the terminal, don't just poke through the wire plastic covering, becuase the terminal could have a cold joint.
you're feeling a physical misfire, it has to be an inj, plug, coil, and dealing with wiring, or at least that is the first place i'd start.
the lean code, well it might have something to do with the misfire, or there is a bad o2 on that side or an exhaust leak.

it's gotta be wiring, at least that is a very good place to start.

Bet it's a wire.