hnaskoct

iTrader: (31)

[B]code p0300 random mutiple missfire..help

sdm1234

iTrader: (8)

i had that code and it was my EGR. but with little to no information other than the code, it could be just about anything. good luck!

horist

need a little (or alot rather) more info...

mods?
what type/year car?
when did it start happening?

hnaskoct

iTrader: (31)

its a stock 02 6 speed with a programming on it and borla exhaust ive changed plugs twice, coils,wires,o2 sensors and it idles real bad and when i give it gas it sounds real bad too from the exhaust and the car barely moves when i tried to drive it it has no power it just bogs out....plz someone help

bradl1982

iTrader: (9)

I have the same problem. I have to get my car home and then I'm going to check out the plugs and change them since it's about that time anyway. Hopefully that's the problem. There's a lot of info on the site about the code. Do a search. I'll let you know what I figure out when I fix mine.

ChrisS@sdpc

Could be lots of things. Need to check the plugs and wires as they are easy to examine physically. Also, examine the intake tract, look for vacuum leaks, etc.

Are you sure that is the only code? From the brief description, it sounds like you could have a problem with the intake track after the MAF. Make sure that all of that is in place with no leaks. I have seen/experienced vehicles where the intake tract fell off the TB, but the MAF remain plugged in. The MAF is reading no airflow, yet there is significant air entering the engine. Thus, fueling and spark are way off. I have also had similar experiences with a melted catalytic converter which basically clogged the exhaust.

What kind of 'programming' do you have? Did this start to occur after something specific (e.g. hard driving or missing a gear)?

jay_99z

iTrader: (5)

Another vote to check out the MAF. With or without code.....it can still cause you trouble.

eallanboggs

iTrader: (1)

P0300:Random misfires. P0301 thru P0308 are cylinder specific. Yours is random so you should look for something common to all 8 cylinders rather than concentrating on a specific hole. P0300 is usually associated with rough idle caused by an aftermarket camshaft with a low LSA.

99hrstws6

i know this wont help you but i had a 96 t/a. same code same drivability problems. and it was a bad optispark

Violatorno1

iTrader: (3)

This is where datastream comes in handy. MAP, MAF, O2, plugs, wires, coils, fuel pressure all could be a cause. Do you get black smoke out the pipes?

Travose21

iTrader: (22)

my friend had the same problem and it was that his cats were clogged

2formulas

iTrader: (2)

I'm hijacking this thread cause I have the same code. P0300.

I have a some black smoke coming from the exhaust while accelerating. I can't see it but my friend behind me can. What does the black smoke indicate?

Also I have a slight hesitation on acceleration that started after I swapped my intake. Could I have pressed in the gaskets too far, causing a leak. Could this be the problem with black smoke.

Seems to pop at idle and someone said it smells rich, I can't tell but thats what they said. I think it smells like a dump truck sometimes. (If thats what rich smells like)

Car has new plugs and wires with a 224 cam and was tuned after swap. Intake, catback and shorties. Cam swap was like over 2 years ago but it only goes out on the weekend occasionally.

2formulas

iTrader: (2)

anyone??

1QK-WS6

you should haave the car scanned to read the misfire counters, if there is one cylinder missing more than all the others that is the primary misfiring cylinder and probably the root of the problem. sometimes one bad cylinder will set off others and cause a p0300(random cylinder misfire) even though the problem is due to one cylinder.

1QK-WS6

black smoke indicates that you car is not burning the fuel correctly. either there is an excess of fuel being delivered or there is no/insufficient spark to burn the fuel. as for the smell it is to be expected with a cam vehicles usually run a little richer after a cam install. and yes that is what rich smells like it will also burn your eyes if it really stinks. if you had an intake leak the car would be lean rather than rich.

2formulas

iTrader: (2)

I just wanted to update everyone on my finds. After 3 months I decided to take a look at my car and I have some cooked wires.

I had this issue about 3 years ago after I put my headers in but I guess the heat shield didn't work. The bundle is on the passenger side going down past the header to the right front o2 sensor/tranny/starter.

Anyway, it's not as bad as the last time, which was making my car stall and after a while wouldn't even start. The wires aren't completely cooked, just a little stuck together. I spliced new wires and have some 2000 degree heat shield on order.

I'll post again when I get it back together and see if this is my p0300 problem.

eallanboggs

iTrader: (1)

If you've had this problem before and you're going to all the trouble of splicing in wires why don't you reroute them away from the headers. You can cut out the bad section and splice in enough wire to be able to reroute the harness away from the head source. That way you won't have this problem again.

2formulas

iTrader: (2)

I was looking in the area and pretty much my only option is to go around all the way around the drivers side, then go under, then back to the passenger side. I really dont see too much room in the passenger side between the header and the body to where I can re route it. It wasnt touching the header but the shield was worn and that is where it was melted. There is another smaller bundle that routes with it and the shield on that bundle is good and that bundle looks great so I'm sure with new sheild it'll be fine. It sits probably 2 inches away from the header.h

eallanboggs

iTrader: (1)

Butane solder pencil, silver solder, heat shrink tubing, black plastic tape, some tie wraps or tie straps and that big can of different color and gauges of standed wire you have sitting under your work bench and you're on your way to a fix. Keep in mind that heat rises when you pick a location to route the harness. Under the header on a frame member is a starting point to begin looking for somewhere to fasten the harness.

2formulas

iTrader: (2)

ya I got it spliced, just waiting for the heat wrap from napa.