Damn POS P0300 code
Damn POS P0300 code Guys I just had a headswap done on my '00 TA. Now pre swap the car was not driven and sat in the garage for 1 1/2 yrs. Only driven once every few weeks. Before the swap P0300 went off. No major issues driving it, but the code was there. Now fast forward, head swap is done, new plugs installed along with a new fuel filter. Wires were added pre swap before the car sat. The day I got it back and drove it there was a slight hesitation at low RPM, but after getting past 1400 or so the car drove fine, it ran right through the hiccup. I drove the car 225 miles round trip to the mountains, same thing sometimes mild hesitation, but otherwise no problems. Today took it to lunch, 1st real city driving since the swap, and it progressively got worse. By the ride home, EVERYTIME I came to a complete stop it idled ROUGH, and from idle to 1700 RPM range in every gear the car just studdered, and putted and didnt want to drive unless I put the pedal throught the damn floor. WTF??? I run 93 octane if that helps any.
THX, is this wire under the car? Im clueless when it comes to this kinda stuff
"Slight hesitation at low RPM" sounds like vacumm leak.Once more air enters engine then it runs better.Here is a great website to help you:
http://www.aa1car.com/random-misfire/
Like it says in there it will definetly cause a PO300,so check it out.
Good Luck!
http://www.aa1car.com/random-misfire/
Like it says in there it will definetly cause a PO300,so check it out.
Good Luck!
I was thinking vacuum leak too, if you search threads on here for P0300 it often ends up being a cracked PCV line causing a vacuum leak, although this would usually also set P0171/P0174. But it's something to check.
OK here is an update. Drove the car today with a scanner and it bogged down real bad while driving and SES was flashing. Plugged in scanner and code came up for O2 lean bank. So even after that we cleaned the MAF, and sprayed cleaner all around the intake to check for a vacuum leak, which came up negative. Tomorrow my bro in law is bringing home his scanner from work to check which cylinders are misfiring and we are going to replace the O2.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Teching In
Joined: Mar 2009
Posts: 32
Likes: 0
the code doesnt mean the o2 is bad.
What exactly is the code?
Is it refering to the o2 heater circuit? or the o2 lean/rich mixture itself?
the o2 COULD be bad. I'd STRONGLY suspect as someone suggested a wire hit the header and got pinched or burnt. if that's not the case, do you hava n exhuast leak?
and is your engine actually running too rich or lean?
Hows your fuel pressure?
Hows your spark?
o2 and fuel mixture problems can be an entire host of things. Not that its nessecarily hard, just that you have to be logical and practical and test properly. Sounds like you've already omitted a vacuum leak as the source. is that the only code you pulled? is it for both o2s or just 1?
What exactly is the code?
Is it refering to the o2 heater circuit? or the o2 lean/rich mixture itself?
the o2 COULD be bad. I'd STRONGLY suspect as someone suggested a wire hit the header and got pinched or burnt. if that's not the case, do you hava n exhuast leak?
and is your engine actually running too rich or lean?
Hows your fuel pressure?
Hows your spark?
o2 and fuel mixture problems can be an entire host of things. Not that its nessecarily hard, just that you have to be logical and practical and test properly. Sounds like you've already omitted a vacuum leak as the source. is that the only code you pulled? is it for both o2s or just 1?
Oh forgot he checked the O2 on the drivers side, it was not stuck to the header or melted, a little of the plastic covering was worn but the wires were intact. He had it jacked up and unplugged both ends, even if its intact it could still be bad correct?
Teching In
Joined: Mar 2009
Posts: 32
Likes: 0
can you visually inspect the o2 and compare it to the other one? you can't look at the o2 and say its fouled just because its black, i mean it is in the exhaust and will have carbon on it ya know? 
but if you compare it side to side and the bank that's not throwing a code looks much better than i'd say thats an indication it is indeed the 02. The best way is to get a scanner that can read the o2 data live and in graphical format. digital format does no use to you. It should be switching evenly. If its not you've either actually really got a lean condition on just that bank or the o2 is bad. Now is it possible to have just 1 bank lean? absolutely. Remember, an o2 doesn't read fuel. it reads oxygen.
but if you compare it side to side and the bank that's not throwing a code looks much better than i'd say thats an indication it is indeed the 02. The best way is to get a scanner that can read the o2 data live and in graphical format. digital format does no use to you. It should be switching evenly. If its not you've either actually really got a lean condition on just that bank or the o2 is bad. Now is it possible to have just 1 bank lean? absolutely. Remember, an o2 doesn't read fuel. it reads oxygen. update bro in law brought home his scanner form the dealer and it showed P0301 cylinder 1 misfire. So he swapped the spark plug wire from that cylinder to cylinder 3 to see if it followed and........................nothing. We drove it for over 10 miles and simulated every kind of driving condition and the car bogged only once during the initial 30 secs after he changed the wires. SO tomorrow is a new day, Im tired of driving around waiting for something bad to happen tonight. Usually the SES light came on immediately after it was cleared. Oh well, whoever thought I would want something to go wrong??
Mine was doing the same thing. I checked and rechecked the PVC tubing and was sure it was fine. Well when I put the new motor in I sold my PVC lines that go around the back of the motor and the guy called and said he found a crack in the line but just spliced it with some tubing and its fine. The covering they put on it makes them hard to find and hear but Id lay 100.00 that if you take it off and blow through it it is leaking. TAKE IT OFF AND LOOK it takes an hour and youll know for sure its not vacuume leak. Hope you find the problem whatever it is...
Been driving pretty good for awhile, the only time it seems to chug for awhile is during a hot start. Like tonight for example, I drove it for 1 hour no problems all kinds of driving, then I stopped to get gas, and as soon as I satrted up and left the lot the car chugged and hesitated, but then cleared up. Doe sthe fact that it happens during a hot start and not cold narrow it to anything in particular or eliminate anything?
Your car is a 2000 so I think you still have an EGR valve.The link I sent you in post 5 also contains info on the EGR and it sounds like a leak:
"On some engines, this kind of problem may not appear until the engine warms up. The EGR valve may remain closed while the engine is cold, but it starts to leak when the engine is warm. This may be due to a weak spring inside the EGR valve. The fix here is to replace the EGR valve."
Sounds like this, doesn't it? Worth looking into.Good Luck!
"On some engines, this kind of problem may not appear until the engine warms up. The EGR valve may remain closed while the engine is cold, but it starts to leak when the engine is warm. This may be due to a weak spring inside the EGR valve. The fix here is to replace the EGR valve."
Sounds like this, doesn't it? Worth looking into.Good Luck!
Your car is a 2000 so I think you still have an EGR valve.The link I sent you in post 5 also contains info on the EGR and it sounds like a leak:
"On some engines, this kind of problem may not appear until the engine warms up. The EGR valve may remain closed while the engine is cold, but it starts to leak when the engine is warm. This may be due to a weak spring inside the EGR valve. The fix here is to replace the EGR valve."
Sounds like this, doesn't it? Worth looking into.Good Luck!
"On some engines, this kind of problem may not appear until the engine warms up. The EGR valve may remain closed while the engine is cold, but it starts to leak when the engine is warm. This may be due to a weak spring inside the EGR valve. The fix here is to replace the EGR valve."
Sounds like this, doesn't it? Worth looking into.Good Luck!
