The Phantom PO300 code!
#1
The Phantom PO300 code!
I've had this damn PO300 "mutliple engine missfire" for the last 2 or 3 months. I've replaced the opti, and the opti harness. New plugs, and new wires. I can't figure out for the damn of me where it is comming from! I currently have the hotcam in my car, i know it does create a slight miss, but I got the car re-tuned twice. So according to SpeedInc it shouldn't be there and yes I've brought it back to them numorouse times.I'm just gettin tired of waitin weeks at a time gettin my car back. Emissions testing is comming up. So does anybody have any quick fixes or suggestions? I am at a totall loss. I know one of my buddies said there is a certain code I can put into the computer via Tec 2 to clear it out permanently, but the only problem with that is, I don't know if its somthing seriouse or not. Thanks gentlemen.
-GTP Stage 2 Heads
-Hot Cam setup 1.6
-Full exhaust
-Long Tubes
-Cutout
-O2 trip sensors
-MSD 6al
-Everybolton
-Walbro 255
-Race tronix 32lbs
- Holley AFPR
Just a list of stuff that may have an effect on answers. If you need anymore information just post, and i'll reply promptly!
-GTP Stage 2 Heads
-Hot Cam setup 1.6
-Full exhaust
-Long Tubes
-Cutout
-O2 trip sensors
-MSD 6al
-Everybolton
-Walbro 255
-Race tronix 32lbs
- Holley AFPR
Just a list of stuff that may have an effect on answers. If you need anymore information just post, and i'll reply promptly!
Last edited by BlackBird97; 09-05-2005 at 04:49 AM.
#2
Re: The Phantom PO300 code!
try your wires see if there is a short by the headers being so close. also try the cps i have a new one im the box if you want to buy it dont need it, i had a short in the wires
#4
Re: The Phantom PO300 code!
CPS = Crankshaft Position Sensor
The good ol' PO300. It seems to be a different cause for everyone who has had it. Most don't post back what caused theirs. I chased it for a couple of months, before the scan tool finally pinpointed the cylinder the miss was in. It turned out to be a bad plug wire that looked perfectly fine, until I took it off, then I could see the fine black line by the sparkplug boot.
Do you actually have a miss, or is the car just giving the code?
The good ol' PO300. It seems to be a different cause for everyone who has had it. Most don't post back what caused theirs. I chased it for a couple of months, before the scan tool finally pinpointed the cylinder the miss was in. It turned out to be a bad plug wire that looked perfectly fine, until I took it off, then I could see the fine black line by the sparkplug boot.
Do you actually have a miss, or is the car just giving the code?
#5
Re: The Phantom PO300 code!
Originally Posted by moparman
Do you actually have a miss, or is the car just giving the code?
#6
Re: The Phantom PO300 code!
Like mentioned before have you checked your fuel pressure at all? with the vehicle running hook a gauge up to the fuel rail (with the shradder valve removed) and pun it through a nice wide RPM range. Also you say it feels as though is missing, and your sure the plug wires are good, i know its a PITA but check all the other to make sure non are carboned up, also if they are good we know u got spark, put a noid light on each injector to make sure they're each firing...can't seeing it being you ignition module....cam position sensor??
just my $.02
hope this helps
Rob
just my $.02
hope this helps
Rob
Last edited by CamaroRob97; 09-05-2005 at 06:19 PM.
#7
Re: The Phantom PO300 code!
Arrite, I've been doing alot of research on the Crank Position Sensor, I found that its about 70 bucks from GM. I couln't find the Cam Position Sensor, checked Chiltons, engine diagrams and whatnot. Does the 97 LT1 Have one of these ? All I could find was the Crank Position Sensor. Looks like an easy install.
#8
Re: The Phantom PO300 code!
Well in all honesty its been bout 2.5 years since i've even really touched an LT1 let alone an f-body, so yeah my Cam posi. sensor info may be off. But as far as the CPS Yes its at the bottom of the timing cover...can't remember if its d/s or p/s...(Man i need to get to the desert so i can my off the 'clipse an get another f-body )
#9
Re: The Phantom PO300 code!
Originally Posted by CamaroRob97
Well in all honesty its been bout 2.5 years since i've even really touched an LT1 let alone an f-body, so yeah my Cam posi. sensor info may be off. But as far as the CPS Yes its at the bottom of the timing cover...can't remember if its d/s or p/s...(Man i need to get to the desert so i can my off the 'clipse an get another f-body )
LT1 don't have a seperate cam sensor, all it needs one for is fuel/spark synch, so the high and low res pulses for the opti suffice, and all it uses the crank sensor for is misfire detection
#10
Re: The Phantom PO300 code!
Hmm I see, well tomorrow I'm goin under the car, checkin for burnt wires, and investigating the CPS. Are those things prone to go out after a while? And Rob, it's arrite man, there will be an F-body there for ya when ya want one! We'll all still be here!
#11
Re: The Phantom PO300 code!
On OBD2s (particularly LT1), P0300 can show up after installing a cam that is more radical than stock. If it does, there is not much you can do about it since the system was designed for checking misfire on a stock cam. Having said that, I'm almost 100% sure a new sensor won't solve your issue. Your best bet, in my opinion is to have the code disabled. You should be able to pass with 2 "NOT READY" flags and this would only trigger one.
Last edited by madwolf; 09-06-2005 at 01:48 AM.
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