2000 corvette need help asap
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
2000 corvette need help asap
my 2000 corvette has aftermarket 3" long tube headers, x pipe, z06 exhaust installed in oct. 2011. i ran the car for 4 months without rear o2 sensors installed. before any1 says it, i know, that was stupid. i got down on it last week and now the car is wanting to bogg down and not run like its not getting fuel. i installed new rear o2 sensors, new spark plugs, plug wires, and air filter. problem still exist. when i read it out it comes up random misfire (P0300). i dont have any cats on the car currently as well. also just checked all the coil packs today, all checked good and had spark. is this a fuel problem or a spark problem. im thinking i could have a fuel filter, or cylinder. has any1 had the same problem or have any advice.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Usually when I see the 300 code, first thing I think of is the ground wire on the rear of the driver's side head, coming lose. Is it idling correctly and just bogging down? You might have one of the plug wires isn't on all the way or a cracked plug. I asked about the idling in case of a possible cracked valve spring.
Cruising
Joined: Oct 2011
Posts: 14
Likes: 0
Misfire? Pull the plugs, check the gaps. Make sure wires are SECURELY in place.
Serive manual says 2 to 4 cylinders on the SAME BANK.
It states to check the injectors. One injector may cause the whole side to malfunction.
Inspect O2 CONNECTIONS for corrision or water intrusion.
Excessive backpressure.
And finally swap O2 sensors to detect a faulty sensor.
Serive manual says 2 to 4 cylinders on the SAME BANK.
It states to check the injectors. One injector may cause the whole side to malfunction.
Inspect O2 CONNECTIONS for corrision or water intrusion.
Excessive backpressure.
And finally swap O2 sensors to detect a faulty sensor.
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
All the plugs are gapped correctly and new plug wires installed. it idles pretty rough. it has the new o2 sensors but ill swap them around and see what happens and then let you know. Ive been told that i could have a bad fuel filter, cracked valve spring, or a bad ECU. ill be changing the fuel filter today and checking the valve springs this week. ill let you guys know what i come up with. thanks so much for the info.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Yes a broken valve spring can give you a mis-fire code---
The rear 02's have NOTHING to do with how the engine runs--They are there only to report the condition of the cats-mostly to see if they are overheating
However the FRONT 02's are what set the fueling during all PT operation
Make sure the front 02 voltages are bouncing around rapidly from .100 to .950 millivolts
You can check this with most any handheld scanner that shows real time data--
A lazy 02 or a bad 02 will make the engine run in a sort of limp mode--
A bad 02 will be flatlined at .450 millivolts
ALSO--a P0300 code i believe will set your timing to the "low octane" timing table to protect your engine--can be the cause of a lazy engine---NO TIMING-( about 1/2 the normal amount)
Can you feel or hear the misfire ?????
Check the LTFT's right vs left
A bad 02 on one side will mke your engine unbalanced as one side will be correcting the AFR to 14.68 all the time and the other side will be running in a back-up table
The rear 02's have NOTHING to do with how the engine runs--They are there only to report the condition of the cats-mostly to see if they are overheating
However the FRONT 02's are what set the fueling during all PT operation
Make sure the front 02 voltages are bouncing around rapidly from .100 to .950 millivolts
You can check this with most any handheld scanner that shows real time data--
A lazy 02 or a bad 02 will make the engine run in a sort of limp mode--
A bad 02 will be flatlined at .450 millivolts
ALSO--a P0300 code i believe will set your timing to the "low octane" timing table to protect your engine--can be the cause of a lazy engine---NO TIMING-( about 1/2 the normal amount)
Can you feel or hear the misfire ?????
Check the LTFT's right vs left
A bad 02 on one side will mke your engine unbalanced as one side will be correcting the AFR to 14.68 all the time and the other side will be running in a back-up table
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
i had the same issue and it turned out to be a loose plug wire.
You said you did new plugs and wires. quite possible one wire is not all the way onto a plug. the oem wires click twice if i am not mistaking (it has been a while since i did them)
You said you did new plugs and wires. quite possible one wire is not all the way onto a plug. the oem wires click twice if i am not mistaking (it has been a while since i did them)
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
ive double and triple checked the plugs and wires and all check good. but i will have to check the front o2 sensors while i have it lifted up. could the car running without the rear o2 sensors hooked up for so long cause the fronts to go bad in the process??? i talked to someone the other day who was also talking about the car being in possible limp mode. before i changed the plugs and wires you could hear the misfire, now its not as bad. but thats all great advice and i will check all of that. thnk you for all the advice.
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Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
so this weekend i changed out the fuel filter and read out the injectors, coil packs again, fuel pressure gauge, cylinders, and spark plugs. all checked good, but cylinder 6 is the main problem misfiring. i swapped spark plugs and coil packs from another cylinder with no problems and problem still exist. only other thing i can think that might be wrong is bad front 02 sensors since they read the fuel to air ratio or the ECU. Looking at ordering front 02 sensors today. im thinking it has to be a bad 02 sensor upstream. anyone have any other thoughts or ideas that hasnt already been discussed?????
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
If you are sure the problem is on a single cylinder which you identified as #6, then pull the valve cover and inspect the valve spring. Also possibly do a compression test on that cylinder. I'm hoping you verified the fuel spray pattern from #6 injector is normal as well.
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
so this weekend i changed out the fuel filter and read out the injectors, coil packs again, fuel pressure gauge, cylinders, and spark plugs. all checked good, but cylinder 6 is the main problem misfiring. i swapped spark plugs and coil packs from another cylinder with no problems and problem still exist. only other thing i can think that might be wrong is bad front 02 sensors since they read the fuel to air ratio or the ECU. Looking at ordering front 02 sensors today. im thinking it has to be a bad 02 sensor upstream. anyone have any other thoughts or ideas that hasnt already been discussed?????
since it seems to be #6 cylinder looks like it is time to pull a valve cover.
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
i checked the compression on cylinder 6 and it was good. I did get a code for the sensors, PO131; PO132; PO137; PO138. so thats why Im going ot change out the front sensors and see what happens. Im going to pull the valve covers and check the valve springs as well after doing the front sensors. I had random cylinder misfires, but #6 was the main one. I swapped the coil packs from a non misfiring cylinder and spark plug and wires but still exist.
Thread Starter
Heel & Toe
Joined: Jan 2011
Posts: 20
Likes: 0
From: Middleburg, FL
So Ive changed both front o2 sensors and these are the new codes I have coming up now.
PO174; PO152; PO131; PO132; PO300. I was told if the valve springs were bad that the problem I'm having would be consistent all the time and not come and go when it pleaze. Ive also been told that it could possibly be the ECM gone bad and sending wrong or mixed signals in and out. Does anybody agree with that about the ECM???
PO174; PO152; PO131; PO132; PO300. I was told if the valve springs were bad that the problem I'm having would be consistent all the time and not come and go when it pleaze. Ive also been told that it could possibly be the ECM gone bad and sending wrong or mixed signals in and out. Does anybody agree with that about the ECM???