Diagnostic help.. Plugs pulled.. not good
Thread Starter
Teching In
Joined: Aug 2005
Posts: 38
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Diagnostic help.. Problem solved???????????? After getting the following codes I replaced the primary 02 sensors which did nothing.. I then replaced the MAF, let the car idle for 5 minutes and the 0171 code came back (nothing else)... Mods include LG headers, vararam and tune.. The car WAS running fine with those mods for about 2 months until recently.. Oh yeah, I also broke the #8 cylinder exhaust spring valve (passenger side) but that was replaced and okay..
PCM P0171 H/C - Fuel Trim System Lean bank 1-B
PCM P0300 C - Engine Misfire detected-B
PCM P1133 H - Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1-8
Well, I decided to tear my motor apart and along the way I found some interesting things.. First, the plugs (see pictures below), second, the gaskets for the PCV hoses to the headers were never used, and last, the plug wire for the 7 cylinder wasn't even on the spark plug (could this cause a lean code?)
I was wondering if there was a plug wire not being fully connected with the spark plug could that cause the car to think that the car was running lean?
What sensors tell the cars' computer that its running lean? Obviously the car is not running lean simply by looking at the plugs..
P0171 Fuel Trim System Lean bank 1-B
Dark plugs on top (signs of being rich) are from the drivers side.
Normal plugs on the bottom, or what look to be normal.. Passenger side
Larger Picture
PCM P0171 H/C - Fuel Trim System Lean bank 1-B
PCM P0300 C - Engine Misfire detected-B
PCM P1133 H - Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1-8
Well, I decided to tear my motor apart and along the way I found some interesting things.. First, the plugs (see pictures below), second, the gaskets for the PCV hoses to the headers were never used, and last, the plug wire for the 7 cylinder wasn't even on the spark plug (could this cause a lean code?)
I was wondering if there was a plug wire not being fully connected with the spark plug could that cause the car to think that the car was running lean?
What sensors tell the cars' computer that its running lean? Obviously the car is not running lean simply by looking at the plugs..
P0171 Fuel Trim System Lean bank 1-B
Dark plugs on top (signs of being rich) are from the drivers side.
Normal plugs on the bottom, or what look to be normal.. Passenger side
Larger Picture
Last edited by TheAngryTitty; Oct 20, 2005 at 11:42 PM.
It looks like you had some cascading happening with the codes that were set. The plug wire not being attached to #7 could cause a bad enough misfire to throw the P00300 vs P00307 (cylinder 7 misfire). When you get new plugs in make sure you get two clicks on the coilpacks and one solid click on the plugs.
When you say the pcv hoses on the headers had no gaskets, I assume you are talking about the AIR fittings. If these connections were leaking, it could have let air in upstream of the O2s, causing them to show lean. This, and the fact that you have longtubes, probably was the main cause for the 171 code. The O2s show lean due to the air leak, the PCM commands more fuel, car runs extremely rich for a while and burns up the O2s causing the P1133 code.
Try replacing the spark plugs and installing gaskets on the AIR fittings. You should also check the AIR system check valves to ensure they are operating properly.
Did you reset your fuel trims after installing the new MAF?
When you say the pcv hoses on the headers had no gaskets, I assume you are talking about the AIR fittings. If these connections were leaking, it could have let air in upstream of the O2s, causing them to show lean. This, and the fact that you have longtubes, probably was the main cause for the 171 code. The O2s show lean due to the air leak, the PCM commands more fuel, car runs extremely rich for a while and burns up the O2s causing the P1133 code.
Try replacing the spark plugs and installing gaskets on the AIR fittings. You should also check the AIR system check valves to ensure they are operating properly.
Did you reset your fuel trims after installing the new MAF?
Go to this site for diagnostic tests for specific codes:
http://www.gearchatter.com/index.php...eb627c9ff85cee
http://www.gearchatter.com/index.php...eb627c9ff85cee
Thread Starter
Teching In
Joined: Aug 2005
Posts: 38
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Alright.. So after replacing the plugs, I think I found the culpret and its not looking good.. The deeper I dig the worse it gets.. Now I have to figure out where these wires go, and how Im going to replace them.. 
This could explain things, right?
Remaining Pictures
Large Version
This could explain things, right?Remaining Pictures
Large Version
Last edited by TheAngryTitty; Oct 20, 2005 at 11:34 PM.
That could be the cause depending on what the wires go to... Have you tried posting this on the vette forums here, or some of the other vette specific sites? They might also see something that we wouldn't recognize right off the bat.
