C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

??Pulled engine codes tonight

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Old Aug 1, 2011 | 11:19 PM
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Default ??Pulled engine codes tonight

My 96 LT4 has had a check engine light on and off and more on than off lately. Car first had a strong fuel odor that i couldnt find a reason for. Then, the car would start to run rough and idle poorly. Then, now if its warm (or especially has been driven awhile) it barely starts. Or maybe i should say it starts but dies within seconds, unless i keep giving it throttle/gas. But! If I can get on the highway and heading down the road for a few miles it will stay running/idle. Granted rough, but will drive. SO I went and pulled the check engine codes and the codes were: Random misfire, and Too lean bank 2. I'm mechanically inclined and do all of my own wrenching. But, looking for some knowledge from the members here on where to start?? Even though I can sometimes smell a strong fuel odor and that would make sense for the too lean fuel bank, I have never been able to find an actual fuel leak anywhere. So?? Any thoughts?
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Old Aug 2, 2011 | 12:48 AM
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How old are the front O2 sensors?
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Old Aug 2, 2011 | 11:43 AM
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Original? Is there a code for bad o2 sensors?
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Old Aug 2, 2011 | 07:53 PM
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Originally Posted by Huntervangolf
Is there a code for bad o2 sensors?
The "lean exh indicated" code could also mean the O2 sensor is faulty.

The ECM is seeing a lower voltage than it expects to see which may be caused by a bad sensor and not that the engine is actual running lean

For earlier (OBD1 ) cars but analysis the same
http://www.mifbody.com/DTCs/DTC%2044.jpg

What were the DTC # you actually pulled?

Last edited by rodj; Aug 2, 2011 at 07:56 PM.
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Old Aug 2, 2011 | 08:14 PM
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P0174, P0300 were the two codes. Random misfire and bank 2 too lean
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Old Aug 2, 2011 | 09:10 PM
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Not a bad idea to check fuel pressure...
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Old Aug 6, 2011 | 02:09 PM
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If it was low fuel pressure wouldn't both banks be lean? And which side is bank 2?
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Old Aug 6, 2011 | 10:21 PM
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Bank two should be the passenger side, I think...whatever side cylinder 1 is is bank 1 and cyl. 2 is bank 2.

If you can see it, which ever bank is more forward in the car is bank 1.

I'm going my memory here and I have CRS.

Yes, logically, if you only have a bank 2 lean code, then fuel pressure might be ok. Better to be sure than not. Then again with a random misfire and a lean bank 2, how you do know it is NOT a fuel pressure issue or insert whatever you want here.

Four things I have learned working on cars is A: Never assume anything B:If not not sure, test until you are. C:Often times things defy the Service Manual and Logic. D: Cover your basics first and remember the KISS principle.
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Old Aug 7, 2011 | 10:45 PM
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If its showing a 'lean condition' the PCM will try and compensate by adding more fuel, hence the fuel smell. Or the missfire could be allowing unburnt fuel through the exhaust, again fuel smell.

It does sound a lot like an O2 problem, if the sensor is still within range, it won't throw a code, but still being within range can be significantly off to cause problems.

Sara Lou
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Old Aug 8, 2011 | 01:49 PM
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Well, I replaced the MAF. Reset the engine codes. Drove great for about 20 miles. Shut it off and waited for an hour and restarted fine, so i thought i was in the clear! Then took it for a little spin, shut it off and it wouldnt start and idle, unless i hold it at about 2500 rpm. Even then its really really rough. And the check engine light came on. so went and pulled the codes again. Random misfire, and cylinder 06 missfire.
So at this point it seems the MAF took care of the lean condition. But! Now the missfire codes????? Im also believing when you give it full throttle it seems to run perfect, which makes me wonder if it isnt a sensor that goes close loop at WOT. And what is with this runs fine til you restart it???

Last edited by Huntervangolf; Aug 8, 2011 at 01:52 PM.
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Old Aug 8, 2011 | 07:32 PM
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Could be a injector bleeding down.

Sara Lou
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