O2 sensor problems

[LS1CHEYENNE]

From the moment I got my wiring harness hooked up ( I got the truck and the Transam harness grafted by the guy in Erie, PA ) this engine has purred like a kitten but I couldn't immediately hook up the oxygen sensors because of clearance problems . I was told this would be ok and that it was safer for the engine to run too rich than too lean . Today I went down to the exhaust shop and had them make the necessary adjustments and install an O2 bung in a place that I could get the sensor to clear the frame .This is only until I get my headers . But as soon as I hooked up the 2 front ones and installed the simulators for the two rear ones the truck refused to run right . It would buck in drive and then die . I would be able to restart it and it would ,but hesitantly so . It seemed to idle alright in park , though . I disconnected the two front ones and it returned to normal operation . I've been told that I'm probably only running at 2/3 to 3/4 of the potential HP of this engine like this and , obviously , I don't want to be running around with no forward O2 sensors sending a signal to the computer . I 'd really appreciate some input on this . Thanks guys .

[docgreen9]

question first .... it did throw codes because you didn't have the O2's hooked up .. right?

After installing the O2's did you reset the PCM? If the codes are still there sometimes they act funny if you just hook something up with out unhooking the battery.

Stupid ?? You sure you got the O2's hooked onto the front plugs and the simulators onto the rears?

Are they old O2's out of a wreck?? One or both might be FUBAR.

just getting the silly, DOH, stuff out of the way .... lol

[LS1CHEYENNE]

I may be stupid , but uh ain't dumb! Yes , I did disconnect the battery for about 20 minutes . It still does it . It revs up and down while idling and then dies . When I disconnected the two front sensors this morning it went back to normal . I don't think you could even get the front plugs confused with the rear ones - both of the rear ones come right out of the transmission branch of the harness ,right ? Could it be an EGR related issue? I still have the large rubber hoses that cross over between the stock exhaust manifolds ( yes , they're still on the engine ) and tee off to the air pump . Of course , I don't have this pump , so I've closed off this line . All of this is new to me and I have no problem admitting that , in all actuality , I don't really know what I"m doing ! I have limiited automotive experience. I didn't even really know what these engines were 6 weeks ago ! I never liked the newer camaros and firebirds and paid little attention to them . I did know that they had well designed engines and ran like hell . NOw I have one in my truck and it runs pretty damned good and I did it in the span of little more than a week . I have not had any computer burning done and when the harness was done the VATS was somehow bypassed and I was told that the EGR would also not be a problem . Do I need this air pump ? Thanks Doc

[docgreen9]

man I was just throwing some ideas out there.... I'm working on about 2 1/2 hrs sleep. That must be an early LS1 motor I think those had that x-over tube... not really sure. I'd still double check those O2 sensors you got to make sure they aren't bad. Also did the exhaust shop put the new bungs in about the same place as the old ones??

Maybe someone else will chime in here... I need to get some sleep.

[RedHeartbeat]

sounds like you need to bypass the EGR. You don't need it. Plug the hole at the top of the intake with a rubber freeze plug and cap the air inlet on the exhaust manifolds. When done, toss the EGR in the trash or Ebay it. Mine passed with flying colors without the EGR.

[RedHeartbeat]

Who burned your PCM? You should have had them disable the rear O2 sensors in the PCM and then you wouldn't need the simulators. Are you confident you have good sensors up front? Are you getting any codes?

[LS1CHEYENNE]

My PCM was not reprogrammed at all . I don't even have a reader at this time but am going to get one . Any suggestions on where to find one for a reasonable price? I looked on Ebay and didn't really like what I was seeing . This is a 1998 year engine , Doc. The only bung that needed relocation was the pass. side and it's probably about a foot and a half further back than where it was but the wires still reached . I wondered if that was a factor myself . I need to go get a scantool , at the very least . I have no way of knowing if the forward O2 sensors are any good .Is there a particular brand that anyone can recommend ? I think that one of the rear ones got moved to the front but I don't think this matters does it ? So , is the estimate of 2/3 of actual HP fairly accurate until I get this matter resolved ? My truck totally hauls ass now . It's hard to believe that I might get another 80 to 100 HP just by getting the sensors back online . Just wondering .

[LS1CHEYENNE]

UPDATE ! I went to my sister's house and her husband had a universal scan tool . It read a code 0113 and he looked it up . It said it was the air temp inlet sensor (that's approximately what it was called ) and I don't have this sensor hooked up yet because I don't have my aftermarket filter system yet . This is the one in front of the MAF , right ? But , it didn't mention a thing about the O2 sensors . How is this possible ? They're not even hooked up . Also , after I reconnected the battery this morning again with the forwards connected and the rears with simulators installed , the service engine light was still on . Is there some way that the PCM didn't clear , even after 20 minutes of being without power ? After this scantool cycled 5 times it cleared the code and my check engine light went off . Is it possible I could hook up the 2 forward sensors now and it run as it should ?

[RedHeartbeat]

If you do not have the air temp sensor at least hooked up to the wiring harness you will get codes all day long. Hook it up and strap it down somewhere in the engine compartment. You have to have it hooked up or the codes will not go away. Every time you hit the key the PCM scans all the sensors to see if they are there and working.