Alright guys i have more questions.... i have had my car for 3 or so weeks now and finally got it licensed and have started driving it quite a bit. I am going to try to describe everything about the car the best that i can so you guys can help, so if some of the stuff doesn't have anything to do with my problem bare with me... the car is a very clean 2000 trans am with 58k miles, it has long tube headers, k&n cold air, weiand lingenfelter aluminum intake manifold, a helix throttle body spacer, a strut tower brace, 3.73 gears (at least i think, im at 2k rpm at 60mph), 3 inch flowmaster exhaust, a granatelli maf sensor... those are all of the mods i KNOW about. the guy i bought the car from didnt know hardly anything about the car, all he told me was that it had intake and exhaust and didnt even specify which before i went to look at the car, and when i got there i found a lot more mods than he knew about. he was not a very car smart guy and i think he bought it at a action or something and that's why he sold it to me for cheap.... i am not sure if anything was done to the throttle body or not because i dont know what i stock one looks like, also i would disregard this because i cannot prove it but when i was right about to buy it he mentioned that it had a hotcam in it as well but i have no idea. it also shifts very hard and firm, especially from first to second, i almost wonder if it has some kind of shift kit?.... the things i have done to it since i have got it (that matter)- changed the oil with full synthetic 5w30, cleaned the throttle body, cleaned the maf sensor, cleaned the k and n filter (and re oiled it, i might add that we cleaned and re oiled the filter after we had already cleaned the maf), tightened all spark plugs (3 or 4 were lose enough to turn by hand!), and changed the gasket between the headers and the exhaust because there was a leak. there is also a exhaust leak right now coming from where the headers connect to the engine.

alright! now for my questions! the other day when i was driving home from town my "service engine soon" light came on ... i took it to Napa and had it hooked to a scanner and it is throwing the codes p0171 (it said fuel trim system lean bank 1), p0174 (fuel system lean bank 2), p0135 (H02S Heater performance bank 1 sensor 1), and p0155 (H02S Heater Performance bank 2 sensor 1)...i have looked up all the codes but it looks like there are lots of possible answers to each. what would be the most likely cause for the codes i am throwing based on my mods... also it seems like im running rich? it was like this before the codes were thrown but while at a idle and not moving there is a stronger than usual smell of gas (i think, i have never been around any other ls1s), it is not bad by any means but if you are standing out side of the car, you can smell it. I also want to mention a weird idle sometimes.... it has not happened in a while and has only maybe happened a few times but while at a stop light or something it has dipped below the usual 500 or 550 idle and almost acted like it was going to stall or die but it never has, the lights would dim but once you are driving or giving it any gas it was fine, that only happened a few times and i was out driving today and there was no sign of that happening.... the last thing im going to mention is that while i was driving today i decided to do the maf test and unplug it and see if it was any different. when i unplugged the connector going into the maf i almost want to say it was a little quicker? maybe its all in my head but i thought i could maybe tell a difference, if there was any, it was not that noticeable just thought id mention it...

Overall i want to get everything figured out that way i am sure my car is running full power how it should be. I dont wont to be wondering if my car could be faster than it is!............ and the very last question- is it okay to drive my car with these codes or could i potentially hurt something? same thing with the not sure if im running rich, is it okay to drive like that?.....

any input would be appreciated! sorry about the long post!

 

Tough spot since no one knows about the car and if it was tuned and tuned correctly for the mods.

If it were me, I would:

remove the tb spacer, it's useless
try to find someone local with HP Tuners or EFI Live to see if the tune is altered or at least post it here for you so someone can compare it to stock
if the MAF table is stock in the tune, switch for a stock MAF
post a video so maybe we can tell if it's cammed or not

 

I am with thunderstruck on the maf , haven't heard anything good about granatelli maf , not sure if it has a resistor on it like the slp does but stock maf/stock table would be a good start.

You also need to address the exhaust leaks you mention that sounds like flange/flange gasket this can cause your 02 codes although long tubes and 02 codes go hand in hand unless the person doing the tuning is good lol , I would also be checking for vacuum leaks , with leaky exhaust , loose spark plugs , etc... you have going on I would be starting with those basics as it sounds like the car had a careless mechanic in its recent past.

got any friends with a wideband you could put on it to see what the fueling looks like?

 

alright sorry about the crazy late reply guys, i have been working alot but i have the day off!..... first off, as for the weird idle i mentioned it has not happened once since i posted this or even like a few weeks before soo for now i guess ill try to address the other issues.... I will definitely check all of the hoses for wear. so pretty much any hoses in between the maf and intake manifold? I do still have the exhaust l mentioned from where the headers connect to the engine on the drivers side, do you know if you can buy the gaskets for those at any auto parts store?... and im definitely going to replace the o2s once i buy tires (lol). after you place the sensors will the ses light just go off or will you need it cleared?......... and is it okay to drive the car in the mean time? i have been driving it to work with how it is right now