cbonjour

well i have a 98 z28 A4. it was purchased out of san diego, ca. it has the california emissions controls on it, which i dispise, and i'm not sure if it has anything to do with the fact that when i'm at WOT it will shift from first to second at about 6000 rpm, its factory tune btw, and it will hesitate for a brief second then shift, almost like its trying to keep from breaking traction, and then it will turn on the service engine soon light. i had it scanned at advanceauto and it said it was O2 sensors. it usually goes off either later that day or the next day. its rather confusing. also as i'm going down the road with my lights on they will flicker, at first i thought it was something on the motor, maybe smog pump, kicking on and i wasn't too worried about it but then i noticed that everytime they flicker, the check gauges light comes on. the lights flicker off and the check gauges flickers on but they do it once very quickly and then do it again maybe a minute or two later and its never stopped doing it. any suggestions or advice would be greatly appreciated.

01ssreda4

iTrader: (96)

the lights sound like a loose connection under the hood. if the battery voltage drops then the check gauges light would come on. sounds like something is loose, gotta do some hunting to find that. also for the o2s i would replace them, they prolly need it anyway as a maintenece item. as far as the trans, welcome to the wonderful world of the 4l60e.

cbonjour

sounds reasonable but i can't really tell if the voltage is dropping or not cuz it happens so fast. and what possible connection could it possibly be that would flash the light in the dash and cause the lights to flicker?
and its going to have headers and full exhaust put on it in a month or two as well as a computer tune so i'm trying to hold off on replacing the O2's and see if the tune helps the problem out any.

99345hp

The first place I would check would be the battery connections. Sidepost battery terminals are notorious for leaking and causing corrosion. As far as the check engine light, I would replace the O2s, because you can just put them in the new headers when you get them. You should replace them when you do them anyways.

cbonjour

do you think the fact that it has california emissions has anything to do with it? could it be set to accept such a small range of acceptable levels of O2 in the exhaust that its causing it? and i've also wondered if it could be the difference of air quality or O2 levels from california to arkansas. i can accept the fact that the O2's are bad but i don't want to replace them unless i know that is what the problem is. cuz new O2 aren't exactly cheap and not something i WANT to spend my money on. i've also wondered if it may just be the ones after the cat that is throwing the code, cuz at 6000 rpm there is alot of exhaust gases going through the cats and it cant efficiently convert it all to have acceptable levels. the cats are going to be removed after the headers are installed and that will do away with the back ones. so i'm wondering if that and a computer tune would give it a larger range of acceptable O2 levels and thus fix the problem.

99345hp

what was the code it gave you? That would really help in diagnosing the problem.

cbonjour

the p.o.s. scanner that they used at advanceauto said it was the rear oxygen and the front ones on both sides. idk what code # it was. so i'm thinking it could possibly be the back ones telling it to run rich or lean and then in turn making the front ones throw a code. but idk cuz it fixes itself after about 50 or so. and it only sets it off at very high rpm's about 6000. i'm just trying to get as much input on what people think it could possibly be before i spend the money to replace the O2's

99345hp

there are many different codes that relate to each O2 sensor. Not switching, heater circuits, many things. The rear one wont telll the computer to run rich or anything of that sort. It only tells the computer if the cats are doing there job. It wont effect the a/f ratio. The fronts could be not reading correctly, reading slow, any of that and they will throw a code. The problem could also be MAP, MAF, or anything else that is part of a/f monitoring. If the MAF isn't reading the right amount of air coming in, then the computer wont know the right amount of fuel to add.

ajsfirehawk

iTrader: (4)

+1 on battery connections and closely inspect the cables. They can corrode inside the insulation. If they look bulged or swollen near the terminal you should swap them out. Might want to break loose and retorque the ground connections under the hood.

blue98Z

iTrader: (29)

+1 on the battery connections. My 98 did the same thing until I put a new battery in and now doesn't do it all. The O2's are probably the most (IMO) neglected items of maintenance on vehicles by most people. They're not that expensive for our cars. Just buy 2 for when you get ready to do your header install and have the rear ones deleted along with the AIR and EGR when you get it tuned, then remove all of that stuff from the car. I think I spent roughly $40 bucks on two from Advanced Auto Parts. I wanna say they were about $18 a piece, but that was 3 yrs and 7500 miles ago. Oh yeah, while you their pick up an expandable freeze plug to plug the top of that LS1 intake after you tune all of that out. I think its a 1 3/8". Someone correct me if I wrong on the size. I have one, but it doesn't say the size on it and I can't find my tape measure.

ghardester

There is also the wild possibility, call me crazy, but maybe the scan tool was right and you should just change the O2's.

nd4spd22

iTrader: (6)

check the connection on the rear driverside head, When I put my heads back on, that connector was broke, And it did some funky things with the gauge lights.

cbonjour

[QUOTE=CodeRed2000SS;10828088]ok now i work at advance auto and we have great tools. we also have " the right parts at the right price" budday. i honestly believe its your turn signal fluid level that is too high thus cause your headlights to blink. my RS camaro does that to when i got my two 12's thumpin. budday.


ps. make sure that thing has got winter air in the tires.

i love advanced. i go there for almost everything i get. most of the time one of my buddies cuts me a little bit of a discount. but as the scan tool they used, it was about the size of my cell phone i'm gonna say it wasnt exactly the best on the market. but i'm not complaining cuz it was a free scan.