MikeDwhoROCZImports

iTrader: (1)

I have an 87 IROC LG4, 5-spd. My oxygen sensor is busted, but it's rusted into my exhaust manifold so I can't take it out because it may crack it and I don't plan on gettting headers untill I get some money and do my TPI swap.
My basic question is, how is this busted oxygen sensor affecting my performance or drivability?
Another question. I am considering going to an exhaust shop this summer and having them modify my y-pipe so that I can put a new oxygen sensor in there, as a temporsry fix untill I get my headers. I know the results will be off a little bit because of the placement, but I think this would be better than just the broken one. Any suggestions?

Ed Maher

With a hosed O2 sensor your entire computer will be angry. It will set a code as soon as it realizes it after a few minutes of driving, every time.
The easiest way i can think of for you to 'bypass' this would be to hook up a pot in place of the TPS, and set it for low-mid 4V on the signal wire. This is duplicating a stuck TPS, and usually the CCCS computer will ignore it, and at the same time, ignore it's desire to go closed loop cuz of the high throttle input. The post 85 computers may be a little smarter, but i know this would work in an early car.
Don't get me wrong, you won't be running ideally, way overrich in fact, all the time. Gas mileage will suffer, and if you don't get into it a lot you will carbon your compbustion chambers up pretty good. Get an O2 sensor back in there ASAP, even if you put it in the Y-pipe.
...ed

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Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

merf23

Where in CT are you? I am in Plainfield (near Foxwoods casino). If you bring the Y-pipe and a fitting up Id be happy to Tig weld it for you.

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1984 Z28 (L69) monochrome tangerine orange with IROC decals and hood
1987 IROC wheels with Goodyear GSC's
305 from 87 IROC with 1994 LT1 cam (203/208 .450/.460")
performer intake with holley 600 (#1850)
Qjet is in the works
dynomax cat-back
non WC T-5 with 0.73 5th
3.27 nine-bolt

MikeDwhoROCZImports

iTrader: (1)

Ed, you said the computer would set a code every time after a few minutes of driving. Wouldn't this make the check engine light come on? If so, it onlyy comes on after about 15 min of highway driving, and goes off if I open it up a little bit. Also, I have an aftermarket chip in my car. Does this make a difference as far as how much this affects my driveability?

Merf 23. Thanks for the offer! I live in Farmington, which is about 15 min west of hartford, so you're about an hour or so away. I'm not going to have the car back until late May (I'm currently at College and my car is sitting in my garage), but if you wouldn't mind doing it then, I might take you up on that!

[This message has been edited by MikeDwhoROCZImports (edited April 06, 2001).]

MikeDwhoROCZImports

iTrader: (1)

bttt

lukerene

mate get onto it A,S,A,P, i live here in Australia,you never see these cars, unless you go looking,or know people who have one,even i can get a manifold or engine pipe for $100 here, the sooner the better, i would get onto it right away, the oxygen sensor is vital on most cars ,,good luck,the unleaded fuel rots engine parts ,,its eaten out 2 catalictic converters ,,due to over fueling,,the cat gets red hot, burns out, blocks up ,with the crap inside ,,,stuffs up everything,

Ed Maher

Well, that really makes no sense, if your O2 sensor is broken, thats that, you cannot enter closed loop, and thus the computer would throw a code. Period. Your car isn't magically ignoring that the most important sensor is dead.
So, my next guess is that your TPS is way out of adjustment or shot. Like i said in my other post, a shot TPS could make your computer ignore the O2 sensor by making it think you are at WOT all the time.
...ed

MikeDwhoROCZImports

iTrader: (1)

Ok thanks for the input guys. As soon as I take my car out this spring I'll throw an O2 sensor in my y-pipe. I had taken my car to a Chevy Dealership last summer and paid $90 to tell me why my car was running like crap. They scanned my codes and told me I had a busted O2 sensor. If that doesn't solve everything, I'll mess around with the TPS then.

Oh, by the way, the reason I would put it in the y-pipe rather than the manifold isn't because of the cost of the mainfold. It's because of the work involved in taking out one crappy exhaust part just to put another in. You have any idea how hard it is to swap out one of those things????

Ed Maher

Actually i'm quite aware of how bad getting the O2 sensor out of a maniflld it's been seizing in for near 20 years. I bet there's stil an O2 sensor in the trunk of the grand prix i was driving cuz the stock one apparently wasn't as bad as i thought afte ri got it running right. And it sure as hell wa s alot more work than i felt like getting into.
Check your TPS voltage. The easiest way is to pierce the bottom 2 wires on the 3 wire connector on the front driver's side of the carb. With the throttle closed (not on the fast idle cam) you should see 0.5V. If you are seeing anything over 0.75-1V you are way out of adjustment. If you are seeing near 4V the sensor may even be shot. If you search around on this board you'll find a lot of info on adjusting/replacing the TPS. IMO it is the sole reason that CCCS gets such a bad rap, as it commonly fails, never sets codes, and causes bad gas mileage and hesitation, and causes excessive carbon build up in the cylinders which leads to detonation and lost power. Whenever i see someone complaina about gas mileage with a CCCS this is their problem 99% of the time. My 85 used to get 26mpg highway running high 13s with a way off balance combo. My 83 GP was getting 18+ mpg highway with no OD and brickwall aerodynamics.
...ed

MikeDwhoROCZImports

iTrader: (1)

Awesome! Thanks for the help, Ed. I am getting bad gas mileage (13mpg in the city) and hesitation (when I floor it the car hesitates under 2000rpm). I thought I might have needed a carb rebuilt, but so this sounds like it might be what's been giving me problems. I can't wait to pull my car out in a month and test out my TPS. It would be great to FINALLY have my car be as driveable as I've wanted it to be.