BiZ

When installing headers should a different O2 sensor be used? I was looking into O2 sensors and they all made a reference to "Before Catalyst"

And are our O2 sensors heated? Mine have 3 wires. I was told that 1 wire is not heated and 3 wire are heated. Is that true?

My main concern is that my loading up symptoms have returned. I thought before that it may have been bad gas. But now some cooler weather is setting in and I have noticed that the symptoms have returned. It was mentioned to me that since the headers move the location of the O2 sensors back further than factory that there may be a problem with them maintaining proper operating temps. Can the O2s on the ZR-1 be eliminated with programming? I may just have a couple of old/bad sensors. But I would like to find out any more information into this.

Anyone else with headers experience any loading up symptoms or anything else in cold/cooler weather after installing the headers?



[Modified by BiZ, 11:29 PM 10/16/2002]

vettl83

Biz, I believe your correct the three wire sensors are heated. Hot lead, ground lead, and ECM lead. I have heard of wide band O2 sensors, but don't know anything about them. I'm sure someone on this forum with headers that lives in the north country can help. Good luck 84 CF 91 ZR-1

Rkreigh

they are heated, and yes you can get an"open loop" chip. most headers have the 02s in the top or side of the collector and they should get plenty hot there. did you install new ones??? if not, try that first.

it may be a different problem too. the car won't go closed loop until the 02s respond after getting hot. an ecm scanner will tell you if the car stays closed loop after warm up. you really need to scan the ecm to see what's going on. (tec II, diacom, EASE, ect....)

92 ZR1

My 91 does this when its cold and idled for a minute, then I have to clear its throat. After it warms up it does not do it anymore. My 92 never does this. I believe its a fuel/ignition issue. The 91s problem is the Nology wires, the 92 has MSD wires. Every since the Nology wires were put on the car has been cold natured.

fort94z

Biz,

I had the same problems with my car after the install. After some research, I did narrow it down to the O2 sensor. The manual refers to them as H02s, as Ron said they are heated and need to get to 600 degrees Far. to operate in the closed loop. I didn't feel the operating temp. was really the problem, more likely was my careless handling of the sensors when I re-installed them. Also cutting to make longer the wires I have been told will and can contribute to them not operating properly.

I went with the new HO2s and installed them. The car ran perfectly and just as smooth as with the stock manifolds. I sure this is your problem. Keep in mind I DID NOT extend the wires on the new sensors. You can make them fit if you move a few wires around. Also, GM price was about $119 each , I looked on the Bosch web site and got a their part number for the ZR-1 , # 13077. The local Auto Zone had them in stock. I paid $48.00 each Just check their site to confirm your part number. When I removed my original sensors they were stamped with the Bosch markings. It will save you a few bucks.
: :yesnod: :cheers: [IMG][/IMG]


[Modified by fort94z, 12:54 PM 10/17/2002]

BiZ

Thanks for the replys guys. I will be picking up new sensors today. I have no idea how old the ones in there now are. **Looks like it is the same part# for my year also.

fort94z -- How long are the leads on the new sensors? I do not think I can make the passenger side work without extending them. The connection was tucked up next to the motor mount on that side. The drivers side looked like it could be routed around to work. Did the rest of you just extend the wires to make the sensors work? Or did you reroute them like fort94z did? And is there a certain gauge wire that should be used to extend them?

I would assume that the car would need to be experiencing the symptoms at the time of scanning. Would this be corrrect?


[Modified by BiZ, 8:43 AM 10/17/2002]

W i l l

BiZ,

Extending the O2 sensor wires will not hurt a thing. The sensors don't care if there is an extra few inches or a few feet of wire. Just about every ZR-1 with headers has at least the passenger side wire extended. The only people that have problems apparently did a poor job splicing the wires together.

I don't like to splice wires because it doesn't look good to me, so I bought the male and female connectors, pins and rubber grommets at NAPA and made my own extension cords. That way I got them exactly the length I wanted and route them so that direct exposure to the header heat is minimized. If you make your own extensions, just be sure not to get the wires crossed. :) I used about the same gauge wire that is there from the factory.

Will


[Modified by W i l l, 9:11 AM 10/17/2002]

BiZ

Are there any disadvantages to using an "Open Loop" chip?

A26B

I noticed in the new Ecklers catalog that they sell a 3ft roll of reflective heat shielding for wiring. I would think it would be the thing to do as I have read quite a few time about headers melting the insulation, especially since the factory heat shielding is removed.

Biz, did you remove all the AIR piping from around the engine when you put your headers on?

DDSLT5

Interesting - I am trying to remember my fuel injection book by Probst - i am still at work - I'm sure that the 90 had non heated O2 sensors, and later they went to heated sensors, but I thought it was when they also went to egr on the LT5 in 93 - but obviously I'm wrong - gotta go home and look this one up!!

fort94z

Biz,

The new sensors from Bosch were about the same length for the leads. On the passenger side, I pulled the wires for the sensor out from the harness and it gave me enough wire to make the connection. I also put some wire insulation on the new leads. I sure Will is right in regards to the length of the wires but I was just trying to give some additional information that I was told. Also I just didn't want to take the chance on cutting and extending the wires in the event it truly did contribute to the failure. You can make the connections if your able to get under the car and work up into that wire harness. :cheers:

Rkreigh

I'm not sure there is a need to go to a full time open loop unless you go to very radical mods like huge cams (low vacuum) or really big ports/injectors which isn't really that common on the LT5..

the 02s help give the computer additional feedback to try and keep the mixture near stoch 14.7 A/F ratio at idle and crooze. without that, the chip has to approximate.

that being said, I run an "open loop" chip on my turbo buick (just tried it today), because of the cam profile, bigger ports and HUGE 72 lb injectors,the open loop chip ignores the o2 feedback and actually runs/idles better.

the car will "hunt" at bit as the A/F ratio adjusts and the IAC compensates. when the 02 sensors get lazy, and cross counts get less and the adjustments aren't made frequently enough to be smooth. the cross counts are amount of times the 02 goes above and below .5 volts reading the 02 content in the exh.

when radical changes like no cats, and other mods are made that keep the 02s from operating the car will set a code and just not run right. but with the heated 02s, this isn't a problem with headers and relatively stock engines, even with porting ect....

replace the 02s, see if it helps. a big problem with the heated 02 sensors is that they gey "lazy" (don't react fast enough) and yet don't set a code to let you know they are bad.

many of the turbo buick guys went to heated 02s to try and run leaded high octane gas (they last longer, lead ruins the 02) but found that they would continue to operate without a code and yet the car ran crappy.

that's the biggest need for an open loop chip, running leaded gas to get the really high octane. due to the efficient combustion chamber and dished piston, the LT5 is VERY detonation resistant and doesn't typically need higher than 93 octane to run well unless their is carbon buildup.

best way to get rid of the carbon is frequent floggings!!!! good luck. :p:

BiZ

Yes I removed everything AIR related excpet the pump itself.

I picked up the new sensors but won't have a chance to get under the car until this weekend. So I hope I can survive till then :lol:

DDSLT5

Shows what I know - I just consulted my "Corvette Fuel Injection and Electronic Engine Management" publication, and sure enough - the O2 sensors on all ZR1s are indeed heated - so HO2!!

Sorry about being :sleep:

BiZ

I installed the new O2s today. The old ones looked very old to me. Very dirty too. So far I have noticed a decline in the pops and girggles the car had before on decleration and those WOT blurps. I didn't get much time behind the wheel today. I will post any further changes as they occur.

BiZ

So far so good. :D

xlr8nflorida

Biz,

Please let me know how it goes. i want to do a set of headers but I want to be happy when I am all done.

Did the popping and stuff go away? Do you need a new calibrated chip? :cheers:

BiZ

Since I have put the new O2s in the popping and such has greatly declined. There is still a pop now and then when shifting under hard acceleration. But I think that is normal. But before I put the new O2s in the pops and girgles were getting rather annoying. I am still using the DRM chip that was in the car when I bought it. I will be getting a chip burned once I P&P the top end.

I know the headers are pricey. But they are a real nice piece and really wake the car up in the upper RPM band. If you want to feel better about buying a set go take a look at header prices for a C5. :lol:


[Modified by BiZ, 12:34 PM 10/23/2002]

zipnz

Same issue here. Ever since I installed headers, my car acts like an old 60's era muscle car when I first start it up(and until it warms up). You know, like an old Holley carb w/o a choke, you kinda have to "feather" the gas pedal to keep it running. Again, when the car warms up, it runs perfect. I going to try replacing my O2 sensoers as well!

BiZ

Well I am happy to report that the new O2s seemed to have solved the problem. I have driven the car in very similar conditions as when the hesitation would occur. And the car has not don't it as of yet.
:smash:
WOOD

If anything comes up I will be sure to post about. My recommendation would be for anyone installing headers go ahead and put new O2s in as well.

:cheers: