Blade

Hey guys. I just wanted to ask this question to get some opinions. It looks like I might have to get one. I installed Edelbrock headers on my L98 engine and the brand new 02 sensor I put in, swings from like 54mV to almost 900mV at idle. I even got a "low 02" error code once from the ECM. Would a heated 02 sensor help alleviate this ? Is one necessary when putting headers on ?

92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)


[This message has been edited by Blade (edited November 01, 2000).]

JETHROIROC

A heated O2 sensor just warms to operating temperature faster than a standard one, thereby allowing the car to begin closed loop operation in a much shorter period of time after cold startup, reducing emissions and fuel consumption. I don't think the lack of a heated sensor is your problem. It's more likely that the sensor is just a bad one.

Mongoose

iTrader: (2)

A heated O2 sensor wouldn't hurt. I'm using one after I installed headers. Since the headers don't retain heat as well as the stock manifolds it helps in keeping the sensor at operating temps and helped in everything jethro said. It's worth it if you ask me.

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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,no cat,SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit,MacEwen White face gauges,84 T/A cold air induction air cleaner.

Jim85IROC

iTrader: (2)

If the O2 sensor is too far from the combustion chambers it won't ever reach full temperature and can provide innacurate readings. As far as I'm concerned, any car with the o2 sensor in the collector of a header should have one. Some headers have the bung in one tube near the combustion chamber, which sucks because you're only getting the oxygen readings from that one cyllinder instead of the combination of the 4.

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JETHROIROC

Good point about the headers not retaining heat as well, Mongoose, assuming they aren't wrapped. It couldn't hurt to exchange it for a heated one and pay the difference, especially if you live in a cold area. The only disadvantage I can think of is the extra expense of buying a heated sensor. Good luck and let us know how it turns out.

Blade

Well this one's pretty damn close to the collector. At least 6-7 inches down from where the original one was in the cast iron manifolds. I got the closed loop timer in the chip set at 30 seconds. The computer doesnt look at the 02 to decide when to go into closed loop. It's mainly coolant temp and the timer set in the EPROM But I'll buy a heated one (from a ZR1 Corvette right ?) and put it in this Monday

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

JETHROIROC

A typical oxygen sensor must be at about 300C before it is taken into the control system to form a closed loop. Of course, the computer in your vehicle does not directly monitor the EGO sensor temperature. The computer is programmed to know what coolant temperature corresponds to what warming of the EGO sensor. Accordingly, the addition of a heated oxygen sensor will provide no benefit if the closed loop control is initiated by the ECU based on coolant temperature sensor output....But....AHA! The unheated oxygen sensor may never reach the operating temperature of 300C in the setup you have, and therefore, the ECU may rely on it in situations for which it is not ready and its output is incorrect. It is for this reason that the heated oxygen sensor is recommended by Mongoose and Jim. Hope this helps a little! Let us know if it works.

8Mike9

__The computer is programmed to know what coolant temperature corresponds to what warming of the EGO sensor___

No, I don't think so.

The wording in manuals regarding the O2 sensor needing to reach about 600*F for the ECM to go into closed loop, is known not by the coolant temp, but when the O2sensor begins to output at least 400??mv...may be 350mv...don't recall....but regardless, there's no calibration between coolant temp and EGO temp in the ECM.

JP84Z430HP

I always thought it had to do with O2 sensor activity, not a certain voltage. I know the computer has the timer, and the coolant temp has to be up, and the o2 sensor heated up, which I thought was determined by activity.

I could be wrong though!

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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Starting to look like the Kicker poster child!

Blade

The 02 will definately reach 400mV especially on startup when the ECM throws a very rich AFR ration at it. You need more gas for a cold engine. Kinda like a choke. BUT the ECM has a timer, after a predefined number of seconds it will switch to closed loop. It also looks at the coolant temp to see if the engine is heated up.

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92 Z28 L98 350
---------------
Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)