Jed

In the latest issue of GM HTP Ray Bohacz stated that they switched from the stock single-wire 02 sensor to a heated three wire 02 sensor on their Formula 350. The stock sensor was not heating up fast enough, thus providing inaccurate readings to the ecm and resulting in a sloppy idle and rich air/fuel ratio.

I have a feeling I'm experiencing something similar with my car and was wondering if anyone here has switched to a heated 02 sensor, what brand of sensor they switched to, and how the car ran after the switch. All input is greatly appreciated.

Jed
89 Formula 350

TRAXION

Jed -

What's up! Been a long time. Anyhow - no, you don't need to switch to a heated O2. SLP, Edelbrock, and/or any shorty type of header will work fine with the stock O2. It is only when you switch to long tube headers that you need a heated O2.

The reason that GHHTP experienced a bad idle is because either...

they had a bad O2 to begin with (possibly fouled the O2 during the install)

or..

they didn't have a custom chip so naturally it idled like crap until the computer went into closed loop mode. This is normal for guys with heads/cam that don't have a TRUE custom PROM. Bigger cams pull less vacuum so the AFPR sees less vacuum and therefore dumps more fuel into the engine. The ECM WILL NOT compensate injector pulse width until the ECM goes into closed loop. This could take several minutes. GMHTP probably assumed it was idling bad because of the non-heated O2.

My Level V TPIS PROM was crap for idling in open loop. They didn't adjust the fueling for first starting the car (open loop). It idled like crap until it went into closed loop and then all was fine. I started burning my own PROMs (now moderating the PROM board) and now she idles PERFECTLY on first starting ... heh heh ... and I even have 30lb injectors

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-

Pablo

iTrader: (1)

but, a heated O2 can help! youll go into closed loop quicker, and be able to get more consistent, accurate readings from your O2 monitoring equipment. .but its not totally neccessary like trax said, if you really nail down the prom you dont even have to have an 02 sensor period! FYI little known fact, the cars GM ships to foreign countries with leaded gas dont have O2 sensors they run in open loop all the time, the proms are just nailed down on them

Jed

Tim & Pablo - nothing's up! Between school and work it's tough finding time to wrench on the car. According to the article they didn't have a custom prom when they experienced this problem...and who knows, maybe the sensor was trashed anyway. I'm looking into getting a heated sensor because mine is on the way out -sluggish readings, - so I'd have to buy one anyway.

The other thing is this: I have two Autometer Air/Fuel meters, one for each side of the engine. And of course, these gauges are totally inaccurate until the 02 sensors reach 600 degrees or so. I was thinking it'd be cool to have heated sensors, I'd get more accurate readings all the time, not just after the engine warms up.

I'm just not sure if I should spend the money on aftermarket sensors (Autometer or Accel) or just buy heated sensors for a later application, which would be cheaper considering I get a discount at work. Anyway, I'm rambling... thanks for your thoughts guys.

Jed

Pablo

iTrader: (1)

I think a heated one for just a generic application or just a universal three wire will do the job fine
(and save you some cash)
good luck!

Pablo

[This message has been edited by Pablo (edited September 14, 2000).]

irocz

Are these things hard to wire up? I assume one is ground and the other just goes to a 12v ign-on supply?

What late model vehicles came with these stock? I have a bunch of new ford 5 wire sensors...will they work?



------------------
87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP cam, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax/Flowmaster catback
Coming Soon - Fasttrack/Accell DFI

SOLD ->91 Z28, 5.7, 3.23, Ported Plenum, Accel runners & lower intake, Accel distributor module, !dual cats, POS Edelbrock catback, K&N'S, ram air, tb airfoil, !tb coolant
Coming soon - Compucar N20 kit, Accel AFPR

Jim85IROC

iTrader: (2)

My 3 wire o2 sensor is one from a 92 ZR1 corvette. Since the dealership had it in stock, I assume it was used on a zillion other models too. I don't think a ZR1 has ever even driven through our town. I only drove my car a couple miles since I put the heated oxygen sensor in, but the car's manners seemed MUCH better. Funny thing is, my car spits black crap all over my garage floor (i.e. very rich) when I start it but when I pulled my oxygen sensor it looked just like my plugs: Shiny, bare steel with virtually NO black residue. That surprised me.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

Matt98SS

hey Jed whats up...like Tim said long time to see....

how is the car? what is the set up now?

------------------
Pretty Quick - NOT STOCK