shift it around 5800, and let it rip! hehe :lol: :smash:

It's actually going to the track this weekend. We'll see how it does with the DFI. I know it isn't anywhere near perfect on the tune and it's de-timed. We'll see what the MPH is...thats all I care about.


[Modified by Jay 383, 2:22 PM 10/20/2003]

 

The Control System,...
Yeah, I can see it all adds up. The toggling action on the L98 isn't necessarily there to help the cat, as these engines had air pumps.
It does explain how the LT1 and later engines can get away w/o air pumps. (I wondered how they were getting around that.)

The sensors dying,... It is difficult to nail down if apply a voltage (forward or reverse polarity) to the sensor killed it, but I had suspected the failure was due more to static punching thru the thin coating on the ceramic. (man-handling issue) I have not seen this type of failure in a while, so I can only guess the sensors can take more abuse these day's.

A little info from Bosch: ---------------------------------------------------------
To minimize the consequences of normal aging, Bosch recommends oxygen sensor replacement for preventative maintenance at the following intervals:

Unheated O2 sensors on 1976 to early 1990s application: every 30,000 to 50,000 miles.
Heated (1st generation) O2 sensors on mid-1980's to mid-1990's applications: every 60,000 miles.
Heated (2nd generation) O2 sensors on mid-1990s and up applications: every 100,000 miles.
Keeping the sensor fresh may improve fuel economy as much as 10-15% (which can save $100 each year in fuel costs on the average). Keeping the sensor in good operating condition will also minimize exhaust emissions, reduce the risk of costly damage to the catalytic converter, and ensure peak engine performance (no surging or hesitating).

For these reasons, the O2 sensor should be considered a "tune-up" replacement item just like spark plugs, especially on older vehicles (those built before the mid-1990's).
-------------------------------------------------------------------------------------


Thanks for the info. :thumbs:


[Modified by ZylaRace, 9:29 AM 10/22/2003]

 

lots of good info there :cheers: mine isn't having any problems, but i'll check it to be on the safe side. since i already have a digi volt meter it can't hurt to check it. thanks for the tip jesse

 

The Field Service Mode can also be used as a rudimentary way to monitor O2 sensor. Short ALDL A to B with your handy dandy paperclip as you would do when checking for codes, but this time actually start the engine. Watch the SES light. In open loop the SES flashes 2.5 times per second, when the ECM goes closed loop, it flashes once per second and will be out most of the time if lean (< 450mv) and on most of the time if too rich (> 450mv). If the O2 sensor is dead, the ECM may never go closed loop, in which case the SES will continue the rapid flash indefinitely.

Just another trick if you find yourslef without a scanner or DVM.

 

Ray,

I remember reading that also. Never actually tried it, but that would also be a great way to check the functioning of the 02 sensor. That would also ensure that the wire is in sound condition!

Great addition to the topic.... :cheers: :thumbs:


[Modified by ski_dwn_it, 3:49 PM 10/20/2003]

 

Excellent info and very informative.......Thanks! :)

 

Is the exhaust air passing over the O2 sensor actually cooler with long tube headers? ceramic coated or non coated ? and if so, wouldn't putting on a heated O2 sensor be a good safety for any one with long tube headers?

I'm planning on putting on headers (one day) is it really hard to install a heated O2 sensor?

 

The toggling helps the converters on both ends. The lean swings provide the extra oxygen to help them with the oxidation, this is the main source for the oxygen, the air pump is supplemental. The rich swings also help the converters by providing extra fuel to help keep the converters hot so the catalysts can work. They don't start working until about 650 degrees. The LT1 and LS1 have smog pumps, but they are electric. Their job is mostly to help reduce cold start up emissions and help the cats warm up to operating temperature. Once the catalytic converters reach operating temperatures the extra oxygen needed for oxidation comes from lean swings in the fuel systems, the electric pump shuts off. On the L98 the smog pump was spinning all the time anyway so it was used to help the fuel system with extra oxygen when conditions were right.


Great Post Jesse!!!!!! This is one of those areas where people always have questions and some misunderstandings. I think you covered all of them.

:hurray: :hurray:

 

"fuel system", do you really mean fuel? :confused:

 

I just meant fuel system as ECM, injectors, and all of that stuff.

 

The stef,

The heated o2 is not hard to install at all. It has 3 wires instead of 1. 1 carries the ECM information, one goes to the + and other other to a good ground. The worst part is finding a good 12v source...I used the one wire to the wiper motor, till I just installed a painless fuseblock under the hood for all my goodies.

But really its not hard at all and really if your going to go with a new sensor, you might as well get the heated one, it will not hurt to be safe.

PS: Thanks for all the comments. GLad to see the time it took to type it was not wasted.

:cheers:

 

Thanks for the info. Clears up a lot and gives me something to do that is actually productive.

 

Ski,

Thanks for the excellent information. I do have one question though. If the car is OBDII equipped, is it possible for the O2 sensor to be defective and not pull a code?

Thanks again for your wealth of information.

Mark

 

Good write up Jesse :thumbs:
:cheers:

 

Excellent write up. Took time and effort to bring this to us. Thanks Jesse. First thing I look at when going into closed loop is cross counts, intergrater, and blm. Can never know to much. Keep up the good work. :chevy

 

ski and the guys

Thanks for all the helpfull inputs. This realy helps me undersand my car better. You can bet this one will go in my notebook.

I Second the motion to put this one at the top of tec/performance permenantly

 

TTT everyone needs to read this one :party:

 

I don't think that I will need new O2 sensors on my '96 following the install of TPIS LT's. I'm usually really good with the "SEARCH" option, but I'm having trouble confirming that the '96 has 2 heated pre-cat sensors (with 2 non-heated post cat sensors). If the factory pre-cat O2 sensors are heated, will they suffice in a coated long tube application?


[Modified by Midgetfist, 11:30 AM 10/21/2003]

 

Hey Ski:
That was a great treatise on O2 sensor function. Very well written and totally understadable. I've printed it out for insertion in my shop manual (where I keep all the best CV tips). My sincere compliments. Thanks.
Cire96

 

ski_dwn_it, DAMN YOU! :mad

...now I have ANOTHER thing to do under the car! I'm never gonna finish! ;)

All kidding aside, MUCHAS GRACIAS, that's something I would have never thought to do on my own.
-keith