Normal? Or is my O2 sensor going bad?

[2QUIK6]

hehe, Bryan's got your bank account wiped out for a while I think we were only thinking to cure his current issue, ei lower timing so no knock with pump gas.... but yes you need to decide what your goals are for the car before you start buying parts twice....as we all have done in the past
I strongly recommend an alky kit for street driven cars that want a tad more boost with no knock...or a ton of boost with no knock depending on how hard and fast you want it.

 

[Quick6'n'-K.C.]

I hear ya, but if he wants to lower the timing he has to buy a chip:redface:

Or go the other way and loop the compressor. What is the boost pressure at right now? 14-15?

If you take a NEW 7/32 vacuum hose and loop from the silver side of the turbo (compressor side) straight to the wastegate. You "should" get around 12-13 psi of boost. It wont spike like some cars do, and "shouldnt" creep more boost at 100mph plus. Thats it, just take a simple single hose and loop from the compressor to the wastegate. If you want more boost, it will cost ya about 3 bucks at the hardware store to make a adjustable wastegate actuator if yours isnt adjustable.


And i could wipe out the bank account just reading thru the parts for sale section in less than an hour LOL :biggrin:

These cars are all about the small simple mods before you dive in and "go fast" ..
BW

 

[ChavoLC2]

Turn down boost for now.

You need to Figure what chip you have as far as Boost and Timing and most importantly is that it's burnt for your combo i.e Injectors,turbo etc.etc.. Lets say You have an old ATR PitBull chip as they had high timing and a car on pump gas ain't going to handle that chip. What's nice about Eric's chip is you can adjust WOT Fueling and WOT timing. For now I'd turn down boost and add fuel(if you have an adjustible FPR) your better off running a tad Fat then too lean at this point, if money is the issue and you want to ruleout octane related KR then For 25 bucks(cost of a good meal) you might think about getting a couple gallons of Race gas and see if knock/KR goes away at WOT.

Getting some race gas would be the cheapest to see if your knock goes away or decreases. Good luck tuning hope it's just crappy pump gas like we have here. We have 91 octane talk about crap you don't want to be running high boost with that crap . Thank God for Razor Alky kit allows me to get away with 91 pump gas and run higher Boost pressures(20+) without KR. I usually add a lil' Trick 101unleaded to the mixture to make 93 as a safety measure without it , it would be HG city. Wish we had 93 pump gas around here like some of you back East do.

 

[VadersV6]

There are several sources of knock. One is caused by mechanical means, such as the engine was rebuilt with too much compression. Anything over 9.5:1 is too much IMO and you better have race gas or alky and/or a good tune with a safe timing curve if the compression is anything over stock. Another is if you have excessive deck height and/or a bad piston design. Either of these will create poor quenching. Excessive deck height is where the piston, at top dead center, is too deep in the bore. A typical depth for a stock motor from this era, would be .020-.040 deep. When the piston comes up and compresses the mixture, its ideal to have as much of the mixture as possible, squeezed into the center of the piston, and all in the combustion chamber.
From Wikipedia:quenching is used to prevent low-temperature processes such as phase transformations from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible.
Basically, if the piston is too deep in the hole when combustion occurs, the flame front is disrupted. The spark plug is in the chamber, so this is where combustion is initiated (in ideal conditions). The flame front travels across the chamber. When the flame has traveled to the ends of the chamber, the flame front should end and the gases expand. But since there is a pancake shaped area above the piston outside of the chamber which is filled with air/fuel, a second event occurs, triggered by the initial event. The flame fronts collide. This is pretty much the definition of detonation. A second combustion event is occuring after the initial one, and they collide. The expansion of gases is not controlled. Its damaging to the motor, but not in the same way pre-ignition is.
If there is some hot spot in the chamber, then dieseling can occur, i.e., pre-ignition. People who baby their hot rods and put put around town, usually have alot of carbon buildup in the chambers and on the valves. This carbon tends to glow like a glow plug in a diesel motor. Same goes for casting flash or a spark plug that has too little heat transfer to the cylinder head, for the conditions, so it overheats and glows, which also can set off pre-ignition.
The piston comes up on the compression stroke, compressing air/fuel mix, but because of a glow spot (or fuel which is overly volatile...low octane), combustion occurs while the piston is still heading upward. Combustion always occurs during the upward compression stroke, but at a point much closer to top dead center, so that by the time the gases begin to expand with alot of force, by then, the piston is heading back down. But with pre-ignition it happens far too early, and a complete combustion event happens by the time the piston has just completed the stroke. Force=mass x acceleration (the machanical inertia), and force=pressure x area (the expanding gas's force on the piston), so figure how much inertia the piston/rod/crank throw has while heading upward, and top it off with incorrectly timed combustion pressure causing severely rapid deceleration while another piston/rod/throw in another cylinder is being accelerated by a correct combustion event. Its absolutely catastrophic. Ive seen that my own knock sensor doesnt seem to pick up on both detonation AND pre-ignition. Which one it is, I'm not sure. It sounds like popcorn, and WAY too loud to be detonation, and nothing at all shows up on my scanmaster. I was doing this to my motor for like 6 months. I figured I had a blown head gasket or an exhaust leak since it was louder than any detonation I'd ever heard, and I had no knock retard. But I knew the knock sensor worked. For fun, I pulled some timing out and noticed the popcorn went away. Added the timing back and it was there again. I had thought my car was a freak since I was driving around with 27 degrees timing on 89 octane and no alky at 18psi. I had no KR. But it had the popcorn sound. Thank God my motor held up.
Remember how combustion is always initiated while the piston is heading upward, like 23 degrees before top dead center like on my car. Like I mentioned, by the time it reaches TDC, the gases havent expanded enough to create the forces needed to damage the motor. If you didnt fire before TDC, the gases would burn incomplete. But if you have low octane or too lean a mixture, the combustion event can begin at the correct time (25 degrees before TDC), but the a/f mix burns so fast and is so volatile, that the gas has expanded enough, before TDC has even been reached, that damage occurs. It can also simply pre-ignite because the autoignition temperature of the fuel is too low, like low octane or too lean.
I had alot of detonation and knock retard going on when I had a whole host of vacuum leaks. I had a couple torn injector o-rings that were causing those 2 cylinders to go super lean, and Id see as much as 14 degrees of KR at only 12psi and 91 octane. After replacing the injectors, replacing all the hoses and pulling the intake manifold off and replacing the intake gasket with a fel-pro, most of the KR issues went away.

 

[ChavoLC2]

Kr -wow

Man thanks Vader as I'm still learning and appreciate the detailed information, very informative and put in words that one can understand. That's what's good about this Board there is always something to learn about these cars, a life long passion these cars are awesome especially when they're running right on the money .

 

["Turbo-T"]

Quick6'n'-K.C., I'd like to one day have my car running mid 11's, but that won't be anytime soon.

In fact I've been told when it comes to that time I better have all of the aftermarket bracing put in my car unless I want to be cracking the roof line. So I figure I need to plan on this before buying some sticky meats.

I've not had the car to the track yet so I do not have any idea what it runs. Probably high 13's if I had to guess.

As a new TR owner I'm still learning, please inform me on what the "fast update" is? Is this something in the chip?

I've heard some of you swear by your Turbo Tweak chips. I plan to get one, and I guess i could keep my Jay Cater for a back up spare. As of now I drive my TR daily so it's got to stay in there until then.

I plan on keeping things simple as of now and running my blue tops and the current turbo (don't think it's stock), I've been told the downpipe I have (2.5) is good for low 12's- high 11's. My current turbo does have an adjustable wastegate rod, and I've been told it can go up to 20 lbs or more boost. I think 20 lbs is a goal for me but I do know eventually you grow out of and then start wanting more.

I have considered an exhaust upgrade because them damn Flowmasters breathing thru a stock 2.25 inch tube drive me nuts with their choking back pressure and drone.

And yes the boost is currently set at 14 psi.

ChavoLC2 I am still waiting on Jay C to give me more info on this chip, I can only hope he remembers. No I don't have the adjustable fuel pressure reg. but it's definitely on the to-do list.

I did notice at idle I have a rather rich fuel mixture, would this be due to the timing in the chip or the injectors?

I think I am going to invest in one of those knock gauges that has the LED lights, sounds like one of those is a must-have.

I will definitely look into getting an alcohol kit, although I'm not real familiar with them, or how they work, or how often you have to service them. All I've heard is anything over 15 lbs of boost you want/need one.

 

[2QUIK6]

The chip has everything to do with your rich idle, could band-aid it with an Adj fp reg, but who knows what thats doing to your WOT AFR.
For Jay to know what chip it is, you'll need to pull it out of the ECM and see what type of sticker is on it. Most chip burners put a label on the chip with various numbers or codes...Jay use to use colored smiley face stickers and each color meant something. It will be on the chip itself, you may have to remove it from the plastic holder. (push down in the center of the chip and carefully pull apart the plastic legs and then release pressure from the center of the chip)

TT chips aren't that expensive, he may even offer to upgrade the chip to alky, big injectors, etc as you grow for a minimal fee, maybe $25 or so I'm not sure, or you can sell the chip later and upgrade that way.
With what you have described, I'd say a TT chip and get rid of the Flowmaster restrictive muff, get a straight thru muff, like a Magnaflow SS or something like that which will last a long time.
But, in order to adj the TT chip, you may need a laptop scan tool like the Powerlogger or Direct Scan in order to adjust it per my comment before since you need to see all the differetn BLM cells while adjusting it, not just the "Current" cell....you'll need to ask Eric that if no one else knows or comments on here.

 

["Turbo-T"]

Thanks, the chip I have now just has a green label on it, no smiley face or anything like that.

I am planning on running a Dynomax Ultraflow muffler and maybe a single 3 inch mandrel bent pipe.

I'm also curious if not having an adjustable fuel pressure regulator would play an effect into the air/fuel mix running lean while in boost?

 

[DynoTune]

Thats fine..... the car coming in and out of PE mode...

Actually, it's not coming in and out of PE...

The O2 sensor toggles (swings back and forth) during normal driving, this is called "closed loop". This is how the ECM self corrects fueling based on what the O2 sensor sees. The O2 will tell the ECM that is rich, the ECM backs off fuel, then the O2 sensor see's that it is lean, and the ECM adds fuel. This is how the BLM and INT are updated, and it happens many times per second.

PE mode is when you are at or near wide open throttle. At this point the ECM no longer relies on the O2 sensor for input since the desired air-fuel ratio is richer than the stock narrow band O2 sensor can accuratley measure and switches to another table in the chip for fueling

You should also see a delay when starting your car where the O2 sensor is not toggling, this is "open loop" mode. There is yet another table in the ECM for this mode. One reason for this is that the O2 sensor needs to heat up to work. Once everything is up to temp, it will switch to "closed loop" and thats when the O2 sensor will toggle back and forth.

Dave

 

["Turbo-T"]

Thanx for the info.

Is the closed loop and open loop the same thing when I go out and start the car after sitting for awhile and upon firing the rpms go to about 1500 and slowly drop down ot maybe 1100, and then a few minutes later drop to like 800?

 

[SS/GNX]

That LED knock gauge works to show you when you have knock, but istn always accurate and doesnt show you HOW MUCH.

Get a scanmaster first if you dont already have one! That gauge is not enough.

 

[DynoTune]

The high rpm on startup is like that to help everything get up to temp, and to keep it running when it's cold (sorta like a choke on a carb).

Open loop and closed loop are different, in open loop, the ECM doesn't care what the O2 sensor is saying, it's running off of a predetermined fueling strategy in the chip, with no way of self correction. In closed loop, the ECM uses the info from the O2 sensor to self correct the air-fuel ratio to maintain a predetermined ratio.

If your chip is not setup correct, and you are in open loop, it could be running very rich or very lean, but as soon as the ECM goes into closed loop mode, the O2 sensor will tell the ECM if your to rich, or to lean, and the ECM will self adjust (to a point, there is a limit to how much it corrects for). You can use a scan tool and look at the BLM and INT to see how much the ECM is self correcting. A value of 128 is perfect, anything less than that, the ECM is pulling fuel out, anything higher than that, the ECM is adding fuel. the BLM value will be an indication of trends of the INT.... sorta like the BLM is the coarse adjustment and updates slow, and the INT is the fine adjustment and updates quickly.

 

["Turbo-T"]

Get a scanmaster first if you dont already have one! That gauge is not enough.

Thanks, already have one, that's why I was asking about why it was reading knock retard when I was getting on it. :wink:

 

[2QUIK6]

Thanks, the chip I have now just has a green label on it, no smiley face or anything like that.

I am planning on running a Dynomax Ultraflow muffler and maybe a single 3 inch mandrel bent pipe.

I'm also curious if not having an adjustable fuel pressure regulator would play an effect into the air/fuel mix running lean while in boost?

If the Dynomax is the "aluminized" one, just be aware that the insides are not aluminized and it will eventually rust out in the inside while the outside looks new...I had one for about 10-11 years, looked fine till one day I removed the muffs and discovered they were severely restricted with chucks of the piping clogged at one end..this was a superturbo dynomax, not the ultra...as long as its a striaght thru muff you should be good for a while. The Magnaflow SS I mentioned earlier is complete stainless steel construction so it should last a very long time.

On the adj fuel pressure reg...you can use it to make WOT lean/rich...BUT by doing so skews the entire fuel curve rich or lean..not just WOT...adj fp reg are nice to haves, but once the fp is set to 42psi with the vac line off, you should never have to touch it again, if the chip is tuned correctly you should never have to mess with fp adjustment.....this is where TT chips come into play...you can adjust his chips for WOT rich/lean only without effecting the rest of the fuel curve.

You could go a step further too if you want to run a LS1 MAF or no MAF at all and get a Gen2 Translator, or Translator Pro...then get a WBO2 and then just program in the AFR you want at the different rpms and never mess with a chip again, even if you later get alky There's lots of cool stuff for these cars and will keep you busy for years to come. Mine's to the point where I'm happy with it and it runs consistant so I haven't had to wrench on mine in over a year and it runs mid to high 11's..but it took 16 years to get to that point ..mostly before this this website was around.

 

[SS/GNX]

had you mixed up with another guy on another thread!

Sorry for the mixup

 

[Quick6'n'-K.C.]

I'm also curious if not having an adjustable fuel pressure regulator would play an effect into the air/fuel mix running lean while in boost?

Absolutely not. 1 pound of fuel for every 1 pound of pressure put on the regulator.

My white car last month went 11.1 with a stock non adjustable regulator, i just installed a factory regulator, checked the fuel pressure, and smacked the top of the reg with a 9/16 deep well socket twice and raised the fuel pressure a pound or two. That is all i needed to do.

Even on my daily driver, i pretty much never have to mess with the regulator, i think i set it 2 years ago and its the same pressure.

BW