I was going over my possibilities as far as why my car blew ring(s) or cracked a piston, and I dont know for sure, but thought of this a a posibility. When I installed my header around 10 months ago, I didnt have the right size wrench to remove the 02 sensor. So what I did was stupid, and cut the wires and used a socket. After I went ahead and installed the same 02 sensor back into the header, and just crimped the wires back. Ever since then I noticed my car appered to be running rich (black bumper and smelled) more than usal. Here is my idea, Maybe the 02 was sending a signal to my ECU, telling it I was rich due to a bad 02(maybe) and causing the ECU to adjust incorrectly and as a result I actualy ran lean. This with the extra boost might have caused the problem I now face.
What do you guy's think?
Possible?
Not possible?
Probably?
or am I just reachin?
Mind you my FPR and my S-AFC were tuned according to my Air fuel reading, if that was not correct then my settings could have been set to lean from the start.
Please all clarifing or opinons are needed.
SEE YA!!!!!!!!!!MWC









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I'm very new to turbocharging, but what you just described makes a lot of sense; it's seems logical to me that, that's probably the cause of the engine problem. Just my .02 cents.

Later,

fly1
http://fastgs.homestead.com/fastgs.html

___________
Kon C

"Sometimes, a man has to do what a man has to do."

Well, if your O2 sensor was having problems, I agree the richness was very much a possible by-product of it. No question about it. People with both 420a's abnd 4g63 report that their gas-mileage suffers as well as their performance on a faulty O2 sensor(because of extremely RICH conditions). I'm guessing that the O2 sensors that the 4g63 people and us have are very much alike, if not the same.

Anyways, the thing is, assuming that the O2 sensor was faulty, you probably did run rich (to a degree), but not lean. However, I think they set the whole system up in mind that there is a STRONG possibility that the sensor will fail and if it does, you WILL NOT run lean. That means, unless the sensor all of the sudden started reading "too much" fuel and started sending the ecu signals of a higher, richer voltage, then and only then, would you start having the ecu tell the injectors to go leaner. Again, I don't think the O2 sensors work that way. When they start going bad, the signal in turn gets weaker, and the ecu reads a less stronger signal and in turn repsonds by telling the injectors to pulse more fuel, not less.

On another note, I thought some S-AFC users on the board had already questioned your S-AFC settings on high throttle. Wasn't some of those settings in the negative or something? From what little I understand in regards to the S-AFC, it should almost never be negative in the high throttle high RPM's.


Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

_____________________________________
Jason ESi-T

04' BMW 325Ci
91' Nissan 240SX
98' Eagle Talon ESi (sold)

That is the first I heard about my S-AFC settings being quetioned, but might be so. The reason for the Negatives are do to the 440's I have. not only are my high throtle settings in the neg, but so are my low. As far as your thoughts on the 02, I can see where you are coming from. But if the 02 sends the sigal to the ecu and the ECU controls the injectors, then that leans toward my thinking of the ecu getting these rich conditions (as you agreed with) but being that it is the duty of the ECU to adjust, it could have done that. Remeber the reading the 02 shows is after the gases has made it throgh the motor, so if the 02 was "stuck" no mater what the ECU does the Air fuel/ 02 would naturaly always read rich. So if the ECU did adjust and make me run leaner, I would not be able to tell cause as you stated when the 02 goes bad it seems to go bad in a way that appears to run rich. Am I making sense or am I missing something? Its just that I have a NEW fuel system and NEW RC 440's NEW plugs and the FPR was not lower than 32 at idle and 60+ at boost. There has to be a reason this happend, and I realy dont think (or am not sure) that it was the one time I over boosted. Dark one say's he hit higher boost levels than I did and has had no problems as a result. Where do I go after I finish building this new motor, so it doesnt happen again?
Thanks. SEE YA!!!!!!!!!!!MWC




http://smkn95eclipsemwc.homestead.com/mainpage.html

hmm - I was under the impression everyone with an AFC is using it to lean out and not richen. I am negative across the board.

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
89 Accord LSi - yes it's mine
http://murix.home.icq.com/index.html

05 Mazda RX-8
06 Lotus Elise

LAST EDITED ON 08-Mar-01 AT 07:49 PM (PST)

Has it occured to you that our cars have POS pistons (or
rings).... My car has done the exact same thing. So have SEVERAL
other 420A owners..Something about lots of boost on stock
internals. My car was well tuned to the limit. 0.88V just on the
border of lean and safe and 1550 degress F at full throttle.
It is very possible that it may have run lean for a little while
then blown.

Lets just put it this way, in stock form, our engine internals
aren't terribly forgiving to tuning errors....


Guy
RS_Guy



13.9sec @ 105mph passes
w/ Blown piston rings,
on Stock Internals
at 10psi Boost....

-----
www.GTuned.com

Thanks bro for your reply, and I could not agree with you more, that a miss tuned car can result in major motor failuar. How ever that does not fully answer the 02 question at hand. As you stated there is little to no room for error when turbo charging a motor that was not designed for a turbo, so is a blown 02 the little bit needed to do that kind of damage.
SEE YA!!!!!!!!!!MWC




http://smkn95eclipsemwc.homestead.com/mainpage.html

LAST EDITED ON 08-Mar-01 AT 08:35 PM (PST)

Could've been a number of things, but blaming it on the O2 sensor I just don't know man...

Never heard of anything like that ever.

I've never ever heard of that causing leanness before.

Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

_____________________________________
Jason ESi-T

04' BMW 325Ci
91' Nissan 240SX
98' Eagle Talon ESi (sold)

thats funny..hahn tells us the exact opposite...that our motors are kind of forigiving to slight tuning errors....that our heads are designed to resist detonation.

obviously you didn't have enough fuel when you detonated...

http://members.dencity.com/xtdsm




ok our ECU uses, TPS, MAP, O2 sensor, and some other sensors to manege our fuel curve, if any of those sensors go bad, the CEL will come on and the car is going to be running in the rich side, and even in some cases it will retard the timing to keep things alive. another thing, let's say your O2 goes bad, while the ECU lights the CEL up, it will also use the other sensors that are not bad, and come up with a nice fuel curve using the working sensors.

and like what you guys said, if the O2 sensor goes bad, your car will run richer not leaner. I think it's just a matter of boosting on stock bottom end (maybe you could have gotten away with less boost, but it was gonna happen sooner or later, or pistons and rings are known to be very weak)

Adel

Well guy's I realy thank you for your opinons on this. If I knew the answer I would have not posted the question. Now that I have several other opinons to go by I see that there is no sure answer. At any rate I am replacing my 02 at a cost of $150+, just in case, as far as what you said Jason GS, that is a givin (not enough fuel) the question I was trying to figure out was why? I think I am just going to bag that Walbro and go with one of those massive fuel pumpsthe V8 guy's use, something that pumps like 1000 gal per minute lol well maybe not that much, but I realy dont trust the walbro by itself to supply my fuel needs, and I am not in a hurry to blow my motor again anytime soon.
SEE YA!!!!!!!!!!MWC





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