Dangers of Running Rich, 3sgte owners Options

[jgreening]

Well, ten days into ownership of the 3sgte and I can safely confirm what everyone else has said over and over....these engines run very rich. I have read many posts about this and about the fact that Toyota made it this way to avoid lean conditions. However, I would imagine that running an overly rich condition cannot be good for the engine over time either. I am wondering whether for engine longevity and reliability purposes, us 3sgte owners should take action either through an S-AFC or stand alone to lean out the A/F ratio. Obviously, we can see some horsepower gains from doing so but I am particularly interested in responses dealing with engine life.

[Jdog1385]

you should try to lean it out a bit. nothing crazy b/c you'll definitely run into problems. you don't want to start replacing parts.

[lagos]

my theory is that the swap runs richer then a normal alltrac. it may have somethign to do with the fact that we are running supra fuel pumps with no fpr. the fuel pump resistor pack isint pluged in either (what the hell is it for anyway).

i was driving behind DG and saw nothing but constant black smoke. i doubt an alltrac would do that with just a 3in exhaust

This post has been edited by lagos: Sep 29, 2004 - 11:08 AM

[jgreening]

Lagos, I am still running the 5sfe pump. Jayson claims it will be fine up to 18 p.s.i. Even with the 5s pump, the mixture is way rich. Anyway, the pump only supplies what is demanded from the ECU so, in general, the pump shouldn't act to cause rich conditions even if it is way overkill.

Also, there is a very interesting thread over on mr2oc.com that suggests you should never upgrade to a supra pump unless you upgrade the fuel rail. It was started by Wolfkatz (sp?) and has a lot of testing to back up his claims - although I must admit, I couldn't follow much of the fluids engineering hyper talk. Also, its quite possible that the conclusions only refer to conditions above the horsepower levels we find ourselves at - so far.

This post has been edited by jgreening: Sep 29, 2004 - 11:13 AM

[Supersprynt]

Keep in mind they have 3sgte fuel pumps that are rated into the 300whp range and we're stuck with the 100whp pumps, thats why he says that. I go the Walbro to put in so that the 5s pump would not fail because its being asked to constantly pump more fuel than it ever did before, this IMO will cause wear faster. Its not meant for these conditions.

Running very rich may cause some cat problems, but if u dont have any then dont worry about that. Its better to be rich than lean, but I think a good tune will do the car well.

[jgreening]

[Supersprynt]

I figure because they are a different generation. The 5th Gen Celica and MKII's MAY have a different pump setup, its worth looking into. I did some reseach and found the Supra pump would fit with not much fuss so I just got that one, gives me room to breath when I put in the 550cc's and upgraded TC.

[jgreening]

Whats a TC? Also, are you going to do any engine management when you upgrade Super?

[Supersprynt]

tc - turbocharger, my bad I start shortening things. Well I am strongly considering the ATS "CT27" upgrade, I'm looking for around 300hp at the crank and this seems like a good option over a used CT20b, which still is something i'm considering. ATS offers a package deal which includes thermostat and fuel pressure regulator and also a ROM tune. Where you send them ur ecu and they tweak it a little bit. If I do that, I'll have them tune the ecu for 93 octane and 550cc injectors. I figure that with a new fuel rail, water injection, (maybe a FMIC dont kno yet. The W/I will help with detonation so the FMIC may not be necessary), a downpipe (2.5 or 3 havent decided), and midpipe it should get me there. That should be good for low 13's if not 12's along with the CM S4 & LSD.

This post has been edited by Supersprynt: Sep 29, 2004 - 12:13 PM

[97sccelica]

it fouls o2 sensors sooner(only if very very very rich)

but other than that, dont worry about it, unless its so rich that it bogs nearly to the point where the engine stalls

the JDM swaps probably run richer due to the fact that they are programmed for much higher octane, on the 91-93 octane we have here, the ecu sees some knock and probably dumps in more fuel.

[Supersprynt]

ECU's dont dump more fuel they retard timing. And the 93 octane here is like 97 in Japan. On top of that, Japan uses RON (highest) gas ratings. Europe uses MON (lowest), we use PON (the avg of the 2). So in actuality, its the same gas, just different numbers. Quality controls differ however, depending on the country.

This post has been edited by Supersprynt: Sep 29, 2004 - 12:27 PM

[shid]

I think the issue about fuel pumps might be something akin to the issue behind hard drives.

You can always buy a bigger hard drive; but the bigger the hard drive you buy, the larger the "smallest" file becomes. IE, on a 60 MB hard drive, u could have files that were sized at only 200 bytes; but if you're hard drive is 60 GB, your smallest file size is now 800k (I forget what the exact numbers are, but the principal should be aptly demonstrated).

This is because hard drives, no matter how large, have a set number of sectors. So, 60 MB divided by 500,000,000 sectors; or 60 GB divided by 500,000,000 sectors.. The one with the 60 GB will have larger sectors; and since a file cannot take up less than one sector, it has to take up a full 800k.

Maybe fuel pumps are the same thing; and can only be divided into so many increments based on the delivery system.

Like, the stock 5fse fuel pump is small, and so 50% of that pump is delivering for 50whp; (or something, I might just be acting crazy), and 49% is 49 whp. But with a Supra fuel pump rated at 500 whp; 50 percent is 250whp, while 49 percent is 245 whp.

Then, instead of risking running lean, the ECU rounds up, and has the pump deliver more fuel in the next incriment it can go.

What do you guys think? Talking out of my ass? No sense?

[Supersprynt]

No, that doesnt make any sense at all, LOL sorry I tried but I cant make a darn thing outta that.

Your pump doesnt divide anything up, its a pump. Its function is to pump fuel, thats it. Your ecu, using sensor like the AFM, O2 sensor, boost sensor etc..determines the a/f ratio. The pump only knows pump, pump more, pump less.

The reason for upgrading a pump is because at some point the pump becomes a bottleneck. Whereas, it physically cant pump the amount of fuel the engine demands, thats when your in danger of burning your cylinders and detonation.

[Kwanza26]

Running a bit rich doesn't hurt the engine. It'll eat away at your cat (if you have one) and your O2... but it's a LOT safer than running a bit lean. Running rich has little to do with the fuel pump, although running lean does. It's more than likely the ECU, AFM, TPS, O2, or something between those sensors.

[shid]

[Doge]

[Doge]

[jgreening]

Thanks for the post Doge. It looks like up to 12psi and 200 whp I would be ok but beyond that, you are correct - its playing with fire. I have been running 10psi so far and am probably at about 180 whp. The supra pump is going to be ordered tomorrow.

[Supersprynt]

[thedevilmaycrie]