S15 SR20DET Running Lean! Running out of option

[CalPolyKing]

Thanks got my answer

[benarovi]

whats it at WOT?
that really isnt that lean at idle. stock sr20s usually lean out on the wideband or close to at idle. 15 is fine for idle. just from what ive seen personally.

[CalPolyKing]

whats it at WOT?
that really isnt that lean at idle. stock sr20s usually lean out on the wideband or close to at idle. 15 is fine for idle. just from what ive seen personally.

At WOT it drops to about 13.5-14.5 range. The moment I release the pedal it shoots to 17 a/f momentarily, then it stabilizes at 15 range.

[snafupossum]

what and who did your tune?

[Dboyizmlg]

Well that's a big turbo for stock injectors and ECU.

It will be lean at WOT, with that size turbo as your ramming more air in than fuel.

At idle you should be around 14.7-15.2.

Is this motor installed on as S13 chassis? Also Fuel pressure should be 38psi with hose pluged in

[Dboyizmlg]

what and who did your tune?

OP mentioned it's pretty much stock except the turbo upgrade I assume ...
OP more details about engine mods would help a bit.

[CalPolyKing]

OP mentioned it's pretty much stock except the turbo upgrade I assume ...
OP more details about engine mods would help a bit.

- garrett t3t4 turbo
- Greddy FMIC
- aftermarket exhaust manifold to fit t3t4
- TurboSmart UltraGate38 Waste-gate with 10psi spring.
(This is why I don't believe the turbo has any effect. The T3T4 spools late and psi levels are almost stock. So, I don't think it's ramming much air into the engine. Correct me if I'm wrong)
- aftermarket air filter
- aftermarket oil catch can

S15 sr20det on my 1998 s14. Not to many upgrades to effect a/f ratios to cause a running lean issue.

[pacotaco345]

- garrett t3t4 turbo
- Greddy FMIC
- aftermarket exhaust manifold to fit t3t4
- TurboSmart UltraGate38 Waste-gate with 10psi spring.
(This is why I don't believe the turbo has any effect. The T3T4 spools late and psi levels are almost stock. So, I don't think it's ramming much air into the engine. Correct me if I'm wrong)
- aftermarket air filter
- aftermarket oil catch can

S15 sr20det on my 1998 s14. Not to many upgrades to effect a/f ratios to cause a running lean issue.

You put a massive turbo on the car and didn't put bigger injectors on it or even get a tune.. And you're wondering why the car is running lean? 10 psi on a t3/t4 is not the same as 10 psi on an s15 turbo, its more like 18.. which on stock injectors you would be leaning out. Get injectors and a tune before you ruin your motor.

[Mikester]

- garrett t3t4 turbo
- Greddy FMIC
- aftermarket exhaust manifold to fit t3t4
- TurboSmart UltraGate38 Waste-gate with 10psi spring.
(This is why I don't believe the turbo has any effect. The T3T4 spools late and psi levels are almost stock. So, I don't think it's ramming much air into the engine. Correct me if I'm wrong)
- aftermarket air filter
- aftermarket oil catch can

S15 sr20det on my 1998 s14. Not to many upgrades to effect a/f ratios to cause a running lean issue.

You are wrong- If you note the size differences between the compressor wheels and housings between the T28 and a T3/T4, you will see that not only does the T3/T4 dwarf the T28 in both... the VOLUME of air moving into your intake, measured in cubic feet per minute (cfm) is substantially more.

Second, Idling at 15 or 16 is not a problem- It's normal. In a perfect world, I suppose idling steadty at stoich (14.7) is optimal... However, in most engines, that number will vary with idle, fuel quality, ambient temperature & pressure... and a number of other factors that someone smarter than me would have to explain. Bottom line, idling at 15-16 is good... If you see 15-16 under load, get off the pedal lol

Under boost, your AFR should be 11.5-12.5...

Sucks you swapped out a bunch of parts when your only issue is too much turbine and not enough injector. The only thing you need is a tune.

[CalPolyKing]

You are wrong- If you note the size differences between the compressor wheels and housings between the T28 and a T3/T4, you will see that not only does the T3/T4 dwarf the T28 in both... the VOLUME of air moving into your intake, measured in cubic feet per minute (cfm) is substantially more.

Second, Idling at 15 or 16 is not a problem- It's normal. In a perfect world, I suppose idling steadty at stoich (14.7) is optimal... However, in most engines, that number will vary with idle, fuel quality, ambient temperature & pressure... and a number of other factors that someone smarter than me would have to explain. Bottom line, idling at 15-16 is good... If you see 15-16 under load, get off the pedal lol

Under boost, your AFR should be 11.5-12.5...

Sucks you swapped out a bunch of parts when your only issue is too much turbine and not enough injector. The only thing you need is a tune.


Thanks for the info. I actually bought this car in a trade. I would have personally never put this size turbo on. I'm happy with a gt2871r or something bottom mount.

I don't plan on keeping the car long. So I was debating installing my good t28 with my used exhaust manifold, downpipe, and elbow I had stashed away for another build.

Suck! Now I have to decide whether it's cheaper to tune it, or drop my t28 BB on there. :(

What do you guys recommend?

[Dboyizmlg]

If it was mine, I would sell it the way it is. I wouldn't want to put more money into it if it didn't need it.

Making sure of course that you let the new buyer know about the size turbo and stock injectors. Lol

[Kingtal0n]

Put the stock setup back on it and run it just fine,

or,

buy a PFC and learn to tune it (make your mistakes on this car so you know what you are doing on the next car)

[mogli9000]

Car is not setup properly.

Get a standalone ecu, buy supporting mods, and tune.

t2 series turbos = stock ecu with piggy backs = Gets you by.

Proper tune is recommended

t3 or t4 series turbo = standalone needed.

Running a top mounted turbo on a stock ecu is SKETCH as fuck.

[jedi03]

Tune it!!!!

[CalPolyKing]

Bought an s15 t28 turbo and put it back to stock. :)
Runs good now.