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View Full Version : Sr20 running dangerously lean. Need some help


newdude1
04-05-2010, 07:32 PM
So I am having this problem for quite sometime now. I have been on nico and they cant figure it so I decided to give yall a try. Heres my situation. My car is running REALLY lean at all rpms. I took it to a good shop here in VA and everything checked out fine. They checked for vac leaks, the maf, injectors, tps, and they threw my car on the dyno to get air fuel readings. This is what they ended up getting.
RPM Air fuel ratio
1500- 17.7
2000- 16.5
2500- 16
3000- 14.5
3500- 13.8
4000- 13.6
4500- 13.5
5000- 13
5500- 12.8
6000- 12.5
At idle my wide band wont even read and when I am at crusing speeds it wont read till I hit the gas more then half way

Now my set up I am running is a s14sr. With S15 turbo, all new exhaust gaskets and intake gaskets, z32 maf, 740cc injectors, tomei fpr, z32 fuel filter, 255 walbora fuel pump, hks bov, greddy front mount, and JWT ecu.

See I dont get how Im running so lean when everything checks out. Could it be my tune? Any ideas on what to check next would be great.

army240
04-05-2010, 07:48 PM
First, I hope you don't have an exhaust leak before your wideband. Second I'd check your fuel pressure! Third, yes, it could be your tune!

Frank

newdude1
04-05-2010, 07:52 PM
No I do now have an exhaust leak. And My spark plugs are straight white/leanish color. Fuel pressure is all correct too atleast what I read online. 38psi at idle and 43 with the vaccum unplug.

Have you heard of people getting bad rom tunes from JWT?

army240
04-05-2010, 08:04 PM
No, I've never heard of a bad JWT tune. It also could be a bad cooling temp sensor, telling the engine is too hot, but it would be a long shot... what's the voltage of your temp sensor at ECU? Give us the reading with cold coolant and at normal operating temperature!

EDIT : Check the resistance of the sensor, according to the FSM, it should be 2.1K to 2.9K @ 20 Celcius, 680ohms to 1k @ 50 celcius, and 300 to 330 ohms @ 80 Celcius.

Frank

newdude1
04-05-2010, 08:16 PM
I replaced that sensor aready with a brand new one. But I will have to check that tomorrow when I get off work.

army240
04-05-2010, 09:05 PM
Just to make sure, it's the one with 2 wire on it, not the one with only 1 wire! :)

Frank

fliprayzin240sx
04-05-2010, 09:58 PM
Is that your reading or the shops? If its off yours, did you try recalibrating the sensor for open air to make sure its good to go?

jspaeth
04-05-2010, 10:14 PM
Unless I misread, that AFR info is useless, because we don't know what the load on the engine is.

If that is under vacuum, then you are running very rich at high RPM, but if it is under heavy load, then you are scary lean in the midrange

newdude1
04-06-2010, 03:31 AM
That is under a load. Their wideband read the same results as mine. And I know its scary lean thats why Im trying to figure out why lol.

fliprayzin240sx
04-06-2010, 04:11 AM
Hmm...do you have a fuel pressure gauge? I'd check that and make sure you're getting good pressure when the boost starts building. Since you have a Nismo/Tomei one, that shit have a tendency to leak and not bump your pressure when its under load. My shit was leaking vacuum around the top hat area, basically it was leaking around the crimped area. Look at it and you'll realize what I'm talking about.

I pressurized my vacuum lines and found air leaking thru my FPR. I then JBwelded the fuck out of it to keep it from leaking again.

newdude1
04-06-2010, 03:21 PM
Yup I have an electronic one and a inline gauge. And the fuel pressure looks ok. What is it suppose to rise too under a load? And ill check for a leak here in a little bit.

jspaeth
04-06-2010, 05:01 PM
Yup I have an electronic one and a inline gauge. And the fuel pressure looks ok. What is it suppose to rise too under a load? And ill check for a leak here in a little bit.


The fuel pressure should rise 1:1 with boost.

So 43.5 with the car at 0 boost.

~36 psi for a stock SR at idle (about 7 psi vacuum) and then rising 1 psi per 1 psi boost.

So for 14 psi boost, you should see ~57.5 psi fuel pressure

newdude1
04-06-2010, 07:36 PM
Ok. Thanks Im gonna take it out for a spin and see what happens with the fuel pressure. Now would the be wot?

jspaeth
04-06-2010, 10:31 PM
Ok. Thanks Im gonna take it out for a spin and see what happens with the fuel pressure. Now would the be wot?

WOT is irrelevant. All that matters is manifold pressure