running lean at 5k rpm and up what to do??? please help out.

[david200095367]

I have a ka24det, and i have a tuned ecu for 370cc and stock maf. When i do a 4th gear pull on the street, all the way to 5k the car runs a good afr. From then on it jumps to about 13 afr all the way to redline. So i added +50 fuel from 5k to redline, and the afr dropped to 12.3. I dont think im maxing out the injectors on 7-8 psi on a s14 t28 bb turbo. What do you guys think it is?

[BadMojo]

Stock fuel pump? If so, could it be going out on you?

[nb07bcar]

ya you might. I running 460cc injectors and max them out at 10-12 psi on a 15G turbo. Up the fuel pressure a little. That makes a difference.

[david200095367]

no i have a walbro 255 lph.

[david200095367]

the 370cc and stock maf max out at about 250-260hp. i dont think im hitting that much on 7-8 psi with a s14 t28 bb?

[Jookmasta]

its ur maf............with a stock maf, at that power level, you could very well be maxing out the maf. what does the safc read for airflow?

[david200095367]

havent looked to see what its reading. what should it be thou?

[fiznat]

What fuel pressure are you running?

[KATwo40]

Guys, when the MAF maxes out, it hits 5.11v and the ECU goes full rich. I doubt he's maxing it out at 7-8psi on that turbo.

Sounds to me like you should remove the SAFC from the loop, then do some pulls on the ECU alone. If it goes closer to the correct ratios, then your SAFC is the problem.

[Florida240sx]

Is your vaccum good? My fpr line wascracked and leaking, and gave some fuel issues in the higher rpms. Once boost happened fuel pressure wasn't raised so I couldn't spray enough.

[david200095367]

im runnning a stock fpr with a walbro fuel pump. so it might have bumped it up a lil.

[david200095367]

i noticed the boost creeps up to 9 psi in the higher rpms.

[Craving4Boost]

I have a ka24det, and i have a tuned ecu for 370cc and stock maf. When i do a 4th gear pull on the street, all the way to 5k the car runs a good afr. From then on it jumps to about 13 afr all the way to redline. So i added +50 fuel from 5k to redline, and the afr dropped to 12.3. I dont think im maxing out the injectors on 7-8 psi on a s14 t28 bb turbo. What do you guys think it is?

sh*t...i think i have the same problem! someone help

[2_Liter_Turbo]

Change your stock KA Fuel Filter to a 300zx Filter, and go from there.

[david200095367]

ok im gonna try unplugging the safc 2morrow and then changing my fuel filter to a z32 filter.

[Jookmasta]

well wait, what is the boost normally running at and what is at at 5K or above. u just said it creeps so if that be the case, then obviously ur gonna be more lean if ur not tuned for it.....but u said u have a tuned ecu? um whats the specs on your turbo btw.

[david200095367]

its at 7 and then after 5k its at 9 psi. The ecu is tuned, but if i added 50% then why would it still be lean? Its a stock s14 sr ball bearing turbo.

[david200095367]

also i started my car on a cold start and the idle afr was at 12.3 ish so i minused 9% and it was at 14.7-15 afr at idle. so i drive it for 20 minutes and then i stop at the idle is back at 12.3ish with -9%. So i minus some more fuel and it doesnt do anything. I minus 50% and still nothing. then i add fuel and it gets richer. So at idle it wont get leaner but it will get rich when i mess with the fuel. And if i mess with the fuel before 5k rpm it works, but after 5k it will only richin up from 13ish to 12.3 ish after i add 50% (this is in full throttle). Something is wrong here and i dont know what. Anybody else have any suggestions?

Thanks to all who have contributed so far!

[DammitBobby]

Have you checked your SAFCII settings? How do you have it setup? There is a option to check your sensor to make sure it is working correctly. What voltage reading do you have at idle and at WOT?

[david200095367]

I checked the sensors they are fine. The maf only gets up to 4.4 which means im not maxing it out.

[Jookmasta]

whats the throttle point on the safc for the low and high map?

[david200095367]

its 15% and 35%.

[david200095367]

i tried a z32 maf and it does the same thing. so i know the maf is not bad.

[DammitBobby]

I have a ka24det, and i have a tuned ecu for 370cc and stock maf. When i do a 4th gear pull on the street, all the way to 5k the car runs a good afr. From then on it jumps to about 13 afr all the way to redline. So i added +50 fuel from 5k to redline, and the afr dropped to 12.3. I dont think im maxing out the injectors on 7-8 psi on a s14 t28 bb turbo. What do you guys think it is?

1. You swapped out the MAF so lets rule that out.

2. We still don`t know what fuel pressure you are reading. All ECU`s are programmed for 34psi at idle to +1 psi per pound boost. So you will need to buy a mechanical gauge and a adapter all for around 30 bucks to make sure the fuel pressure is reading correctly. You will have to do a pull on the dyno and look at that gauge to make sure it is reading correctly.

3. If the fuel pressure is reading correctly then we have ruled out fuel pressure. Next I would give the person who tuned the ECU for the 370 injectors a call and see what he says. The other thing you can do is send the injectors to Deatschwerks and have them flow test it.

Unless you do these things it is a guessing game. When trouble shooting problems such as yours it helps to test components so that you can eliminate the components that work to narrow down what the cause could be.

I found this book to be a great help learning about EFI. It give you a basic understanding of the EFI systemhttp://www.efi101.com/

I would love to go to those classes!

[david200095367]

hey thanks. i think i will buy a fuel pressure gauge.

[david200095367]

Change your stock KA Fuel Filter to a 300zx Filter, and go from there.

ok i fixed my prob, if was the fuel filter. thanks all who responded especially to elnegro for the great info.

[2_Liter_Turbo]

ok i fixed my prob, if was the fuel filter. thanks all who responded especially to elnegro for the great info.

No problem. Glad I could help.

[Craving4Boost]

did you change to 300zx fuel filter or another stock one?

[2_Liter_Turbo]

did you change to 300zx fuel filter or another stock one?

He changed it to a Z32 filter. It flows a lot more than the stock KA filter. This is why us SR guys swap to them when we do our engine swaps. The KA filters just can't support the higher rate of fuel flow.

[Craving4Boost]

is the z32 TT and NA fuel filter the same? if not, will both fit? probably the TT is most reccomended?