Yet another Lex AFM question thread

[TargaMK3Turbo]

So, I ddi a search, and found, well, not much usefull info. It seems that the Lex AFM sparks up arguements so I'll ask my questions for an answer only and no opinions, lol.
-I have a Lex AFM and PTE 580's, I realize most people go with 550's, wo'nt I be running a lil rich then?
-Will I need a 255lph pump or is the stock pump suitbale for what I need it?
I have a full 3" exhaust, intercooler kit, and GM MSD coild as my mods other than the injectors and Lex AFM.. Oh, and a boost controller but it's not hooked up bc I was hitting about 10psi with my stated mods on the stock AFM.
-What does the Lex AFM raise the fuel cut to?
-Is a FPR nessesary?
-Is a wideband nessesary?
I ask thes questions somply bc I have basic mods and really don't plan to do much with it for a lil wihle as I'm saving money as I have accumulated more bills than I can handle..

Thanks and if these questions have been asked an answered before, please post the thread so I realize I didn't look hard enough.

Thanks again!

Oh, and I have a Blitz BOV thats vented. It's obvious my car hates it, well, it makes the car idle weird sometimes. Other than buying a new BOV, what can I do to help it idle consistent?

 

[hellraiser456]

you will run rich...very rich
i would get a better pump.
fpr would be a good idea as it may help get you a/f ratios in line for those injectors.
i believe your f/c will be raised significantly..if i recall your stock ct-26 will have trouble hitting it.
A wb is a good idea...especially if you want to tune your setup (which is ALWAYS a good idea)

the cheap way to fix your bov is to recirculate it like the stock one...the expensive way to fix it is to switch to a map sensor and eliminate the afm all together.

 

[mkIIIman089]

-550s run rich, you'll be very rich
-255LPH
-More then stock
-for 580s? Yes.
-No

Recirculate it

 

[dbsupra90]

i wouldnt trust a 15yr+ old fuel pump for anything. that would be a for sure replacement imo.

wideband would be the next for sure addition as well.

with the lex afm, drill out the plug over the screw. adjust the screw out about as far as you can get it. dont go too far or it will fall out lol. do this on the dyno or after you get a wideband. see below.

next i would do the afpr. it would be wise to get this, and bypass the j-tube restriction in the fuel return line. mostly tho, you can tune your a/f using the afpr. you can move the whole fuel curve up and down by increasing or decreasing fuel pressure.

with the screw and afpr, you can tune your a/f to where the car is happy. maybe not fine tuned like if you had an afc, but atleast you can get it in the ballpark.

if you dont get a wideband, atleast go to the dyno that uses a wideband to do any kind of tuning, or boost level increase.

 

[TargaMK3Turbo]

could I lean it out by raising boost? my turbo has no shaft play and spools fine.

also, noob question. by adding a 255, how will that help lean it out? that's flowing more fuel, right?

 

[WhtMa71]

255 wont lean it out but it will keep you from blowing up you motor when it runs lean because the stock pump craps out on you during a high boost pull.

 

[TargaMK3Turbo]

how many lph does the stock pump put out?

 

[dbsupra90]

how many lph does the stock pump put out?

 

[TargaMK3Turbo]

I see... I'm liking the dual Walboro.

So, back to what needs to be done soon. How can I lean this pig out? Raising boost? Is there a writup on how to do that little trick to the Lex AFM?

I'm going to look for a SAFC or SAFC 2, they are kinda cheap now. Are they hard to install? That would do the trick as far as tuning my car, right?

 

[TargaMK3Turbo]

Injectors came in today. PTE sent us 550's because 580's were backordered.

I specifically ordered 580's but, I'm kinda happy they only sent 550's, lol!

Man, I lucked out!

So, how close is my car now? Still rich, but can I tweak it a lil adjusting the AFM screw?

 

[bountykilla0118]

LOL man u are going to be rich a hell ..... The stock setup is very rich from the get go. You will need to either decrease your fuel pressure and/or tune it. Now the car will be driveable but you will lose a good amount of power b/c of how rich u are and you will notice extra fuel on the back of your car

 

[dbsupra90]

lexus stock afm screw, afpr, afc to tune.

a fuel pump in good shape that can keep up with the fuel demand.

a wideband to monitor.

done and done. ive ran 680cc and eric has ran 720cc on a lex afm.

 

[TurboStreetCar]

your asking about things other then lex afm and 550cc's.

Running the lexus afm and 550's will net a negligible increase in power, force the TCCS to pull fuel to help with the rich condition and fool the computer by showing less airflow in turn raising fuel cut.

No other mods are necessary at this level.

When you start talking about raising boost and tuning, its a guessing game at what mods you might/will need based on condition of your parts that you are using and desired power output.

If you want to tune, you need either a MAFT or equivalent or Standalone Engine management and Wideband.
If you want much more then stock power then you need a bigger Pump.
If you get a bigger pump and want to tune further you need an Adjustable Fuel Pressure Regulator.

How much the LexAFM raises fuel cut is dependent on your car, could be to 12psi could be to 22psi. Every car is different, same with how rich you will be.

 

[mkIIIman089]

So much for no opinion...

 

[TargaMK3Turbo]

thanks for all the help! I've learned a lot and I appreciate it.

sorry this went off topic, I shouldve made a better title...

the car is going into storage next week, but ill be doing a lil racing sunday. so ill go with an afc next year I guess...

can I use JUST the lex afm screw to get a decent ballpark tune.

I didn't realize 550s would make the car run THAT rich.. I shoulda just stuck with my 440s.....

I only plan on running enough boost that the ct26 can produce efficiently, which I'm not sure how much that is...

so increasing boost won't compensate for the extra fuel? I just want to make sure I understand that.

once I get that check from taxes, I plan on upgrading my pump, and getting all the things needed, maybe even an sp61

 

[TurboStreetCar]

So much for no opinion...

No opinions here, just answers to multple questions

TagraMK3Turbo: Increasing the boost wouldn't account for the extra fuel because of the air flow sensor, same reason why switching to a bigger AFM housing raises fuel cut because approx 25% per metered "unit" more air is entering the engine then the computer/afm electronics know about. thats why the use of 550's witch are approx 25% larger injectors are used to even it out.

Your not going to be that rich, stock the car will run in the high 10 A/F's, with this you might be mid 10's????(maybe someone has logged a/f's with lex 550's mod??) At idle and cruising or anything closed loop the computer will account for the extra fuel if any.

Basically what i was trying to break down in my last post is that if all you swapped is the AFM and injectors the car is still basically stock. Tuning the car isn't necessary to make the car run, nor to make sure its not going to go lean. im sure you could turn the boost up to fuel cut and run it like that with no problems, but just like a stock car theres power to be found by tuning the car.

 

[TargaMK3Turbo]

No opinions here, just answers to multple questions

TagraMK3Turbo: Increasing the boost wouldn't account for the extra fuel because of the air flow sensor, same reason why switching to a bigger AFM housing raises fuel cut because approx 25% per metered "unit" more air is entering the engine then the computer/afm electronics know about. thats why the use of 550's witch are approx 25% larger injectors are used to even it out.

Your not going to be that rich, stock the car will run in the high 10 A/F's, with this you might be mid 10's????(maybe someone has logged a/f's with lex 550's mod??) At idle and cruising or anything closed loop the computer will account for the extra fuel if any.

Basically what i was trying to break down in my last post is that if all you swapped is the AFM and injectors the car is still basically stock. Tuning the car isn't necessary to make the car run, nor to make sure its not going to go lean. im sure you could turn the boost up to fuel cut and run it like that with no problems, but just like a stock car theres power to be found by tuning the car.

thank you! that's perfect! I understanf now. so my A/F is about stock, that's not too bad, I'd rather be safe then sorry.

my mods are a turbo back 3" exhaust, full intercooler kit with spearco replica intercooler, msd gm coils and ngk wires, pte 550's and lex afm, intake adaptor, titan gasket and arp studs, and my exhaust has no convertors. I think that's it motor wise...

so is there any way to trick the sensor into thinking there is less airflow?

also, what exactly does the screw do on the lex afm?

these are the last questions I have. thanks! I'm glad I understand now lol I was a lil confused...

postin from my phone ftl also.....

 

[dbsupra90]

you also have to keep in mind the fpr. one psi of boost = one psi more fuel pressure.

the screw on the afm regulates the unmetered air going into the motor. the more you turn the screw in, the more it closes off the unmetered section of the afm, the less unmetered air that gets to the motor. of course, the more the screw is out, the more unmetered air that gets into the motor.

what this does, is lean out the a/f. any unmetered airflow will not be compensated for by the ecu since it does not see it. so the more you have, the leaner it will be. this is how you can mechanically trick the ecu and why the lexus afm raises fuel cut.

electrically, you can trick the ecu by means of an afc, emanage, maftpro, etc.

 

[TargaMK3Turbo]

good stuff! so by turning the screw out, I can lean it out a lil...

how sensitive is this screw?
I'd mess with it myself before asking that question, but I have no type of meter so I don't wanna turn it too much...

 

[dbsupra90]

without a wideband, i wouldnt want to go all the way out. 1/2-1/3 way in would be fine.