Lexus maf + 100ll

pyrows666

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Oct 11, 2009
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So i have an 89 MKIII

Shimmed to 12psi

Ive been Running 100LL because i can get it for cheaper then 91 in California...


I recently installed a Lexus Maf,

Seems to be running much better and alot responsive... Do i still need to install 550 injectors and a walbro? Am i doing damage Running the Lexus Maf with out 550 and the recommended mods???
 

suprajim54

Member
Sep 2, 2009
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Running the car with the Lexus AFM allows more air to enter the engine, but you need more fuel to go along with it (bigger injectors). The previous owner of my car only put the AFM on and the car was running max lean according to the wideband. I swapped it for the stock AFM and AFR's are where they need to be and no worry about blowing the engine.
 

Nick M

Black Rifles Matter
Sep 9, 2005
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The larger meter produces a slower wake(vortex). That in turn results in a slower frequency at the same airflow levels. That is why you want the bigger injectors. To correct the miscalculation by the TCCS.
 

gottadiesel

Flyin Low
Feb 16, 2009
459
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Vancouver, Washington
pyrows666;1698519 said:
So i have an 89 MKIII

Shimmed to 12psi

Ive been Running 100LL because i can get it for cheaper then 91 in California...


I recently installed a Lexus Maf,

Seems to be running much better and alot responsive... Do i still need to install 550 injectors and a walbro? Am i doing damage Running the Lexus Maf with out 550 and the recommended mods???

How cheap are you getting 100LL? or should I say how expensive it your 91? In WA, I am paying $4.08 for 92, but AvGas is somewhere along $4.75 to $4.99...

Anyone have comments about using 100LL in a 7m, you being in CA, I assume have Cats on your car or are you off-road only (technically speaking), I was under the impression that the lead would kill a Cat...

On the other - like Nick said - the mods go hand in hand... You should have a WB AFR gauge also so you know where you are running at mid and WOT...
 

pyrows666

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Oct 11, 2009
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@Jetjock - LMAO, what never ends?

@GottaDiesel - Depending on the day i get the 100LL for free, some other days i get it at a discounted fee... I am an Aircraft Mechanic.. So i am surrounded buy it. It is so depressing going back to 91 Oct. at 4.49 a gal. ( My Cat and O2 sensors are still Functioning properly ive been feeding 100LL to her scince December. Although i have plans to delete them.

To my understanding the 100LL does contain a an additive (tetra-ethyl lead) tetra-ethyl lead (TEL), a lead compound that reduces gasoline's tendency to spontaneously explode (detonation or "knock") under high loads, high temperatures and high pressures. Sustained detonation causes catastrophic engine failure. (so i was thinking of the possibilities... no knock... hmmm

@Nick M & Suprajim54 - I guess i should put my stock maf back on.. By the sounds of it with me just running the Lexus AFM and nothing else im probably running lean, which is BAD... And i am not running a wide band as of yet... Nor do i have 550cc injectors.. :(

ive been aquiring parts here and there... im always missing somthing..

I have an HKS intercooler but im missing a "J" pipe to complete it. (Not Installed)

I have the Lexus AFM but no injectors, no wide band (probably doing damage)

1 have a safc2 i have yet to find the time to install...

GRRR...

Thanks for the info guys.. ill be taking that AFM out and re installing my stock 7M Maf until i get injectors...
 

Kai

That Limey Bastard
Staff member
Well, the question about 'do i need 550's with the Lexus AFM?' it's asked usually once a week around here - people not searching for the same question thats been answered about a hundred times by now.

The Lex AFM is 25% bigger than the stock one. 550cc injectors are 25% larger than the stock ones. You need BOTH at the SAME TIME. There's no cheating that on stock management. You're running lean, and risking putting a hole in a piston by not running 550's. Switch to the stock AFM, or upgrade your injectors - one of the two.

SAFC2 you can install with everything at stock without issues. It'll come in handy for the 550's mod, trimming the fuelling a little, to run slightly less than pig rich.
 

Nick M

Black Rifles Matter
Sep 9, 2005
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pyrows666;1698852 said:
@Jetjock - LMAO, what never ends?

This stuff.

pyrows666;1698852 said:
To my understanding the 100LL does contain a an additive (tetra-ethyl lead) tetra-ethyl lead (TEL), a lead compound that reduces gasoline's tendency to spontaneously explode (detonation or "knock") under high loads, high temperatures and high pressures. Sustained detonation causes catastrophic engine failure. (so i was thinking of the possibilities... no knock... hmmm

I can't comment on aviation grade fuel. But I can comment on lead. That is what "leaded gas" was up until the early 80's. It isn't legal for use in cars because it puts lead on the side of the road. And it damages catalytic converters. You are much better off with gas that has a high "octane rating". The molecules themselves are less prone to explode and more likely to burn rapidly and evenly.
 

pyrows666

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Oct 11, 2009
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well yeah, ill definatly try using the search more... sorry.. and ill use the stock afm for now until i get 550's. thanks for the advise guys.