I'm gonna give this a shot too. Went to the dmv a few weeks ago and tried running the car through ( 88 Gxl, na, unmodified) And I ran 3000+ hydrocarbons. lol. As far as I know I don't have any vacuum leaks and the engine starts fine hot or cold. Compression was 95 psi ( measured with a Re compression tester I borrowed from work) give or take two or three psi on each rotor. So I figure I either have toasted converters, or she is just running pig rich. Fuel holding pressure was good, and so was running pressure. This I believe is my next step, that, or several gallons of de-natured alcohol. hahah

Bad converter .............or bad no functional ACV ........or no airpump........and or a bad 02 sensor which would only effect the emissions if the car was being driven on rollers over 1700 rpm, not the major player in emissions testing, but a player.

The AFM you have is from a turbo supra...the turbo and non turbo supras have diffrent AFM. And a S4 rx7 and Mk3 non turbo supra both use a AFM made by bosh, which are identical from the outside but i do not know if they are calibrated the same.

Yeah, I found the front secondary valve stuck wide open due to a jammed up vacuum valve. It was difficult to see and didn't cross my mind until I went to screw around with the car a bit today. Just need to get some gasket material and change it out with one of my spares. Gotta love the tech on these cars.

Flapper door style afm's suck period.

Its not worth swapping to another one just to experience a slight variation of suckassness. Nor is it worthwhile to monkey with them to try to achieve a reduced level of suckassness.

If someone finds a way to easily swap a commonly available maf or cone style afm, that would be worth reading.

i'm curious about the maf mod, my N/A runs really rich and if i could lean it out i know i'd beable to flat outrun that m3 that im only hangin with :)

(everyone now runs up to my car cause i could hang with a modded bmw m3... its odd)

Lol this isnt much of a mod is it if you are just swapping a part for an identical part from a different car. Either way no one has even posted up whether there is similar resistance so you could be slowly killing your engine.

Thread Revival
 

Don't give me shit for reviving this.

1993 LS400 MAF plugs in directly in 1990 S5 FC RX-7
Clearly better flow. Larger diameter as well.

A lot of Toyota/Lexus MAF's are compatible, so then finding one that us the easiest to mod is the next step.
I'll figure out how to find the resistance on this MAF eventually

https://cimg7.ibsrv.net/gimg/www.rx7...3f5379cbac.jpg
93 LS400 MAF SENSOR
https://cimg6.ibsrv.net/gimg/www.rx7...3dfd0c4009.jpg
93 LS400 MAF SENSOR
https://cimg2.ibsrv.net/gimg/www.rx7...199b02eb23.jpg
93 LS400 MAF SENSOR
https://cimg4.ibsrv.net/gimg/www.rx7...3e1ab65304.jpg
93 LS400 MAF SENSOR

No I don't know the resistances. Yet.
I don't have a running engine rn but if someone else is interested they can check it out

the plug is the same, but is the pinout the same? (not hard to move the pins around)

you could probably get this to work with an SAFC or something.

Haven't looked into it yet, I'm at the end of the school semester so I'm really busy with that rn. In a couple weeks I'll look into it.

https://splitsec.com/product/psc1-00...nal-calibrator
This could be used

So I tried it in reverse, meaning I put the RX-7 maf on my ls400 and didn't find any issues. The car has been running like trash after I fixed the vacuum leaks and runs great with a slight vacuum leak.. so with the slight vacuum leak I notices no difference in the way it ran. Ran decent. Will look into it eventually, rn really focusing on grinding on the work my 7 needs so I can enjoy it this summer.

The reason why I want to get rid of the Flap Door AFM is because when turning hard left creates enough inertia that the flap moves open more than it should and the ECM cuts fuel. Let go of the gas, wait a few seconds for the inertia to decrease and the engine runs again.
I flipped the AFM upside down and the problem is now when turning hard right.

Has anyone had this problem also?

I've had an S4 for over 30 years.. .I've never seen this issue .. . ... Maybe your spring on the flapper door in the MAF is bad/weak?

Change the MAF. . . .pretty cheap to get a rebuilt one still .