Converting MAF to MAP in AE92?

[clintnixwood]

Hello all, I have a 1990 Corolla GT-S, and I did a little bit of research. In North America the engine is rated at 130 hp and 105 lb. ft of torque. In other markets the engine is rated at 140 hp and 110 lb. ft. It was said on wikipedia that this is because the MAF for the NA market was added for California restrictions on emissions, and reduces air flow considerably. In other markets the part is called a MAP, and I'm not sure what the difference is.
Can someone explain the differences, and also is there an easy way to convert the MAF to MAP to gain the loss in power for the engine?

[cEtnA]

Dr. Tweak makes a conversion i think but i don't really see much a point to going map unless you want ITBs if you Google "4age MAP conversion" you should pop up with a few links

[Blof-fan]

Well, first of...you're on the right path. But the info you found isn't entirely correct.

Although I'm in Europe, I have e US spec Corolla AE92 GT-S aswell. I've overhauled my engine so I have seen some differences with our Euro spec engines en I'm formiiar with the different 4A-GE versions.

We would wish our US spec Bigport 4A-GE's would produce 130bhp! With the AFM (Air Flow Meter, that thing that's sitting on the airfilter housing and has a big flap in it) the Bigport churns out something more like 115bhp. That's a dissapointment ain't it?

Our Euro spec Bigport 4A-GE's. With MAP (Manifold Absolute Pressure) sensor are know to produce something in the region of 120bhp.

The later Smallport 4A-GE's are known to produce about 125 to 130bhp. But that engine has a different head, MAP and ECU. So unless you find a complete Smallport engine, you won't gain anything.

The difference between the AFM and the MAP sensor is that the AFM has a large flap that is opend by air passing through it. So yeah, although it is very minor (The opening is larger than the throttle body, so more air can pass through it) there is a restriction. The MAP sensor just senses the vaccum that is present in the inlet manifold.

But that alone doesn't account for 5 to 10 horses being missing. The US spec engines also have a EGR system that redirects exhaust gasses to the intake, which isn't a good thing. And for all that to work there is a ECU that is programmed to work with that specific engine. The programming in the ECU alone could cost you a few pony's.

So If you really want those missing horses, you would have to find a MAP sensor and a wiring harness and ECU that go with it. And everything that comes with it and I haven't thought of or mentioned here.
I think that's a whole lot of trouble and would probably pretty expensive for those 5 to 10 horses
Besides, you won't be shaving seconds of your sprints with that.

So if you ask me. There are better ways to spend your money on that engine

[Bitter]

http://www.maftpro.com/

That. It will let you easily run a MAP setup inplace of the flap MAF or run a GM style hotwire MAF which is no impediment to airflow at all and more accurate than either MAP or the flap MAF.

[SuperRA]

Originally Posted by Blof-fan

The later Smallport 4A-GE's are known to produce about 125 to 130bhp. But that engine has a different head, MAP and ECU. So unless you find a complete Smallport engine, you won't gain anything.

If he has a 1990 GTS, then he should already have a smallport. That's what my car is and has.

[Blof-fan]

1990 was the year of the facelift and the changes were made, so it could be either way

Were the red-tops equiped with AFM aswell stateside?

[SuperRA]

Originally Posted by Blof-fan

1990 was the year of the facelift and the changes were made, so it could be either way

Were the red-tops equiped with AFM aswell stateside?

My smallport has a flapper style AFM and every 4AGE I've seen in the Junkyard had one, but that's just my account.

Were the actual engines mixed btw the years? I thought it was just the valve covers that were mixed. I.e, you could have a red lettered valve cover on a bigport but I didn't think you could have an 89 smallport or a 90 bigport. Eh, I dunno.

[clintnixwood]

thanks for all the info, guys. It's nice to hear people who know about this car, as there isn't much to search for on the internet. From what I know, all of the 1990-1991 corolla GT-S that were produced were the same with the 130hp engine, unless some of you know better. Is there any way to tell by looking? Anyway, I will just assume for now that it is the smallport. So what would be needed is an entirely new ecu along with other parts related to the airflow. Or instead is the converter on maftpro, which will allow for the conversion without getting a new ecu. I'll do some research, like someone said, the 4age conversion to map search.
I also have some pics of the car and engine on my Facebook site, if anyone is interested in looking. Facebook page is Clinton Nix, anyone can friend me, just say you're from toyota nation.

[SuperRA]

Originally Posted by clintnixwood

Is there any way to tell by looking?

If the manifold says TVIS on it, then it's a bigport. Like this:


If it has ridges on the top then it is a smallport. Like this:

[clintnixwood]

Thank you for the images, it in fact has the ridges and does not say TVIS on the manifold. It also has the red lettering on the engine cover, so I think it is confirmed being the smallport. Also I was wondering, and please forgive me if I sound ignorant, as I don't know much about it, but are there ways to simply remove some parts that are restricting airflow instead of changing the MAF altogether?

EDIT: I have uploaded the picture of the engine to my photo gallery.

[clintnixwood]

Also, another thing, about the redirecting of the exhaust gasses, I also own a 1991 Mistubishi eclipse gsx. Well, one day I met a DSM fanatic (there are a few of them), and he was explaining a few things to me. The engine in the eclipse also does the same thing, and he simply sealed off the hole with a plate. Is it possible to do the same thing with this engine, or is there some more difficult procedure?

[Blof-fan]

'90 was the year of the facelift for the AE92 and with that facelift, the Smallport 4A-GE was introduced.
I don't know how it was in the states, but I pressume that the Corolla GT-S's sold in the states didn't have the face-lift on 1-1-1990...If the facelift was sold from Juli or something like that, there could still have been AE92's with the Bigport still in them from earlier that year

Thank you for the images, it in fact has the ridges and does not say TVIS on the manifold. It also has the red lettering on the engine cover, so I think it is confirmed being the smallport. Also I was wondering, and please forgive me if I sound ignorant, as I don't know much about it, but are there ways to simply remove some parts that are restricting airflow instead of changing the MAF altogether?

No, it is not possible to just remove the flap or something like that. Tha AFm is a critical sensor for the ECU to make the engine run. It let's the ECU know how much air is sucked into the engine.
From that info (and others, but the AFM is the main sensor), the ECU can calculate how much fuel has to be injected.

Also, another thing, about the redirecting of the exhaust gasses, I also own a 1991 Mistubishi eclipse gsx. Well, one day I met a DSM fanatic (there are a few of them), and he was explaining a few things to me. The engine in the eclipse also does the same thing, and he simply sealed off the hole with a plate. Is it possible to do the same thing with this engine, or is there some more difficult procedure?

Yes, it is possible to do the same. I have done it on my US spec. 4A-GE Bigport.
And although it hasn't run yet. It should work. I blocked off the opening on the intakemanifold with a plate and gasket. Blind off the connection on the exhaust manifold and just remove the hardware of the EGR system.
Just blind off all the vaccuum connections that ran to it.

That being said. I don't know if your car will still pass emission tests after that! Here in the Netherlands it will since regulations were not that strickt yet. But I don't know the regulations in the states.

[clintnixwood]

I'm not sure how the generations of corollas were introduced in other countries, but my car looks like yours, the same generation, in fact a new style for the corolla wasn't introduced until 92 or 93 in America. I took a quote from the consumerguide review of corolla, the one that is stickied to this forum:

"A 130-horsepower version of the Corolla's 1.6-liter 4 cylinder engine went into the performance-oriented GT-S coupe (1990 91). All other Corollas used a 102-horsepower rendition. The GT-S came only with 5-speed manual shift, but others could have a 3-speed or 4-speed automatic transmission instead."

For some reason, Toyota felt daring and decided to put the red top engine in the gt-s for two years in America. And as far as I know, after 91, the gt-s was eliminated entirely (in America). BTW, can anyone tell me what cars the 20 valve engine went into? Also was there a performance oriented corolla in Europe after the 88-92 generation?

Ha, emissions tests are kind of a joke, really. I haven't had to do it yet, but really you just pay for the test, and then you have to pay up to a certain amount to fix the 'problem' if it fails. If that doesn't work, you still can't really fail it, you just end up paying a little bit of money. They don't do it in all states, and may be different for each state.

[toyotaspeed90]

the JDM smallports were reated at 140ps..... which isn't hp...... it translates to just a tad higher than 130hp.

the smallport 4age makes 130 over the 112hp of the bigport due to a different electricaly system that includes larger injectors, a different ignitions system, almost a full point in compression being higher, a redesigned intake port/head.... there were also different cams, but that's another story.

Seattle has emissions..... but the smallport should pass with an egr blocked off..... it's not a big deal.... all you need is to create a plate for the intake manifold, remove all of the EGR related items, then use a transmission drain plug to cap the hole on the exhaust manifold.


the corolla went on as a 2 door in pretty much everywhere other than North America. the 20V started in 1992... which is why there is no such thing as a 1992 corolla gt-s here in the states, yet there's a 1992 ae92. It's sort of an odd year.

Smallports came out in production year of 1989... so if the car is a 1990 it's a smallport.

there are other, smarter, ways to run a map system.... but unless you do any decent mods I would advise against it. I'm pretty sure there's no translator that works for a 4age....

[REN69]

I remember someone selling AE92 MAP conversions before... basically the harness, ecu and sensors... $600... at that point I rather do a 20V conversion than a map conversion.