Confused about Air Intake Metering - HELP!

[Guest Roger NE]

The 2JZ-GE engine (from a Mk4 Supra) I'm putting in my Mk3 has arrived today

 

But I'm rather confused about what I do and don't need for the air intake metering !

 

The Mk4 TSRM I've got shows a large metal VAF Sensor just after the air filter, with an electrical connector going to it (rather like the AFM I have on my 7M-GE engine) . . . and I can see that on some 2JZ-GE engine bay photos I have

 

But OTHER photos just show a black plastic tube coming out of the air filter and going to the corrugated intake tubing

 

So how is it that some 2JZ-GE have this, and others don't??

 

ALSO . . . I was under the impression that these Mk4 N/A engines simply use a small MAP Sensor on the intake somewhere, with a small Vac line that goes to the MAP control module mounted on the bulkhead.

 

I need to make sure I have the Sensor on the engine . . and need to get the Module . . but I can see no mention of it in the TSRM or the TOYO Parts diagrams !!

 

Hope someone can explain, so I can get hold of exactly what I need !!

Edited September 16, 2013 by Roger NE (see edit history)

[Guest Roger NE]

Is there nobody technical on here who can answer this?!

[Gpro]

i think from 1993 - 1995 had maf sensors and after 1996 they didn't.

Also if you have a standalone ecu you can get rid of the MAF sensor

[Guest Roger NE]

So it's only the very early 2JZ-GE engines that have the air flow meter then? (what Toyota call the VAF Meter)

 

(thought more techie people would be on here to explain !)

 

I must admit that I find it difficult to understand how they get the fuelling correct WITHOUT this expensive item in the intake!

 

By the way, if anyone has fitted an Aftermarket Air Filter, I'm in need of the black plastic bit that goes from the stock air filter box to the corrugated intake piping (ie where the AFM would go on the earlier engines)

Edited September 17, 2013 by Roger NE (see edit history)

[Digsy]

I had a 1994 normally aspirated Supra and it didn't have a MAF meter. I may be wrong but I think the engines with MAF were UK and Federal spec. Imports are speed/density (MAP and MAT).

[David P]

With the 2J engine, loom and ECU; MAP and AIT are all the induction sensors you need.

 

Bin the 7M MAF.

Edited September 17, 2013 by David P (see edit history)

[Guest Roger NE]

No I wasn't planning to use the 7M AFM, as I have the 2JZ-GE ECU and loom . . . . and the little MAP Sensor . . . but was just trying to understand how it works without it, when the TSRM shows a big AFM after the air filter (as on my 7M)

[David P]

The AIT tells the ECU the Air Intake Temperature and the MAP tells the ECU the Manifold Absolute Pressure.

[Tricky-Ricky]

No I wasn't planning to use the 7M AFM, as I have the 2JZ-GE ECU and loom . . . . and the little MAP Sensor . . . but was just trying to understand how it works without it, when the TSRM shows a big AFM after the air filter (as on my 7M)

 

If you have the 2JZGE loom ECU etc and its pre MAP and AFM then whats the problem? but if you have a later ECU that's expecting a AFM and MAP signal then you going to have problems,

IMO AFM works just as well on an N/A motor as MAP (prefer MAP for a boosted engine though) but I have tuned plenty of boosted AFM motors, the only reason I can see for running both is down to emissions constraints.

[Guest Roger NE]

No, I now understand it's OK, as this engine (and ECU/loom) doesn't have an AFM . . . I now gather it was in the EARLIER 2JZ-GE engines that they have the AFM (just like my 7M does)

 

The AFM is obviously MUCH more expensive way of doing it . . . I was really just curious how Toyota managed to abandon using them and just use the really small little MAP sensor, yet still get the fuelling correct.

[David P]

I'm not going to wager a pint on it, but have an inkling that the U.S. spec N/A's with EGR may function with MAF?

 

Think U.K. spec T.T's do too?

 

1 bar Map sensors work as well as 4 bar Map sensors and feed the same pins on ECU.

Edited September 17, 2013 by David P (see edit history)

[straightsix]

US spec 2JZGE uses MAF.

Jap spec 2JZGE uses MAP.

 

However, Lexus 2JZGE models in UK, US & JAP use MAF (both VVTi and non VVTi)

 

At least, that's as far as I figured out.

[David P]

You say MAFato and I say MAPato etc.

[Guest Roger NE]

Lexus 2JZGE models in UK, US & JAP use MAF

Yes I think you're right . . .

 

Looking again at the photos I have of 2JZ-GE engine bays with the VAF Meter (that's what Toyota call that MAF), I can see they're actually LEXUS models, not Supras !

 

I know how temperamental AFMs or MAFs can be . . . so I'm glad this new engine doesn't need one !

[Chris Wilson]

straightsix is spot on, to meet US emissions the US N/A's used MAF sensing, cars for proper markets used the far more efficient MAP sensor.

[Guest Roger NE]

So the MAF sensor gives SLIGHTLY more accurate fuelling . . . .

 

But given how expensive (and temperamental) an AFM is, the tiny (and cheap) little MAP sensor method is good enough?

 

I guess I'm just surprised nobody came up with doing it that way in the first place (on the 7M engines, for example)

 

Maybe it takes more computer power to work out what fuel is required . . . . which previously was more limited?

[Chris Wilson]

Mass air FLOW sensors are generally better for emissions, they are not good on engines with anything but the tamest cams though, (flow reversal sends them crazy). They also impose a restriction in the intake and modern crankcase ventilation systems do them no favours as they tend to get oil contaminated. In particular the hot wire type do not like that at all, and the hot oil eventually causes problems as the carbony deposits insulate the junction from the temperature changes by which they work. The MAP sensor for the 2JZ-GTE is about £300 plus VAT from Toyota, so they ain't exactly cheap!

[Tricky-Ricky]

Never know MAFs to be particularly unreliable either, had plenty of MAF cars, also never known MAP sensors to be cheap! even the old jag ones where £200 a throw, and most aftermarket MAP sensors are around the £100-200 mark.

[Guest Roger NE]

When I was saying a MAP sensor is a cheaper way of doing it I meant because a new MAP sensor is about £200 . . . . whereas a new MAF Meter is about £1000 !

 

And although the AFM on my 7M has never played up, I know a lot of people have had problems with them, like you describe Chris.

 

Certainly the MAP Sensor seems a lot simpler way of doing it . . . and as you say, without the restriction in the Intake.

Edited September 19, 2013 by Roger NE (see edit history)

[Tricky-Ricky]

Don't know where you got the £1,000 price tag for a MAF??

http://www.ebay.co.uk/itm/like/230895370668?lpid=83&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=83&ff19=0

http://www.ebay.co.uk/itm/like/251012009358?lpid=83&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=83&ff19=0

http://www.ebay.co.uk/itm/like/251267847331?lpid=83&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=83&ff19=0

http://www.partstrain.com/store/??N=0&Ne=12058&Nr=AND%28part%3AMass+Air+Flow+Sensor%29&PN=0&VN=4294959021+4294958921+4294967145&Nr=AND(part:Mass Air Flow Sensor)

[Guest Roger NE]

I'm talking about the price from Toyota for the complete Air Flow Meter on a 7M or a 2JZ

 

The point I was making is that just using a little MAP Sensor rather than a complete AFM is a much cheaper way for the Manufacturers to do it