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[Mk2] [Turbo] Afm adjustment

 
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Bear87
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sat Dec 17, 2016 3:20 pm    Post subject: [Mk2] [Turbo] Afm adjustment Reply with quote Reply with quote including images

It occurred to me today while tinkering on my project that I'm continuing having issues with over fueling.
One of the first things I did a while ago was test the afm and it was faulty.
Got a replacement which I have tested and the adjustment screw is correct to the numbers etched onto the afm unit.

My question is should the adjustment be as is on the afm. Or should I be adjusting it to the etched numbers on my "original" afm that came with the car originally?
Cheers chaps
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Pauln
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sat Dec 17, 2016 6:33 pm    Post subject: Reply with quote Reply with quote including images

I believe the number is stamped on the body by the manufacturer when the AFM is originally setup up to give the correct pin out readings. So if that's the case I would say you always setup an AFM according to the number stamped on the body.

If the adjustment screw is correct, and you checked the resistance between the various pins on the connector as per the book, including when operating the flap, that would suggest your issue is elsewhere.

As far as I can see the screw just alters the amount of air being bled into the system via the bypass channel, so screwing it out would lean the mixture a little. But presumably would make progressively less difference as the flap opens. A bit like the screw on the throttle body controls the amount of air bled into the system when the butterfly is fully closed.

In both cases I can see how the way they are set might make a difference at idle, but I wouldn't have thought either would make the car run too rich when on the move.

I would have thought that's more likely to be a faulty 02 sensor, or perhaps an issue with the ECU.

I can't remember whether you've put the car through an MOT and it failed on emissions, or whether your just concerned that it may be over fueling.

Paul
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Bear87
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sat Dec 17, 2016 6:48 pm    Post subject: Reply with quote Reply with quote including images

Thanks for your reply Pauln I think your right with the set up in just wanted to make sure I wasn't missing anything! I assume I may have multiple issues as this is an on going problem. I'm miles of a m.o.t as have raw fuel blowing out the back end. So far new afm, ecu, injectors, injector seals, fpr, fuel filter, fuel pump, knock sensor.
But is a rebuilt forged engine so my problem may well be deeper inside as it was built in 2007 and never run until I bought as a project. [Brick wall] clutching at straws now.

Cheers
Brad
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Pauln
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 18, 2016 12:09 am    Post subject: Reply with quote Reply with quote including images

Wow, that sure is over fueling.

I assume you've checked the Lamba sensor is operating as per the book?

Other than that, it sounds as though you've checked or replaced most of the other external fueling components. I'm really clutching at straws now, but I wonder if it's worth checking the cold start injector is operating as it should and switching off. Sounds pretty unlikely I know. But I don't know what else to suggest.

Hope you manage to get it sorted.

Paul
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Bear87
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 18, 2016 12:02 pm    Post subject: Reply with quote Reply with quote including images

Yea I have checked the cold start injector and that seems fine has no let by and even tried running with it unplugged.
Lambda sensor is my next port of call. However doing some research it would appear that the lambda sensor is only active during open loop or when engine temp has risen and or WOT. Although I suspect with the amount of fuel running past it there isn't much left of it.

Also strugging to find a reasonably priced single wire lambda. Is it possible to run a 4 wire lambda and only connect the read wire and discard the heater and the earth cables?

Thanks for your time with your replies Paul

Brad
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Pauln
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sun Dec 18, 2016 2:18 pm    Post subject: Reply with quote Reply with quote including images

It's not something I've ever tried so I don't really know for sure.

I would have thought it ought to be possible. My main concern would be check whether the four wire type will "earth through the body" like the single wire, or whether you need to connect the sensor earth wire to the body somewhere.

My only other thought would be whether the 4 wire type with the heater unconnected will perform similar to the single wire when cold.

I guess it all comes down to the difference in cost between the two types. It might be worth having a chat to someone like tcb parts about this as they have a good reputation for being helpful.

Paul
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Truzo




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PostPosted: Mon Dec 19, 2016 12:00 am    Post subject: Reply with quote Reply with quote including images

Hey i used this one recently. http://service-parts.co.uk/denso-oxygen-sensor-dox-0107
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Bear87
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon Dec 19, 2016 12:02 am    Post subject: Reply with quote Reply with quote including images

Top man thank you thats more like the money I'm willing to spend to problem solve! [thumleft]
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Truzo




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PostPosted: Mon Dec 19, 2016 12:24 am    Post subject: Reply with quote Reply with quote including images

Not a problem, This is for the rev 2 single wire bolt in type and the cross reference on the listing matches the toyota part number. I have it in my rev 2 right now and all seems fine. (no warning lights/codes)

However, Double check for yourself as i don't want to recommend a part that's not right. [thumleft]
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Bear87
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1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Mon Dec 19, 2016 12:28 am    Post subject: Reply with quote Reply with quote including images

One step ahead of you [Wink] the Internet makes research a breeze
Seems a few people are using that one on rev2
Will be ordering shortly. I don't have any codes but it's another thing off my list of possibilities!

Did you have to solder the connector On?
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Truzo




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PostPosted: Mon Dec 19, 2016 12:36 am    Post subject: Reply with quote Reply with quote including images

Iirc it's universal so comes with heat shrink and bullet connectors.

Or you could just solder it into your factory plug.
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platmatt8
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1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Tue Jun 12, 2018 10:42 pm    Post subject: Reply with quote Reply with quote including images

Wow, this was just the good news I was after that sensor is a great price! Beat the more than double recommendation from other mr2 specialists.

Did this solve the issue you had?
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