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Thread: TPS Connector and Injector connectors off mk1a please

  1. #61
    MR2 Obsessive Sweetpea's Avatar
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    Time for more speculation! 'cos it's easier to sit here and speculate than go and fix my leaky distributer...

    So, in the late 80s Toyota were scared about the introduction of unleaded and they 'backed off' the ECUs. Thinking about this, what would they have actually done?
    If you are worried about combustion chamber temps you aren't going to reduce fueling, if anything you'd make it richer. (Not that I fully believe the old story that lean mixtures run hot and rich ones run cold.) So, I reckon you'd retard the ignition. Especially at high revs where it's more likely to suffer detonation (pinking). And that would cause it to be less rev happy and feel flat.
    I believe one of the early techniques for a rev limiter was just to keep retarding the ignition until the engine wasn't producing any power and the driver had to change up. I don't suppose you can do that with catalytic converters so they just cut the fuel off.

    Two things I believe Jeremy Ross said (although I'd struggle to find the quotes)...
    First he suspected that the 17070 was intended for a different territory. So perhaps Toyota, suddenly afraid of fuel quality in the UK, went and rummaged in the parts bin and found a suitable ECU that would do the job until they did the proper facelift later. Hence we get the 'crossover' cars.
    Second, I'm sure he said that the early 17030 ECU had a fully 3d mapped ignition all the way to the red line. But the later two ECUs were only fully mapped to 4500 revs (or something like that). After which what are you doing? My guess would be that you ignore the revs and pay attention to the MAP sensor. But I'd ned to think about that...

    I think it's a shame Jeremy disappeared too. I think he'd be a fascinating chap to get in the pub for an evening.

    James
    There's no rust on my car. But there are some sizable holes where the rust fell out.

  2. #62
    MR2 Obsessive jimi's Avatar
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    mmmmhhh bear in mind that Japan had fully phased out leaded petrol by 1986 so they already had a MK1 ECU (and engine) capable of running OK on unleaded before it's introduction into the UK.
    Black is not a colour ! .... Its the absence of colour

  3. #63
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    Quote Originally Posted by jimi View Post
    mmmmhhh bear in mind that Japan had fully phased out leaded petrol by 1986 so they already had a MK1 ECU (and engine) capable of running OK on unleaded before it's introduction into the UK.
    But the grade of the Unleaded was different I think. Japan have had 100RON fuel since the mid 80's and we had 95RON. However there is another standard that Japan use called PON where 100PON = our 95RON. its all speculation and we will never truly know what went on but my MR2 feels like the ignition timing is too retarded at the top end because it is less rev happy and runs richer than I think it should from 6500 onwards. When I fitted the 17070 ECU last summer I felt my car was much more like the AE86 I remembered driving, but the fuelling was all over the place! This was due to my injectors being 200cc where as the ECU was expecting 182cc. Maybe also the TPS had a different response curve, But I aim to test this over the coming weeks as I now have a TPS from the mk1b X-over which ran the 17070 ECU. I also have a map sensor with the different plug so I will test this using a multimeter and a vacuum tester I have.

    Its nice to know the exact differences between the versions! I love finding out all the hidden stuff which is made easier with both your help .

    Thanks James and Jimi !

  4. #64
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    Quote Originally Posted by Sweetpea View Post
    I think it's a shame Jeremy disappeared too. I think he'd be a fascinating chap to get in the pub for an evening.
    I seconds that !!!!.. Such an interesting and clever guy

  5. #65
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    Just opened up a 17030 ECU to have nosy. I can report that it has the BF connector like the 17070. Also all the pins are the same as the 17140 except the BF pin.

    It would seem that the 17030 and the 17070 should be interchangeable without modifications and both ECU's should run the cars with no discernible difference - if the pin labels are anything to go by.

    Can anyone confirm that a 17070 and 17030 run the car without differences ?

    Note : The Grey and Red injectors of the mk1a and the mk1b X-over are both low impedance (2ohms) and that the power transistors are the same in the 030 as the are in the 070 so nothing is more heavy duty in in either ECU.

    Just out of interest, here is a pic of the inside of the larger 17140 ECU I have removed the sockets from (this is going in the bin at some point) and the 17030 which I intend to run in my car.
    Click image for larger version. 

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  6. #66
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    Hi Guys does anyone have a schematic of the Mk1b 89661-17140 Late UK) ECU. I have looked everywhere but can't find one to match my set up

  7. #67
    MR2 Obsessive jimi's Avatar
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    Depends what your looking for, you won't get a complete schematic for the ECU, Toyota never made them available, you can get schematics showing the pinouts for the ECU.
    I have a scanned pdf copy the 1987 (May) Toyota 4F, 4A-GE engine manual I've uploaded it to my website and you can download it using this link CLICKY I'll leave the link active for a day or so to allow you to download it. Once you have it go to page FI-31 for the pinouts.
    N.B.
    The manual covers several variations of the 4F, 4A-GE make sure any sections you are looking at refer to the AW11 version W/O (without) Air Flow Meter. There are differences and it's very easy to get mislead by looking at the wrong variation
    Black is not a colour ! .... Its the absence of colour

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