Bench testing 808

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Handy Andy
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Bench testing 808

Post by Handy Andy »

I have an 808 ECU that has - so I was told - lost its injector pulse. The MOSFET is OK so I want to check overall operation.
What signal inputs do I need as a minimum to make it generate an output.
Do I need both inputs from the dizzy or will one suffice?

Does anyone have the datasheet for the 16034984 PLA?
BennVenn
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Re: Bench testing 808

Post by BennVenn »

You'll need 12v, a 5v square wave to simulate the dizzy (REF signal), or a dizzy and a drill or something else to turn it. You'll also need to satisfy the MAP, IAT, CLT, TPS signals or else it'll go into limp mode (but will still fire the injector)

The ECU grounds the Injector negative, the positive IIRC is fed from the ECU relay. Make sure you have 12v on the injector plug before you go fault finding.

If this is a paid job, the time fault finding and a replacement mosfet/driver will be far more than a $40 ECU from a wrecker.

Also, the Mosfet has a current sense resistor on its source which goes direct to the harness, it'll either be grounded on the harness if its a multi point injected loom, or it'll loop back into the ecu if its a low impedance injector (Throttle body injected motors) to limit injector peak/hold current.
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antus
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Re: Bench testing 808

Post by antus »

Also, if you want more information about these ECUs you should have a look at the guides in the FAQ are (link up near top right). If you want to go deep you can put a high speed comms interface on it (home brew or from here), and burn a 12P memcal, then you can use tunerpro to see everything about it. What input its getting from sensors, what the outputs are doing, any error codes etc etc.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
Handy Andy
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Re: Bench testing 808

Post by Handy Andy »

BennVenn wrote:You'll need 12v, a 5v square wave to simulate the dizzy (REF signal), or a dizzy and a drill or something else to turn it. You'll also need to satisfy the MAP, IAT, CLT, TPS signals or else it'll go into limp mode (but will still fire the injector)
I have the 12V and a suitable square wave - I have a workshop full of electronic test equipment - Limp mode is OK, I've already tested the Mosfet, I know it's OK.
BennVenn wrote:The ECU grounds the Injector negative, the positive IIRC is fed from the ECU relay. Make sure you have 12v on the injector plug before you go fault finding.
I have the circuit for the ECU and the car wiring diagram. It's from an early Nissan Pulsar - Astra with a new badge,
BennVenn wrote:If this is a paid job, the time fault finding and a replacement mosfet/driver will be far more than a $40 ECU from a wrecker.
True, I look at it as a learning experience - My background is in electronics, not vehicles, although I have been known to replace the odd engine and gearbox. We used to have a decent wrecker locally, sadly he got rid of all the vehicles and sold the land to a developer early this year.
BennVenn wrote:Also, the Mosfet has a current sense resistor on its source which goes direct to the harness, it'll either be grounded on the harness if its a multi point injected loom, or it'll loop back into the ecu if its a low impedance injector (Throttle body injected motors) to limit injector peak/hold current.
I saw that in the circuit, according to the car wiring it's not used, but then, Nissan may have just left it out on the diagram.
antus wrote:Also, if you want more information about these ECUs you should have a look at the guides in the FAQ are (link up near top right). If you want to go deep you can put a high speed comms interface on it (home brew or from here), and burn a 12P memcal, then you can use tunerpro to see everything about it. What input its getting from sensors, what the outputs are doing, any error codes etc etc.

I'll have a look at the guides, I doubt a 12P memcal would even work in the Nissan. I have a VX commodore ECU sitting around. I may do a bit with that.
At this stage I would like to know what signals I should expect to see on the 16034984 PLA ( U12 on the circuit) Some of the signals look a bit low but I'm not sure what the switching level is.
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charlay86
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Re: Bench testing 808

Post by charlay86 »

All the ICs are either custom or rebranded with delco PNs so you won't have much luck with a datasheet.
12P will work on any 808, but the Nissan software should also be fine. 12P just has a bit more documentation and people who know how it works :)
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Re: Bench testing 808

Post by BennVenn »

12p works just fine in a pulsar/astra. Its running my 89 n13 18le turbo build. Handy for testing the entire system too, sensors, loom etc

There's not a lot that can go wrong for the injection side of things. It doesn't even need the CPU.

The fuel modeling ic will generate the pulse synced to the ref pulse, I don't recall if it goes direct to the MOSFET or if it goes to a gate driver first. I remember it being a BJT rather than a MOSFET though it's been a while since looking at the schematics (hosted here). The FMIC is available new old stock on AliExpress.

The 808 routes the source leg of the FET (or emitter maybe?) direct to the harness and it's up to the harness to either Gnd it, or gnd it via the sense resistor. That's the only difference between the 18le and 16lf loom (and the iat sensor).

Bad grounds are common in pulsars, the two main grounds go to the head bolts up on the cam gear side of the head. It's common for these to corrode or degrade causing sensor issues and without a good gnd, you won't get good injector current.

Interested to hear what you find!
Handy Andy
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Re: Bench testing 808

Post by Handy Andy »

charlay86 wrote: 12P will work on any 808, but the Nissan software should also be fine. 12P just has a bit more documentation and people who know how it works :)
That's good to know
Handy Andy
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Re: Bench testing 808

Post by Handy Andy »

BennVenn wrote:12p works just fine in a pulsar/astra. Its running my 89 n13 18le turbo build. Handy for testing the entire system too, sensors, loom etc

There's not a lot that can go wrong for the injection side of things. It doesn't even need the CPU.

The fuel modeling ic will generate the pulse synced to the ref pulse, I don't recall if it goes direct to the MOSFET or if it goes to a gate driver first. I remember it being a BJT rather than a MOSFET though it's been a while since looking at the schematics (hosted here). The FMIC is available new old stock on AliExpress.

The 808 routes the source leg of the FET (or emitter maybe?) direct to the harness and it's up to the harness to either Gnd it, or gnd it via the sense resistor. That's the only difference between the 18le and 16lf loom (and the iat sensor).

Bad grounds are common in pulsars, the two main grounds go to the head bolts up on the cam gear side of the head. It's common for these to corrode or degrade causing sensor issues and without a good gnd, you won't get good injector current.

Interested to hear what you find!
Iv'e got it working now. I got hold of an old circuit that showed the connections from the ignition module to the distributor. Once I had that I could trace the circuit from the module and discovered the input is ESTHI, not EST as I had been previously told. Once I connected a 20Hz square wave to ESTHI it all came to life.
The current sense circuit isn't connected at all. According to the Pulsar wiring diagram INJGND is connected to the other GND pins on the ECU. Q1 is definitely a MOSFET.

I'll mark up the relevant circuit with some notes and waveforms and add it to this thread.
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Re: Bench testing 808

Post by antus »

there is also this https://pcmhacking.net/ludis/1227165schematic.html its the same ecu, just a different service number. you need 12p for the faster data stream with more in it versus the stock 160baud. there are other programs too, but thats not relevent. you would need to do a comms mod as the sxr chip is missing on the 808. Im running pulsar 808 with 12p on my 4cyl too. theyre easier to find at the wreckers than vn/vp commodore.
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
Handy Andy
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Re: Bench testing 808

Post by Handy Andy »

It's all good, I've learnt a bit more about these now, I doubt it will be the last one I see.

This is the relevant section and the waveforms one would expect to see. It may be of use to somebody.
Attachments
808 ECU ignition and Injector waveforms.png
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