14Cux bench test

14Cux bench test

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FFMan

Original Poster:

410 posts

248 months

Thursday 24th April 2014
quotequote all
As you may have seen in other posts I am developing an 14cux interface with a Bluetooth android display.

I have my bench 14cux powered and some resistors to give sensible signals to the temp, fuel and tps inputs so no faults are flagged.

I am trying now to get it to think the engine is running by feeding an rpm signal but so far no joy. I am using rovergauge to verify ecu readings to ensure a bug in my code is not incorrectly reporting rpm but so far I can't get any rpm readings. I am feeding a pulsed 12v from a transistor driven by a pic but what I see is that the input to the ecu drags the voltage to zero - maybe my transistor output does not provide enough current. after all, in the car, the coil switch side will be strong. maybe this is the problem, or maybe the ecu needs some other input before it thinks the engine can run. so far I have no maf or lamda signals, but I wouldn't have thought that would prevent running.

from previous development of a shift light I do have motor driven dizzy and coil setup in the garage I could recommission but I wondered if anyone had any thoughts.

thanks




stevesprint

1,114 posts

178 months

Thursday 24th April 2014
quotequote all
Sounds like a questions for Mark (Blitzracing) but I can confirm the engine will run without the MAF, Lambdas or throttle position sensors connected. You should be able to connect via serial with the ignition on without running the engine. Is the fuel pump output activated when you simulate the ignition pulses? What rpm are you simulating because the ECU does consider the engine running until 500 rpm.

Good luck
Steve

FFMan

Original Poster:

410 posts

248 months

Friday 25th April 2014
quotequote all
the communications is running just fine.

After I put up the original post, I did put a meter on the fuel relay output and noticed no output on there. I tried 2 ecus and forcing the pump to run via rovergauge but could get no output, nor does it prime. suggests something else amiss in the wiring though half an hour checking it revealed no obvious issue.



blitzracing

6,387 posts

219 months

Friday 25th April 2014
quotequote all
You forget the coil switching voltage includes the ringing signal as the coils magnetic field collapes. This is way above 12 volts- typically 150 to 300 volts for a millisecond or so, so the ECU input is protected from this spike with a 6.8 k dropper resistor and possibly more inside the ECU, so if its only 12 volts I doubt any trigger signal will be picked up without the spike on it. You could probibly generate a simular signal using a 12 volt relay as a buzzer so the relay coil produces the spike, but you wont be able to vary the frequency easily. Otherwise something like the Velleman amp could be used with a variable frequency input switching a coil on the bench, but keep away from the output!

FFMan

Original Poster:

410 posts

248 months

Friday 25th April 2014
quotequote all
thanks - I did wonder about this as the input s neutralising any signal I currently give it. i'll dig out my bench dizzy, coil and variable speed motor. nothing like the ticking of a spark plug in the house !

any idea why the fuel pump relay doesn't fire on power up or force on using rovergauge. I have tested for both a 12v and gnd switched output but do not see any change at any time.

blitzracing

6,387 posts

219 months

Friday 25th April 2014
quotequote all
Same reason I suspect- it needs the initial spike from the coil to enable the fuel pump as you turn on the ignition.

blitzracing

6,387 posts

219 months

Tuesday 29th April 2014
quotequote all
In trying to trace a fault with my mapped ignition, and the coil -ve supply was disconnected, the fuel pump still primes without a spike from the coil, so you must have another iisue there Im afraid.

FFMan

Original Poster:

410 posts

248 months

Tuesday 29th April 2014
quotequote all
ok that's interesting.

I have only a couple of bugs left so will continue to test in the car. if I can't nail them i'll progress the bench ecu to get it running. I'm not keen on keep starting/stopping the Griff but its getting close to complete now.

danbourassa

246 posts

136 months

Tuesday 29th April 2014
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Alex, you also need +12V to the inertia switch input (I think it's Pin 19 but please double check this).

Also, Mark is right about the coil voltage. 12 volts won't do it. I use the output of an HP 8111A through a boost transformer and no inline resistor. It's about a 30 volt spike direct into the ECU.

FFMan

Original Poster:

410 posts

248 months

Tuesday 29th April 2014
quotequote all
thanks - i'll check pin 19 when I get home.

if that gets the pump priming i'll fire up my bench dizzy or find a cheap function generator with a reasonable output.

stevesprint

1,114 posts

178 months

Tuesday 29th April 2014
quotequote all
In the UK pin 19 is the ignition switch supply and our inertia switch only interrupts the fuel pump. Dan, this means the inertia switch on NAS vehicles interrupts the ignition switch feed which sounds like a sensible idea.

Here's the wiring diagram I've always used and you can see pin 19 is the ignition feed. www.stevesprint.com/remap-14cux/14CUX_Wiring.pdf

FFMan

Original Poster:

410 posts

248 months

Tuesday 29th April 2014
quotequote all
I wonder if pin 34 needs setting to manual gearbox now I look. I think when I plug rovergauge in it says something like auto/drive.

I have a feeling pin 19 is already a positive feed into the ecu but when home Thursday I can check.

is gearbox mode a possible too ?

stevesprint

1,114 posts

178 months

Tuesday 29th April 2014
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Good point, If you don't have a 510 ohm resistor just ground P34 for auto parked.

danbourassa

246 posts

136 months

Wednesday 30th April 2014
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I haven't found all my notes on this yet but here is more info that may be useful.

There are 4 grounds on the board and they are not all internally connected to each other. They depend on the wiring harness for interconnection. This was probably for isolation of the analog and digital parts of the board (for noise control) as well as separate ground references for low level or sensitive inputs. You may need to connect these for proper ECU function. The pin numbers are 4, 14, 27 and 40.

The ECU controls it's own power by a signal out to the main relay at pin 2. Pin 15 is +12V unswitched. This is trickle current that maintains fault codes, TPS minimum, etc. Pin 12 is +12V switched. This goes away when you turn off ignition or pop the inertia switch.

This part may not be critical for your troubleshooting but may give you some insight. When you remove the voltage from pin 12, the fuel pump relay, if energized, will de-energize immediately. The ECU monitors this voltage at ADC channel 0 and when a number of consecutive samples indicate the voltage is gone, the ECU starts a shutdown sequence. This shutdown sequence updates battery-backed memory, backs out the IACV and turns on the fan timer, if needed. At the end of this process, the 14CUX software just spins in a tight loop waiting for either the voltage to come back (at which point it reboots) or for the ECU to shut down. After about 5 seconds, the output from pin 2 de-energizes the main relay. I think this time is controlled by analog circuitry on the board (an R-C time constant).

davep

1,141 posts

283 months

Wednesday 30th April 2014
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Dan, do you have a schematic diagram(s) for the board?

Just a heads up for early pre-cat Griffith owners the inertia switch circuit probably has a so called 'fuel pump' relay (controlled by the ECU) on the fuse/relay panel (position R8). This is in addition to the fuel pump relay in the floating loom. Nothing is clear cut where TVR electrics are concerned!

danbourassa

246 posts

136 months

Wednesday 30th April 2014
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davep said:
Dan, do you have a schematic diagram(s) for the board?
Dave, other than the small serial interface schematic on Colin's site, I only have a few bad sketches in the notebook I can't find. My work area is a mess.