Instructions to change fuel maps on 14CUX Griffith, Chimaera

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Steve, JOOI which tune and map are you running there?

Spill the beans then Glyn.

It's sort of on there, so fingers crossed ... that's if I still have the Griff, decisions, decisions.

No, we have Day of the Dead (Dia de los Muertos). I didn't realize until now that it varies by country.

Does anyone know if the 14CUX has a MAF hot-wire burn-off cycle? If so, I imagine that the control for it must be contained entirely in the MAF which can tell when the engine stops.

Dan, wouldn't the amount of current needed to do a burn-off require a separate relay controlled supply? Hotwire temperatures for burn-off are very high I believe.

I dont think its that clever- but you do a get a big spike on the output on initial turn on, but this is due to a cold wire, so little resistance until the wire heats up and the voltage stabilises. The circuits inside seem to be just current regulation and op amps to amplify the voltage change. More to the point you also loose the 12 volt feed when the ignition goes off, so you cant do anything then anyway.

I'll try to address this soon -- I'm thinking it's a result of the RPM limit location only being populated after the ICI has been run.

Thank you for your very in-depth reply.
It was random or possibly temperature related - it could go OK for hundreds of miles then suddenly drop into a misfire 'mode' so serious that the engine would barely run and certainly wouldn't idle without throttle. This could persist for minutes at a time but sometimes resolved with a full switch-off and restart. I suspected everything from the fuel pump to EMI from a phone charger.

When checking the ECU for dry joints, I found almost literally a smoking gun. There were scorch marks on the inside of the ECU case and about 6-7 obviously blown earth tracks on the rear of the PCB near the connector but no obvious component damage. Further examination revealed a couple of clean unburnt breaks in the earth plane which were under the lacquer on the top side of the board. I don't know what triggered the fusing, but I suspect the 'original' breaks may have meant some overloading of thinner tracks. Anyway, I made a temporary repair by soldering extra copper wires all over the place which seemed to work but I no longer trusted it so have now replaced it with one from a newer Disco after swapping the PROMS. I can't be sure its solved until I've put some more miles on it but so far, so good!

Ah yes, I remember reading about scaling and offsets now. I'll have another look. I have a 2nd hand Lucas 20AM and a Bosch AFM neither of which I've tested yet, but I'm favouring the 20AM even though it's narrower as it's probably not going to outflow standard 500 heads, should be simpler to rescale and will look more 'period' under the bonnet.

Thanks - I'm very grateful. Hmm, that last row does look odd and in fact the earlier rows also show dips and/or tailing off towards higher revs. On the assumption that the 500 is airflow restricted, I can see why it might not be a big deal that the fueling doesn't increase after 5500 RPM. On the second assumption that replacing AFM and trumpets and widening the throttle will overcome that, I guess that the multiplier would need upping a little and the (squashed in 2 dimensions) original table values would need reducing proportionately so that the new bottom right of the map could give a little more fuel.

Not yet, but I'm thinking it will be the best way of remapping. I know I should probably just get one of the established experts to do it, but I get a perverse pleasure from understanding how things work and doing it myself. I do have a MIG welder and some stainless wire, but don't know how big the boss would be and where to put it - does it need to be the first point the banks merge or can it be further downstream? I'd be more comfortable hiding it in a thicker, cheaper section in case I cock it up.

Feel free to suggest taking some of this dialogue offline or to a different topic if it's becoming OT.

Hi Griffian,

You're very welcome to join our team! Stock shares in assembly language programmers are on the rise.

http://www.theregister.co.uk/2015/10/31/brush_up_o...

I have lots of ideas for improving the 14CUX code. Some are simple, such as deleting obsolete and ineffective code (there is a surprising amount). Some are more complicated. The main goal is to have a little breathing room at max RPM. Right now it looks like the processor is 100% utilized at about 5000 to 5500 RPM. As noted earlier, serial port communication then grinds to a halt. I don't even understand how the system appears to function up to 6000 RPM and beyond.

Work on the 14CUX code is usually seasonal for me so I haven't done much lately but it's time to get back into it.

No obvious water, just scorching. You might not be so complimentary if you saw it

Thanks - I'll have a look at that. I have now spent some time analysing the rev table and the corresponding code. I think I've found some extra information and perhaps a simpler/safer way of doing this now. I'll put up a separate post with my theory.

Thanks for the offer but I'm sure one of the ones you have already worked on will be fine. I had further thoughts about placement:

I'm not keen on adding an O2 sensor at the Y piece, and any further down will be after the main cat so I guess will also skew the readings further. I only plan to put the sensor in temporarily when remapping.

What I'm considering now is to do the Joolz trick of duplicating my map from 5 to 2 and frigging the tune resistor to go open loop. Then I thought I could run with the wideband sensor in place of one of the standard sensors whilst I log it? It would obviously only measure one bank, but Im guessing it's a similar level of inaccuracy to a blended reading after the cat.

If the map starts out reasonably close, I would think there's not too much risk of frying the cat given that it normally runs open loop at higher revs anyway.

Standing by to be told how crazy an idea this is...

Thanks for telling me that. I'd read that they were all 18mm but now I see that the Titania ones also come in 12mm. DOH!

Looks like I'll have to put it in the Y-piece above the main cat then. I'm really not sure my welding skills (or MIG) are up to that so I think I'll get someone with a TIG to fit the boss. I presume there's nothing to hit inside with the drill/cutter until you get down to the parallel section.