CO Trim - do I care?

[chillman]

As part of the instructions for setting up my Tornado chip it was recommended to adjust the CO trim setting.

My setting is 0v and no matter how many times I turn the screw on the MAF it stays the same. The screw turns endlessly in either direction.

Do I need a new MAF or not worry?

[Old Farang]

Unusual for the trim pot to fail. Are you sure that you have the correct pins? The pot has about 20 turns from end to end, so may appear to be endless.

The following is a good description by Tim Lamont of ACT Products, worth reading.

ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. - 0870 7070110 +44 (0)1342 311790 (http://www.actproducts.co.uk/)

Sorry, it wont copy, but is easy to find. Technical Data Archives - ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. (http://www.actproducts.co.uk/category/lucas-injection-technical-data/)

[chillman]

Unusual for the trim pot to fail. Are you sure that you have the correct pins? The pot has about 20 turns from end to end, so may appear to be endless.

The following is a good description by Tim Lamont of ACT Products, worth reading.

ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. - 0870 7070110 +44 (0)1342 311790 (http://www.actproducts.co.uk/)

Sorry, it wont copy, but is easy to find. Technical Data Archives - ACT Performance Products - your source for after market TVR upgrades, components and performance accessories. (http://www.actproducts.co.uk/category/lucas-injection-technical-data/)




Thanks, that is the exact same info I was using but from another source. I drilled 1 mm holes in the rubber boot (that I'll fill with black silicon when I'm done), to ensure had a good connection to the pins - which I verified. The voltage was sat at fraction above 0v and didn't change when the screw was turned numerous times in either direction. The screw spins freely with no resistance.

I've just found a chart with CO Trim voltages vs AFR Lucas 14 CUX Map / Tune /Prom Files for Rover V8 (http://www.remap-14cux.uk/bins/) Looks like it will make it run too lean. I think I'll just replace the MAF to be safe.

[Old Farang]

It may not be too easy to just replace the MAF. The OEM ones are no longer available, unless you have a known good unit. The after market replacements do not have a very good reputation. The trim pot is not actually anything to do with the airflow (MAF), it is a separate resistor just mounted in the same housing for convenience. It's output goes to the ECU, but not as part of the airflow signal.

Never had to try it, but a separate small, 1 watt about 300 ohm if I recall, variable pot may be a better solution.

[Rick1970]

The adjuster on the outside is not an actual part of the trim pot, just a connector link. It can slip on the pot if turned past the pot's range of adjustment. You can remove cover off AFM and get it connected again, tho i done one just by being patient with a allen key in the adjuster, just 'feel' it back unto place, if that makes sense.