using a universal lambda sensor possible

[AdrianS]

I think you misunderstand me. I have read (I don't have the data on this PC) that some ecu's can tweak the open loop fuelling by a small amount, based on how the engine behaved in closed loop - I'll try to find it.

This is not to say don't use a universal sensor, but it would be adviseable to match the heater resistance - a low resistance heater will draw more current, and it depends how over-engineered the the heater circuiry in the ecu is : Bosch universal 4-wire sensors come with 7, 12 and 18 watt heaters.

[AdrianS]

Thanks wilbo - I won't bother looking up the docs I was thinking of - Long Term FT is it exactly.

[George]

+1, a very useful description! Wilbo, do you have any more of these?

[thechuckster]

so it's possible that OBD 2 engines/ecu's support long-term trim - but otherwise, any closed loop data is temporary?

[CrUZida]

OBDI has fuel trim too

[Z2TT]

AdrianS as for fuel heater circuitry, on my car power comes from the EFI Relay, and is grounded by the ECU.

[AdrianS]

AdrianS as for fuel heater circuitry, on my car power comes from the EFI Relay, and is grounded by the ECU.

The ECU will be grounding it via a transistor of some kind; going to a higher resistance / lower power heater should be fine, but I'd rather not go the other way.
It shouldn't be a problem going universal, as they (bosch ones at least) are available with different heater resistances anyway.

[AdrianS]

For some more technical stuff on oxy sensors, see

http://www.tayloredge.com/reference/...gensensor1.pdf
http://www.tayloredge.com/reference/...gensensor2.pdf
http://www.tayloredge.com/reference/...gensensor3.pdf

[thechuckster]

fwiw: after reading Adrian's post mentioning heater circuits I had a look at some of the wiring diagrams squirrelled away on my Mac - 1G ECU provides switched 12V heater supply, '03 corolla provides an earth, 3SGTE provides switched 12V. I did wonder whether the switched 12V supplies simply run a trace from the B+ supply (coming from EFI main relay) around to the Hx pin.

[cosworthpower]

thanks for all the interest guys, but can someone give me a model make and number to ask at a parts store?

[George]

Can you do vice versa and say what's in stock at your store? I doubt of too many models available.

[BLK_20v]

on a bt20v it comes from the ecu....

[oldcorollas]

either direction, it is easy to set it up to switch a relay for the heater power if you are concerned, so the heater current may not be such a hassle.. but may need to know. (i think i wired mine off fuel pump circuit anyway...)

[wilbo666]

+1, a very useful description! Wilbo, do you have any more of these?

Sorry, missed your post there..,!

There are some more, quite a useful resource!

http://www.autoshop101.com/autoshop15.html

Cheers
Wilbo

[George]

Thank you, great source!