Jump to content


Photo

Tune Resistors


  • Please log in to reply
7 replies to this topic

#1 streaky

streaky

    Old Hand

  • Settled In
  • PipPipPip
  • 614 posts
  • Location:United Arab Emirates.

Posted 14 January 2008 - 05:52 AM

In an effort to pin point the Disco's appauling fuel consumption I have just imported a TechEdge O2 sensor from Australia.

This along with other emails from various sources is making some noise about different coloured Tune Resistors. WTF is a Tune Resistor? What are the differences between different coloured ones? Are they simply soldered in line? How would I know if I had the correct one fitted?

Any information about these little buggers would be appriciated.

Thanks & regards.

S.

#2 Guest_diesel_jim_*

Guest_diesel_jim_*
  • Guests

Posted 14 January 2008 - 07:59 AM

They just clip into the wiring loom (assuming you're using a 3.9 efi?.... may be the same for 4.0 and 4.6, i don't know)

its just a resistor fitted into a little bullet plug thing. different values "tell" the ECU about the installation of the engine, ie whether it's manual/auto cat/non-cat

See bottom LH of this page...

Posted Image



All the 3.9 EFI test sheets are here

#3 streaky

streaky

    Old Hand

  • Settled In
  • PipPipPip
  • 614 posts
  • Location:United Arab Emirates.

Posted 14 January 2008 - 12:57 PM

Thanks Jim.

Looks like I'll have the change mine then. My current wiring loom is a standard 3.9Efi without cats or lamdar.
The new set-up is 4.6Efi with a chipped ECU and a single Lambdar sensor. The instructions that come with the O2 sensor are making references to the Tune resistor. I wasn't too sure what it did.

Thx.

S.

#4 webbsite

webbsite

    Member

  • Settled In
  • PipPip
  • 58 posts
  • Location:Riyadh, Saudi Arabia.

Posted 14 January 2008 - 01:26 PM

Hi Streaky,

There are 3 governing factors here which all contribute to poor fuel consumption:

1) 4.6 with uprated ECU

2) Cheap fuel in Dubai

3) Knowing your extremely heavy right foot

You have absolutely no chance of getting decent fuel economy

:(
Roger_____________Roger

'88 RR Changed into a Traka
'08 JK Wrangler as daily driver

#5 jwriyadh

jwriyadh

    Member

  • Settled In
  • PipPip
  • 138 posts
  • Location:Boston

Posted 15 January 2008 - 03:06 AM

Heyup lad,
The tune resistor is in the wiring loom just down from the ECU plug, look for a blue two pin connector(sometimes taped into the loom). The colours mentioned are a simple way of differentiating the five different values without using an ohmmeter, ie yellow is 910 ohm, green is 470 ohm, etc.
Your original standard 3.9 system uses a yellow tune resistor. This tells the ECU NOT to use any lambda sensor signals and that you don't have cats. If you use this standard ECU then check the resistor is yellow.
If you use your modified ECU then you need to change the tune resistor to a green one. You will be lucky to find one where you are so get a spare yellow one, cut out the resistor and solder a 470 ohm resistor back in. This value also instructs the ECU to ignore lambda sensors and that you don't have cats.

Although both the above instruct the ECU about cats and lambda sensors the different values also instruct the ECU about which of the five fuel maps to use. ie changing from yellow to green moves you to a different map. In your case the move to the green map is because this is the map Mark Adams has modified.

You cannot run your ECU on one lambda sensor, this would cause massive problems. I suspect the sensor you refer to is the WB one from TechEdge, this does not count because no signals are connected to the ECU.




Roger, that is just cruel........but true. :lol:



jw

#6 streaky

streaky

    Old Hand

  • Settled In
  • PipPipPip
  • 614 posts
  • Location:United Arab Emirates.

Posted 17 January 2008 - 06:28 AM

Cheers JW...I'll revert back to the 3.9 standard ECU for the moment. We've got a whole bunch of exercises & tests to perform down at the shop.
I've shed around 200+ kgs from the truck too..that got my economy down to around the 300km to the tank. I've been "Driving Miss Daisy" for the past few months in an effort to pin-point the problem.
The TechEdge arrived but has a busted socket...they are sending me a replacement from Oz. As you rightly state...I'm only using the WB as a monitor.

Roger...check yer wheel nuts mate!

We're under floods in Dubai right now...2 inches of water in my kitchen has distracted me from getting the truck sorted again.

I'll post updates as and when they arrive.

Thx.

S.

#7 streaky

streaky

    Old Hand

  • Settled In
  • PipPipPip
  • 614 posts
  • Location:United Arab Emirates.

Posted 17 March 2008 - 03:23 PM

I've changed the tune resistor to the green resistor value. So far I haven't been able to see any difference in the fuel consumption.
I calibrated the lambar in free air as it suggusts in the manual.
After some fiddling around I managed to get the WB sensor to read 14.7 on tick over and then when I get moving the LCD display on the LX1 reads below 13.00...which can't be good. This translates to very rich on the bar scale.
I plugged the WB into my lappy and went for a 200km drive...again teh mixture keeps reading rich! According to the colour coded tune resistor I'm on the right map for the 4.6.

Everything I do tends to make the mixture read rich.

Ideas & thoughts?

#8 TomG

TomG

    Old Hand

  • Settled In
  • PipPipPip
  • 400 posts
  • Location:Inverness

Posted 18 March 2008 - 07:36 PM

When the engine is up to temperature and cruising on light throttle e.g. constant 50mph on flat tarmac then the reading from the WB sensor should fluctuate around 14.7 if your ECU is running closed loop using the standard lambda sensors to keep the mixture around 14.7:1

When the engine is under higher load (e.g. accelerating or flat out), the WB sensor will read richer e.g. 12.5 or 13

Overrun / downhill should i think see leaner mixtures or no fuel/fully lean (overrun fuel cut for economy)

Am not too familiar with the Lucas ECU but i think the above is correct tuning for most NA petrol engines.


Wow.. I typed all that without mentioning Megasqu... oops :lol:
Tom - LR 90 4.6V8 MSnS




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users