Tune Resistor - ECU Mate "Limp No CATS"
Discussion
MPoxon said:
This is what the tune resistor looks like Eddie:
There is a small blue connector in the loom near where the relays are where this connects in.
I will try all the suggestions above later today and report back.
Hello I was looking for the tune resistor under the seat and found this one that was taped to the outside of a wiring harness behind the EAS ECU.There is a small blue connector in the loom near where the relays are where this connects in.
I will try all the suggestions above later today and report back.
It is a resistor but does not have that socket. Instead it goes directly into the harness and is soldered in place. At first I figured this is the tune resistor
but may need to change my mind. The color codes on the resistor tells it is 1 kOhms which does not make sense when comparing to that list of resistor values.
I will check again and see if I find more resistors...
My LSE 4.2 1993 runs Blue tune according to ECU Mate and I will attempt to set Yellow tune (no cats) since the exhaust pipes
have lambda sensors but not cats. From what I have read this can give a slight rich mixture that smells bad.
I picked up some info that the slightly richer mixture is for giving cats something to burn so they get up to temperate. While without the cats
that extra combustion go right into the atmosphere. And that the blue mode would also ignore the AMF sensor CO adjustment.
I will try to check if this changes running a yellow tune.
Edited by gunnarLSE on Thursday 25th April 21:32
Thanks my findings got documented in this thread; http://www.pistonheads.com/gassing/topic.asp?h=0&a...
hi
I have some problems with 3.9 efi v8 range rover classic , manual ,non cat ,14cux AMR 3242 , tune resistor -green, uprated cam, RPI amplifier right now .The problem was that flooding the sparks may now to eliminate the problem with RPI amplifier .
All the sensors are new .
I got a spare ecu to check it AMR3729 14cux 80506A Data code 4594 and i think that i bought it from USA .
When i drive with this ecu AMR3729 with the tune resistor(green) the 4x4 cut the rpm above 3000 and again gives some rpm.
Can you help me?
Can you help me ?
Not enough information here. There is nothing in the ECU that will limit it to 3000 rpm, so this could be anything from a coil / ignition failure, sensor failure, or fuel supply. You need either an ECU mate, or Rovergauge to see what the ECU is doing fuel wise. These diagnostics wont pick up ignition failures, but if you have the original Lucas amp still, try it without the RPI amp, as this unit adds no value to the ignition system whats so ever unless you are running LPG.
You can do some basic ECU testing with a voltmeter:
http://www.g33.co.uk/images/PDFS/14cux_fuel_inject...
You can do some basic ECU testing with a voltmeter:
http://www.g33.co.uk/images/PDFS/14cux_fuel_inject...
ok thank you may the ECU is faulty
more questions
First I saw at the output of the main connector of the Ecu inside a Co - trimmer with value 1.3 V
What is the use ? need to match with maf reading?
second I had inside the wiring of the fuel pump a resistor which i remove it because was broken
can this resistor make the car to run rich ? (fuel pump and regulator are original)
more questions
First I saw at the output of the main connector of the Ecu inside a Co - trimmer with value 1.3 V
What is the use ? need to match with maf reading?
second I had inside the wiring of the fuel pump a resistor which i remove it because was broken
can this resistor make the car to run rich ? (fuel pump and regulator are original)
The most likely point of failure is your AFM- its the one item that has the biggest effect on mixture, and frequently when they fail the output voltage will go too high and this makes the ECU overfuel badly. Likewise a broken connection to the AFM will cause the ECU to go into limp home mode, and the engine will not rev. There is no point in guessing at at faults like this- you need a methodical approach to fault finding with the correct tools. You wont know if the ECU is in limp home mode without an ECUmate or RoverGauge.
The CO trim simply set the idle mixture up to around 2400 rpm. It has nothing to do with the AFM output- that is purely dependant on airflow. If the trim voltage is too high, the idle will be very rich, and too low, it will go lean.
The CO trim simply set the idle mixture up to around 2400 rpm. It has nothing to do with the AFM output- that is purely dependant on airflow. If the trim voltage is too high, the idle will be very rich, and too low, it will go lean.
Edited by blitzracing on Friday 10th March 09:19
Rovergauge is at the top of my list .I did`t know that was a software sorry.
I don't worry about the second ECU from USA . I place right now the previous which i sent it to check it with no false and works fine .
I am going to give some more details about my car and the history of it .
It is a Range rover classic trayback for off road use .I use it 4-5 times a year.
Before 3.9 efi was 3.5 efi no cat .
Right now is 3.9 efi no cat ,no lamda ,uprated cam , green resistor .
always symptoms flooding or burning the spark plug . (I know that the causes may from cam,no lamba or no chip)
I get a new AFM and the garage say to me that is impossible to set up properly too much fuel because there is no lamba . checked fuel pressure ,sensors ,air leaks, cleaned injectors
When I buy the rpi amplifier i try to adjust the AFM alone and try to find a solution .
I saw The AFM reading was 1.9 V (the workshop has changed it when play with the bolt of AFM. They have not too much details about the engine values or software only emission test ) .
I adjust it to 1.5V and check the other reading are ok as ( www.g33.co.uk). it seems that the car smell less . but more heat on headers.
Right now I don't know about the values of CO-trimmer inside the socket of ecu mine read 1.3V is it ok ? This value is for cat with lamba or fixed ?
I don't worry about the second ECU from USA . I place right now the previous which i sent it to check it with no false and works fine .
I am going to give some more details about my car and the history of it .
It is a Range rover classic trayback for off road use .I use it 4-5 times a year.
Before 3.9 efi was 3.5 efi no cat .
Right now is 3.9 efi no cat ,no lamda ,uprated cam , green resistor .
always symptoms flooding or burning the spark plug . (I know that the causes may from cam,no lamba or no chip)
I get a new AFM and the garage say to me that is impossible to set up properly too much fuel because there is no lamba . checked fuel pressure ,sensors ,air leaks, cleaned injectors
When I buy the rpi amplifier i try to adjust the AFM alone and try to find a solution .
I saw The AFM reading was 1.9 V (the workshop has changed it when play with the bolt of AFM. They have not too much details about the engine values or software only emission test ) .
I adjust it to 1.5V and check the other reading are ok as ( www.g33.co.uk). it seems that the car smell less . but more heat on headers.
Right now I don't know about the values of CO-trimmer inside the socket of ecu mine read 1.3V is it ok ? This value is for cat with lamba or fixed ?
Regard the CO trim as you would a mixture screw of a carburetor. It may have a "factory setting" on an unmodified engine, but the mixture could then be wrong if you change the camshaft, so dont get too hung up about it must be 1.3 volts or whatever- you just need to get the mixture right for a smooth idle. Ideally you set this whilst checking the emissions, but you can do it by ear- one way the car will run too rich, and sound like its on choke as it over fuels- the otherway the idle will become lumpy as the mixture becomes too lean, so now just back the adjustment so the idle smooths out and no more. The CO trim is just a variable resistor inside the AFM to set the low speed mixture- it does not affect the AFM electronics at all, so if the AFM electronics is failing, messing around with the CO trim wont fix it. The garage is partially correct about the lack of lambda probes as the ECU cant auto correct the mixture, so if you are running on green tune, the fuel map has to match what your engine needs closely. As you have changed the camshaft, that wont be the same as the fuel map supplied in a standard ECU. Ideally you need someone who can remap the ECU to suit your current engine set up- and don't think by buying a "high performance" chip for your engine will fix it- they are nothing more than best guesswork, you really need a rolling road set up. Having said all that you must get the basics right to start with, and if the AFM is defective , remapping is a waste of time. Start by doing the AFM check found here- the bit about the start spike is very relevant- its about 1/4 of the way down the page:
http://www.g33.co.uk/fuel_injection.htm
There is no big advantage to running without lambda probes and on the green tune, unless you have an engine that shunts at low speed (typically 1700 rpm in higher gears) where you can force the mixture richer to help mask it, but this is really only a problem on high performance cams that will let the engine rev to 6000 rpm plus. The white tune and Lambda probes will produce the same peak power, and will auto correct the mixture below 3400 rpm including the idle mixture, and the CO trim values is ignored. It cant however correct for failing sensors like the AFM.
Just added- the reason why there are two values for the CO trim for cat and non cat maps is misleading. If you run green tune the CO trim alters the mixture directly. On the white tune, the DC CO trim is just a start value that represents a zero long fuel trim value in a memory location inside the ECU to start with, but once the lambda probes warm up this value is overwritten, and never used again as the ECU auto corrects and sets its own long fuel trim. You will see no change in mixture values whatever you do with the CO trim on white tune.
http://www.g33.co.uk/fuel_injection.htm
There is no big advantage to running without lambda probes and on the green tune, unless you have an engine that shunts at low speed (typically 1700 rpm in higher gears) where you can force the mixture richer to help mask it, but this is really only a problem on high performance cams that will let the engine rev to 6000 rpm plus. The white tune and Lambda probes will produce the same peak power, and will auto correct the mixture below 3400 rpm including the idle mixture, and the CO trim values is ignored. It cant however correct for failing sensors like the AFM.
Just added- the reason why there are two values for the CO trim for cat and non cat maps is misleading. If you run green tune the CO trim alters the mixture directly. On the white tune, the DC CO trim is just a start value that represents a zero long fuel trim value in a memory location inside the ECU to start with, but once the lambda probes warm up this value is overwritten, and never used again as the ECU auto corrects and sets its own long fuel trim. You will see no change in mixture values whatever you do with the CO trim on white tune.
Edited by blitzracing on Friday 10th March 14:31
thank you very much for the information
As I said before the Air flow meter is a new unit . The garage if saw first reading on AFM 1.8V played above 1.8 or little lower . and that' why I think running rich at idle .
But i saw on g33.co.uk that the reading will be for a non cat between 0.9 to 1.4-1.5 V and maybe more to match what engine needs closely .
when I change the value from 1.9V to 1.5V i see a better result less rich, smell less but more heat on headers .
Can i use or change the value of the CO trimmer (higher Voltage gives higher CO) which located inside the ECU connector shell? The garage did't know that was a CO trimmer inside the ECU connector shell
I know that most of the times l will have a rich mixture but to try only to not flooding the spark plugs . I am using the car 4-5 times a year most .
Flooding the sparks most of the times at the garage .They need to place another car start the engine getting out and switch off without warm .
I am using the car 4-5 times a year most .
As I said before the Air flow meter is a new unit . The garage if saw first reading on AFM 1.8V played above 1.8 or little lower . and that' why I think running rich at idle .
But i saw on g33.co.uk that the reading will be for a non cat between 0.9 to 1.4-1.5 V and maybe more to match what engine needs closely .
when I change the value from 1.9V to 1.5V i see a better result less rich, smell less but more heat on headers .
Can i use or change the value of the CO trimmer (higher Voltage gives higher CO) which located inside the ECU connector shell? The garage did't know that was a CO trimmer inside the ECU connector shell
I know that most of the times l will have a rich mixture but to try only to not flooding the spark plugs . I am using the car 4-5 times a year most .
Flooding the sparks most of the times at the garage .They need to place another car start the engine getting out and switch off without warm .
I am using the car 4-5 times a year most .
There are two outputs you need to measure- The AFM output at idle- this should be around 1.6 volts at idle on a 3.9 lts engine. If yours is 1.8, then that's too high and why its running rich. The second output is the CO trim that you use to set the mixture- normally around 1.3 to 1.5 volts. The Lucas AFMs are getting impossible to source new now, and there are lots of Chinese copies that look identical, but are nothing but trouble- so check whats been fitted, see if its branded Lucas or not.
I had these reading on AFM ( I think it is a copy i need to check it)
Using a voltmeter between red and black wire and blue and red wire I checked the voltage with the ignition on, but the engine not running
Red/black. Ground - checked ok
Blue/Green Air flow signal- should be .2-.7 volts (no air flow). mine was 0.4
Brown Orange +12v -checked ok
Blue/red CO trim value. Was 1.9 V and i have changed to 1.5 V
Using a voltmeter between red and black wire and blue and red wire I checked the voltage with the ignition on, but the engine not running
Red/black. Ground - checked ok
Blue/Green Air flow signal- should be .2-.7 volts (no air flow). mine was 0.4
Brown Orange +12v -checked ok
Blue/red CO trim value. Was 1.9 V and i have changed to 1.5 V
On green tune You can check engine temp, fuel temp, speed, RPM, Voltage, Throttle pot, AFM voltage, idle status, live fuel map display, fuel pump status, injector pulse width, and stepper motor position.
You cant measure lambda trim- you need white tune for this.
You cant check HT voltages or fuel pressure as they are not checked by the ECU at all
You cant measure lambda trim- you need white tune for this.
You cant check HT voltages or fuel pressure as they are not checked by the ECU at all
Interesting to read this:
http://www.ebay.co.uk/itm/LUCAS-HOT-WIRE-AFM-AIR-F...
I think the Jag used the 5AM without the CO trim pot- otherwise its the same unit. You just need a 5k ohm trim resistor you can solder into the loom for the CO trim on the green map.
http://www.ebay.co.uk/itm/LUCAS-HOT-WIRE-AFM-AIR-F...
I think the Jag used the 5AM without the CO trim pot- otherwise its the same unit. You just need a 5k ohm trim resistor you can solder into the loom for the CO trim on the green map.
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