Discussion
I have plugged in RG the other day as I had been out for a day long drive and during the drvie the car became quite lumpy and had problems coming to idle as I pulled up at a junction.
It wasn't all the time but there was a point in the drive when it was quite noticeable but it by the end of the day it seemed to be back to normal.
I found a number of fault codes logged but I was unsure how long they had been there. I cleared them and restarted the car and let it idle until it got up to temperature and none of the fault codes was relogged. I cleaned the stepper motor as a precaution.
Took the car out for a drive at the weekend and it seemed to be running fine apart from the very occaisional stall as I pulled up to a junction. When the car stalls it restarts firt time on the key and usually it will idle quite happily.
I plugged in RG when I got home just to see if anything had been logged and faults were logged for both lambda sensors (no toher faults). I also noticed that the long term trim was 0 but both short term trims were +100, this after being out for several hours driving.
I need to test the lambdas but find it strange that they are both throwing a fault.
I ran that test that Mark has recommended and saw the AFM voltage jump up to .44 and then slowly decline to .35v which I believe is an indication that it is faulty. Could that cause the 2 lambda faults I'm getting?
Assuming it is faulty - where is the best place to get a replacement AFM?
A couple of screen shots from today after running the car up to temperature at idle. MAF reading seems fine in these examples from what I have read. The car died at idle a couple of times but restarted without issue and apart from when it died seemed to be stable.
Long term trim
Short term trim
It wasn't all the time but there was a point in the drive when it was quite noticeable but it by the end of the day it seemed to be back to normal.
I found a number of fault codes logged but I was unsure how long they had been there. I cleared them and restarted the car and let it idle until it got up to temperature and none of the fault codes was relogged. I cleaned the stepper motor as a precaution.
Took the car out for a drive at the weekend and it seemed to be running fine apart from the very occaisional stall as I pulled up to a junction. When the car stalls it restarts firt time on the key and usually it will idle quite happily.
I plugged in RG when I got home just to see if anything had been logged and faults were logged for both lambda sensors (no toher faults). I also noticed that the long term trim was 0 but both short term trims were +100, this after being out for several hours driving.
I need to test the lambdas but find it strange that they are both throwing a fault.
I ran that test that Mark has recommended and saw the AFM voltage jump up to .44 and then slowly decline to .35v which I believe is an indication that it is faulty. Could that cause the 2 lambda faults I'm getting?
Assuming it is faulty - where is the best place to get a replacement AFM?
A couple of screen shots from today after running the car up to temperature at idle. MAF reading seems fine in these examples from what I have read. The car died at idle a couple of times but restarted without issue and apart from when it died seemed to be stable.
Long term trim
Short term trim
The fact that both probes are "adding fuel" says you have 0 volts from the probes and the common point here is heater supply, unless you have killed both probes with zinc oil or silicone gasket or spray somewhere. When the AFM fails it tends to over fuel and the probes would remove fuel. Having said that, this is the correct start up spike on the AFM, its all done and dusted within 2 seconds- the uplift on the graph is the engine starting and idle voltage.
As your long term does not appear to be set, have you got the engine hot and let it idle for about 3 mins to set the long term? Have you unplugged the ECU recently to cause it to loose the long term trim? The lambda faults are thrown if the ECU cant get the probes to switch having reached its maximum long term trim.Trouble shooting lambda codes here:
http://www.g33.co.uk/img/fuel/14cux-fault-finding....
As your long term does not appear to be set, have you got the engine hot and let it idle for about 3 mins to set the long term? Have you unplugged the ECU recently to cause it to loose the long term trim? The lambda faults are thrown if the ECU cant get the probes to switch having reached its maximum long term trim.Trouble shooting lambda codes here:
http://www.g33.co.uk/img/fuel/14cux-fault-finding....
Edited by blitzracing on Monday 27th July 17:21
blitzracing said:
The fact that both probes are "adding fuel" says you have 0 volts from the probes and the common point here is heater supply, unless you have killed both probes with zinc oil or silicone gasket or spray somewhere. When the AFM fails it tends to over fuel and the probes would remove fuel. Having said that, this is the correct start up spike on the AFM, its all done and dusted within 2 seconds- the uplift on the graph is the engine starting and idle voltage.
As your long term does not appear to be set, have you got the engine hot and let it idle for about 3 mins to set the long term? Have you unplugged the ECU recently to cause it to loose the long term trim? The lambda faults are thrown if the ECU cant get the probes to switch having reached its maximum long term trim.Trouble shooting lambda codes here:
http://www.g33.co.uk/img/fuel/14cux-fault-finding....
I don't know why there is no long term trim. The ECU has not been unplugged nor has the battery been disconnected recently. The engine was idling for over 10 minutes today while it was hot, before I took those screen shots and the car was driven for a couple of hours yesterday.As your long term does not appear to be set, have you got the engine hot and let it idle for about 3 mins to set the long term? Have you unplugged the ECU recently to cause it to loose the long term trim? The lambda faults are thrown if the ECU cant get the probes to switch having reached its maximum long term trim.Trouble shooting lambda codes here:
http://www.g33.co.uk/img/fuel/14cux-fault-finding....
Edited by blitzracing on Monday 27th July 17:21
I'll check the lambdas are getting 12v and check the resistance of the heater coils, I don't have access to an oscilliscope so checking the switching is going to be tricky.
Had a bit of a check around and the 12v supply to the lambdas was broken.
Earth wire cnnection was good and the resistance on the heater coils seemed reasonable (can't remember what it was exactly but it was around the figure quoted in the Rover ECU manual I have.
The feed comes from the central pin on the fuel pump relay, and there was a bad connection happening there. Fixed that and then tested I was getting 12v at the barrel connector in the engine bay.
Once I fixed I can see the lamdas short term trim cycling around zero on both sides. I've let it idle for a while and a long term trim has been set for one bank but not the other (or it is set at zero?). The short term trim seems to by cycling up and down so I think the lambda is working correctly. Will need to take it for a run out and see if aany codes are set.
Short Term
LongTerm
Earth wire cnnection was good and the resistance on the heater coils seemed reasonable (can't remember what it was exactly but it was around the figure quoted in the Rover ECU manual I have.
The feed comes from the central pin on the fuel pump relay, and there was a bad connection happening there. Fixed that and then tested I was getting 12v at the barrel connector in the engine bay.
Once I fixed I can see the lamdas short term trim cycling around zero on both sides. I've let it idle for a while and a long term trim has been set for one bank but not the other (or it is set at zero?). The short term trim seems to by cycling up and down so I think the lambda is working correctly. Will need to take it for a run out and see if aany codes are set.
Short Term
LongTerm
Edited by Colin RedGriff on Saturday 1st August 18:04
It is possible the long term trim is simply spot on for that bank, so still at 0. If the short term cycles evenly around it's center point, the long term wont move. It is visible at idle if the short trim is cycling around one side, you will see the long term slowly move untill the short term cycles around the central point.
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