Discussion
I run an air / fuel ratio gauge in my M3 and the usual reading is around the 14.4 to 14.8 range. On lift off (if lifting off whilst approaching a corner, whilst going down hill) the gauge usually reads LEAN, which as the throttle is then closed, I assume is correct. Recently however, I note the gauge no longer changes the display on lifting off the throttle pedal. I've scrolled through the functions on the gauge, but it still just reads the usual AF ratio. (I hope I've explained this clearly enough?)
The wideband lamda AFR gauge in question is a Tech Edge LA1.
Please excuse the lack of knowledge my end. This is the first car I've owned with such a gauge and I generally just use it to make sure the mixture remains in what I am told, is the safe range.
Does the failing to show as LEAN on overrun point to a fault with the lambda sensor, or am I worrying over nothing? It just seems odd, that it simply stopped displaying this.
Thanks in advance.
The wideband lamda AFR gauge in question is a Tech Edge LA1.
Please excuse the lack of knowledge my end. This is the first car I've owned with such a gauge and I generally just use it to make sure the mixture remains in what I am told, is the safe range.
Does the failing to show as LEAN on overrun point to a fault with the lambda sensor, or am I worrying over nothing? It just seems odd, that it simply stopped displaying this.
Thanks in advance.
Sounds as though the engine's over-run fuel cutoff system is no longer working and the cylinders are still being fueled even with completely shut throttle. Normally fuel is cut off completely above about 1800 rpm when the throttle closes to save fuel and that's why you used to get an off scale lean reading on the AFR gauge. Now apparently it's being fueled at stoichiometric all the time even with throttle shut. That could point to a fault in the TPS or some sort of on/off switch which registers closed throttle.
Steve - the gauge stays at the usual range of 14.4 to 14.8, which I was told was about the correct level "on throttle" ?
I'll look into the potential for a TPS issue. I know next to nothing about Alpha N but have a few places to mail for advice. There has been a slight hesitation issue recently, which was mostly sorted by replacing parts on the ignition side, but could also suggest the TPS was deteriorating. Could a fault with the lambda sensor cause the same issues?
Thanks in advance.
I'll look into the potential for a TPS issue. I know next to nothing about Alpha N but have a few places to mail for advice. There has been a slight hesitation issue recently, which was mostly sorted by replacing parts on the ignition side, but could also suggest the TPS was deteriorating. Could a fault with the lambda sensor cause the same issues?
Thanks in advance.
On the the TPS there is a closed throttle switch. If you go to MAXX Automotive web site you can download the software and chech operation with a laptop.
Register at www.s14power.com forum for advice from lots of MAXX A/N users.
Register at www.s14power.com forum for advice from lots of MAXX A/N users.
Thanks Steve. I've just been reading the instruction PDF from Maxx and I'm thinking the TPS or the wiring was disturbed recently, when the exhaust manifold studs and cam cover gaskets were replaced?
I feel like I'm on the correct path towards sorting this now anyway. I'll let you know how I get on.
I feel like I'm on the correct path towards sorting this now anyway. I'll let you know how I get on.
Put a meter on the TPS yesterday and got a reading but am I right in thinking it acts as a potentiometer in this application?
I've been trying to source a new one, but neither BMW or Bosch have stock. It could be a month minimum, so still searching or else it'll be an overseas supplier.
After messing with it yesterday, it cured itself briefly but issue soon returned.
I'm at Santa Pod today so long shot, might find a used one as a temp' fix?
I've been trying to source a new one, but neither BMW or Bosch have stock. It could be a month minimum, so still searching or else it'll be an overseas supplier.
After messing with it yesterday, it cured itself briefly but issue soon returned.
I'm at Santa Pod today so long shot, might find a used one as a temp' fix?
Just test the pot. If it's reading the correct voltage at closed, reads smoothly throughout the travel of the throttle with no dropouts etc then I wouldnt worry.
As someone else mentioned there may also be a closed switch with the TPS, depends how many wires it has.
But really, if the only time you're seeing something you dont quite like is when your foot is not on the throttle.....stop worrying about it.
As someone else mentioned there may also be a closed switch with the TPS, depends how many wires it has.
But really, if the only time you're seeing something you dont quite like is when your foot is not on the throttle.....stop worrying about it.
"Heat" means it has applied voltage to the sensor heater circuit and is waiting for it to come up to temperature. Should be no more than a few seconds.
The LA1 connects to a WBO2 controller like a techedge 2J1 or similar and that connects to the sensor so likely problems are the controller or sensor and the sensor is cheaper. I have had very few failures on the Techedge controllers.
During normal running there should be quite a wide variation in the reading of the LA1 from 12:1 (ish) during acceleration down to 15:1 or leaner during over run. When the sensor fails the Techedge controller units assert a fixed output reading of 14.7:1 rather than either full rich or full lean which might make the EMS massively over compensate and leave you with a flooded engine or holed pistons.
Sensor or controller seems more likely than a TPS problem to me.
The LA1 connects to a WBO2 controller like a techedge 2J1 or similar and that connects to the sensor so likely problems are the controller or sensor and the sensor is cheaper. I have had very few failures on the Techedge controllers.
During normal running there should be quite a wide variation in the reading of the LA1 from 12:1 (ish) during acceleration down to 15:1 or leaner during over run. When the sensor fails the Techedge controller units assert a fixed output reading of 14.7:1 rather than either full rich or full lean which might make the EMS massively over compensate and leave you with a flooded engine or holed pistons.
Sensor or controller seems more likely than a TPS problem to me.
Thank you to all who've responded. I really appreciate all your help as till now, my usual cars have nothing more complicated than points!
Anyway, there should be a new sensor awaiting collection shortly and I bought a TPS as one presented itself. At least I'll then know when these parts were replaced, instead of having to hazard a guess. I'll let you know how I get on, once I've fitted them.
Anyway, there should be a new sensor awaiting collection shortly and I bought a TPS as one presented itself. At least I'll then know when these parts were replaced, instead of having to hazard a guess. I'll let you know how I get on, once I've fitted them.
I had a google and found the 0 280 120 402 has a WOT switch and a Closed throttle switch.
My guess is that the closed throttle switch is not closing. Can you see the closed throttle switch activatein the software?
When googling I found
Pin 1-black wire-5volt in
Pin 2-shielded wire-ground
Pin 3-yellow wire-signal out
Pin 4-ground
Pin 5-WOT switch
Pin 6-Closed switch
So on closed throttle pin 1&6 should have continuity. If not, you can slacken the two screws securing the TPS and rotate the TPS until you get continuity. You may need to re scale the TPS in the software, which you will have to do if you replace the TPS.
My guess is that the closed throttle switch is not closing. Can you see the closed throttle switch activatein the software?
When googling I found
Pin 1-black wire-5volt in
Pin 2-shielded wire-ground
Pin 3-yellow wire-signal out
Pin 4-ground
Pin 5-WOT switch
Pin 6-Closed switch
So on closed throttle pin 1&6 should have continuity. If not, you can slacken the two screws securing the TPS and rotate the TPS until you get continuity. You may need to re scale the TPS in the software, which you will have to do if you replace the TPS.
e21Mark said:
Thanks. I think I'm going to replace the TPS as a matter of course anyway, as it's a few years old now.
Pointless and a waste of money if it's not actually faulty. If there's a closed throttle switch in the system that's what will be causing the problem and is probably just a matter of adjusting its position relative to the butterflies until it triggers when the throttle is shut.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff