CO/ mixture not adjustable?
Discussion
Hello everybody,
I have an issue with my '85 350i.
Trying to adjust CO at the (flapper-type) AFM I cannot change the value no matter how much I turn the little screw either direction.
It sits at 7, going down slightly when turning anti clockwise only to come back to 7 shortly after that.
Only if I fully close the bypass anything does change: the engine stops.
It runs fine except for fuel consumption (who cares?), but next emissions test might be an issue.
I am lost here.
-recently removed the aftermarket cat -that's why I started.
-recently changed a faulty temp sensor -must have died over the winter break, after changing engine ran fine again.
-(nearly) all ignition related bits were changed last year, it's at 8° at the moment.
-idle is at 880-900rpm, it just does not stall when fans kick in.
Any ideas are greatly appreciated!
Thanks
Henning
I have an issue with my '85 350i.
Trying to adjust CO at the (flapper-type) AFM I cannot change the value no matter how much I turn the little screw either direction.
It sits at 7, going down slightly when turning anti clockwise only to come back to 7 shortly after that.
Only if I fully close the bypass anything does change: the engine stops.
It runs fine except for fuel consumption (who cares?), but next emissions test might be an issue.
I am lost here.
-recently removed the aftermarket cat -that's why I started.
-recently changed a faulty temp sensor -must have died over the winter break, after changing engine ran fine again.
-(nearly) all ignition related bits were changed last year, it's at 8° at the moment.
-idle is at 880-900rpm, it just does not stall when fans kick in.
Any ideas are greatly appreciated!
Thanks
Henning
Thanks for the reply,
it is a 1985 model 350i, so a MKI flapper type with the earlier 14CU injection.
The aftermarket cat was a HJS system with an additional ecu(?)/ black little box. All of this installation was removed. As far as I can see there were bits added only, after having removed these I hope to be back to the original setup now. So no lambda at the moment.
Guesswork is hard for me as I have no mechanics background...
Hearsay so far implies a faulty aux air valve. I was thinking it does give extra air on startup only? So it should close after the engine is at working temp. Or should it be the other way round, as in open during normal operation?
Best regards
Henning
it is a 1985 model 350i, so a MKI flapper type with the earlier 14CU injection.
The aftermarket cat was a HJS system with an additional ecu(?)/ black little box. All of this installation was removed. As far as I can see there were bits added only, after having removed these I hope to be back to the original setup now. So no lambda at the moment.
Guesswork is hard for me as I have no mechanics background...
Hearsay so far implies a faulty aux air valve. I was thinking it does give extra air on startup only? So it should close after the engine is at working temp. Or should it be the other way round, as in open during normal operation?
Best regards
Henning
Hi mate..The AAV closes off once the engine is warmed up...If the CTS (Temperature sensor) is playing up then it will be running in limp mode and will be dumping loads of fuel in..A good indication is if the car starts on the button from cold and then starts to mis-fire or fidget once warmed up..Check the wires inside the connectors by carefully prising back the rubber boot, The wires can become brittle or as in my case get twisted together and short out.
This could account for the over-fuelling...I take it you have a healthy spark from the coil and the right plugs..I use iridium plugs as they are a 6 rating which is in the middle of the two temperature ranges of the two recommended types..BPR 5ES are a bit too hot and can cause pinking..The BPR7ES are too cold and can cause fouling..Hope this helps...Cheers...Ziga
This could account for the over-fuelling...I take it you have a healthy spark from the coil and the right plugs..I use iridium plugs as they are a 6 rating which is in the middle of the two temperature ranges of the two recommended types..BPR 5ES are a bit too hot and can cause pinking..The BPR7ES are too cold and can cause fouling..Hope this helps...Cheers...Ziga
Thanks for the info on the EAV. I will check the wiring on the temp sensor. Although I just changed this very sensor, before that change it died a minute after cold start from way too much fuel.
The cat ECU was taking temp, Ignition, some info off the flapper and lambda, as far as I recall.
It added extra air via two additional vales to adjust the mixture.
I just thought maybe the basic setup with the cat was extra rich so it could be adjusted via extra air through the additional valves of the cat system? How should the cat ECU have been able to adjust towards "richer", if it had only additional air to work with? Am I completely wrong here? Still the question would be how the basic setup was done, there only is the little screw at the flapper, right?
H.
The cat ECU was taking temp, Ignition, some info off the flapper and lambda, as far as I recall.
It added extra air via two additional vales to adjust the mixture.
I just thought maybe the basic setup with the cat was extra rich so it could be adjusted via extra air through the additional valves of the cat system? How should the cat ECU have been able to adjust towards "richer", if it had only additional air to work with? Am I completely wrong here? Still the question would be how the basic setup was done, there only is the little screw at the flapper, right?
H.
I had a similar issue with a Rover Vitesse once.
It was cured by setting up the throttle pot properly by measuring the voltage across two of the wires that go to it and setting it at 0.95Volts across them, I cant remember which colours it was sorry.
Once this was set up I could then make fine adjustments on the metering unit to get it set just so.
I may be talking b
ks for your issue but it worked on mine which was also running very rich.
It was cured by setting up the throttle pot properly by measuring the voltage across two of the wires that go to it and setting it at 0.95Volts across them, I cant remember which colours it was sorry.
Once this was set up I could then make fine adjustments on the metering unit to get it set just so.
I may be talking b
ks for your issue but it worked on mine which was also running very rich.As bobby said a wideband will tell you exactly what is going on, without knowing exactly how the cat closed loop controller worked it's difficult to know what has been done. As the 4cu is pretty limited the external ECU would either have to fiddle with one of the sensor inputs or as you have the extra air vales they may have just raised the baseline pressure to run a rich mixture throughout engines operating range and then used the air valves to put the the mixture back to where it should be.
Is the Fuel Pressure regulator adjustable ?
Is the Fuel Pressure regulator adjustable ?
Hi Henning I am slightly confused because if it's a flapper then it should be a 4CU - please confirm?
I agree with the suggestions above plus offer up:
- if you have removed some kit then maybe you have broken the wiring loom or a connector somewhere and this is causing bad sensor readings and therefore misfuelling?
- have you got access to an oscilloscope? If so put it on the injector lines and you should see very narrow pulses at idle - maybe only 5% duty cycle? It's about time I got a storage scope on mine and posted up some reference traces.
- sometimes the ECU itself goes bad and needs resoldering - take a look at the FAQ articles and follow the ECU thread. It's not a hard job.
- I always start with the coolant temperature sender with this type of problem and make sure you also measure it from the ECU multiplug to make sure it's not the loom either. Note that the senders can fail open at intermediate temperatures so measure across the range from cool to hot.
I will keep an eye on progress because we have a comedian in the UK called Henning and he makes me piss myself laughing - so I feel I owe Hennings everywhere... ;^)
I agree with the suggestions above plus offer up:
- if you have removed some kit then maybe you have broken the wiring loom or a connector somewhere and this is causing bad sensor readings and therefore misfuelling?
- have you got access to an oscilloscope? If so put it on the injector lines and you should see very narrow pulses at idle - maybe only 5% duty cycle? It's about time I got a storage scope on mine and posted up some reference traces.
- sometimes the ECU itself goes bad and needs resoldering - take a look at the FAQ articles and follow the ECU thread. It's not a hard job.
- I always start with the coolant temperature sender with this type of problem and make sure you also measure it from the ECU multiplug to make sure it's not the loom either. Note that the senders can fail open at intermediate temperatures so measure across the range from cool to hot.
I will keep an eye on progress because we have a comedian in the UK called Henning and he makes me piss myself laughing - so I feel I owe Hennings everywhere... ;^)
gruffalo said:
I had a similar issue with a Rover Vitesse once.
It was cured by setting up the throttle pot properly by measuring the voltage across two of the wires that go to it and setting it at 0.95Volts across them, I cant remember which colours it was sorry.
Once this was set up I could then make fine adjustments on the metering unit to get it set just so.
I may be talking bks for your issue but it worked on mine which was also running very rich.
This is another possibility....Also the wires to it can become brittle and break...Normally where they enter the unit.It was cured by setting up the throttle pot properly by measuring the voltage across two of the wires that go to it and setting it at 0.95Volts across them, I cant remember which colours it was sorry.
Once this was set up I could then make fine adjustments on the metering unit to get it set just so.
I may be talking b
ks for your issue but it worked on mine which was also running very rich.Hello again,
Sorry for the long silence. I had no chance to work on the car for a some time. Finally at the weekend I had another go at it:
I wanted to change the injectors for a long time. So finally I took the plenum of and stuck new injectors in.
While I was at it I had another look at the extra air valve. It made odd "click" noises when I shook it, so I replaced it, too.
I had another look at the throttle potentiometer as well. It reads 0,324 now, so I hope it will be fine.
Unfortunately I do not have a gas tester myself so I will have to find a garage to do that measurement again.
The old lambda sensor is still in the car although not connected to anything. I was thinking to use that one.
As it seems there are some differences between them (wideband or not?), so I do not know if this might work.
There are kits with wideband sensors and some gauge to constantly be informed about afr/CO on eBay.
First of all I have no idea if one of these would fit into the thread that is welded to the manifold.
And generally I am just not sure this is what I need. I am not aiming for some very hot turbo installation...
There is a fuel pressure regulator ready for installation, too. For the moment I just do not want to change too many things at a time.
The new coolant temp sensor was measured at the sensor and through the loom, apparently no problem there.
Best news of the weekend is this:
I took apart what felt like half of the car to me -put it back together, no bolts left over, and it ran fine on first try: success!
So I had some quality-time with the wedge -no idea if I did any good to solve the problem, but I enjoyed myself;-)
Best regards
Henning
PS:
Some error corrections:
Yes it is an early flapper type with a 4CU ECU, I was just confusing things.
I adjusted the bypass at the flapper for CO, this caused the readings of around 7.
I adjusted idle at the plenum to 900rpm before that.
What is the full name of the comedian;-)
Sorry for the long silence. I had no chance to work on the car for a some time. Finally at the weekend I had another go at it:
I wanted to change the injectors for a long time. So finally I took the plenum of and stuck new injectors in.
While I was at it I had another look at the extra air valve. It made odd "click" noises when I shook it, so I replaced it, too.
I had another look at the throttle potentiometer as well. It reads 0,324 now, so I hope it will be fine.
Unfortunately I do not have a gas tester myself so I will have to find a garage to do that measurement again.
The old lambda sensor is still in the car although not connected to anything. I was thinking to use that one.
As it seems there are some differences between them (wideband or not?), so I do not know if this might work.
There are kits with wideband sensors and some gauge to constantly be informed about afr/CO on eBay.
First of all I have no idea if one of these would fit into the thread that is welded to the manifold.
And generally I am just not sure this is what I need. I am not aiming for some very hot turbo installation...
There is a fuel pressure regulator ready for installation, too. For the moment I just do not want to change too many things at a time.
The new coolant temp sensor was measured at the sensor and through the loom, apparently no problem there.
Best news of the weekend is this:
I took apart what felt like half of the car to me -put it back together, no bolts left over, and it ran fine on first try: success!
So I had some quality-time with the wedge -no idea if I did any good to solve the problem, but I enjoyed myself;-)
Best regards
Henning
PS:
Some error corrections:
Yes it is an early flapper type with a 4CU ECU, I was just confusing things.
I adjusted the bypass at the flapper for CO, this caused the readings of around 7.
I adjusted idle at the plenum to 900rpm before that.
What is the full name of the comedian;-)
black_350i said:
Best news of the weekend is this:
I took apart what felt like half of the car to me -put it back together, no bolts left over, and it ran fine on first try: success!
So I had some quality-time with the wedge -no idea if I did any good to solve the problem, but I soiled myself;-)
PS:
What is the full name of the comedian;-)
Tommy cooper....."Just like that"...I took apart what felt like half of the car to me -put it back together, no bolts left over, and it ran fine on first try: success!
So I had some quality-time with the wedge -no idea if I did any good to solve the problem, but I soiled myself;-)
PS:
What is the full name of the comedian;-)
black_350i said:
So I had some quality-time with the wedge -no idea if I did any good to solve the problem, but I enjoyed myself;-)
Now you are getting the idea ;^)Yeah I think the lambda that is fitted will be toast by now because they are supposed to be powered at all times when installed and the engine is running.
I have a good idea that the wideband one will be a straight swap in - I have one ready to go in and it's a standard thread (boss already welded in there.) So you could get a secondhand kit for about £100-150 and plug that in, and set it up yourself. It helps if you take a passenger for road testing who can read out/record the gauge, unless you are good with computers, then some of them do data logging so you can record your runs.
100 - 150P sounds similar to 209€ for sets I have seen on fbay: "AEM" "UEGO" afr ratio gauge with a Bosch 4.9 LSU.
This is about the same price as simple measuring equipment for stationary use.
Not too bad, just a little over the top for one-time adjustment.
Oh, not to forget the boy-racer potential: additional gauges -very 80s!;-)
I guess I'll try to set it up stationary at a friend's workshop and think again when installing the adjustable fuel pressure regulator.
Thanks so far, I'll keep you posted about the results.
This is about the same price as simple measuring equipment for stationary use.
Not too bad, just a little over the top for one-time adjustment.
Oh, not to forget the boy-racer potential: additional gauges -very 80s!;-)
I guess I'll try to set it up stationary at a friend's workshop and think again when installing the adjustable fuel pressure regulator.
Thanks so far, I'll keep you posted about the results.
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