 |
|
I tried to cure my air/fuel leaness by swapping out some of the usual suspects, but it’s still in the ‘red’ zone from 2.5-4.7 rpm range.
Clean/flow tested injectors
New AFM
New wires
New plugs
New cap
New rotor
What else is there?
Attached is the graph
Change the DME. It looks like (since you have a new AFM) that the AFM input section of the DME is bad.
I also added a new fuel pressure regulator.
Good tip. I have a total of three ECUs that I have tried and all of them gave me similar results, but this was before I got a new AFM, so I’ll do the ECU dance next time at the dyno.
Any other suspects? Vacuum lines? Fuel pump(s)?
Test the TPS. At ~80% throttle it’s supposed to tell the DME that you are at WOT. The test procedure is in Bentley.
Ranger wrote:
Thank you. I’ll run that test in a few hours.
Do you think there’s any value to doing a leak down test?
Re. a leakdown test. There’s always value in testing things, but the low-mid rpm lean condition isn’t being caused by a compression problem.
Ranger wrote:
The TPS tested to be bad and so did my backup. Luckily, the last one from my other motor passed the test. I’ll button up the rest of the car and hopefully hit the dyno early next week.
Thanks guys!
Where was the A/F being measured? Do you have a bung welded in pre-cat?
A tailpipe sniffer is not accurate enough.
A tailpipe sniffer is definitely accurate enough to measure the problems with his ratio. The true levels might need to be adjusted to more rich if measured in the tailpipe versus the pre-cat bung.
Copied from: http://forums.pelicanparts.com/bmw-5-series-e28-e34-e39/534490-motronic-1-1-1-3-details.html
[Adaptive function
The ECU is adaptive to changing engine operating characteristics and constantly monitors the data from the various sensors (ie MAP, ATS, CTS and TPS). As the engine or its components wear, the ECU reacts to new circumstances by adopting the changed values as a correction to the basic Map. When the adaptive map is used in conjunction with the OS, Motronic is able to respond much more quickly and retain tighter control over the changing gases in the exhaust system. During closed loop operation the basic injection value is determined by the values stored in the map for a specific rpm and load. If the basic injection value causes exhaust emissions outside of the Lambda value (ie 0.98 to 1.04 AFR) the mixture would be too rich or too lean and the OS would signal Motronic which in turn will correct the mixture. However, this response takes a little time and so Motronic learns a correction value and adds this ‘Adaptive’ values to the basic map. From now on, under most operating conditions, the emissions will be very close to Lambda and so, after reference to the OS signal, the ECU will only need to make small corrections to keep it that way. Adaption and correction of the map occurs during the following engine operations.
CFSV operation
ISCV operation
Idle mixture adjustment
part load mixture adjustment]
I wanted to post about giving your ECU time to adapt before but I wanted to find a reference other than that my brother is a BMW tech and he says so. He says that it can sometimes take weeks of daily driving for motronic to make corrections. I can tell you that after installing my battery cutoff this weekend it wouldn’t idle on its own until wednesday. So if you have a thoroughly worn out motor or a .020 over motor it may take some time for motronic to fix itself. Swapping an ECU while your at the dyno could be part of the problem not the solution.
Thanks for that information. Doesn’t the ECU have permanent system memory? I confused on why after installing your cut-off switch, the ECU had to re-learn your car?
turbo329is wrote:
Every time you use the kill switch, the ECU has to relearn? That doesn’t seem right?
this is also from http://forums.pelicanparts.com/bmw-5-series-e28-e34-e39/534490-motronic-1-1-1-3-details.html
Basic ECU operation
A permanent voltage supply is made from the vehicle battery to pin 18 of the ECU. This allows the self-diagnostic function to retain data of an intermittent nature. Once the ignition is switched on, a voltage supply to ECU pin 27 (not 1987 M1.1) and to the ignition coil is made from the ignition switch. This causes the ECU to connect pin 36 to earth, so actuating the main fuel injection relay. A relay switched voltage supply is thus made to ECU pin 37, from terminal 87 of the main fuel injection relay. The 1987 M1.1 system relay is connected to earth and not to the ECU. However, once the ignition is switched on the relay operation is similar to later models.
The majority of sensors (other than those that generate a voltage such the CAS, CID, KS and OS), are now provided with a 5.0 volt reference supply from a relevant pin on the ECU. When the engine is cranked or run, a speed signal from the CAS causes the ECU to earth pin 3 so that the fuel pump will run. Ignition and injection functions are also activated. All actuators (Injectors, ISCV, CFSV etc), are supplied with nbv from the main relay and the ECU completes the circuit by pulsing the relevant actuator wire to earth.
turbo329is wrote:
[quote]this is also from http://forums.pelicanparts.com/bmw-5-series-e28-e34-e39/534490-motronic-1-1-1-3-details.html
Basic ECU operation
A permanent voltage supply is made from the vehicle battery to pin 18 of the ECU. This allows the self-diagnostic function to retain data of an intermittent nature. Once the ignition is switched on, a voltage supply to ECU pin 27 (not 1987 M1.1) and to the ignition coil is made from the ignition switch. This causes the ECU to connect pin 36 to earth, so actuating the main fuel injection relay. A relay switched voltage supply is thus made to ECU pin 37, from terminal 87 of the main fuel injection relay. The 1987 M1.1 system relay is connected to earth and not to the ECU. However, once the ignition is switched on the relay operation is similar to later models.
The majority of sensors (other than those that generate a voltage such the CAS, CID, KS and OS), are now provided with a 5.0 volt reference supply from a relevant pin on the ECU. When the engine is cranked or run, a speed signal from the CAS causes the ECU to earth pin 3 so that the fuel pump will run. Ignition and injection functions are also activated. All actuators (Injectors, ISCV, CFSV etc), are supplied with nbv from the main relay and the ECU completes the circuit by pulsing the relevant actuator wire to earth.[/quote]
So when wiring in a kill switch, you need to run a wire to pin 18 to ensure that the ECU remembers self-diagnostic function? This whole ECU learning feature is very interesting.
I don’t think any of this will matter on the dyno as when you go WOT you enter open loop operation.
The kill switch has to kill all power. Otherwise the car won’t shut down. There’s some old threads here re. kill switches that deal with this. Every time you use your kill switch you set your DME back to factory default.
I have a book on Motronic ignition systems. I’ve studied the(inadequate) chapter that deals with our system at length. What follows is from the book. Whether or not it’s true, I can’t vouch for.
Adaptation impacts the WOT map too, as does coolant (more) and intake temp (less).
Most adaptation takes place in 10min.
Adaptation is pretty limited by the fact that our O2 sensor is narrow band (on/off) vs. wide band (lots of info). IMO the O2 sensor can detect only “ok” and “too lean”. That’s not a helova lot of info.
