SandmanEnters
New member
Hey guys
I'd like to hear your opinions on this one. (Might be a long post again):
I have been having a error code problem (0120 - pedal position potentiometer) for a while now. Thought I had gotten to the bottom of it a few times, but it seems to re-appear everytime with the same symptoms a few days later.. Here is the link to the post about this for details: https://www.bmwfanatics.co.za/showthread.php?tid=58270
Continuing from the end of that post, the problem returned a day later. At this point I had also installed my new Racechip Pro 2 (which is flippin awesome btw, but I'll get round to a review on that at a later stage).
I went over to netercol to run diagnostics, at his gracious invitation. He was happy with all my pressure readings, but the pedal reading did indeed deviate between the actual position (driver's wish) and where the Ecu thinks it is. The low pressure fuel pump was on 4.1 bar if I remember correctly, which seemed a little low, but not enough to be overly concerned about. Quite relieved, I proceeded to replace the pedal the next day with one that I got from Bemow Spares.
This immediately solved all issues. Car was running exceptionally well.
Not even two days later the symptoms were back though. :argh: The car had noticeable hesitation, this happened intermittently in multiple driving situations and at random rpm's. The only consistently strong (push-you-back-in-the-seat) pull has been when accelerating past 120km/h in 4th and 5th. I have left the racechip in, as I tested it by removing it and determined it had no the no effect on the symptoms. It simply made the car a lot more driveable.
The engine cut out/brick wall problem still happened at full throttle as well. I have now noticed that the car gets to full throttle (with kickdown switch depressed) without issues, but if any incremental amount of weight gets added onto the pedal when already fully depressed, the fuel supply gets cut off and the rpm's drop to idle speed. Lifting off the throttle a tiny bit then brings the fuel supply (and consequently the engine) back to life, but with a vengeance.
Then yesterday I was pulling away at a robot and the car went into limp mode. I had a mini freak out for a few moments because the last time this happened my gearbox had fused a few gears onto each other. When I calmed down I returned to intense research regarding all (or any) of my symptoms associated with limp mode. At this point I had driven home (about 1.5km) in limp mode and left the car in my garage as I had to get back to work.
I have since then started to genuinely appreciate the immense effort that went into building this engine and how complex it truly is. There are a variety of things that have all been documented on the interwebs that relate to these symptoms in some way or another. I have found these symptoms in posts from the petrol guys who have similar pedal resonse problems with the 528, as well as 330 problems with crankshaft sensors, wheel speed sensors, bad wiring harnesses, minute vacuum pipe splits, lift off pumps and pressure regulators, among others. I started to get that sinking feeling that I will never escape from this pit. (Keep in mind, it did occur to me that the secondhand pedal might also have gone bad, but this seemed highly unlikely, as the chances of one failing are very small. So both failing seemed a bit of a stretch.)
I then decided to clean the MAF again, as its involvement in limp mode seems popular. No signs of dirt/filth were apparent when I had a proper look at the sensor itself, but sprayed it down with MAF cleaner anyway. I also cleaned the plug connectors of the pressure regulator sensor, cam sensor, and the one on the MAF itself. Put everything back and started her up. Limp mode was now gone. I didn't put too much stock in this, as the battery had been disconnected as well, which could simply have reset the ecu out of limp mode.
On my hunch about the low pressure pump being a bit too low, I got a new one and installed it. I did this a few months back for the first time, but I got a proper one this time, as previous one was the cheaper version of the two. New one runs much quieter than the cheapy, and the car did drive and idle a bit better. (The overall driving experience at this stage was not at all terrible, most people I know would have been happy - I was not.) All the symptoms were still present. The hesitation seemed to be less obvious when driving in Sport mode and especially if I reset the pedal adaptation before driving off. To feel an improvement, I had to do the reset every second or third time I started the car though. (Procedure: key on pos. 2, engine off -> kickdown switch depressed for 10sec -> foot off pedal -> key back to pos. 0 -> start engine)
I went for a drive earlier tonight to open her up a bit, and once again i chose a stupid time off day for this. Traffic on the R28. In the opposite direction the highway was much clearer, so I turned back. As I was nailing it a bit on the on-ramp onto the highway, the car shifted very hard from 3rd to 4th - almost felt like I had hit something. I massive cloud of black smoke shot out of the exhaust at the same moment as the hard shift. Immediately thereafter: THE CAR WAS ABSOLUTELY BRILLIANT???
The pedal was softer and immensely more responsive, the gearshifts were completely smooth, and the power was REDONCOULOUS. I had to stop myself from driving 180km/h every few seconds - it seems I have gotten used to much more depressed pedal at highway speeds than is normal.
I proceeded to test the engine cut off problem. Instead of cutting off, the engine just did a little shudder and promptly went on with it's business. Tried this a few times, but only got the shudder.
Another thing that has never happened before while driving in sport: If I lifted my foot from the pedal to decelerate without braking, the car shifted down from 5th to 4th if the rpm's got a bit low. I assume this is the way it is supposed to be, but usually the car stayed in 5th if I did this.
Basically the car was an absolute pleasure to drive, and a monster when applying foot.
I do not know what to make of this, maybe a carbon deposit stuck somewhere important that burned off? I thought you chaps might have something to say, or at the very least find it interesting reading.
I am very happy right now, but past behavior indicates that it wont last. Should I just leave everything alone for the moment and see what happens?
Thank you for your time, as always comments are welcomed and advice is appreciated.
Cheers
I'd like to hear your opinions on this one. (Might be a long post again):
I have been having a error code problem (0120 - pedal position potentiometer) for a while now. Thought I had gotten to the bottom of it a few times, but it seems to re-appear everytime with the same symptoms a few days later.. Here is the link to the post about this for details: https://www.bmwfanatics.co.za/showthread.php?tid=58270
Continuing from the end of that post, the problem returned a day later. At this point I had also installed my new Racechip Pro 2 (which is flippin awesome btw, but I'll get round to a review on that at a later stage).
I went over to netercol to run diagnostics, at his gracious invitation. He was happy with all my pressure readings, but the pedal reading did indeed deviate between the actual position (driver's wish) and where the Ecu thinks it is. The low pressure fuel pump was on 4.1 bar if I remember correctly, which seemed a little low, but not enough to be overly concerned about. Quite relieved, I proceeded to replace the pedal the next day with one that I got from Bemow Spares.
This immediately solved all issues. Car was running exceptionally well.
Not even two days later the symptoms were back though. :argh: The car had noticeable hesitation, this happened intermittently in multiple driving situations and at random rpm's. The only consistently strong (push-you-back-in-the-seat) pull has been when accelerating past 120km/h in 4th and 5th. I have left the racechip in, as I tested it by removing it and determined it had no the no effect on the symptoms. It simply made the car a lot more driveable.
The engine cut out/brick wall problem still happened at full throttle as well. I have now noticed that the car gets to full throttle (with kickdown switch depressed) without issues, but if any incremental amount of weight gets added onto the pedal when already fully depressed, the fuel supply gets cut off and the rpm's drop to idle speed. Lifting off the throttle a tiny bit then brings the fuel supply (and consequently the engine) back to life, but with a vengeance.
Then yesterday I was pulling away at a robot and the car went into limp mode. I had a mini freak out for a few moments because the last time this happened my gearbox had fused a few gears onto each other. When I calmed down I returned to intense research regarding all (or any) of my symptoms associated with limp mode. At this point I had driven home (about 1.5km) in limp mode and left the car in my garage as I had to get back to work.
I have since then started to genuinely appreciate the immense effort that went into building this engine and how complex it truly is. There are a variety of things that have all been documented on the interwebs that relate to these symptoms in some way or another. I have found these symptoms in posts from the petrol guys who have similar pedal resonse problems with the 528, as well as 330 problems with crankshaft sensors, wheel speed sensors, bad wiring harnesses, minute vacuum pipe splits, lift off pumps and pressure regulators, among others. I started to get that sinking feeling that I will never escape from this pit. (Keep in mind, it did occur to me that the secondhand pedal might also have gone bad, but this seemed highly unlikely, as the chances of one failing are very small. So both failing seemed a bit of a stretch.)
I then decided to clean the MAF again, as its involvement in limp mode seems popular. No signs of dirt/filth were apparent when I had a proper look at the sensor itself, but sprayed it down with MAF cleaner anyway. I also cleaned the plug connectors of the pressure regulator sensor, cam sensor, and the one on the MAF itself. Put everything back and started her up. Limp mode was now gone. I didn't put too much stock in this, as the battery had been disconnected as well, which could simply have reset the ecu out of limp mode.
On my hunch about the low pressure pump being a bit too low, I got a new one and installed it. I did this a few months back for the first time, but I got a proper one this time, as previous one was the cheaper version of the two. New one runs much quieter than the cheapy, and the car did drive and idle a bit better. (The overall driving experience at this stage was not at all terrible, most people I know would have been happy - I was not.) All the symptoms were still present. The hesitation seemed to be less obvious when driving in Sport mode and especially if I reset the pedal adaptation before driving off. To feel an improvement, I had to do the reset every second or third time I started the car though. (Procedure: key on pos. 2, engine off -> kickdown switch depressed for 10sec -> foot off pedal -> key back to pos. 0 -> start engine)
I went for a drive earlier tonight to open her up a bit, and once again i chose a stupid time off day for this. Traffic on the R28. In the opposite direction the highway was much clearer, so I turned back. As I was nailing it a bit on the on-ramp onto the highway, the car shifted very hard from 3rd to 4th - almost felt like I had hit something. I massive cloud of black smoke shot out of the exhaust at the same moment as the hard shift. Immediately thereafter: THE CAR WAS ABSOLUTELY BRILLIANT???
The pedal was softer and immensely more responsive, the gearshifts were completely smooth, and the power was REDONCOULOUS. I had to stop myself from driving 180km/h every few seconds - it seems I have gotten used to much more depressed pedal at highway speeds than is normal.
I proceeded to test the engine cut off problem. Instead of cutting off, the engine just did a little shudder and promptly went on with it's business. Tried this a few times, but only got the shudder.
Another thing that has never happened before while driving in sport: If I lifted my foot from the pedal to decelerate without braking, the car shifted down from 5th to 4th if the rpm's got a bit low. I assume this is the way it is supposed to be, but usually the car stayed in 5th if I did this.
Basically the car was an absolute pleasure to drive, and a monster when applying foot.
I do not know what to make of this, maybe a carbon deposit stuck somewhere important that burned off? I thought you chaps might have something to say, or at the very least find it interesting reading.
I am very happy right now, but past behavior indicates that it wont last. Should I just leave everything alone for the moment and see what happens?
Thank you for your time, as always comments are welcomed and advice is appreciated.
Cheers
raise:
