AC Air Valve correct function ?
You said the O2 was good, do you mean a new sensor or the measured output is correct and dithering? There's a difference.
Mike W.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
I measured it with a volt meter and it jumps around the .5 volts like it's supposed to... .275-.750. Is that too much of a swing maybe?
What about that aux air valve, I have checked it out but I still suspect it is not right. I have pulled it off before and inspected the opening cold and it seems like it should be bigger (only like a 1/4-1/3 open), does that sound right? It closes all the way though when warm.
Thanks Mike
What about that aux air valve, I have checked it out but I still suspect it is not right. I have pulled it off before and inspected the opening cold and it seems like it should be bigger (only like a 1/4-1/3 open), does that sound right? It closes all the way though when warm.
Thanks Mike
'81 528i... mfg date 10/80...owned since 1990
If I may...
Just a suggestion here, but you have to go all the way back to square one, bone stock, as Mike said. That means - dead cold valve adjustment, I like .012", gives good running performance with a steady idle. You have to go from there, and inspect every aspect regarding fuel and ignition. I had a buck off-idle condition that turned out to be faulty HT wires that were only two years old. Timing -2200deg. BTDC, vacuum advance pulled from the dist. and line to the intake PLUGGED. Vacuum advance operational and smooth. Correct plugs and gap. Cap and rotor. These are the basics, from there leads to component parts like the ICU, known to have infrequent issues, and ECU but they rarely fail. Frustrating at times, yes, but methodical is the only way. Compounded by the fact that somebody else 'did something' to correct a condition that only masks the problem or worse.
AAV sounds correct, freezer cold, (0deg. F) should be 1/4 to 1/2 open. Too much open imparts another problem with idle as the engine is warming and the valve is closing. Look up old posts regarding this. Operating temp. should be fully closed.
O2 sensor readings look good, too. I'll go back to one of your original posts to say you noticed a pickup in engine performance when the WOT switch is engaged. That means the engine is happily wanting to process the extra fuel and not at the expense of poorer running, indicating there is too much air.
I will take another WAG regarding your findings so far to say you still have an air leak, a sneaky, hidden one like o-ring failure around either the AFM CO adjustment screw or the same o-ring on the main idle adjustment screw (top of manifold) or something like that. Careful spraying of ether on suspected points of air entry will pinpoint them, but you have to learn where air can enter to know where to spray. There are many. Valve cover elbow breather hose comes to mind.
Hang in there...
Just a suggestion here, but you have to go all the way back to square one, bone stock, as Mike said. That means - dead cold valve adjustment, I like .012", gives good running performance with a steady idle. You have to go from there, and inspect every aspect regarding fuel and ignition. I had a buck off-idle condition that turned out to be faulty HT wires that were only two years old. Timing -2200deg. BTDC, vacuum advance pulled from the dist. and line to the intake PLUGGED. Vacuum advance operational and smooth. Correct plugs and gap. Cap and rotor. These are the basics, from there leads to component parts like the ICU, known to have infrequent issues, and ECU but they rarely fail. Frustrating at times, yes, but methodical is the only way. Compounded by the fact that somebody else 'did something' to correct a condition that only masks the problem or worse.
AAV sounds correct, freezer cold, (0deg. F) should be 1/4 to 1/2 open. Too much open imparts another problem with idle as the engine is warming and the valve is closing. Look up old posts regarding this. Operating temp. should be fully closed.
O2 sensor readings look good, too. I'll go back to one of your original posts to say you noticed a pickup in engine performance when the WOT switch is engaged. That means the engine is happily wanting to process the extra fuel and not at the expense of poorer running, indicating there is too much air.
I will take another WAG regarding your findings so far to say you still have an air leak, a sneaky, hidden one like o-ring failure around either the AFM CO adjustment screw or the same o-ring on the main idle adjustment screw (top of manifold) or something like that. Careful spraying of ether on suspected points of air entry will pinpoint them, but you have to learn where air can enter to know where to spray. There are many. Valve cover elbow breather hose comes to mind.
Hang in there...
HTH
'80 528i
'80 528i
Thanks for coming back in to help Lenny. I have gone through all of your suggestions with the exception of the valve adjustments and the HT wires.
Even though I have tested them I may try the wires 1st since they have about 20K miles on them and are 4 yrs old and see if that helps
Will report back.
Even though I have tested them I may try the wires 1st since they have about 20K miles on them and are 4 yrs old and see if that helps
Will report back.
'81 528i... mfg date 10/80...owned since 1990
I decided to try another vacuum test with some carb cleaner and did find a point where the rpm"s increased. It was at the throttle switch shaft. it would only happen when you spray directly at the throttle shaft..not from a 90 degree angle. Is this normal or should I take apart the throttle switch and search a bad gasket ring/spacer as in the OEM diagram #26 & 27?
http://www.realoem.com/bmw/showparts.do ... g=13&fg=05
The throttle switch diagram doesn't show the shaft and any gaskets or o'rings.
http://www.realoem.com/bmw/showparts.do ... g=13&fg=05
The throttle switch diagram doesn't show the shaft and any gaskets or o'rings.
'81 528i... mfg date 10/80...owned since 1990
I would have to verify beyond mistake that that is the source. It is precariously close to the throttle screw. You have to pinpoint the exact location of false air. I've attached a pic from the Bosch Fuel Injection & Management book showing points of false air entry. It covers a wider variety if injection systems than just L-jet but the object is the same. Anyplace where air can enter past the AFM is suspect.
I've never delved into the throttle shaft and associated bushings, but if this is where your air leak actually is, I might suspect looking for another throttle body assembly to replace would be less work. I also suspect the Lambda 'window of operation' would correct slight instances of system degradation to accommodate for this. I have also not read about the throttle shaft being problematic, that's not to say anything is possible.
I've never delved into the throttle shaft and associated bushings, but if this is where your air leak actually is, I might suspect looking for another throttle body assembly to replace would be less work. I also suspect the Lambda 'window of operation' would correct slight instances of system degradation to accommodate for this. I have also not read about the throttle shaft being problematic, that's not to say anything is possible.
HTH
'80 528i
'80 528i
I decided to dismantle the throttle switch assembly yesterday and was a bit of a pita with all the small screws/nuts, lucky I remembered to put a rag under it all to catch what I drop. I managed to get to behind the shaft circlip and washer where there is a plastic bushing. It looked a little worn but has been pressed fir in there for all this time that when I poked it out I must have sliced it with the small screwdriver I was using. Anyway I just rigged another one in there with a plastic cap I had in my "extra parts bin".
Put it all back together and no improvement. Don't think that is/was the leak point of entry. Must be around it though so I will check the points in this diagram that you sent Lenny, and see if I can pinpoint.
Thanks!
Put it all back together and no improvement. Don't think that is/was the leak point of entry. Must be around it though so I will check the points in this diagram that you sent Lenny, and see if I can pinpoint.
Thanks!
'81 528i... mfg date 10/80...owned since 1990