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Old 08-04-2019, 06:48 PM
dkuchan dkuchan is offline
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Location: Michigan
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Update: I still have issues with this...I actually broke down and paid my local import shop to diagnose and they came up empty-handed. After talking to them it seemed like they had no idea what they were talking about so I don't have a lot of faith in anything they told me. They said they smoke-tested it and there were no vacuum leaks. Tested the MAF and it tested good (I ended up replacing it anyway and it didn't help). They re-taught Vanos system (not sure what that entailed).

Anyway, I have also since replaced the spark plugs, Vanos solenoids (OEM), and the IVM. Spark plugs didn't seem to do much, but they needed to be done anyway. The IVM however seemed to help quite a bit (at first). My shifting problem appeared to be gone, but my throttle and idle issues were still there. I also regained a decent amount of power. The shifting problem has returned, but at least now I feel confident that it is related to my other problem(s) and not a mechanical issue with the trans or valve body. My power still seems better so I think the IVM did help solve something (just not what I was chasing). My shifting problem being better after changing the IVM seems to be related to simply unhooking the battery for a half hour or so (planning on testing this theory, but haven't had time yet). I have a subwoofer box in the back and stuff so it takes a bit of time to get in there to unhook the battery. Maybe there's a better way than digging in there?

I have also learned another thing in this process...When I start the car cold (ambient/overnight/70F-type conditions) and immediately take off I get the throttle issues. If I wait about a minute and half the idle will stumble and surge for a few seconds at about that time and then it will level out. If I take off after that happens I don't seem to have the throttle issues. Also, if I do take off right away cold and am experience the issues I can pull over and shut the car off and turn it back on immediately turn it back on and the throttle issue is gone. The 1.5 min waiting period hasn't failed me yet so I think there's something to this, but I have to say that's it's more related to engine temp than time because if it sits for an hour or so the time will be cut down to say 30s instead 1:30.

My new question is, is there something that happens that you guys can think of related to engine temp that can cause this? Emissions control or something?

Also, that import shop told me that the throttle body works in unison with the variable valve lift. That doesn't make a ton of sense to me because it seems like there would be no point to variable valve lift if it worked that way, but maybe I'm wrong. If it's true, could this be an issue with my throttle body? I've cleaned it up a bit, but didn't remove it or take it apart. Just cleaned what I could get at. I thought I read that the throttle body is just a fail safe and in normal conditions it is wide open when the engine is running. Does the throttle body maybe work in unison for that first period when I start the car until it gets to a certain temp? If so, it might be my issue and it might be what the import shop was talking about (even though they claimed it worked like that continuously because I asked this question...I first received the glossy-eyes looked when I asked which is why they didn't seem credible).

Let me know what you guys think because I'm about to drop it off at BMW to pay diagnostics, but I really don't want to do that because it's 40 minutes away and I don't have a spare car or anybody that can help me get to and fro.

Thanks
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