N52 Electronic Throttle Hang

[Kgolf31]

So I've always been questioning this issue, or to better phrase it occurrence with the car and never got a straight answer. Perhaps someone can help me further

There is a throttle hang with the car, when you get off the throttle completely (aka your foot off the gas) there is still throttle being applied to the car.

Some people say it's for emissions, but whatever it is it's not conducive for track or autocross.

Here is a video trying to show it. Watch as I go off the throttle for a long time (the turn around at the end and after the finish) how my throttle percentage goes to about 13% and slowly decreases. So, when I'm completely off the throttle, it's still being applied which is not good.

Anyone think we can find a fix?

[jvb6806]

I was actually talking about this with a guy last weekend after he drove my car. The NOx and SOx gas emissions are highest on high RPM High Vacuum conditions (or snap the throttle plate closed) so BMW brings the throttle by wire back down slower than we would like when you lift. I have had it to the point of reving up after when I put the brake and clutch in a stop box.

I would imagine this could be taken out through a tune. Might be worth a call to AA.

[MightyMouseTech]

My Civic had the same thing. Was incredibly annoying. A tune fixed it right up.

[Kgolf31]

Originally Posted by jvb6806

I was actually talking about this with a guy last weekend after he drove my car. The NOx and SOx gas emissions are highest on high RPM High Vacuum conditions (or snap the throttle plate closed) so BMW brings the throttle by wire back down slower than we would like when you lift. I have had it to the point of reving up after when I put the brake and clutch in a stop box.

I would imagine this could be taken out through a tune. Might be worth a call to AA.

Originally Posted by MightyMouseTech

My Civic had the same thing. Was incredibly annoying. A tune fixed it right up.

Tune doesn't fix it. I'm running an AA tune and they couldn't do anything with their maps to fix it. Which makes me think it's on the backend

[jvb6806]

Maybe they don't have access to that part of the throttle mapping? Or maybe it is in a different part of the code for emissions? I don't have any experience changing throttle maps but I have the TMS tune and it still does it.

This issue was the 1st thing that came out of a buddies mouth when he drove my car at a test and tune last weekend. He is used to driving an STR s2k with a real throttle cable.

[chris82]

I get it too, kinda annoying. It's especially noticeable when you're in the upper revs, above 4.5k. I just got used to it.

[aquasurf]

Originally Posted by Kgolf31

So I've always been questioning this issue, or to better phrase it occurrence with the car and never got a straight answer. Perhaps someone can help me further.....Anyone think we can find a fix?

I looked into the issue of rev hang and its causes in some length and published my findings here with graphs and videos.

jvb6806 was right about "the NOX gas emissions being highest on high RPM High Vaccuum condition (or snap the throttle plate closed)."

[jvb6806]

As I was blowing though the back of a turn around today I was wondering if throttle hang could be the reason why our cars don't stop from time to time when we go from WOT to full on the brakes. Could this have an impact on the car going into "ice mode"? The brakes don't work, and the throttle not closing right away isn't ideal for the slow stuff.

I have had a few co-drivers in the past few weeks and they have all blown out the back side of a chicago box or turn around section because the brakes didn't work. I have done it as well.

I am going to try and record some data at the last event of the season and send it into TMS and see what they can do.