Weird Idle B58

[mk5nate]

So I am having this issue where after a cold start when I sit in the car for it to warm up a bit, car will shudder/shake and it can be felt sitting in the car and the car sounds like rpm’s drop and wants to die out but goes back to normal after a second or two. I’ve replaced all my coils, sparks, cleaned fuel injectors, car has no codes or anything drives perfectly fun not loosing power absolutely nothing! Just that little thing that happens at cold starts and I am trying to see what’s going on!!! It drives me pretty crazy. Also!! It happens at warm starts after a drive if I where to slap it in park and sit there car will start acting up at idle and move around. I wanna say more noticeable at cold starts. What can be the issue ? Like I’ve said I had replaced coils, sparks, and cleaned out fuel injectors still does it! Car only has 14k miles 2020. I’m tuned and this happened even before being tuned.

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[itzTang]

1. try doing a full system scan and see if anything comes up.
2. check battery voltage
3. throttle/map sensor/air filter flush. may have build up/dust/contamination.
4. fuel pressure

 

[mk5nate]

1. try doing a full system scan and see if anything comes up.
2. check battery voltage
3. throttle/map sensor/air filter flush. may have build up/dust/contamination.
4. fuel pressure

Will do!

 

[ATinyCthulhu]

So I am having this issue where after a cold start when I sit in the car for it to warm up a bit, car will shudder/shake and it can be felt sitting in the car and the car sounds like rpm’s drop and wants to die out but goes back to normal after a second or two. I’ve replaced all my coils, sparks, cleaned fuel injectors, car has no codes or anything drives perfectly fun not loosing power absolutely nothing! Just that little thing that happens at cold starts and I am trying to see what’s going on!!! It drives me pretty crazy. Also!! It happens at warm starts after a drive if I where to slap it in park and sit there car will start acting up at idle and move around. I wanna say more noticeable at cold starts. What can be the issue ? Like I’ve said I had replaced coils, sparks, and cleaned out fuel injectors still does it! Car only has 14k miles 2020. I’m tuned and this happened even before being tuned.

Mine does this sometimes too and mine is completely stock. As someone else said, could just be a quirk of the B58

 

[a90_don]

From what I’ve read it’s pretty normal for rhe b58’s. I have a 2020 and noticed that before and after being tuned.

 

[itzTang]

Not sure about that. Mine has never shuddered cold start or warmed up. Only time idle dips is after a cold start after 20-30 seconds which is normal

 

[m340_B58]

Happened to me on pump gas. Happened even more on e40 after I got a tune.
Additionally when I would do WOT pulls on e40 I’d get an error code saying mixture too rich.

I pull out the MAF, bathed it in MAF cleaner and reinstalled when dry.
I also replaced the precat o2 sensor. The one I pulled out was contaminated with all sorts of shit.
And then before you turn your car on, go into bootmod3 or whatever tune you have, and reset adaptations for both lambda options.
Turn car off and on, I haven’t had any cold wiggles or mixture too rich errors since then. BMW engines of all types are notorious in destroying o2 sensors.

 

[razorlab]

Happened to me on pump gas. Happened even more on e40 after I got a tune.
Additionally when I would do WOT pulls on e40 I’d get an error code saying mixture too rich.

I pull out the MAF, bathed it in MAF cleaner and reinstalled when dry.
I also replaced the precat o2 sensor. The one I pulled out was contaminated with all sorts of shit.
And then before you turn your car on, go into bootmod3 or whatever tune you have, and reset adaptations for both lambda options.
Turn car off and on, I haven’t had any cold wiggles or mixture too rich errors since then. BMW engines of all types are notorious in destroying o2 sensors.

Gen 2 b58 doesn’t have a MAF sensor. That is a temp sensor.

 

[Kujiwara]

That was the first thing i noticed with my 2023 when i got it new, random little shudders at idle before it's warmed up and there are no codes. Direct injection cars are more prone to idle issues, especially cold. As long as you dont have continuous idle issues all the time you'd be fine. Most people don't notice it but some of us do, when you look up the 40i car forums it's pretty normal.

 

[m340_B58]

Gen 2 b58 doesn’t have a MAF sensor. That is a temp sensor.

The sensor connected to the stock intake box/pipe is for temp?
Where does the engine get its airflow reading from then?

 

[razorlab]

The sensor connected to the stock intake box/pipe is for temp?
Where does the engine get its airflow reading from then?

Yes, just a temp sensor. Gen 2 is modeled. Basically speed density.

 

[m340_B58]

Yes, just a temp sensor. Gen 2 is modeled. Basically speed density.

thanks buddy, learning a lot from you!
Quick question if you don’t mind

yesterday you said you’re running a DI setup with dorch HPFP and injectors. Im running the same on stock turbo and learning how to identify when I’ve reach fuel limitations through logs.

from your other posts I’ve learned that when the HPFP final angle is 126°, it is maxed out. Do you happen to know what’s the maxed out end angle for the fuel injectors?

thanks bro

 

[razorlab]

thanks buddy, learning a lot from you!
Quick question if you don’t mind

yesterday you said you’re running a DI setup with dorch HPFP and injectors. Im running the same on stock turbo and learning how to identify when I’ve reach fuel limitations through logs.

from your other posts I’ve learned that when the HPFP final angle is 126°, it is maxed out. Do you happen to know what’s the maxed out end angle for the fuel injectors?

thanks bro

Anything over 400 start angle is basically maxed out. You won't ever get there with the stock turbo.

 

[lucky phil]

So I am having this issue where after a cold start when I sit in the car for it to warm up a bit, car will shudder/shake and it can be felt sitting in the car and the car sounds like rpm’s drop and wants to die out but goes back to normal after a second or two. I’ve replaced all my coils, sparks, cleaned fuel injectors, car has no codes or anything drives perfectly fun not loosing power absolutely nothing! Just that little thing that happens at cold starts and I am trying to see what’s going on!!! It drives me pretty crazy. Also!! It happens at warm starts after a drive if I where to slap it in park and sit there car will start acting up at idle and move around. I wanna say more noticeable at cold starts. What can be the issue ? Like I’ve said I had replaced coils, sparks, and cleaned out fuel injectors still does it! Car only has 14k miles 2020. I’m tuned and this happened even before being tuned.

Just a thought. Does it do this with the A/C turned off? Typically most cars will go sub idle for a second or so as the a/c compressor cycles on and the ecu lags a little bumping the idle up to compensate for the additional load. I've not noticed it on my Supra but I have on my other 2 late model cars and older previous cars as well both injected and carburetted. No compensating system is perfect.
Phil

 

[mk5nate]

Just a thought. Does it do this with the A/C turned off? Typically most cars will go sub idle for a second or so as the a/c compressor cycles on and the ecu lags a little bumping the idle up to compensate for the additional load. I've not noticed it on my Supra but I have on my other 2 late model cars and older previous cars as well both injected and carburetted. No compensating system is perfect.
Phil

Only when it’s off. When I turn the AC on and the extra bit of idle comes up with it, it won’t stumble at all or very very minimal which is what I like! Idk something weird is going on.

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