Surging while cruising at 1900 RPM

[veer90]

I have never seen it work with a cable (even when turned off for several mins) and always seen it work flawless by youtube vid. And that was even pre mhd - using a BAVtech cable.

For throttle I reset exclusively by MHD/cable, but I do a little extra dance to simulate leaving the car and getting back in.

1. reset throttle
2. ignition off, key out
3. unbuckle seat belt
4. open/close drivers door
5. lock car
6. unlock car
7. open/close drivers door
8. key in / ignition on, wait 1 min
9. start car

works every time lol

 

[13tx-IS]

And I manage to skip steps 2-9 by just using the Pedal..
Whatever works I guess.

 

[Ace718]

I’m in the same boat myself. Reset adaptations last night only to have it happen again. I was JB4 only for about a year before adding a Wedge E30 BEF and xHP stage 3 about a month ago.

Neither a throttle reset or JB4 adaptation reset has worked for me. The problem seems to have developed in the last few weeks. My issue seems to be based on maintaining low, constant throttle openings at high speed regardless of gear. Shifted down to 5th and 3rd to see if it made a difference. It just bucked harder in lower gears as the RPMs exacerbated the problem. I’m just trying to have a game plan before I start throwing money and parts at it.

 

[Ffwturbo]

Just recently began to get this surge. I'm MHD STG2+. This began after I removed the throttle body and intake for cleaning and external PCV mod. Have the surge now for over a month. Looked everywhere for leaks cracks, reflashed tunes, replaced intake gaskets, reset throttle adaptations with pedal and MHD...Nothing. Gonna try to go back to stock tune and see what happens..

 

[colinod]

i had this "galloping" issue when my car took on a little water and fried the primary o2 sensors. log if you can (you need logging/monitoring capabilities if you want to custom tune anyway) and check out lambda 1 and lambda 2 readings. they should be on the same level between both 1-3 and 4-6 cylinders and hit 12-13 on throttle

 

[N54QC]

i had this "galloping" issue when my car took on a little water and fried the primary o2 sensors. log if you can (you need logging/monitoring capabilities if you want to custom tune anyway) and check out lambda 1 and lambda 2 readings. they should be on the same level between both 1-3 and 4-6 cylinders and hit 12-13 on throttle

So are you saying a lambda reset fixes the issue over a throttle reset? Did several adaptation resets last year at the same time so never narrowed down of which one temporary fixes the issue. Still need to do it this year as I have the same issue, just haven't had time.

 

[colinod]

So are you saying a lambda reset fixes the issue over a throttle reset? Did several adaptation resets last year at the same time so never narrowed down of which one temporary fixes the issue. Still need to do it this year as I have the same issue, just haven't had time.

when my car was doing this the lambas were too far gone for an adaptation reset to fix it. like i said, monitor your lambdas to see if they are giving you issues

 

[08_335i]

Interesting, my car has always done it. But it seems like it's at the oh so slightest pedal position (like 5% throttle maybe?) like when cruising at 25mph on a backroad and just barely touching the throttle. I'll have to try the manual throttle reset rather then MHD.

 

[silverstreak18]

My car has always done this. It did it completely stock, then with jb4, then with jb4 and full bolt ons, then with jb4 and new stock turbos, on the stock tcu flash, on the xhp stg 3, and now with mhd and new stock turbos. I have updated injectors to index 12, new plugs/coils, new boost solenoids, new vacuum lines, new vanos solenoids, new vcg and external pcv, walnut blasted at 60k and 80k, new n20 map sensor, etc.

Theres stuff Ive done that I'm surely forgetting, but Im just trying to get the point across that Ive had this highway surging issue at light throttle with almost every combo of tuning and parts and its the same no matter what. The only times I remember it going away for awhile is after I've done something that involved having the battery disconnected for an extended period of time, but it always comes back sooner or later.

This is probably the only aspect that I currently hate about my 335i. It would be interesting to see if any of the single turbo guys have this problem?

*Car is an auto with fbo and inlets

 

[Mikenazz]

My did this when i had a small boost leak at the bovs. Fixed the leak and all good now.

cruising at 1900-2000 rpm and keeping the pedal still it would surge every second. when you are above or under that rpm it doesn't surge.

 

[silverstreak18]

Is it possible that too strong of a BOV spring could cause this surging on my car? I have a Tial Q and just opened it up and there's a yellow spring inside of it. I was just reading a thread that the black spring may actually be the best one to go with even though it's not what Tial recommends on their chart?

 

[Rcboosted2007]

Had this issue and replaced both vanos solenoids. It didnt throw a code yet.problem never came back

 

[Rcboosted2007]

My car has always done this. It did it completely stock, then with jb4, then with jb4 and full bolt ons, then with jb4 and new stock turbos, on the stock tcu flash, on the xhp stg 3, and now with mhd and new stock turbos. I have updated injectors to index 12, new plugs/coils, new boost solenoids, new vacuum lines, new vanos solenoids, new vcg and external pcv, walnut blasted at 60k and 80k, new n20 map sensor, etc.

Theres stuff Ive done that I'm surely forgetting, but Im just trying to get the point across that Ive had this highway surging issue at light throttle with almost every combo of tuning and parts and its the same no matter what. The only times I remember it going away for awhile is after I've done something that involved having the battery disconnected for an extended period of time, but it always comes back sooner or later.

This is probably the only aspect that I currently hate about my 335i. It would be interesting to see if any of the single turbo guys have this problem?

*Car is an auto with fbo and inlets

Did you ever have your timing
Adjusted or looked at? Worn cam ledges/bearings will muck with intake/outlet vanos funtion

 

[silverstreak18]

I'm in the process of getting it custom tuned on 93 oct because I have inlets and it hasn't thrown any VANOS codes. I'm going to send over a log of the surging to Justin at TwistedTuning and see what his thoughts are. I want to replace that BOV spring first though and see if it does anything.

Just did a 7 hour drive though and it was surging so when I stopped for gas I reset lambda regulation, air/fuel sensors and load control through MHD, it didn't surge for the remaining 4 hours of the drive.

 

[Rcboosted2007]

Shout out to Justin, hopefully he sees whats up. Have you swapped out lamda senors for new ones?

 

[all4bspinnin]

The surging is caused by your fuel trims over correcting. It can be fixed by resetting lambda adaptations then logging both stft & ltft bank 1 and 2. Then make the adjustment to the scalar table. Your o2 sensors could be getting old.

You can see the stft spikes in the log where its overshooting target trying to balance itself.

 

[silverstreak18]

The surging is caused by your fuel trims over correcting. It can be fixed by resetting lambda adaptations then logging both stft & ltft bank 1 and 2. Then make the adjustment to the scalar table. Your o2 sensors could be getting old.

You can see the stft spikes in the log where its overshooting target trying to balance itself.

That sir seems to make a lot of sense to me.

 

[silverstreak18]

Shout out to Justin, hopefully he sees whats up. Have you swapped out lamda senors for new ones?

I have not. I just hit 85k, you think they're ready to be swapped out already?

 

[Rcboosted2007]

I had a similar issue while freeway cruising. I used to reset adaptations every day, almost
Every start up. I thought it was going to be the norm after tuning etc. I replaced both With some amazon ones, issue stayed, i chased it around then went and bought some oem lamda and problem stopped.

 

[Jeffman]

This looks suspiciously related to the OBD emissions diagnostic drive cycle software routine the ECU runs when cruising on the highway between 50-60 mph while below 3,000 rpm to test the proper functioning of the oxygen sensors. My car runs fine but I needed to do a drive cycle to get OBD readiness to pass emissions in my state since I had just reset ECU errors using MHD. (Everytime you reset errors or reset adaprations you reset OBD emissions readiness.). While doing the highway cruising portion I watched in amazement STFT1 and STFT2 cycle regularly up and down between values of 2 and 10 (IIRC). My car didn’t surge at all. RPM must have been around 2400 in 5th gear.