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Help me diagnose an oscillating throttle issue
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09-26-2015, 01:05 AM | #1 |
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Help me diagnose an oscillating throttle issue
Hi guys,
I'm having an oscillating throttle issue while driving at ~2k rpm, always at part accelerator. I've had this problem for a little while but now its gotten worse. The car feels like it's surging really gently. You can't really see the revs moves but it feels like the revs are going up and down. Here is a log: http://datazap.me/u/harms/oscillatin...=1-18-19-24-27 I've tried resetting adaptions through MHD. I've tried a linear throttle map instead. No error codes. Car drives fine otherwise. I'm thinking O2 sensors might be the problem as looking at the log the AFR is jumping up and down with the oscillation. Car is FBO running an E60 custom flash. I've emailed the tuner to see what he thinks too, but thought I might reach out to the interwebs for some advice. Cheers Andrew |
09-26-2015, 02:47 AM | #2 |
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I don't think resetting adaptations in MHD would reset the throttle adaptions?
If I reset throttle adaptation in INPA (i reset everything when I walnut blasted), you actually have to go through the throttle relearn sequence. Otherwise I got a whole load of error codes related to no adaptations stored. I did this to relearn: http://www.e90post.com/forums/showthread.php?t=544115 Does this issue happen on stock map?
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09-26-2015, 03:05 AM | #3 |
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I posted this back in the early days... worked for me
This is what I did... 1. Insert key and press start button without foot on brake 2. Press gas pedal all the way to the floor and hold there for 30 seconds 3. Without releasing the gas pedal press the start button 4. Release gas pedal and without touching anything wait 2 mins 5. Press brake and start button to start the car 6. Go for a drive and see if it has made a difference Resets the driving style your car has learned to default I used my iphone to time the 30 seconds and 2 mins Worked a treat for me, but the car was pretty sluggish to start with |
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09-26-2015, 06:11 AM | #4 |
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Hey mate, does this happen when you're on cruise control??
I feel like mine does it too while on cruise, the car feels like it's accelerating and decelerating without any input. |
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09-26-2015, 06:47 AM | #5 |
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Yes MHD does throttle adaption resets. When you do it and start the car afterwards the revs bounce around and it won't idle. When you turn off the car it then throws an error code -I can't remember what. Clear the code, restart, go for a drive and it's the same. I have tried this several times to no avail. Socket i will try your method tomorrow.
I haven't tried another map yet. I have E60 in the tank and don't want to mess around with different mixtures just yet. But this oscillating has suddenly gotten a lot worse in the last few days which is strange. Yes Scott it also does it on cruise. I can pretty much replicate the issue holding any speed as long as its between 1.5-2k rpm in any gear. Gentle accelerating through the gears also feels a little jerky. |
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09-26-2015, 06:56 AM | #6 | |
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09-28-2015, 03:48 AM | #7 | |
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This weekend I'm going to clean the map sensor and clean the throttle body and see if that helps. Then i'll try the OEM map sensor again, then if all that fails flash back to stock and try and rule out the easy stuff like maintenance and tuning. Socket you replaced your injectors recently didn't you? Have you noticed it since then? |
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09-30-2015, 05:17 PM | #8 |
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Replaced about 10k ago mate and yes I have noticed it since then but only when the cruise control was on
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10-02-2015, 04:13 AM | #9 |
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So, the MAP sensor was really gross (the one in the manifold, not the charge pipe) and I gave it a good clean.
It improved things quite a bit - the issue is better but still not fixed. I've ordered a new sensor just in case it's gone bad and not operating as it should. The exchange rate sucks at the moment. Before and After pics! Last edited by harms; 11-01-2015 at 12:55 AM.. |
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10-02-2015, 04:16 AM | #10 |
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And while I was at it pulled off the throttle body and manifold to give them a clean too. Manifold wasn't too bad but had a bit of gunk built up.
Throttle body butterfly was a little dirty; this cleaned up nicely. Before and After pics of TB! |
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11-01-2015, 12:55 AM | #11 |
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I just wanted to give a big shout out to Socket who swapped throttle body's with me today in my mission to solve this issue. What a good bloke.
Special mention to Scotty89 who offered to do the same. Unfortunately the TB didn't fix the issue, but this saved me a few hundred bucks from not replacing parts that don't need to be. So, back to square one |
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11-01-2015, 01:08 AM | #12 |
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For anyone who's interested, here is what i've tried so far :
Cleaned MAP sensor Replaced MAP sensor Checked spark plug condition looking for leaking injector Cleaned intake manifold Cleaned CP Returned to original TMAP sensor Tried E60 base map Tried stage 2 MHD map Flashed back to stock Tried another throttle body Nothing has fixed it. I read an old thread saying BMW replaced vac canisters to fix the issue. I have another recommendation to clean the vanos solenoids. So i might try these things... but I'm open to idea's on where to go next. |
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11-01-2015, 02:09 AM | #13 |
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This issue seems to pop up all the time.
I had 3k kay old plugs (according to the bmw servicing schedule) replaced those and the car felt heaps stronger as i was having a jerky sensation at low speed coming out of corners at suburban speeds but it was still there. I then replaced the vanos solenoids and 02 sensors and bam it was like a new car, so much smoother and no more jerkiness at low speeds. It wasn't cheap ($7-800 with parts and labour) but totally worth it in terms of refinement and giving me the shits driving the car at suburban speeds! |
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11-01-2015, 02:50 AM | #14 | |
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How often should the vanos sensors be changed? yours sincerely Socket |
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11-01-2015, 03:00 AM | #15 | |
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My car was at 72k kays and 6years old when i changed mine FWIW Some guys use carby cleaner to flush them, i didnt stuff around and decided to swap em. |
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11-01-2015, 03:01 AM | #16 |
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11-01-2015, 03:50 AM | #17 |
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Have you already replaced all your vacuum lines? Long shot since its at low rpms and your logs don't seem to indicate the boost correlates with the oscillation but worth ruling out.
I'd say O2 sensors are next on the list if they've never been replaced. O2 sensors have a zirconia element which gets depleted over the course of normal operation. I'd say if you were 120k+ they might be on their way out but might be less depending on conditions. Vanos solenoids I'd be surprised if they were the cause if you're not throwing codes and the car is pulling good to redline. Just give them a clean since its doesn't cost anything. I ran carby cleaner through them while energizing them with a 12V power supply. Didn't notice any difference but good to know they're good.
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11-01-2015, 04:06 AM | #18 |
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When I played with jb4 menu 10 and 12 and placed them too high oscillating occurred.
Your tuner might have wastegate set to tight for good throttle response. I had a bump around 2000rpm and got rid of it by resetting 's few things with my bt cable. O2 sensors, Throttle and a couple of other things relating to the throttle. Hope you get it sorted |
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11-02-2015, 01:09 AM | #20 | |
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Vacuum lines are all brand new. So are boost solenoids.
My initial thought when this started getting bad was O2 sensors, but guys over on *********** reckon it isn't O2 sensors, as both banks are following the same oscillation and apparently its unlikely both will go at the same time. Quote:
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11-02-2015, 01:11 AM | #21 | |
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It does it exactly the same on stock MAP. No jb4 in the mix either.
I still reckon its mechanical/electrical, but really have no idea. Quote:
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