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Throttle issue?

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Weird one I noticed earlier, I've always felt my car was sluggish for a 530i. Sometimes it goes flat out and it's alright, but earlier today in just sport mode and 1/4 throttle it goes like a rocket ship.

Now fuel economy isnt the best on it, I average around 18mpg and on a run if I tease it I can just get 29mpg, and I mean tease it.

 

So it has me to question the throttle module or sensor, it shows no codes flagged up, but earlier it actually felt fast

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 Sounds like you could have a faulty maf or possibly cam sensor, I believe these can actually be way out of tolerance without throwing a code, my old 535i had a similar problem which turned out to the cam sensors whereby it became very sluggish with no fault codes showing but sometimes would spring to life and take off down the road like it's arse was on fire. A quick way to check the maf would be to disconnect it and see if the car runs any different (sorry if that is teaching you how to suck eggs!:D).

Edited by NWJW

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As above for me as well, but see if there's a vac leak anywhere...

 

Clean the MAF with dedicated cleaner and see if that helps... 

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Do the revs rise on idle but at other 

Times are steady ? This and feeling

Of low poor at times but again at other

Times of full power is another sign of

 a faulty throttle sensor.

 What are the miles on your 530?

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I've never noticed the revs rise, but I do sometimes notice a dead spot in the revs, or sometimes the revs drop 500rpm when accelerating from a steady speed but not changing down.

 

I'll check Mac and get the sensors tested.

 

Just all the way home I experimented and full throttle seemed normal but quarter throttle it was actually quick

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A 530i that feels flat at lower revs points to worn vanos seals

 

When I had mine it made a huge difference changing the seals. Lots of low down torque and it felt effortless again

 

A cheap if rather involved job, think it was around 20 quid for the seals

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 I've been doing a bit more playing around with it, and noticed a complete dead spot in the pedal, and the pedal is very notchy when rocked back and forth.

 

Explain it a bit better, seems you have to push it to half throttle or more, then back off the throttle to get speed up, but only notice it in manual as gearbox detects you backing pedal off and changes up.

 

Pt, its flat everywhere, unless 1/4 throttle, don't get me wrong I'd imagine vanos seals need doing, but it's just constantly flat.

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I think your throttle is fly by wire, if it is, I'd suggest that's your problem. To test, measure the resistance across the pedal. It should change smoothly as you depress the pedal. If it's jumpy or randomly changes that's your problem. 

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I wouldn't bother with measuring resistances etc, I'd connect up INPA and look at the throttle pedal there by looking at the live values

 

Much easier and it's what the ECU 'sees' that's important

 

If you haven't got INPA its a 5 quid cable from ebay and a bit of software on a Windows laptop. Lots of how-to's on here and elsewhere

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Did live diagnostics on it the other day, it's showing up faulty cam sensor, but going on the live data, everything is in perfect alignment to what it should be, o2 sensors all good, AFM measuring correctly, inlet and exhaust cam sensors are where they should be, throttle is reading smooth with no dead points.

 

May swap out cam sensors from spare M54b25 I have and see if that solves anything, but everything seems to be where it should be

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Plugged this into a Delphi system yesterday and it's now showing a code that doesn't show up on the Solid.

Throttle/brake pedal plausibility.

 

 

Anyone got any ideas?

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A plausibility error occurs when the ECU finds that the sensor is not reading what it expects it to read. So the options are either the sensor is at fault and giving an incorrect reading or there is something else at fault that makes the ECU think the pedal should be in a different position. For example it may be reading that the throttle body is fully open but the pedal isn't depressed. Can't remember exactly but in INPA the pedal is PWG angle and the throttle body is DKP angle I think.

 

Strange it only shows up on the one system

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