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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Wed, Jul-18-2018, 08:19:09 PM   #21
Texaz3
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Default Re: Idle jumps up and down after hot restart

Quote:
Originally Posted by HassanEido View Post
If it hunts,it aint running right. Your maf would be on its way out more likely than not. If no vaccum leaks and icv is ok, then its ur maf , no ifs buts or maybes about it
I said intermittent.
There is more to idle hunt issue than just MAF.
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Old Thu, Jul-19-2018, 06:20:19 AM   #22
HassanEido
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Default Re: Idle jumps up and down after hot restart

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Originally Posted by Texaz3 View Post
I said intermittent.
There is more to idle hunt issue than just MAF.
Trust me on this, it should NEVER have unstable idle. Ever.
It's just how it works. You must've missed the part where I said, if there are no vacuum leaks, and ICV is ok, then your only cause would be your MAF.
An inaccurate maf doesn't throw codes until it's way way off.
For example, a brand new maf will read around 3.3 grams/second(depending on elevation, temp etc..),and as it ages it can up to 6 g/s without every throwing codes. The car will of course adjust for this margin within limit. A CEL will be thrown when it reaches 6.5 g/s or higher. At this point it is way way off, and outside the tolerance. Mind you, the car would be running like crap compared to car with a good MAF, as the car can only run as good as it's maf is accurate(given stock tune etc..).
I have seen an instance where a car didn't have issues, but ran a bit too lean up top(into the 14s), idled fine, but intermittently hunted for idle. His maf read 5.4 g/s. Swapping a new maf, car wouldn't idle anymore. It had been adapted to the old crappy maf so much that it couldn't hold idle. Reset adaptation and it ran perfectly. Rock solid idle no matter what. That's just one example..If had far too many experiences with this than I care to mention. I'm mafless since a few months ago, but I've logged and studied these for 5 years before.
Anyway, my comments are advice to all of you still running a MAF, if it hunts even if intermittently or rarely, it's not running right, change ur maf , and clear ur adaptations.
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Old Thu, Jul-19-2018, 01:53:22 PM   #23
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Default Re: Idle jumps up and down after hot restart

I'll try it out brother. Thanks for the insight.

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Old Thu, Jul-19-2018, 02:14:07 PM   #24
Texaz3
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Default Re: Idle jumps up and down after hot restart

Quote:
Originally Posted by HassanEido View Post
Trust me on this, it should NEVER have unstable idle. Ever.
It's just how it works. You must've missed the part where I said, if there are no vacuum leaks, and ICV is ok, then your only cause would be your MAF.
An inaccurate maf doesn't throw codes until it's way way off.
For example, a brand new maf will read around 3.3 grams/second(depending on elevation, temp etc..),and as it ages it can up to 6 g/s without every throwing codes. The car will of course adjust for this margin within limit. A CEL will be thrown when it reaches 6.5 g/s or higher. At this point it is way way off, and outside the tolerance. Mind you, the car would be running like crap compared to car with a good MAF, as the car can only run as good as it's maf is accurate(given stock tune etc..).
I have seen an instance where a car didn't have issues, but ran a bit too lean up top(into the 14s), idled fine, but intermittently hunted for idle. His maf read 5.4 g/s. Swapping a new maf, car wouldn't idle anymore. It had been adapted to the old crappy maf so much that it couldn't hold idle. Reset adaptation and it ran perfectly. Rock solid idle no matter what. That's just one example..If had far too many experiences with this than I care to mention. I'm mafless since a few months ago, but I've logged and studied these for 5 years before.
Anyway, my comments are advice to all of you still running a MAF, if it hunts even if intermittently or rarely, it's not running right, change ur maf , and clear ur adaptations.
How do you clear your adaptations after changing MAF? I have MAF on order, so will swap as soon as it gets here.

Btw, I was not disagreeing with you, just said that most cars at this point will have some sort of issue with MAF, icv, vacuum, etc to hunt a bit intermittently. Doesn't mean its not an issue, just maybe not critical enough until it becomes a nuisance.
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Old Thu, Jul-19-2018, 03:44:45 PM   #25
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Default Re: Idle jumps up and down after hot restart

My car has been doing this for 8 years, since the day I got it! Also intermittent and goes away after 30-60 seconds on a warm start so it hasn't bothered me much.

I've cleaned and then replaced the MAF, no change. In that time period I've also replaced the fuel filter a couple of times, spark plugs, coils, fuel pump, etc.

I don't have any visible tears in the intake or anything,


I'm going to be cleaning the ICV and throttle bodies some time this summer, just haven't gotten around it.

Quote:
Originally Posted by Texaz3 View Post
How do you clear your adaptations after changing MAF? I have MAF on order, so will swap as soon as it gets here.
INPA or similar tool.
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Old Thu, Jul-19-2018, 03:51:34 PM   #26
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Default Re: Idle jumps up and down after hot restart

After my 60k mile work including Beisan VANOS oil disc and seals, I had intermittent idle hunting and thought it was some combination of my valve adjustment and timing. I typically clean my MAF every 10-15k miles, so didn't think that was related. At about 73k, finally cleaned up a very dirty ICV...idle seemed worse especially on cold starts, and so a couple weeks ago at 75k I did another valve adjustment (heard some clicking in there so figured it was worth opening the cover anyway to make sure nothing else was wrong) and that improved my cold start idle to almost rock steady again.

Then...I noticed hunting idle, read this thread, and it matched the conditions...warm/hot start, hunts for about a minute, then settles down to steady. Had it happen a couple days ago on a warm start and pulled the MAF connector. Immediately the idle jumped and went steady. Showed ~1100rpm, where it normally idles at ~800-850rpm. Looks like at about 70k miles my MAF is heading on out and fits what Texaz3 described, so I'll probably start looking for a new MAF sooner than later.
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Old Sun, Jul-22-2018, 06:16:48 PM   #27
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Default Re: Idle jumps up and down after hot restart

Ive had a bouncy idle for a while. its usually on cold starts and sometimes while idling at a light after warming up. ive cleaned my icv, maf, and throttle bodies, did besian vanos job and valve job. the idle improved the most after the vanos and valve job, but it still hunts for idle occasionally.
Im at 80k mi, so Ill keep an eye out for a MAF meter and post whether or not it improves when I change it
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Old Sun, Jul-22-2018, 08:20:19 PM   #28
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Default Re: Idle jumps up and down after hot restart

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Originally Posted by zingbmw View Post
Ive had a bouncy idle for a while. its usually on cold starts and sometimes while idling at a light after warming up. ive cleaned my icv, maf, and throttle bodies, did besian vanos job and valve job. the idle improved the most after the vanos and valve job, but it still hunts for idle occasionally.
Im at 80k mi, so Ill keep an eye out for a MAF meter and post whether or not it improves when I change it
I'm selling a new Bosch maf on the forum. PM if interested.

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Discussing Idle jumps up and down after hot restart in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)