2003 Z4 3.0i Idle jumping every second - no throttle control

[London Dry]

Hi All -- First time poster -- While accelerating my Z4 lost power, and immediately engine started an erratic recurring idle every second or so. Depressing the accelerator did nothing. In fact the engine stopped and I smelled fuel. Here's a link to a video that shows the problem.

https://thevisioneers.io/z4/

I was in the middle of a drive cycle to pass smog here in California. I had just replaced a cracked intake boot that goes into throttle body. About to get an OBD II and will post codes.

Thoughts?

 

[1000rr]

Maf sensor.

 

[Chris_D]

Get a code reader on it first.
To me, it looks like your throttle body is toast. I had same problem.
Check also for holes in the elbow of your intake boot.
Ccv valve could also be the culprit.
Disconnect maf and run. If you have the same rev bouncing and it isnt a vacuum leak then get a 2nd hand tb off ebay and replace.

 

[London Dry]

Thanks Guys -- I disconnected the MAF and there was no difference in the idle. I'll have the code reader in 2 days. I'll post readings then.

 

[London Dry]

Here are the codes:
P1632 Throttle Valve Adaptation; Adaptation Condition Not Met
P1638 Throttle Valve Position Control; Throttle Stuck Temporarily
P1637 Throttle Valve Position Control; Control Deviation
P1639 Throttle Valve Position Control; Throttle Stuck Permanently
P1634 Throttle Valve Adaptation; Spring Test Failed
P0102 Mass or Volume Air Flow A Circuit Low

Looks like a maf issue, plus a lot of throttle issues. I don't know how to interpret them, although a couple seem obvious. Changing out the TB is first on the list. I hope that solves the "permanently stuck throttle."

Also, Chris_D, I found your lengthy thread on changing out your TB and CCV -- really helpful

 

[ph001]

New throttle body required I expect (as already mentioned above)

 

[Chris_D]

Def new tb required there. Cheaper on ebay. Mine’s still going strong after a few years.
Glad you found my thread. Should give you a few pointers on how to replace.
That maf code looks more like you have a leak in the intake boot than a faulty maf so check for holes in the elbow of the boot. Common problem too.

Good opportunity to give the idle control valve a clean too as you will need to remove it to get to the tb.

 

[London Dry]

Thanks Chris_D. After taking a careful look at the intake boot connections, I cleared all the code and I did another fault code read and only one code came up -- P1633 Pending Throttle Valve Adaptation, Limp Home Position Unknown. I find it curious that the others listed above didn't show up. I'll follow your advice and clean the idle control valve while replacing the TB.

 

[colb]

Regarding throttle adaptions, have a look here for a how to to reset https://z4-forum.com/forum/viewtopic.php?t=195 Give that a go and see if that code dissappears.

 

[London Dry]

The idling issue is fixed. Turns out that when I was swapping out the intake boot a piece of the maf inner rubber neck pealed off and jammed in the TB. Not what I expected, but I'll take it.

Now I'll get a new set of spark plugs and see if I can get all the readiness status categories checked for my smog check. Still an issue with "Compresensive."

 

[London Dry]

Regarding throttle adaptions, have a look here for a how to to reset https://z4-forum.com/forum/viewtopic.php?t=195 Give that a go and see if that code dissappears.

Thanks Colb -- I'll do that on-off-on timing procedure for sure