miss or skip between 3K and 4K, bucking. (325iX)

[ScHpAnKy]

new lines, cap, dizzy... possible foul plugs? it's freezing here and I get one day off during the week to troubleshoot, so I want to eliminate as many possibilities as I can.

16,000mi on the head, 196K on the bottom end, runs absolutely incredible except between 3K and 4K where it will hesitate for a split second before continuing to climb the revs... wtf?

also, when it hasn't warmed up yet it'll buck like a bronco if you don't give it enough revs...

I'm thinking it's a fouled plug but I never have in an m20...

[Kershaw]

sounds like a very small vacuum leak in a rubber line. when its cold its open, but once it warms up the rubber expands and seals.

tried swapping the dme? afm?

does the bucking change if you unplug the afm? if it smooths out, that points to a vacuum leak.

[ScHpAnKy]

sounds like a very small vacuum leak in a rubber line. when its cold its open, but once it warms up the rubber expands and seals.

tried swapping the dme? afm?

does the bucking change if you unplug the afm? if it smooths out, that points to a vacuum leak.

afm is what I'm thinking, I've read on another forum that criv posts on and sometimes they get flat spots when they get worn out, I've got a couple to test with now... vacuum I'd expect to feel different, though.

Any chance a 153 DME would work on a '91? It's got a 173 now and I have other 173's but I've already got a chip for a 153 :woowoo:

[Kershaw]

should work no problem.


....afaik.

[ScHpAnKy]

looks like it was the AFM like I thought, unfortunately I've also found out that I've now got two bad AFM's, one that misses at 3K-3.5K and one that misses after 5.5K until redline haha, but I'm sure as hell not buying a new one for $240 - to the junkyard!

[Kershaw]

a junkyard will charge you $50.

go to someone parting an e30 out, much cheaper. and you'll know if it was a good one or not.

[ScHpAnKy]

a junkyard will charge you $50.

go to someone parting an e30 out, much cheaper. and you'll know if it was a good one or not.

local junkyard will charge me $50 if I grab an interior or fender with it, and I needs me a fender - wanna part one from your firey mishap?

I've actually been meaning to ask if you've got a '88 153ECU

[E30ruben]

Same exact problem I have with my 92 cabrio 318i. Besides the bucking. Mine freezes for a little around 4300..

[ScHpAnKy]

Same exact problem I have with my 92 cabrio 318i. Besides the bucking. Mine freezes for a little around 4300..

swap the afm, I had to a few times on my m42

[bmoores]

Did swapping the AFM fix your problem? I was having similar identical issues. Switched my plugs and all is good now.

[ScHpAnKy]

Did swapping the AFM fix your problem? I was having similar identical issues. Switched my plugs and all is good now.

yes, sorta - it got rid of my issues but this AFM is bad as well, but seeing as the flat spot is after 5500RPM it's much less annoying since I just don't rev that high until I get a new one :)

[E30ruben]

Thanks!