starts missing around 3-4k rpms

[R1ckM]

adjusting the AFM will have little to zero effect in regards to an AFM that has dead spots. See my thread on AFM refurbishing to learn why this happens.

Now that you mention it I noticed this little scratch on part of the strip. Its on the upper area, maybe the 4k rpm area?!
Is this the culprit???




Can I just replace that strip or maybe somehow smooth out the scratch?

[DesertBMW]

Disassemble wiper arm and connector assembly. Clean incoming, and outgoing contacts and bend them to contact fresh material. Clean wiper arm contacts and primary grounding post. Adjust wiper arm to contact fresh material.

4.Reassemble wiper arm and connector. (all contacts touch fresh new material only!)

[Gregs///M]

adjusting the AFM will have little to zero effect in regards to an AFM that has dead spots. See my thread on AFM refurbishing to learn why this happens.

[R1ckM]

Started it up and drove it today, ran just fine. Had a very slight miss right at 4k but smoothed out soon as the rpm raised past it.
So something that acts up randomly causing it to miss?

[Kershaw]

Did you try the fuel pump?

[TobyB]

If you don't trust the wires, I'd still suspect them. It doesn't matter that they're
expensive, it only matters that they're bad.

And if you have an i engine, you need that sensor on #6. Otherwise you may get
a different set of problems from fuel pulsation...

t

[R1ckM]

Check the cps, cleaned it up and checked the nut, it is on there tight. Couldn't get it lose actually by hand, need to go buy some hex sockets and give it a go.
I will try unplugging those and trying them out one by one. The car runs and idles fine but trying to get some power under a load it miss fires.
I want to suspect a injector, when i pulled the plugs cylinder #3 looked like it was running lean.

[Ryan1642]

Did you try unplugging the ICV or the AFM, I had a problem revving my '91 IX past 2k until I unplugged my ICV, the ecu will then go off a preset value. you can fool around with different combinations of the ICV/AFM plugged in or unplugged and it might help you determine whats wrong. check the connectors and wires for both too. ICV's are the root of all evil.

[ak-]

Coils rarely go bad.

Check your CPS and see if it has come loose. My car used to hit a brick wall at around 4900 RPM and it turned out the CPS's nut that holds it was loose and vibrating at that speed.

[Hooffenstein HD]

Also, whats that extra wire with a plug goin from the plug wires? (not the coil wire)

Cylinder identification sensor. Some people say it's not necessary since some aftermarket lead sets don't have them. I lean more towards the theory that BMW put it there for a reason.

[R1ckM]

It runs way better now after cleaning the icv but still misses when I rev it around 4k rpm. Putting a new fuel filter may be a easy cheap alternative.
The way it behaves remind me of my e34 535i, it had a bad tcu. Not sure if manuals have these though.
Gonna try the plugs, probably get a rotor and cap too, maybe even a new coil.

Its not throwing a cel which is annoying. Theres a problem if its missing under a load at x rpm.

Also, whats that extra wire with a plug goin from the plug wires? (not the coil wire)

[BruceJ]

wires link: There's many for much less than $240
http://www.ebay.com/itm/BMW-e28-528-...8f8164&vxp=mtr

http://www.turnermotorsport.com/BMW-...lug-wires.aspx

Check the coil connections - coil wire is very susceptible to moisture and will rust at the wire/coil connection. Will def cause ignition problems.

Good Luck
Bruce

[101]

I got a set of Bremi wires on Amazon for $129. That was about the lowest price I could find for a name brand set.

[R1ckM]

Ok, I adjusted the afm 3 notches left. Removed the battery for a couple minutes then connected and let it idle for 5 mins or so.
Changed the spark plugs, no wires b/c they wanted $250 for a set...

Starts, runs and drives now but misses when under a load.

Will try and clean the icv and tb tomorrow and see if it helps.

It was running without missing until 3.5-4k rpm until i sprayed the engine bay just a bit and not directly on the engine just the outer tracks to get dirt and leaves that were all mushed in there by the hood.

Anything a little water could make not run well?
Its been a full day since then as well.

Also, where can i get a set of wires without spending way too much?

[R1ckM]

The top is sealed very well on it, i will try and get it off there. Would like to set it to run a tad richer.
I pulled the plugs and there were some old champion brand plugs, they looked a bit funky. A little white dust around the threading and dark n crudy at the end.
The wires are very limp and soft, i find it unusual for spark plug wires to be like that but maybe i am wrong.
I am going to order some plugs and wires today, maybe a distributor cap and coil as well.