URGENT, Terrible misfire from 2-3K RPM

[Herr Faust Schinken]

Hey guys this is pretty urgent as i need to get this figured out by tomorrow night.

Car: 05/1988 325is

Problem: Horrible misfire from 2-3k rpm, if you can get the engine to rev past that it will pull hard to redline. But from 2-3k the engine will buck and misfire terribly. Engine idles fine both hot and cold. Will not maintain speed on highway.

Things I've checked:
Fuel pump ( 36-39 PSI) replaced fuel pump and got same number)
Fuel pressure regulator ( when vac hose is pulled off pressure rises 5-7PSI)
CPS ( 540ohm and very clean on the end)
Coil ( resistance was a tad high but i replaced it and got almost the same number with a different coil)
Plug leads all are in good condition
Cap and rotor were done less then 5k ago and when i pulled the engine they looked brand new.
Intake boot is brand new
Fuel lines are good condition
TPS is new and responds perfectly to stomp test
Spark plugs are pretty new
O2 sensor is new
Grounds are good (tested with multimeter from intake manifold to shock tower)
All upper gaskets new ( head gasket is good, no mixing)
Fresh oil and filter
New fuel pump relay
new gates racing timing belt and tensioner
no overheating issues
Engine starts quickly every time.


I'm really running out of ideas here, my friend is bringing over a different ECU later to try and see if its that.
I will post a video in the morning but i really really need to get this fixed tomorrow.


Thanks guys im kinda desperate at this point

[HerbE30]

Have your same friend crank it at night time while you watch the engine bay closely.

[Herr Faust Schinken]

So this is what's happening https://vimeo.com/201444985

[Balleristic31]

What is that knocking sound??
As far as your problem it really sounds like an ignition miss. What brand are the cap and rotor? I've had cheap aftermarket parts store caps cause bad missfires right out of the box.

[Herr Faust Schinken]

What is that knocking sound??
As far as your problem it really sounds like an ignition miss. What brand are the cap and rotor? I've had cheap aftermarket parts store caps cause bad missfires right out of the box.

I need to adjust the valves I think, the cap and rotor are bremi

Replaced eco with known good unit and it didn't make a difference. the misfire seems to be more on throttle position than anything because now it is misfiring at higher rpm also

[MrBurgundy]

maybe the throttle body is fucked up, take the boot off and see whats up

I had a car come through once, and that was the problem with the same symptoms you're having

I replied the same thing in the chat, but lets just talk about that here since you started a thread

[Herr Faust Schinken]

maybe the throttle body is fucked up, take the boot off and see whats up

I had a car come through once, and that was the problem with the same symptoms you're having

I replied the same thing in the chat, but lets just talk about that here since you started a thread

so i changed the AFM and i know get a check engine light for the afm, it dosent misfire as badly but it hesitates and around 1.5k and then catches up around 3.5k .The throttle body pulls back smooth so i don't think anything is wrong there

[rcsoundn1]

That knock is serious. Does not sound like valve noise to me

[efficient]

Adjust valves and check afm

[HerbE30]

So this is what's happening https://vimeo.com/201444985

Can I get the .xdf/bin files for your anti-lag tune?

On a serious note. That knock sounds bad.. I would agree with efficient and check the specs of your AFM.

Keep us updated though

[accident]

I'm voting for spun bearing

[Herr Faust Schinken]

I'm voting for spun bearing

That's what the consensus is, which is really annoying because I just had the motor apart and it was running absolutely fantastic until last week. It went from perfect to fucked in like 100 miles. It has a new oil pump in it too. I think I'm going to try and find a eta long block to build a 2.7i.

[danielpak_ek9]

Had the same problem, i had the bosch 4 prong spark plugs in i switched it out to the single prong plugs and fixed my issue. Worked for me

[Kershaw]

Try replacing the harmonic balancer (what the CPS reads off of.) Honestly.