E30 320 Rev limiting itself at 3500rpm

[bmw325i 0]

has anyone had their e30 create its own rev limiter?

Now firstly, it is a bouncing fuel cutting limiter at 3500rpm, its not running out of balls or cutting out or anything, its limiting consistantly at 3500rpm.

however, up till it limits at 3500rpm the power and engine is as smooth as a brand new motor, no hesitating or surging.

It can pretty much only be.. 2 things, air or fuel but the afm seems to be functioning perfectly which leads me to thinking it is a fuel problem but what do E30's have that could cause a fuel problem. im pretty sure its an electrical problem causing the fuel issue hence leading to the low rev limit.

Anyway if anyone has their 2 cents and are keen to share it go for it.

i have also checked all the fuses and also the two behind the glove box and they all seem to be fine.

[|ncary 0]

Dizzy, leads, plugs need replacing. 99% sure.

[QuickSilver 0]

Motronic or L-jetronic?

[hotwire 352]

Motronic or L-jetronic?

Yes - depends on this as to the reason.

L-Jet uses a spring in the HT rotor to limit RPM with syntrifugal force.

Motronic is controlled by ECU

[QuickSilver 0]

Exactly, in L-jet I've seen the spring malfunction and cause a low limiter. But in both cases, l-jet or motronic I wouldn't rule out the AFM. I've had this crap out on me before too, and in all respects in sounded like an electric REV limiter but the AFM had totally given up.

[bmw325i 0]

hey guys, not sure if its motronic or what it is. havent looked too deeply into what the car is all about as only picked it up the other day and just tried all the obvious reasons for it happening and then had to leave again.

its a 1986 320i manual coupe, and has a MPH speedo so guessing its not a japanese import. hopefully this is enough info for someone to know if its motronic or whatever. will have a decent look at it next time im out at drury where the car is.

I am going to check the undercar fuel pump next though as these can start working on the piss and also the filter it self could be blocked and not allowing enough fuel for higher rpm. Yesterday it was rev limiting at 4500 instead of 3500 so fuel filter could explain that. will keep you posted.

[Guest FrantiC]

Motronic has the dizzy on the front of the motor, rotor is attached to the cam gear.

L-jet the dizzy is found under teh intake manifold and runs off the intermediate gear.

[e30plz 1]

I have a 1987 320i which is L-jet I think, does the same thing at 4k sometimes

[bmw325i 0]

its L-jet then man. so what do you reckon it could be doing? and how do i go about sorting it etc, costly?

[e30plz 1]

I'm not sure, blocked fuel filter sounds like a possibility.

Cause it doesn't happen all the time in (in mine anyway) and always at different RPMs.

Edited October 25, 2009 by E30ONP