85 325e hesitation and idle issue (hear me out)

[TheGrillMan]

ive serched this and other forums untill my eyes hurt so ive desided to finally post and ask a few questions




first.

my idle is quit rough and around 200-300 rpms seems jumpy

mostly does it when first started up but also does it randomly throught my daily driving

the only time im finding the hesitation is when i shift quicker than normal or its dead cold

if im at WOT and shift fast there is none to be found

also if i shift slowly but lay on the gas hard as soon as im getting into gear i get it

i think possibly its a fule or lack there of issue but i honestly dont know where to start

NOTE::

i have replaced my wires, plugs, and fuel filter within the last 2 weeks

its an 85 325e with a mark d chip

[blocke]

Check for Vac leaks, test coolant temp sensor, replace 02 sensor if it has more than 100k on it.

[jlevie]

A common cause of that is intake leaks. And the best way of finding them is to have a smoke test run on the intake. Other causes are possible, but until intake leaks are ruled out there's little point in considering those possibilities.

[ubernasty]

Check for Vac leaks, test coolant temp sensor, replace 02 sensor if it has more than 100k on it.

This, i'm doing that now on my car.

[TheGrillMan]

can you elaborate on this smoke test?


would the o2 still cause this if i have no cat?

[TheGrillMan]

also how might i test the o2 without replacing it?


i dont see the need to drop 175 bucks if its not needed