idle around 1000 rpm m20 engine no p/s.

[madmax1410]

well ive a 325i and i removed the power steering and im running a manual rack im currious is this why my idle is around 1000 rpm?

or is it purely from an a air leak? (slight one some where) the reason i ask is i had a 320i that ticked over at 900 rpm with power steering.

im going to fit power steering back on along with an e46 rack so will this bring the RPM's back down?

[Brianmoooore]

If things are working and set up correctly, power steering will make no difference to the idle speed at all. Idle speed is controlled electronically by a secondary throttle 'butterfly', in the form of the idle control valve, which opens more as load on the engine is increased.
The ICV cannot reduce the idle speed below what it is when it is fully closed, so there's either air getting in where it shouldn't be, or the main throttle butterfly is open more than it should be when the accelerator pedal is not being pressed.

[madmax1410]

id say its the throttle body if anything! as the linkage is worn if i hold it back off the revs drop to a nice idle so maybe its time to replace or rebuild!

[Brianmoooore]

If you can bring the revs. down to normal by manually closing the throttle butterfly against its stop, then that is the problem. Unlike some lesser cars, the E30 uses a tandem linkage to work the butterfly, to avoid a sideways load that may wear the shaft, so there's more scope for something to stick.
Check that the throttle stop doesn't show any signs of having been moved from its factory setting, and that the throttle cable is slack at idle. Even when a throttle cable inner hasn't started to fray, it can wear a groove into the outer sheath over time where it bends.

[madmax1410]

well i think i found part of the problem the 2 pipes that go from the brake servo to the throttle body one is connected the other is blanked of on the pipe but not the throttle body so this is likely were the vacuum leak is?

i pulled the throttle body of the m20 b20 i have here and its in excellent condition so im going to either swap out the linkage of this or use the complete unit if there the same as an m20 b25?

i heard the bore is bigger on the b25 one?

[Brianmoooore]

Are you sure the hole in the TB is open? Later TBs only had one port for the servo, with the area where the second one was left unmachined. If it is open, then it definitely needs to be blocked, but if what you said in your last post - then the revs come down to normal if you press on the throttle linkage, then that is the main problem. When the accelerator pedal is not being pressed the throttle butterfly should be hard onto its stop.
B20 and B25 TBs are not interchangeable.

[madmax1410]

checked the bottom hole on the throttle body for the servo vacuum and its not bored out alright so im going to switch the linkage from the 2.0 throttle body to the 2.5 one!

[madmax1410]

think i found part of the problem this evening the plastic gear like part that's on the big arm of the linkage was broke of so i swapped the 2,0 one over and put more tension on the springs so it ticks over almost dead on 1000 rpm now so there must still be a slight vacuum leak somewhere! i suspect its the pipe for the servo as the splines are worn out on the pipe so i think ill try some thread tape and see if that fixes it!

i ordered a new throttle body gasket so ill pull it of next week and look over it for any points were it may be leaking!