1984 733 i idle problem

i own a 1984 733i and replaced the cam. Afterwards I have run into an increase in idle after start up. I also replaced the idle valve and control unit, and timing switch. But I still have the problem. The car has a little over 200,000 and i am the only owner. She has never given me any trouble before this. can someone please help.

hey yo tight i have the exact same car and maybe we can help each other out...do u have AOL,AIM,Yahoo,MSN?....any of those chaten things...reply....

I dont have an im yet but for now we can exchange over the email. I am working on an im but until then this should work. I have been a tech for over 30 years so i am prteety knowledgable about the automobile but sometimes some problems get the best of us. write back.

I also own a 1984 733I that is gave me the same exact problem. I had the idle lowered and it works alot better now, but I was told that the fuel injecters needed to be replaced to completly cure her (sylvia). I dont have the money for that curently so it still bugs me on occaission, but than again the brakes were a more important repair! Buyer beware high schoolers dont need to drive 1984 7-series, but it works for me! :D

Has any one messed around with the throttle sensor position ?. this will increase/decrease the idle and it dosen't need much movement to do it.
Cheers
Mike

Hi.

I have a question. I chose to ask you because you because you are a owner of a 733 i 1984 BMW. That's the same car I have
I am having trouble with my brake line. When I mash the brakes, she want to pull to the left. I don't know what to do. I got new brakes, now I'm having problems again. What am I to do? My uncle bleed the brakes with 3dot brake fluid. Someone told me I had to use transmission fluid. Are they right?
Please respond.

Patrice

When u say "new brakes" do u mean just the pads? Uneven pressure could be from the master or maybe the caliper is stickin. Although I'm NO expert on BMW's I think that's the same for just about all cars since there's only a handful of parts to a brake system. Hope it helps.
PS!!!! I've never heard ANYONE recomend using anything other then brake fluid except in emergency:alien:

I have the same car, and it has the same problem with the high idle.
It idles at about 1000RPM but should be at 700RPM. I have replaced everything. Trying to fix this.
Sensors, ICV, ICM, Motronic ICU, vac lines.
I'll be darned if I can lower the idle down.
Any help would be great.

If the 'newbie's' would take a moment to fill out their 'forum profiles' a little more to save time referencing model, year, etc...I might take a moment to comment on some.

" jimsbmw "...do you have a service manual ?

Jeffrey,
Yes I have a Bentley book.
The car is an 84 733i 5 speed imported from Germany.
170,000 miles
Ive been repairing cars for about 12 years now.
This is my first BMW, and its not playing nice.
It Idles perfect at 1000 RPM, But like I said before the books say it should be around 700+- 50 RPM.
The only part I have not replaced is the AFM.
I have tested it and it passed no problem.
Replaced all the sensors for engine temp, New ICV, ICM, Motronic ICU, O2 sensor, Vacuum lines, throttle switch, cold start valve, Cleaned injectors (tested), repalced Rotor, coil, dis. cap.... Had engine running and hosed it down with alot of water to see if it would die or hessitate. Ran fine. Tested all wires for OHM's.
So since all this is replaced and working perfectly why do you think the idle will not drop.

I dont think the timing chain could have jumped a tooth or the engine would run ruff, or the valves would get bent possible.
So this leaves me stumped!
Any help what so ever would be very appreciated.

Jim

Hey Jim.....you've replaced enough parts, now let's see if we can fix it. Look in your manual and see if it's got the proceedure for adjusting the throttle plate to original spec's. DON'T do it yet, but get 'familiar' with it and that lever adjustment. Mark the lever plate around the locking nut [10mm hex]...it's the one under the visible elongated slot on the rear side of the throttle housing. Use a scribe as paint would come off. With the engine off, open the throttle slowly and listen for the light
'click' of the throttle switch.......just opening, 'click'
just about closed again, 'click'..........if you hear nothing try lightly forcing the plate closed and listen. [it could be off too much to hear but when the plates adjusted it will be IMPORTANT to adjust the switch to where I just stated]

With it 'idling', loosen the lock on the lever plate and see if moving it 'closed' brings the idle to spec.
If it does, snug it down and recheck the throttle switch [ it MUST close at idle ] and readjust if necc.
See where we are and post back..............jeff.......

Hey guys, I have a 1981 733i and I'm not sure but sure the intake covers aren't leaving air, remember the car, even though old with 200k miles, it has a high compression ratio. mine has over 250k and runs like a champ. I had an idle problem until I checked for air leaks and BINGO that was teh problem forme,... hopefully it helps. you can also try www.bmwtips.com they seem to really know what's going on. great group of people. good luck...

Jeff,

Thanks for the suggestion. I have previously checked and adjusted the throttle body switch. It is working. If I leave it loose when the car is running and turn it either way the idle does change ( High/Low ).
But never goes under 1000 RPM.
The only other strange thing is it will surge occassionly a tiny bit at idle. Maybe at most 50 RPM higher. Tach barly moves, but I can hear it raise. I figure maybe one of the injectors is leaking.
As you can tell Im not afraid to throw new parts at it. So I may order new injectors for the hell of it.

Just an add on:
If I pinch the air intake line to the ICV with pliers the idle drops right down to 800 RPM. Right where I want it. But it will run rich doing this. So in my mind the ICM is not recieving the right amount of info from some sensor to then send the right amount of current to the ICV to close the valve. All sensors are new, and wires are good. Since everything works off of milli amps it could be the slightest amount of dirt, grease, paint, etc on a ground causing it to register a lower amperage. And in turn the ICM thinks the engine is still cold.

When the engine is cold the RPM is around 1100-1200 RPM. Within 5 Minutes the idle does drop down to 1000 RPM.

Crazy engine....

Thanks

jim

Jeff,

Just thought I would add this in.

I also have removed the AC system out of the car. It didnt work anyways. As well as the auxilery fan on the front of the car that was attached to the AC radiator.
Can't amagine the AC pump produced enough drag to hold the idle where it should be. Just to be sure the AC system wasnt sending false signals to the ICM ( ON SIGNAL ) I pulled the fuse for it.
Out to the garage I go....

Jim

hi Jim, sorry for the delay, hope you've fixxed it or haven't gotten too dirty trying yet. Read your latest posts, hummmm...the cold speed and warm idle speed ARE too high........I'm sure you've checked this by now with a tach besides the car's.
you may have been there but the ICU has a seperate 'cold' temp. switch that if open/bad connection will cause a 'cold' higher idle speed

Also, you said you've check the throttle switch, but have you check the 'throttle plate' as I suggested ??? something strange is going on......jb

Jeff,

Thanks for the reply,

I have not used a tach other than the car tach. My meter is broken waiting for a new one. Even just listening to the engine without a tach I can tell it is too high of an idle. The sensor for cold start should go to both the idle control unit and the motronic unit. This is what it says in the bentley book.
Unless the wiring is no good.
And yes I set the throttle plate to where bentley wanted it, and adjusted the switch to click at the right time. Just for the hell of it I plugged
off the throttle throat with a plastic bag to see if it would change the idle any.....Nope!

I feel that the engine is running rich by using the sniff test. Little gassy for my liking. I adjusted the mixture screw to lean it out a bit. and it does help.
Most people say that adjusting the mixture out (lean) should start to make the engine stumble almost stall. Mine does not. So there again it must be running very rich. All I can think of is the injectors are either leaking or they are being told by the system to pulse more. Giving it more fuel.
I think I may try running some new wires from the sensors straight to the ICV unit to see if it helps.
The only sensor I have not replaced is the barimetric sensor. And there is also an outside air temp down by the heater blower which is also wired to the Motronics.
Dought they have anything to do with it though.
Keep racking your brain Jeff. Between the two of us we should figure this one out.....

Thanks,

Jim

Jim, my last post seems to have vaporized, I'll be back 8/5 if you haven't executed the 733i yet. jeff.