hi all i purchased my first 928, an 82 automatic that was not running or shifting, i have fixed the transmition and the car runs now however there is a rough idle for about 5 min when you start it up, when i go to drive the car i have to floor it up untill 35 mph and the acceleration is horrible then its starts to accelerate normally I cannot go up hills at slow speeds !! i punched out the cat, new o2 sensor, new plugs, cap, roater, i am getting normal resistance readings for the temp sensors and cold start device. the mass airflow sensor does work i have seen the gate move as i accelerate the throttel, however on pins 6 and 8 the risitance is too high off by about 100 omes?? if aneybody can tell me wrong it will be greatly appreciated

 

Liam,

Glad to see you got on here and off of facebook,

I would start with the green wire. However it is possible what you are calling the mass airflow sensor (more commonly refered to as the barn door) is faulty and giving you incorrect readings throwing your AFR out of whack.

However I would also recommend doing a brief introduction.

Welcome to the shark tank.

 

i will most definatly look at that green wire,
I guess i will do the intro to
Hi all my name is liam i have always wanted a 928 since i was about 5 years old now that i have my licance, Im 17, i baught an 82 auto for $600 off cl pretty sketchey... however now the car does start stop and go in a stright line for short money so im happy my dad is a bmw master tec so fixing the things the go wrong is no problem however trying to diagnose them is somewhat. i an also a privite pilot and play varsity football/ hockey/ and track for my high school

 

I think if you are patient and spend a few extra hours researching here you will find a lot of past posts that will help you.

There are a series of vaccum lines that you should check, including lines on the carbon canister under the front right (passenger) wheel well. My car wouldn't start until I replaced some of them. And others around the base of the throttle body.

Once you get it running well, and you will, be careful because it will be very fast.

 

today i checked the green wire and it apperared to be fine, however whin i dropped the cat to fix the o2 sensor the left bank of the engine appeared to running very rich as the manafold was coated in a blackish grime, and the right bank of cilinders appeared to be fine??? this is very weard???

 

Have you checked the coils and coil wires?
I had a coil go bad and it was a major reduction in performance/acceleration yet the engine ran relatively smooth considering it was on half power.

 

1982 only has one coil and one distributor.

Have you checked/adjusted the CO / Fuel mixture at idle like in the manuals (Vol 1A 24-3 thru 24-6) ? There is an adjustment screw on the throttle body that must be set correctly. On my 1982 that I got running this was an issue because whoever had tried to get the car running before me had mucked around with this screw.

Also, have you checked the fuel pressure?
How do the injectors look if you pull them, are they in good condition? If it is an 82 that sat non running for awhile and the injectors are original this could be your problem. You may want to test / replace them either way.

What about spark plugs? What do they look like right now? What gap are they set at?

How about plug wires? How are they? I see you did the plugs cap and rotor but not the wires?

Green wire off the distrbutor, how does it look? (it could look fine and still be bad, however)

 

i have looked at the mixture adjustment screw the plug was missing i turned it two turns counter clockwise in an attempt to lean it out a bit im kind of aferaid to turn it alot as i have no co meater, is there aney way to turn the screw and try to cross reffrence with an omes meater??

 

I am not referring the the adjustment on the air flow meter. this adjustment is a large straight blade screw on the front of the throttle body. if you look down in at the throttle body near the oil fill you will see the head of the screw. It is at the very front of the TB

 

o ok, i have adjusted the idle screw and the car does idle pretty good at a solid 750 rpm after about 3 min of running , the car revs fine when in park too but when you go to drive it, it has no acceleration at all

 

the left banks plugs were black, i have run some techron through too and it seemed to fix a leekey injector that i had, i have also herd some horror stories about pulling injectors, my firend said that if you pull one and put a new injector in it will never run right again?

 

Ok, what is the status on the rest of the questions. Fuel pressure?

 

also i did replace the plug wires too

 

I have pulled and put my injectors back in with no problems, not sure what your friend means. You may want to save this for last though.

What do the right banks plugs look like?

Again, what is the FP at the rails?

just reaching here, but it could be that one of the fuel pressure regulators may be bad.

IIRC there is one for each fuel rail. They are located in the back under the air filter box.

 

the right banks plugs look good clean, i have yet to look at the fp yet, that's my next check im wondering it the left banks regulator is bad and allowing stright gas into the left bank causing the cilinders on that side to run rich? do you know if there are aney omes tests i could do before i pull the fp regulators?
thanks alot for your help
- liam