A buddy of mine has a 1990 e32 735il. 230k on the clock. WE've been trying to fix a studdering problem it has. It studders almost all the time when adding gas, espically at high RPMs, but every now and then it can run fine. It seems like it gets worse as the engin warms up, and when it has low octane gas. This problem has been bugging us for about 8 months now...

What we have fixed/replaced...
-o2 sensor
-harmonic balancer
-fuel pump and injectors
-ECU(several times)
-thorttle cable

Please help us out, any ideas or anyone with the same problem?...The engin does have high milage but the compression is right where it should be in all the cycls.

Have you replaced the fuel filter? The fuel pressure regulator is another possibility. This problem seems to me like the engine is leaning out a higher rpm
Hey but what do I know.

Have you pulled the OBDC codes? This can be done by turning the key to position 2 and pushing the accelerator to the floor boards 5 times in five seconds. The codes will flash on the check engine light.

Good luck!

yeah we replaced the fuel pressure regulator 3 times , i forgot to mention that..we check the codes also, even had our mechanic plug into the computer to get codes...nothing, ...fuel filter we have not thought about...good thinking, i forgot about that...thanks

anyone else had/have this problem? or know something about it?

I am having a similar problem with mine, 88 325 with 190K, it stutters when accelerating briskly between 2,500 rpm and 3,000 rpm. The second the tach goes over 3,000 rpm the stutter goes away and it rev's up great. If you are at full throttle or very slight accell the stutter is not present.

I can't figure out what might cause a problem that is so rpm specific.

I've tried plugs, ignition coil, O2 sensor, fuel pump.

I have been playing with the airflow meter spring settings trying to change the fuel mix. I can minimize it but I can not make it go away.

I'm trying an adjustable fuel press reg and or a speed sensor next.

Dave Porter

fuel relay?

I have tried to read the codes from my E32 735I and i press the accelorator 5 times and nothing happens, mine is also having the same problems as stated above

Bad MAF sensor could cause a lean or rich mixture.... I'm not sure what the computer would think when it sees unexpected results at the o2 sensor or if it would throw error codes. This stuttering issue might be a good question on the general maintenance forum, as there are a few bmw dealer mechanics who hang out there. Good Luck!

My money is on the MAF as well. These things get dirty, especially if the air filter is not changed often enough, and can/will stick with a corresponding degradation in performance. e38.org has a blurb on how to take one apart and clean it, if you're interested. Good preventative measure, and fairly easy to do.

jk