Opinions needed re: engine hesitation/vibrations

[D. Clay]

This could be a good time to get a Bentley manual and learn how to tune the car and check fuel injection components. You could also replace all the vacuum and rubber hoses. If you want to get into real rocket science, spray the hoses with WD-40 to check for vacuum leaks. This is the method of choice if you more time than money.

[silverblades181]

All my vaccum hoses are new, replaced when I did my head gasket. ICV is clean, throttle is clean, spark plugs, wires both new. Used injector cleaner aswell. Only thing I can think of now is faulty AFM, O2 sensor or partly clogged catalyser.

[Choking Hazard]

This may sound wacky, but check the attachment at the throttle cable to the top of the intake manifold.  When I first got my car I drove for a week with the little black plastic threaded end totaly out of the metal part that holds it.  Amazing that the car would go at all i think, but it would start and idle really low (and consequently rough) until the ICV responded by cranking the throttle up.  I think it is unlikely to be your problem, but it might be easy to overlook.

[MattyK]

Hey, just signed up, mainly because Im having this same issue (or very close). Im sure its fuel control related. Reason you notice the hesitation is because the engine is getting too much gas, and you need the throttle open for a couple secs to burn it off, then you get normal performance again, if you didn't realize (at least thats my problem). Engine sounds exactly like it did when I flooded my engine with gas for the time when its not accelerating properly. Though I do believe that its that the car is getting too little air, not too much gas - ive had a couple problems in the past with my air system (ICV/AFM/O2sensor), so Im sure its one of those acting up on me. Think thats why the revs are dieing as well (my car isn't stalling, but the idle goes from 800-500 at lights) - too little, air suffocating the engine, revs drop, ICV realizes and brings revs back up, etc...

Im getting a new muffler installed on tuesday and letting my mechanic take a look at the problem before I rip stuff apart myself

[thumper3ld]

This may sound wacky, but check the attachment at the throttle cable to the top of the intake manifold.  When I first got my car I drove for a week with the little black plastic threaded end totaly out of the metal part that holds it.  Amazing that the car would go at all i think, but it would start and idle really low (and consequently rough) until the ICV responded by cranking the throttle up.  I think it is unlikely to be your problem, but it might be easy to overlook.

That just might be the answer for me. The little black plastic jammy is also totaly out of the metal part that holds it. I guess if i can get a new throttle cable, i'll give it a try.

[RED IS 91]

how did you make out with your rough idle and accelleration
I'm having the same problem .
Before the rough idle and accelleration  I installed a new fuel pump ,gas filter and spark plugs .I too am leaning toward the co 2 sensor but will unplug the tps tomorrow to see if that makes a difference.

[billb]

I had a HUGE MISS from 2000-4500 rpm that new coils from BMA solved when I got my 318is 3+ years ago.  Might want to look there...

[melloh]

Just adding to the moral support and encouraging input b/c I have similar symptoms (thoough not as severe).  Mine seems more related to cold engine... but we're not diagnosing me (yet).  Please keep us posted as I too am curious if your solution(s) are applicable to me.

Cheers and GOOD LUCK!

Henry

[RED IS 91]

I did a fault code check and  it came back as no faults .
code #  1444
I will continue to keep checking different items cause I don't want to just start changing parts .
This rough idle and crappy accelleration is very irritating .But it's not a daily driver so I have time .

[RED IS 91]

UPDATE
this evening I
1) disconnected the tps - this made the car run worse
2)took off the mas and cleaned it - this made no difference
3) disconnected the oxygen sensor in the exhaust pipe - this didn't make it run any worse ? HMMM
4) I checked for vacumn leaks on everything I could see - none that i could detect

This is the question
Should there be a difference while running when I disconnect the oxygen sensor ?
Or is it to minimal to notice .It does look old but I didn't get that code fault .
I will solve this mystery

[bmwman91]

You should get a CEL with the EGO sensor off, and the car should run really rich.  I was stuck for a week with a crapped one that I disconnected and had to drive to work.  It did not behave as you are describing with the stalling idle and lumpy acceleration...it just ran extremely rich.

Inspect the crank position sensor and main pulley/toothed wheel.  Check to see if they are damaged.

[RED IS 91]

I just disconnected the o2 sensor and my check engine light did not come on .
What does that mean ?
It does come on when I turn the key to the on position .
I'll check the cps tomorrow and I think I'll put in some injector cleaner and see if that helps anything.

[RED IS 91]

I just disconnected the o2 sensor and my check engine light did not come on .
What does that mean ?
It does come on when I turn the key to the on position .
I'll check the cps tomorrow and I think I'll put in some injector cleaner and see if that helps anything.
i do appreciate all the help I'm getting

[Ramblin MAn]

My daughters e30 had a similar intermittant rough running issue that turned out to be a bad connection to the coolant temp sensor. I found it by accident when I brushed the wire while tapping the FPR. She doesn't have an m42 but the problem does sound similar. I cleaned the connection and it's been fine since.

I just got through rebuilding the front end on her car after she put it into a telephone pole. Everything from the waterpump forward had to be replaced. Anyway, when I took it for a test drive I had severe vibration that would come and go dependant on speed or direction I was turning. Back home I looked under the car and she had hit the pole hard enoght to knock one side of the tranny cross member loose. Anyway, point is to check your motor and tranny mounts. I had the same issue a year after I bought that car and had a motor and tranny mount that had gone bad. I thought I'd spun a bearing or something. New mounts and it was smoothe as silk again.

[Alpine003]

I just disconnected the o2 sensor and my check engine light did not come on .
What does that mean ?
It does come on when I turn the key to the on position .
I'll check the cps tomorrow and I think I'll put in some injector cleaner and see if that helps anything.
i do appreciate all the help I'm getting

I just replaced my bad o2 sensor and here is my experience. The car will run fine  without an O2 sensor. You won't necessarily get a check engine light right away if you disconnect the O2 sensor. You will only get it from time to time when you're in open loop mode while cruising at a steady speed. My o2 sensor did cause erratic idle. The rough running, I'm still trying to sort out.

While the motor is running, try disconnecting your big vaccum breather hose going to the valve cover towards the front and see if there is any difference.