I didn't know if I should put this in the M20 forum or here, sorry if its the wrong place. Either way I'll try to be as brief as I can while still being thorough...
I got my 5-speed '91 325i 3 months ago, its my first BMW. I've spent a bunch of time and money trying to get it to run right, and just about everything I have done has helped to some degree, but now I'm commuting 65+ miles a day in the car and I need to try and speed up the process without just throwing more money at it.
So far I have replaced plugs (NGK copper), cap & rotor (Bremi), O2 sensor, crank sensor, injectors (reman M50 greentops), fuel filter, all underhood fuel lines, exhaust manifold gaskets and performed a valve adjustment (I even bought the proper eccentric tool). After replacing the breather hose, VC gasket and rocker shaft seals it has no sign of vacuum leaks when hooked up to a smoker. The pedal test brings up nothing, and no codes are present when hooked up to my roommate's Snap-On Modis scanner. Temp sensor and AFM both test within spec, though admittedly the instructions AllData gives for testing the AFM made little sense so I may have screwed that up. I have not performed the AFM test where you use the 9v battery.
The worst symptom it has right now is slow, choppy acceleration. As rpms rise above 3500 it begins to be very choppy, lots of hiccups through the rpm range. If I give it much more than half throttle when taking off, it feels like it goes VERY rich and just bogs down and makes no power at all, you have to roll into the throttle. Sometimes if I push the accelerator down further, it actually makes the car accelerate slower. Left turns and highway on-ramps are not my friends right now. When I first start the car cold, I have to roll into the throttle really slow and rev it once before I try to take off, otherwise the car will want to stall and I can smell raw fuel. When decelerating under engine braking, it will lunge forward every second or two. I also think it is doing a subtle on/off sort of thing, possibly a misfire, it feels like its always in a constant cycle of slight accel/decel when cruising at a constant speed, but it might just be wind or bumps... or in my mind. Its just really inconsistent in the way it runs, some days it seems to run much better than others, and also occasionally the idle gets all erratic revving between 1100 and 1400rpm (it normally idles around 1100 which from what i have read is high). The car gets poor mileage and is very slow in general, I was kind of expecting this car to be a bit quicker then the Dodge Neon it replaced, but it isn't even close to the performance I am used to. Despite all of this, it still managed to pass CA smog by a sizable margin.
So, what should I try next? AFM? Coil? Plug wires? Should I try playing with the AFM? It appears to have already been opened up at some point as the cover looks to be held on with hot glue or silicone.
Sorry for the novel, I know I said I was going to be brief.... Thanks a bunch in advance everyone.
I got my 5-speed '91 325i 3 months ago, its my first BMW. I've spent a bunch of time and money trying to get it to run right, and just about everything I have done has helped to some degree, but now I'm commuting 65+ miles a day in the car and I need to try and speed up the process without just throwing more money at it.
So far I have replaced plugs (NGK copper), cap & rotor (Bremi), O2 sensor, crank sensor, injectors (reman M50 greentops), fuel filter, all underhood fuel lines, exhaust manifold gaskets and performed a valve adjustment (I even bought the proper eccentric tool). After replacing the breather hose, VC gasket and rocker shaft seals it has no sign of vacuum leaks when hooked up to a smoker. The pedal test brings up nothing, and no codes are present when hooked up to my roommate's Snap-On Modis scanner. Temp sensor and AFM both test within spec, though admittedly the instructions AllData gives for testing the AFM made little sense so I may have screwed that up. I have not performed the AFM test where you use the 9v battery.
The worst symptom it has right now is slow, choppy acceleration. As rpms rise above 3500 it begins to be very choppy, lots of hiccups through the rpm range. If I give it much more than half throttle when taking off, it feels like it goes VERY rich and just bogs down and makes no power at all, you have to roll into the throttle. Sometimes if I push the accelerator down further, it actually makes the car accelerate slower. Left turns and highway on-ramps are not my friends right now. When I first start the car cold, I have to roll into the throttle really slow and rev it once before I try to take off, otherwise the car will want to stall and I can smell raw fuel. When decelerating under engine braking, it will lunge forward every second or two. I also think it is doing a subtle on/off sort of thing, possibly a misfire, it feels like its always in a constant cycle of slight accel/decel when cruising at a constant speed, but it might just be wind or bumps... or in my mind. Its just really inconsistent in the way it runs, some days it seems to run much better than others, and also occasionally the idle gets all erratic revving between 1100 and 1400rpm (it normally idles around 1100 which from what i have read is high). The car gets poor mileage and is very slow in general, I was kind of expecting this car to be a bit quicker then the Dodge Neon it replaced, but it isn't even close to the performance I am used to. Despite all of this, it still managed to pass CA smog by a sizable margin.
So, what should I try next? AFM? Coil? Plug wires? Should I try playing with the AFM? It appears to have already been opened up at some point as the cover looks to be held on with hot glue or silicone.
Sorry for the novel, I know I said I was going to be brief.... Thanks a bunch in advance everyone.
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