Rubbish throttle response + very little power low revs.

[tuna]

I've had my G reg 316i e30 for nearly 2 years now and i've gradualy noticed the power in low revs has decreased. I do look after my car, oil change, spark plugs the usual things replaced regularly but none of it seems to make a difference. Also, im not sure if its a related issue but again, low revs i seem to get bad throttle response. Another issue which im assuming is related is that when i accelerate using very little revs or off the clutch the car seems to stutter, revs drop and the car nearly stalls, almost as if its kangaroo'ing. As i mentioned before the car never used to do this so im pretty confident its not down to how i drive it.

Ill give you an example

Im idleing at a set of traffic lights, the lights go green and i accelerate using 1k - 1.5k revs in first gear, As the car starts to pull away with a steady throttle / clutch control, the revs will drop and the car will stutter. If i was to put 1.5k+ revs it usualy pulls away okay but there still seems to be a huge lack of power if i was to then put my foot down. This can become dangerous if i say, pull into a blind roundabout and some jackass comes flying round it, resulting in me having to then put my foot down to get out the way, I'd put the accelerater pedal to the floor, first gear, with low revs and the car just sorta seems like it gargles the fuel, after raising the revs by 500 or so, the power kicks in and im off. So basically the only way i can pull away smoothely and with power at my dispense is to give the car 1,5k - 2k revs and ride the clutch, this obviously isnt a very economical way, nor healthy way for the car to pull away, not to mention its a nightmare in traffic! And again, not quite sure if this is related, but the car just seems pretty gutless untill 3 - 4k rpm

Anyway, thanks for your time, and my appologies if this subject has already been covered

Thanks,
Dan

[Brianmoooore]

Check the large hose between the air meter and the throttle body for cracks and splits, check the small 'spare pipe' coming off of the throttle body is plugged, and look for any other possible air leaks in the area.
With the large air pipe off, you will be ale to access the throttle position switch, on the bottom end of the throttle butterfly spindle. Check this is working correctly in all three states.

[tuna]

thankyou, i will check these parts tommorow if its a nice day. I forgot to mention that those symptoms are worse when the engine is running cold.

[tuna]

I've checked everything you mentioned above and all seems fine. The large 'elbow' hose inbetween the air meter and throttle body has been replaced recently and looks fine. The spare plug, im assuming you mean the plug that comes out of the throttle body but dosent actualy go anywhere, just has a rubber cover on the end of it, thats there. The butterfly spindle is also in good working order. The only part thats not as it should be is the air filter box has no pipe going into it. The air simply gets sucked straight into the box. I dont know if this is an issue or not.

I think maybe i'd be best of taking it to a garage and getting the car hooked up to one of their smoke machines to locate the issue.

I also noticed once the car is warmed up, tapping the throttle quickly dosent actualy rev the car, instead the revs drop and the car stutters. If i hold my finger on the throttle cable for a second or more, the car revs as normal, almost as if there is some form of lag on the throttle.

[Brianmoooore]

With the large air pipe off, you will be ale to access the throttle position switch, on the bottom end of the throttle butterfly spindle. Check this is working correctly in all three states.

And that it's adjusted properly.

[Andyboy]

As much as I dislike snap diagnosis, it does sound like a shagged air flow meter. Take it off and make sure the hinged flap inside moves smoothly - an old toothbrush and T Cut cleans up the internal working surfaces a treat but sometimes they're just knackered.

[Billwill]

What Brianmooooore said....check the Throttle Position Switch is working properly and is properly adjusted!

Could be a worn AFM though...there are lots of ways to re-furbish them so that the contact on the potentiometer surface surface is shifted...in the case that the resistor track has worn out.

[tuna]

Thanks again for the replies, will check these parts tommorow.