cant diag. please help.

[skinner1980]

Im new to these cars and I'm having problems. I just got a 86 325es. The car sat for the last year. it starts right up but idles a little rough, so I tried to drive it. If you dont push the accelerator down very far it runs decent, but if you try to accelerate fast or puch the gas down far, it cuts out and runs like ****. the check engine light is on, and I read how to perform a stomp test but I tried probably 50 times and I cant get anything but a steady flash. I even had a buddy try and same for him. Please help, its a sharp car and I wanna be driving it this summer.

[coolbear1]

I don't think the the gas pedal thing works on an 86. That trick works on some early E36 models.

Since you obviously don't have a code reader, check the obvious, air leaks, like cracks in the rubber intake elbow, Vac leaks, fouled spark plugs, bad gas, clogged fuel filter, Bad plugs or wires?
A vac leak will cause the fuel pressure regulator to not to work. It won't allow enough fuel to the fuel rail when the accelerator is pushed. You could have a bad throttle position sensor or ox sensor, you can test them with a good digital ohm meter.
Just pulling your spark plugs and inspecting them will tell you alot.
If all that checks good, Check your compression.
After that, get your codes.
Good luck.

[skinner1980]

OK. Ipulled the plugs & they all were fouled so I replaced them and checked for vac leaks and couldnt find any. If you easy foot the throttle, it will rev as high as you want, but if you just put it to the floor it sputters then revs up; thats without a load. If you are driving the car and floor it, it just cuts out. I don't know if that helps at all.

[Manolito]

I am not at all familiar with your engine so excuse me if I am way off base.

You carefully checked the tube from the mass airflow sensor to the throttle valve to make sure it is not cracked?

You checked the air filter to make sure there is not a rat's nest in it?

Do you have a distributor? If so, pull the cap and look for lines between the metal parts that look like pencil lines indicating that spark is traveling places it should not go, following microscopic surface cracks in the plastic.

Start the engine in the dark and rev it up, watching for sparks jumping from flaws in spark plug wires to the engine.

There should be a fuel pressure regulator attached to the fuel rail somewhere. Pull the vacuum hose off it and see if there is fuel in that vacuum line, indicating that the diaphragm in the regulator has ruptured and is leaking fuel to the intake manifold.

[VIDA]

try replacing your o2 sensor, when i first got my 325es a few years back, it did a similar thing. would almost stall out from a stop then build speed slowly, then when shifted to second, would hesitate and lurch then resume. ended up being the o2 sensor. also as noted by others, check vacuum lines, fuel lines, fuel pressure, and fuel quality (if car was sitting for a year). if you don't know when the o2 sensor was last changed, change it. 100 bucks and 5 minutes can save a lot of headache from chasing down a ghost.

[VIDA]

oh yeah, the o2 sensor sends the signal to the ecu to control air/fuel mixture. sounds like you're running rich, with fouled plugs. when you step on the pedal, you're flooding the engine, like on an older carbed engine in need of adjustment. you can't just adjust the air/fuel mixture manually like you can on some engines unfortunately.

[coolbear1]

Definitely sounds like a fuel/air mix problem, which could be a caused by so many things that you have to start narowing down your search.

So,

Fouled plugs, corrected.

Simple first.

Air leaks? Pay extra attention to this one. Remove the rubber intake elbow, and inspect it, the idle control, and crankcase vent connections, even a small crack, or loose connection, will cause the air fuel mix to get out of control.

Vac leaks? Pull off a hose and see how much vacuum you have, it should whistle somewhat, and does it change the rpm or tone of the engine when you remove it.

Fuel filter? if you have not already changed it, do so.

Air filter? same.

After you do this and still no change, then go on to the more complicated things like sensors, fuel pressure and compression.

[skinner1980]

OK. I can't find vac. leaks. I checked the cap and rotor and they looked pretty good. The wires look pretty old and when you push them onto the plugs you can feel a few clicks, but on 1 of them it doesn't/ And it fits on the plug a little loosely. the little wire in the end of the cable that secures it to the plug is missing on 1 cyl. Could 1 cable being a little loose cause that?

[coolbear1]

If so the plug on that cylinder should have a black sort of sooty appearance and the ones that are firing a grey ash look.