Game of Please Diagnose my Problem

Bugsy969 · 08-17-2011, 10:48 PM

Hi, First thank you for all who Took the time took look at this thread.

I have a 1986 325e BMW that's getting up there, but still have life in it. I'm trying to pin point a problem that i think in the end will end up being a sensor, but which..

It had the problem of kicking and lagging, and bad ( you could push the gas down and it would bogg down and sit there, spiting and sputtering, and you'd either have to ease the gas off and then on, or wait..... and then it would run perfectly fine after that point for whatever gear or as fast as you want to go ) it did it only is lower speed and gear, and only on days when it felt like it (weather/temp/ humidity- i\m not sure) ... it would run great, then it wouldn't...

More recently, that problem isn't there as much ( or noticeable ), but on simailer lines... I tried it a couple times tonight just to understand how exactly it's functioning.. it will idle normally around 600 RPM.... and then drop to around 300-400 (almost stalling), then rase to around 700 and drop to 300/400, and repeat itself.. (when it decides to do this, i smell it is running very very rich..) During this i'd push the gas so it would sit at 2000 RPM, and in the process it would drop down a bit (300/400 RPM) and sit there, poping and gurggleing a bit.... and after keeping it there for a couple seconds, it will rev back to 2000 RPM and idle at that compleately fine with no pops or anything... then i'd let go of the gas, and it would idle normally around 600 or so. but then after a couple seconds it starts reving up and down and drop to around 300/400 and back up to 700.

when it decides to run like this/ if i hold the gas while driving, just at the point that it's not accelerating, but not slowing down, the car will some times violently kick, unless i raise/ or lower the Rev.

This leads me to a sensor problem. I could be Wrong, but it just seems that way.

So i was hoping you would know which one it might be

or what is is.

Thanks in Advance

Allan

Manolito · 08-18-2011, 05:33 AM

I suspect that you have two problems - an air leak and a temperature sensor, but that is just a guess. With symptoms this complicated and intermittent, you won't know for sure what all the problems were until it is fixed.

If it were mine, I would start with a basic preventative maintenance - cleaning, dismantling and examining all the air tubes from the air filter to the throttle. I would clean the MAF and the throttle body and the idle air control while it was apart. Also make sure to unplug the temperature sensors and make sure their connections are clean. This car used a manifold air pressure sensor as well, I believe, so make sure its electrical connection is clean.

When it is back together, spray some ether or propane around the intake manifold to see if there is an intake manifold vacuum leak.

That routine maintenance will eliminate a lot of the usual suspects on a car of this vintage. See what that does to your symptoms.

markdas · 09-15-2011, 04:58 AM

Is there any feedback on how you got on after following the good suggestions posted up? always good to know if things worked or you got some knowledge to share based on how you fixed it!

Beef · 05:06 PM

I have the same problem, it runs smooth when revving or slowing down but when trying to go steady it kicks randomly..

I own a 318 from 1983.. also, I know that my air boot is torn, I taped it airtight, that's probably the problem.

I also don't have a MAF, so the air boot goes straight from the air filter to the engine.. I thought every car had a MAF :/

Any help would be wonderful

edit: I also don't have a kat, is it possible that my lambda is causing problems?