Bad idle/acceleration

[Gordon FAtula]

I have had the following problem with my 85 325e since I got the car. I have taken it to numerous shops and have been charged a LOT of money for their "opinion". The problem isn't fixed and I really need to have some direction as to where to start. I have replaced the following:
1. starter
2.fuel filter
3. timing belt (timing is perfect)
4. spark plugs
5. dist. cap
6. water pump
7. oil and filter
8. throttle body w/ spare ( not new)
9. head and new gaskets

The #5 spark plug is frequently fouling up and not firing. Put that plug into #6 and seems OK. But the real problem that has existed is that when first started it stays at about 300 rpm's. I think it should idle higher when cold and go down a little when warm. And when it's warmed up (let it run 5 mins. or so) you tromp on the fuel pedal and it SLOWLY goes up and then 'catches" at about 1800 rpm's and will run all day above that. At a stop it goes to 300 again. As it gets hot and hotter the car will start to backfire when giving it gas. And it won't even accelerate at all. When it cools down it will do this all over again.

Does anyone have an idea as to where to start looking for problems? I have tried as best I could soap lines etc. for vacuum leaks. I need help even as to where and what to soap. HELP, Guys!

[Jared at Pelican Parts]

If it were me, I'd replace ALL the vacuum hoses. idle problems on these cars are almost always vacuum leak related.

Second, did you do a compression check on the motor?

if you give me a call, I can go over with you everything you need to know..

1-888-280-7799 ex. 259

[Gordon FAtula]

I've replaced all that I can see. Isn't it true, though, that a vacuum leak would cause a fast idle situation, though? I probably didn't get all the lines. IS there a diagram somewhere that would help with this? There are a lot of hoses. And by the way, I can't see an o2 sensor anywhere on the exhaust. Is this normal? I know what they are and have replaced tons on all makes of cars and have always seen them on the exhaust, usually right on or below the manifold or header. I will call Monday morning too. You guys have always come through before so I have no doubt this will be sorted out. Thanks and talk to you soon.

[givot]

I'd definitely look for a vacuum leak. My daughter stared the 323i last week after she had been doing some polishing and had a 2500rpm idle until we found the detached vacuum hose.

I also have a Triumph Stag that had some loose hoses and this caused the same type of problems that you are having. The hoses tended to get looses or tighter depending on where they were or what they were attached to.

[Gordon FAtula]

Well, I replaced a heater temp sending unit that goes on the thermostat housing as I was told I should replace. Nothing. Still idles @ 300 @ start-up and as it gets hot it can drop 100 or so. Also seems to be hard starting when I do it first thing in the morning. If I floor it the throttle won't even go up at all. Like I'm not even pushing on anything.

Wouldn't a vacuum leak cause a fast idle condition all the time? I am having a long lag between 300 and 1800. This thing is starting to get the best of my patience. Of course it runs rich, too. When it gets really hot then it won't even go above 300 rpm no matter how much you try. It also has fouled out the #5 plug numerous times. Always sounds like it has a miss.

Could you have an internal vacuum leak? I hear a sound like rushing air in the big intake, sometimes. I also hear a fairly loud knock from either the rockers or the fuel injector.

If I can't figure this out soon then this car will be sold-CHEAP!!! Someone who has more patience and knowledge may have a lot more luck with it than I. Well, if anyone has any more feasible ideas I'm listening. Thanks everyone....