Symptoms of a vacuum leak?

[nyc525iTe34]

What's up Guys,

I've turned to this forum in the past when I had some troubles and hoped that someone here might be able to provide some advice/expertise with what's currently ailing my old lady - 1993 525i Wagon.

My guess is that I have some sort of vacuum leak issue (symptops detailed below). Initially, I thought that I could have an issue with a faulty Idle Control Valve (changing idle sound while coming to a stop) or a transmission fluid issue (momentary delay in excelleration in reverse). Now I seem to think that I have a vacuum leak issue of some sort. There seems to be some relationship between the fluctuating sound I hear, the delay in acceleration and breaking but I can't pinpoint exactly what it might be.

Hopefully, someone can be more exact and point out 1) where the source of the leak might be coming from, 2) what I might need to fix it and 3) a general guess on how much the parts might be.

SYMPTOMS:
1) Just before I come to a full stop at a light the car emits a sound as if the idle is decreasing and then increasing. (Idle Control Valve issue?)

2) Whenever I slow down in traffic to almost a full stop (but not a complete full stop) and then put my foot on the gas (ever so slightly) there seems to be a momentary delay in acceleration followed by a sudden jolt and then the car accelerates. The sound that is emitted during the delay is similar to the sound that happens when you place the car in neutral, step on the gas ever so slightly to accelerate - engine revs but no movement.

3) Several times over the last couple of days the car has stalled. One example was when the car stalled while I was slowing down at a stop light and the light changed just before I came to a halt and as I was going very slowly without my foot on the gas or break the car suddenly shut down. The car started with no issue.

4) Whenever I am parking the car I put the car in reverse and have to wait a second before I can actually move in reverse. If I do not wait a second the car will not move when I put my foot on the gas pedal.


Thanks!

[e34.535i.sport]

Is it an Automatic? Sounds like the last symptom would be related more to the gearbox if so?

Symptom 2 sounds may be related to the fuel system - pump/pressure?

Hopefully others will be able to be more exact for you...

[nyc525iTe34]

Is it an Automatic? Sounds like the last symptom would be related more to the gearbox if so?

Symptom 2 sounds may be related to the fuel system - pump/pressure?

Hopefully others will be able to be more exact for you...


Thanks for your reply-post. Yes, the car is an automatic (should have noted that in my initial post).

Your guess is as good as mine at the moment. Hopefully, someone will respond to my post with a more specific diagnosis.

Thanks again.

[ScottyWM]

Did you do a stomp test and get any codes? Sounds to me like the idle problem is the throttle position sensor, check out my thread when it happened to me. And it did eventually even stall because of it. The Bently has a good test method in it. Very easy test and fix.
http://www.bimmernut.com/forum/showthread.php?p=237447#poststop

The reverse lag time is pretty normal for this tranny, how many miles you got on your car? I forget exactly what the cause is, a leaking gasket in there somewhere I think. You should be able to search it out here. Someone had a really good write up on it. Mine does it the first time in reverse after letting it sit for a few days, but if I drive it everyday it's not even noticeable. Mines been doing it for at least 50k miles, and hasn't even gotten any worse.

Hope you get it sorted out.

[nyc525iTe34]

Did you do a stomp test and get any codes? Sounds to me like the idle problem is the throttle position sensor, check out my thread when it happened to me. And it did eventually even stall because of it. The Bently has a good test method in it. Very easy test and fix.
http://www.bimmernut.com/forum/showthread.php?p=237447#poststop

The reverse lag time is pretty normal for this tranny, how many miles you got on your car? I forget exactly what the cause is, a leaking gasket in there somewhere I think. You should be able to search it out here. Someone had a really good write up on it. Mine does it the first time in reverse after letting it sit for a few days, but if I drive it everyday it's not even noticeable. Mines been doing it for at least 50k miles, and hasn't even gotten any worse.

Hope you get it sorted out.


Thanks for your reply post. Yes, i've solved the issues I had. After further inspection with my specialist we determined that the problems were caused by the following:

1. Rear transmission oil pan gasket was leaking and needed to be replaced. Once this was replaced and new transmission fluid added I no longer felt the transmission slip and the engine idle sound did not fluctuate when coming to a slow stop.

2. Smoked the engine to check for vacuum leaks and found that there were several leaks - the major one being a large gash in the Air Mass Meter Boot (which needed replacing). This fixed my problem with poor acceleration and loud engine air noise.

3. Checked for oil leaks and found a couple - had to replace the o-ring seals for the rear oil cooler line on the transmission which was dripping onto the oil sensor. We also had to change the seal on the oil dipstick tube.



Thanks to everyone who replied to this post!