At my wits end Bad Idle M42

[1996 328ti]

What's next? Knock sensors?

This is the knock sensor closest to the front looks like.
Of course the original fault was for cylinders 3 & 4 further back.

Also found an interesting read at http://bmw3series.johnavis.com/blog/652/m42-engine-e36/
http://workshop-manuals.com/bmw/3_se...or_%28m_42%29/

[BimmerBum]

I'm at a bit of a loss but I still do not think knock sensors are the issue, I believe they are a symptom. Also, I still feel the best way to get to both knock sensors is with the oil filter housing off. I did it that way without issue.

What have you replaced on the ignition side of things?

Originally Posted by 1996 328ti

What's next? Knock sensors?

This is the knock sensor closest to the front looks like.
Of course the original fault was for cylinders 3 & 4 further back.

Also found an interesting read at http://bmw3series.johnavis.com/blog/652/m42-engine-e36/
http://workshop-manuals.com/bmw/3_se...or_%28m_42%29/

[1996 328ti]

I've replaced nothing regarding ignition.
I should add that I get 22 MPG last time I checked.

[BimmerBum]

Originally Posted by 1996 328ti

I've replaced nothing regarding ignition. I should add that I get 22 MPG last time I checked.

Last time I figured MPG in the ti it was just over 24mpg in town. I would do a visual inspection of the plugs and maybe replace them. I would also test the coils and wires. I suppose it would not hurt to test the knock sensors too. The knock sensor code is the only one you're getting?

[1996 328ti]

I got a knock sensor code once.
I'm not even getting that anymore.
I get a knock regulation fault and that's it. ???

Plugs are less than a year old.
Probably original wires.

[BRADESTAR]

I'd tend to think that the knock sensors are fine too. They are reading the stumbling engine.

I still would guess air/fuel or intake system. Is the second MAF still coming? Yours could be totally shot. Other than that, the usual air leak brake cleaner bit. Maybe be a meter to test fuel pressure at the rail?

I'm struggling to figure out how it is temp related. Maybe the fuel pump can pressurize the lines, but has trouble keeping up when run for a while?

[1996 328ti]

Here is the kicker.
It was fine other than poor gas mileage.
I go to Bimmerfest West for the weekend.
The car sits in the driveway on an incline downwards.
I come home and found these problems.

[1996 328ti]

Well being pissed at the car all week I had to move it out of the driveway to swap out a set of tires on my 96. Car wouldn't start. I knew the battery was old and it was only a matter of time. I jump start it and move it out of the way and let it run while swapping tires on my 96.

Oddly I noticed the idle stayed constant. ??
Could it be fixed?
I drove for a few miles and the car felt normal except for the exhaust sounding like a motorboat. It's a SuperSprint.

I get back to clear the fault codes.
Drive the same route and I still have a knock regulation fault.

I'll drive it back and forth to work this week because previously the CE would come and go. I want to see if that at least is fixed. Suspecting it was an O2 sensor.

[Jsch]

Hello 1996 328ti,

I had symptoms very similar to yours for about 2 years- I tried EVERYTHING, got to the point where the car wasn't even drive-able. I finally replaced the Intake Manifold Adjuster Valve. FIXED!!! This part is only available from BMW as far as I know. It was $365 from my local dealer.

This valve is located in the lower half of the intake manifold, just underneath where the two intake parts come together on the driver side. Its definitely worth a try in order to get a good running car back.

[1996 328ti]

Originally Posted by Jsch

Hello 1996 328ti,

I had symptoms very similar to yours for about 2 years- I tried EVERYTHING, got to the point where the car wasn't even drive-able. I finally replaced the Intake Manifold Adjuster Valve. FIXED!!! This part is only available from BMW as far as I know. It was $365 from my local dealer.

This valve is located in the lower half of the intake manifold, just underneath where the two intake parts come together on the driver side. Its definitely worth a try in order to get a good running car back.

I think I replaced that but it wasn't very expensive.

I'm going to swap out the MAF next.
Do you have a part number for the intake manifold adjuster?
The part I replaced was a small black circular part.

[Jsch]

I think what you are referring to is the PCV Valve. Which is a good thing to replace, but not what I am talking about

The part labeled # 6 is what you need.

As you can see, it inserts into the bottom half of the metal part of the intake.

I have my old part in my garage, and can post the part number after I get off from work!

[1996 328ti]

Maybe it's fig 6 on this?
11611734472

I think it was the PVC.
Well...
I swapped the MAF. Still sluggish at first. I won't really know until I drive for 15 minutes but I still have a Knock control regulation fault.

[Jsch]

I apologize, I have a different engine than you do, I just noticed yours is an M42!! The part in the diagram you posted I believe is called a vacuum box. Maybe that would help?

Perhaps it is your knock sensors-I think that when the sensor detects knock in the engine it will retard the engine timing a bit to try and prevent damage to the engine. A knock sensor that is reading incorrectly will cause a crappy idle. I've replaced it in my M44, not a terrible job to undertake.

I hope something works for you!

[1996 328ti]

Could be knock sensors. I was also told it could be a bad ground as well as the injectors need to be cleaned.

The car seems better because last time I ran the A/C it would stall.
All the problems usually occur when it's in the 90s.
It's a bit cooler right now.

Next I need to fix my seat on my 96.

[BlackBMWs]

Originally Posted by 1996 328ti

Could be knock sensors. I was also told it could be a bad ground as well as the injectors need to be cleaned.

The car seems better because last time I ran the A/C it would stall.
All the problems usually occur when it's in the 90s.
It's a bit cooler right now.

Next I need to fix my seat on my 96.

Steven, have you checked the fuel pressure for your 95 when it's running?