1985 325e runs great but take off and shifts, bog...

[Lizard 1]

So, got my awesome 325 running good. Has a full system with headers on it. When I take off, initially, a bog and then she hits and revs through up to red line if I desire. Then every shift, when I first let out and feed it fuel, she bogs and hits back to normal.


Any thoughts? It has a few things different other than the exhaust. The previous owner disconnected the charcoal canister and appears the ICV is not there and has been plugged off. It has also been a daily but even before I put the exhaust on it, she had the stumble. Not as pronounced.


I also put in a new O2 sensor if that would even matter...


Outside the initial stumble, she runs awesome! Just annoying.

[Lizard 1]

Nobody has any input or thoughts?

[MB07]

Have you done a stomp test?

Can you get an ICV to test with? Mine ran like garbage when I got it but after I cleaned my ICV it ran much better.

[Lizard 1]

Have you done a stomp test?

Can you get an ICV to test with? Mine ran like garbage when I got it but after I cleaned my ICV it ran much better.

The ICV is not even there. Or at least I cannot seem to find it and the hose that leads to the throttle body is plugged...


Now, there is a vacuum oriented thing on the driver's side fender next to the air box. Has a vacuum line and looks to be a valve. Is that something that can be cleaned? Not sure what it is called...

[Lizard 1]

Also, food for thought... I think it’s running really rich. It’s got a full exhaust and headers. Not sure that would cause issue as the system should compensate for it.

But, sometimes, she gets really boggy and acts almost like she’s getting too much fuel and I try to rev it out and nothing but black comes out until she clears up. On the boys at take off and between shifts, same deal. Not white or blue. Black which is indicating fuel.

Any thoughts as to that? Seems to be some type of either MAF or fuel delivery deal. Has had the fuel pump replaced and not sure what was used. Whines a ton when on and running but I would think if it were a fuel pump, she’d be rough all the time.

[e30davie]

sounds like a motronic system.

1 - fix all vacuum and air leaks
2 - stomp test to find codes
3- check the temperature sensor to see if it is within spec.
4- check the AFM resistance to see if its in check

Report back when complete.

[dsphil]

You will need to install the ICV back regardless. Otherwise you can only set the idle with the throttle partial open and the throttle switch maybe always on. The ECU will running with open throttle all the time.

[Lizard 1]

You will need to install the ICV back regardless. Otherwise you can only set the idle with the throttle partial open and the throttle switch maybe always on. The ECU will running with open throttle all the time.

Any thoughts why the previous owner/owners would have eliminated this? Like I said, it runs great, but loads up. Sometimes, I will come to a stop and she will idle perfectly fine. However, when taking off, she bogs and almost stalls and then barely idles and I cannot give it any throttle or she wants to die. Idles for a period of time and then seems to clear out and I can feed throttle and then take off. Loads of black smoke trying to start it as it dies several times.

[101]

The eta ECU can't be stomp tested.

On our eta we chased sililar demons for quite a while. The best medicine I found was following the Bentley manual and testing all the sensors and pins where the harness connects to the ECU (and at the idle control module). Checking in this manner allows you to assess both the sensor and the wiring harness.

Finding a friend with an eta where you can swap individual components one at a time until the problem is isolated would be another option, but a little harder to accomplish

Can you post a few detailed pictures of the engine bay and odd/missing components?