bought a slightly used afm. How to set idle screw

[the bob]

I know

leave it alone.

Now I have bougth a slightly used afm off of ebay to help solve a fuel injection delema. I have no idea what adjustment has been made to the new afm. Are they set at the factory.

Does anyone have a set point for these things. How many turns from the bottom for example. I am not sure.

Do I have to set it while it is hooked up to a CO meter or something like that.

I hope that this sets it up nice.

A tps adjustment, new o2 sensor, temp sensor and afm should cover most of the bases I would hope.

Also about how long to afm last before they get tired and start to go out of range.

As always thank you for your help and input



bob

[325beast]

On some AFMs there is a number cast into the metal next to the CO screw hole. For example 22,6. For some cars this indicates the base depth for the screw, in mm. not sure whether BMW uses this, but other marquis that use Bosch AFMs use this measurement.

[EtaSport]

It has been my experience that the screw is turned all the way in from the factory. If you begin to unscrew it, you will be letting more 'unmetered' air into the engine causing a leaner mixture and lowering the idle speed. It will also tend to pop and sputter a bit. Letting the minimal amount of unmetered air into the engine and letting the computer take care of the rest seems to be the best thing to do.

what sort of problems are you having?

[the bob]

Thanks for your reply and concern

I have had an irregular idle with alot of smoke several weeks ago. Since then I have been ordering parts. The tps was not engaging at idle so I adjusted that and then the car would race up and down form normal or so to about 2000 rpm

I then adjusted the throttle stop screw (which I should have left alone)

I brought it to my mechanic friend (70 year old german man) He thougth that it could be the afm so I bought a slightly used one off of ebay as well as put in a new oem o2 sensor. (I had just put in a universal one that goes those old fords.)

Now I am waiting to get a new throttle body gasket and the afm meter and see what that does.

Ithe car has been running alot better but I get a o2 sensor code when it warms up and idles. I am thinking that the afm might be screwing up the idle mixture. So I will look for vacuum leaks (changed the pcv hose and oil filler cap) and adjust the tps a liittle closer. I think it stays on off of idle more that it should although my mechanic friend said it should be ok. While I have it off to get the throttle stop screw set I will reevalute the tps. Some have said that they get oil in there. what can I clean it out with that wont gunk it up. contact cleaner I am considering or brake cleaner.

Also how should I clean up the throttle body is a consern. I want those springs to work as well as they can so that I can set my tps just right.

as always thanks for your help.

I am still unsure of how to set the idlle screw.


thanks again

this is my first car with electronic fuel injection I have always owned diesels



bob c

[AdamF 88iS]

Set the idle screw to hold it just as the butterfly is touching the throttle housing. You don't want too much contact because the butterly plate edges will get dulled over time.

[EtaSport]

He's right in the idle setting.

I actually have been having the same problems as you. Almost exactly.. Now let me ask you if its cold where you live at the moment. I have discovered that my car idles higher as the temperature decreases. Last week it was in the high 60s and my car was running perfect, idle around 750. This week in the teens and idling around a grand or more.

I have swapped afms from a working eta motor and got no difference. I checked all vacuum lines, and ports. I also replaced my o2 sensor with one for a Ford, which seems to work just fine. That made a little difference but not much. I also swapped ecus and got nothing.

I have noticed that when I unhook the coolant temp sensor, the car will run with a normal high idle for a few minutes (about 1000rpm) but instead of coming off high idle and running at 750, it stays there. If i plug it in, idle goes down, unplug, comes back up. I attempted to check the sensor, but my ohm meter tests did not even work. I didnt even have continuity. If someone know how to check these things and untimately thinks this is wrong please let me know and I will replace the sensor immediately. I have not replaced it yet because I cannot conclude that this is the problem with my idle, so I dont want to spend money on something I dont need.

This seems to be a problem with the eta motor, and I really havent discovered a fix for it through my searches. For now I live with high idle, but I will dig deeper into this when the frigid cold and snow takes off.

[the bob]

Thanks for all the help.

I should be getting the parts in this week so hopefully I can fix the car. Chasing down fuel injection issues does not seem to be a simple simon procedure. I imagine that there is going to be some trial and error. These older cars do not, to my knowlege give specific enough codes. The simplicity of the system does make it easier if you are going to employ the remove and replace phylosophy as there is not as much stuff to change out.

Thanks again

bob

[EtaSport]

Do you have an 'i' or an 'e'? Just though to check out the cold start injector if its an e. Sometimes they leak, as i suspect mine may be doing, that would cause high or irregular idle. Good luck, let us know what you find out.