I fixed my high idle but now....

[Jeremy G]

Alright, so after all my testing and leak searching I decided I didn't have a vacuum leak. The only other possiblity was not enough gas. After reading up on how the manifold pressure sensor worked, I decided that had to be it. So I got the MPS from my parts car and put it on and what do you know....no more high idle but now I've got black exaust and the engine is stumbling. Now I'm too rich, right??? The idle adjustment screw and the f/a mixture on the brain don't change things much. I unplugged the cold-start value, but no change. I didn't check the temp sensor so that will next on the list.

The other thing that I am wondering, if I set the timing w/ a bad MPS in place, will the timing be off when i put a good one in?
Also the MPS that I put in might be bad also but to the other extreme and giving me a rich idle.

Is the only thing that causes black exaust and stumble a very rich f/a mixture?

What do you think JP, DD, John Rogers and everybody else?

Jeremy

[This message has been edited by Jeremy G (edited 05-04-2000).]

[JP Noonan]

Make sure it is the correct MPS and that it was unmolested by a PO. There should be a screw (about 1/2" dia) in one end that is covered in a yellow epoxy. This is an adjustment some people play with, when they really shouldn't. Also for the heck of it I put my 1.7L MPS on my 2.0L some time ago, and I remember it running much like you describe. So make sure the two MPS's have the same part number.

To test the MPS look at the D-Jet article on Tim's 914 fan web site. The resistence can be tested on the internal coils, and uses a vaccuum pump the diaphram should hold a low amount of vaccuum. Some people just suck on it to see if it leaking, not the most scientific way, but in a jam I guess it works.

[Germain]

You might want to check the pressure regulator for the fuel lines. Make sure that the fuel pressure is correct. I've seen my car act up like yours because of that.

And yea Im not JP, DD, or John, but my ideas still count... I think :P

[jmcleod]

i think your timing will not be affected by the MPS. doesn't the MPS just affect mixture, not distributor? the MPS may be connected to the vacuum but timing is supposed to be done w/vacuum disconnected (someone confirm this?)