Changed o2's...now what?

Clean your MAF.

fgtmustang95 said:

Clean your MAF.

Click to expand...

click on link below for info. on cleaning maf.

http://www.muscularmustangs.com/maf.php

If the car wont idle when cold, the IAC isnt functioning properly or getting the signal to letting it know that the engine is cold.

When you set the idle, it was done with the IAC electrical connector disconnected (and not the entire IAC removed) right?

What is the absolute manifold vac reading? If not near 20" hg, I'd wonder about more leaks (which could be between hard parts, not vac lines).

That's quite a slew of crap wrong though. A scope would be nice about now.
Good luck.

extremetrek said:

Thanks for the info...I don't have a vac gauge but I am thinking about getting one. Yes when I try to set the idle I disconnet the IAC connector, car hates it when I do that and the screw thing sucks so I can't adjust it at all...but the car still (normally) idles at 650 or so when it was running right...

Would this possibly be caused by a charging/battery problem? I know in an airplane when you run at low RPM you get a Low Alternator warning because the engine isn't turning fast enough for the Alt to charge the battery, is this true in our cars too? I have a very obvious bad connection to the POS terminal on the batter, sometimes so bad that the car won't start without me messing with the wires...when it doesn't start it has obvious battery power I turn it over and there is a spark from the POS terminal, a loud pop and all the electrical power cuts out which causes lots of things like the electric door locks freaking out.

My theory is that at low (idle) RPM the car tries to run off of battery power but the battery connection sucks so it surges...does this make any sense?

The car does not idle properly when warm or cold...but when its cold it starts RPM's jump to about 1500 then back to 400-500 the car will stutter and then kick it back up to 1500 a couple more times. I have noticed since changing the o2s the car runs better...at first...then after driving a bit it goes back into the same old routine..

Driving 1000+ miles in this car back to school in a week...really like to get this solved. Thanks for any help!

Click to expand...

Your airplane analogy is right-on. At low radial speeds (pulley speed), the alt does have low output. And if it gets low enough, the regulator begins to ground the switch/sense wiring that goes to your battery light and it starts to illuminate said light. I fought a round of this myself some time back on the 94. I had no surging - just low alt output and the clock, radio and something else would shut off when output dropped. I got my idle up and it helped a great deal.

Your battery cable could be causing all sorts of issues. You're right about the battery connection being an impediment to system flux. It's nice having a solid damper in the system, which the battery is if it has solid battery connections. The locks freaking suggests the battery loses continuity momentarily (second-tarily. ). I'd clear that up with new terminals [at a minimum] if the issue is those sucky factory hoops, and see if other issues abate or get better.

Seeing a cold idle of 1500 RPM tells us that the IAC is functional. For the idle adjustment, I use needlenose pliers to adjust the shank. Also, make sure your bleed isnt run too far out (for me, if I ran it all the way in and then backed it out, if I went more than like 1.75 turns outward, the car would surge). Put a little dab of paint or marker on each fastener and record adjustments and your baseline so you can get back to here from whereever you end up (or with two adjustments and other variables with the car not running right, you can end up in no-man's land).

If you have an AODE (I think I recall you do), I have had very good luck setting the idle with the IAC disconnected (hot motor, no accessories on). Get it to idle good like that (around maybe 700 RPM in DRIVE - remember park and Neutral raise the RPM). When you plug the IAC back in, the computer cant lower the idle because you similated zero IAC duty cycle when setting it.

That's about all I got at 2 am. Good luck John.

check the plugs; also is the rough idle in a cycle, i have heard that if its in a cycle then it is a spark or a fuel problem. good luck

you couldnt hear that?