IAB Question....
 

Are all IAB's created equal? Should a Wells brand work the same as one I'd buy from the Ford parts counter?

The reason I ask is because of a problem that popped up when I installed the Wells IAB.

My motor is stock with a B-303 cam/5-Speed. I didn't notice there was a problem with the old IAB; in fact, the idle was pretty good except when I would turn on the A/C, then the idle would drop and run very rough. Turn off the A/C and it smoothed right out. (as smooth as a "B" cam can idle)

I removed the old IAB, tested it and sure enough, no clicking or movement of the plunger. I installed the new Wells brand IAB, didn't notice much difference in the idle but now, with the A/C on, the idle doesn't dip and holds pretty good.

The problem I'm having now is: after the engine is warm, the idle climbs to about 1100rpm. That's not really so bad but the problem is that the idle hangs too long before settling in at 1100rpm's. With the A/C on, it doesn't hang as long and settles in at about 900rpm.

So far, I've cleared the computer by disconnecting the battery for about 20 minutes, cleaned the throttle body, cleaned the MASS air sensor, adjusted the idle position sensor to about .99 volts as well as adjust the idle stop screw as per my Haynes Manual. (.010" feeler guage plus 1 1/2 turns in)

As far as codes, I get an 11 (system pass) with KOEO and 44 & 94 with KOER, these codes both have to do with the Thermactor Air Control System. I'm not running cats and no air pump. The O2 sensors and fuel pump are a few years old, the fuel pressure regulator is stock.

Other than the 1100rpm and hanging idle, the beast runs great.

Could it be the Wells brand IAB or is there anything else I should look at?????
Thanks,
Phil

I hate well. Autozone products suck. The ford products are great.. thats my preference. But sound like you need to do the full idle adjustment procedure. you have to run the car without the IAB plugged in, with an idle of maybe 800rpm. then shut it of, then start it up without the AIB, then turn on the AC. Then shut it off, plug in the AIB start it up and it should be ok.. This is all done after clearing the ECM for about 20 mins. Besides any of this, check for vacuum leaks and fuel leaking into your vacumm lines from the regulator.

Try backing the TPS voltage down to 0.90-0.95V. It really doesn't make a difference whether it's 0.99 or 0.95V over time anyway. The computer will learn, but the 1.0V barrier should not be crossed. You could have a voltage drop in the very leads you're using to measure the voltage, so it's just plain "safer" to go lower.

The other thing I've seen is the computer does have a problem regulating idle if the ignition timing is too advanced. The supposed "Mass-Air Idle Problem" was cured for me by backing the timing off a couple degrees (to 12BTDC). If you really know an EEC's programming and how timing affects idle/throttle response, it does make perfect sense.

I am running at 14BTDC. I'll give those two a try.....Back the TPS voltage down to about .90V and the timing back to 12BTDC.

Will I need to reset the ECU?????
Thanks,
Phil

no you won't have to reset the ECU, just make sure you pull timing spout connector out when you adjust your timing.. However i think you TB is just out of adjustment.

Just got done adjusting the TPS to about .90V and backing off the timing to 12BTDC......

The Idle is now where it should be at about 900rpm but it still hangs too long at 1500rpm before settling in to it's idle.

Guess I'm back to square one on this one!
Phil

well thats good that your idle is ok. For the hangin, disconnect your mass air sensor for a sec, and see if it hangs.. The car will run rough, but you should be able to idle. If it doesn't you might have a dirty mass air sensor or flaky. If it still does it, check for vacuum leaks and Fuel in your Vaccum line for the fuel pressure regulator.

You shouldn't HAVE TO reset the EEC, but if it were me, I'd do it anyhoo. :)

I'm thinking possibly a MAF too, but usually they'll puke harder than this one is....hmm.....it's making my puzzler hurt!!! :(

Just out of curiosity, do me a favor and probe the voltage coming back to the computer from the coolant temperature sensor, both when cold and hot please. :) It might help me get a better picture if something's amiss.

I did reset the EEC, right after adjusting the TPS and backing off on the timing.

Is the Coolant Temperaure sensor located on the intake manifold on the drivers side? I think that's it but not sure.

Somebody else mentioned that if I uplug the MAF and the idle doesn't hang, it could be bad. Does that sound right?

Again, thanks for all the help.
Phil

Okay, I probed the voltage from the Coolant Temperature Sensor and got these numbers:

Engine Cold (KOEO): 5.0V
Engine Hot (KOEO): 2.8V
Engine Hot (KOER): 3.2V

I don't know why there's more voltage with the engine running.
Are these voltages within range?

Also, I uplugged the MAF and although the idle becames rough, it does not hang when I rev the engine. Is there a way to check the MAF?
Thanks again,
Phil

The MAF sensor is flaky, replace it. if its the stock one, get a new one for sure. Mine did the same thing and so did my 93 ford aerostar.

The voltage is higher running because the alternator increases system voltage. Here is some MAF tests you can run.........

tmoss,
Okay, I ran the tests you gave me and on the first two parts of the test, the voltage and resistance are within the specified range on the chart.

On the last test, it says I should have 0.2 to 1.5 volts, but I only measured 0.04V. The chart says the MAF "May Be" faulty if not within the range specified.

I wonder why it says "May Be Faulty" instead of "Is Faulty?"

Thanks,
Phil

Chances are it is..............you know how everybody hedges waht they say nowadays.