corelokt

Well, here's my problem,
Bought my daughter said vehicle and told her daddy could make it right...
Turns out I may have been wrong. It keeps throwing the P0505 code, despite a new sensor and a fabbed o2 simulator. I tried changing the front O2 sensor as well. I then hollowed the cat. as I figured it would need one anyhow and I am running the simulator for now trying to get it to run without throwing the code.
I've also been getting the Idle Air control code. I cleaned the throttle body and valve, no go. I swapped out the control, no go.
I've sunk more than the vehicle cost ($300.00 with a solid body) in to it so far.
2 tires $200.00, stainless muffler $65.00, O2 sensor $75.00, Idle air control $75.00, O2 sim, $30.00, Muffler clamps, brake lines and fittings etc.
How do I lose the @#&&#@ codes?
Anyone know of a person who can program the PCM to pass inspection? It is sure running strong and clean, the low end torque sets you back in the seat. I just need it to pass. I've weeks I didn't have into this.
__________________
Veteran of Desert Storm. Army Res, Naval Res, Sea-Bee Res, NY Naval Militia.

Radi

P505 is an Idle Air Control malfunction. Are you getting other codes as well? If so, which ones?
Since you've replaced the IAC ...try rebooting the PCM:

• Disconnect POSITIVE battery cable and touch it to chassis ground for at least 30 seconds.
• Reconnect battery cable.
• Turn the key to ON. (not start)
• Turn headlights ON.
• Turn headlights OFF.
• Turn key OFF.
• Stand on your left foot, touch your nose with your right index finger and sing verse one of the Beer Barrel Polka.

Ok...I made that last one up.
The rest should reset your PCM and clear out any stubborn codes. Let's see if it comes back after that.

rrich

"""""Stand on your left foot, touch your nose----"""""
That will reset the codes better than the rest of that procedure. Sorry, internet bull!

It takes at least 8 hours of battery disconnect to reset the PCM on the OBDII versions. The old Renix, just cycle the key off once - it has no retentive memory.

He'll never pass cheating like that. if he does manage to pass he's subject to a big fine and even jail time if caught - Violations of State and Federal laws!

Daddy will fix it?

Radi

Good to know. That is FWIW the method that Quadratec recommends:
http://www.quadratec.com/jeep_knowle...article-89.htm
and I've used with normally positive results. But it wouldn't be the first bit of internet knowledge to be confirmed in a circular fashion. Like the Locomotive engineer who sets his watch to the town clock...which the town clerk sets to the train whistle...and both being positive the time is correct.

Now I'm curious what they use for memory devices in the PCM. Bet they've got steering diodes in there too, come to think of it. May have to melt the potting compound out of one and take a look.


I suspect there is more going on here...OP mentioned a IAC code, but is changing o2 sensors along with the IAC.
Waiting to hear what other codes are involved. If it's an o2 sensor code that keeps reappearing, the simulator/gutted cat is probably why. (which will likely not pass a sniff test, and may or may not pass a visual)

rrich

They've been promoting that wive's tale for years.

Easy to see if you have a scanner that will go into the deep memory, or a data link to a laptop (see below.)

That method clears the codes - the surface memory, but it does not reset the "learned" deep memory. The deep memory is protected behind diodes - so it doesn't lose everything on a quick disconnect - like switching batteries, running it down with the headlights, temporary glitches, using a winch etc. The capacitors that keep the 'keep alive' memory alive are behind diodes, so externally momentarily shorting the power does nothing. With no power applied they will slowly discharge by themselves, forgetting everything -- (like Alzheimer's.)

The learned adaptive memory is what adjusts the PCM to slight changes in parts values, altitude changes, tire sizes, accessories, fuel, humidity, temperature, and even driver's habits. It learns what you have and adjusts to the best situation. When you think about it - it's impressive and intuitive.

When a sensor starts to go bad, the PCM "compensates" as best it can by learning about what that sensor is doing. That info is remembered by the adaptive memory.

When you replace that sensor, the memory and PCM don't know it - so it still acts like the old sensor is still in it == that sometimes causes all kinds of strange things to happen. It slowly learns the new sensor - but that can take quite a while. --- One reason new parts are often thought defective and returned. Always use quality parts and reset the computer.

I use the example - a low right front tire causes it to pull to the right. You get used to it after while and compensate by pulling left without thinking bout it.
Then someone fills it up - but you still adjust it to the left when it's no longer needed - now you 'think' it's pulling left till you get used to it. Habits are hard to break. Hey - I thought we are supposed to be smarter than computers! LOL

An 8 hour disconnect - 12 is better - resets the PCM back to default - like it came from the factory. Then it learns again from there.

Like your PC just closing the browser can cure some ills (like the quickie disconnect) but turning off the computer power then restarting/rebooting does lots more.

Often if the deep memory is not cleared, the same code returns - even though it shouldn't now. It's just telling you what is/was wrong without knowing you already cured it.

Ever have the wife remind you of something after you already did it?

Often when one code sets, it sets other codes with it. Everything inter-reacts. You'd think lots of things have failed.
In that case, I've found to find the original code - clear them all - quick disconnect. Then watch close - as soon as the CEL light comes on, shut it off and read - you'll usually just have the one that's the real culprit - fix that, clear it, then try again. Often the others never come back.
But as good practice - do the 8 hour disconnect to reset everything.

BTW - after resetting everything, it my not run perfect - drive it - both hard and easy, and let it idle - it will quickly learn and run great within a few miles.

Look on ebay - you can get a data link that hooks to your PC or laptop - $20? And it includes software. You can get deep inside the PCM - see how it works, and can even change a few things. Then look for more software for it - lots is available for free or super cheap.
At first I used an old obsolete computer I had. I mounted it on a roll around table.
Now I use an old laptop - a little more convenient. It does not have to be fast or modern -- old and tired (like me) works fine.

It's a great way to learn. In the future automotive computers will become more and more sophisticated. Learning the basics now won't hurt.

XJPhoenix

^^^This post...^^^

And then everyone os soooooooo surprised when shows up.