Pats 2 issues

[shadow460]

The mechanic pulled a bunch of codes from my 98 Sport, all related to Pats 2. Question is this: Can the anti theft system shut the vehicle down while in motion or does it just prevent the engine from starting? Mine had stumbled on acceleration and loped badly with the air filter packed solid. There are no other codes except those related to anti theft. Neither I nor the mechanic is able to clear them.

 

[J_C]

First we need to know the codes. It is highly suspect when a mechanic tries to give the abbreviated summary of what codes mean.

I don't understand what "loped badly with the air filter packed solid", especially "packed solid" means?

Regardless of what the codes are, the mechanic is not competent if he can't clear codes or that is what was told to you. Merely disconnecting the battery will clear them, BUT if the fault is still present, THEN the same codes will be generated again.

 

[shadow460]

The engine was loping, that is, the idle was fluctuating by about 1000 rpm up and down. I changed the mass air flow sensor based on advice I found here. That wasn't the problem, so I changed it back and changed the air filter while I was at it. The Haynes book says the air and fuel filter can cause idle issues if either one or both is stopped up. It turns out both of them were.
My mechanic believes the Pats 2 system may have caused the stumbling and loping. I disagree, I think it was the filters.
Certainly either one of us could pull the battery cable to clear the body codes, but with it we lose engine parameters and fault history. I'd rather clear them the right way.
In any case, something is messed up inside the driver's door making it so the perimeter alarm won't set, also the electric lock doesn't always work. I have flat metal keys with no transponder in them that can turn the ignition switch (no way I'm paying $50 for a spare key in case I lock mine in). The very first time I stick one of those in and turn it, it'll set that code again. It'll re set the codes for the driver's door.
I didn't know it could even store codes for this stuff... If I had I would have learned how to pull them so I would know why my alarm doesn't work.
What I need to know is can the anti theft system shut my engine down in mid flight. I've messed with a couple Explorers with this system, the only things I've seen it do is prevent the engine starting, flash the lights, and blow the horn. I've never seen one kill an engine mid stride like that--if it's anti theft related, everyone I know of who's had it had to have the vehicle towed to a shop. I drove mine in.

 

[shadow460]

Oh... I should have the codes available when I pick up the vehicle later today. I'll post them.

 

[J_C]

Hah, I should have realized what "filter packed solid" meant.

I would suspect the IAC needs cleaned or replaced, and don't understand how you have it running at all if you don't have a PATS key with the transponder in it. What exactly do your keys look like? The transponder is hidden in a thick black plastic key handle, is not in a remote control fob. It looks something like this:
https://www.amazon.com/Ford-Explorer-Transponder-Ignition-Programming/dp/B005I60GR8

If you mean that you had a spare made without the transponder, of course that might set a code if you tried to use it to start the engine but if that is the case then I don't understand why you're introducing this information to the topic, and IF that is the case then we can just ignore the PATS codes and focus on other codes.

However if I recall correctly, when my IAC started gunking up it wasn't setting codes yet, though I mostly noticed a change in idle RPM, especially when the A/C compressor kicked on, not so much a stumble in acceleration.

 

[shadow460]

Oh, yeah I have standard PATS keys also. The keys to my wife's truck and my Expedition are programmed into the Explorer's PCM in addition to it's own keys. A simple mechanical mod enabled them to turn the key switch so they'll all start it.
I've turned the switch with the non pats keys before. It'll also turn without a key in it, which is useful when I forget to roll up the windows.
I can pull the IAC off... it's right on top. I had it off last year when I re sealed the intake manifold.

 

[shadow460]

Got the codes:
B 1371: Illuminated entry circuit failure, was caused by faulty door switches. I replaced them a year ago.
B 1834: Door Unlock disarm switch. I noticed a coil of wire on the door cylinder when I replaced the latch mechanism. I think I put everything back but if that coil (an antenna for the key) isn't installed right, it will think someone is unlocking it with an unauthorized key.
B 1347: Rear window defroster. Some of the wires on the glass are broken. I'm too lazy to fix it.
B 1352: Ignition key circuit fault. My ignition lock is missing the plastic switch that tells the vehicle a key is in it... I saw this when I had it out to re key it. Again, too lazy to fix it but I have another key switch in my tool bag at work.
B 1834 door lock cylinder shorted to ground. Gotta be the weak driver's door lock. My ambulance at work does the same thing.
B 1483: Brake switch failure (BOO switch). I had c1155 when I got the truck, which is the left front ABS sensor gone bad. I fixed it with one pulled off my Expedition, which needed front hubs a few years back. The new hubs came with sensors and the old sensors were good so I saved them. They fit the Explorer if you splice the pigtail together. The ABS works great.
B 1152 hood switch shorted to ground. I'll check this.
B 1845 Ignition tamper circuit failed. If course, given the key in sensor is missing and I have non pats keys that I've cranked the vehicle with.
B 1562: Door lock cylinder shorted to ground. See above. I probably set it when I put the door latch in.
Mechanic says all those cleared. Now for the ones that didn't:
B 1600: Ignition switch on without key code read.
P 1260: Engine disabled by PATS
These are again from the non pats keys. They WILL get set again even if I have a locksmith clear it, so I'm not going to bother with them.

One other thing: It possible to remove the key with the engine running. I prefer this arrangement so I can leave the air going in the intense Oklahoma heat while I run inside the store with the key in my hand. That'll cause PATS issues if I put the key in sensor back in. My Expedition has the same issue: it let's keys out with the engine running and it likes any PATS keys that's been programmed into it regardless of what that key fits. It has a PATS 1 system, this Explorer has Pats 2. They are both '98 models, that one is an XLT with a 4.6 Romeo engine, this one is a Sport with a 4.0 SOHC.

 

[J_C]

Maybe someone else will see something I don't, but I still don't think it's PATS related.

 

[shadow460]

I agree. I think it wasn't getting fuel or air either one. Fuel pressure Saturday was 29.5 and went to 40 when I pulled the vacuum line off the regulator. Fuel trim levels are good, meaning no vacuum leaks. That 29.5 reading just screams clogged fuel filter.
My mower was doing the same thing, it has a 16.5 hp Briggs motor. I thought it was bad fuel at first. Cleaning out the mower's air filter fixed that problem and it idles better than it ever has since I got it last year. The mower lacks an ECM, PATS, RAP, GEM or any of that, though it does use a key and I do have power equipment with electronic controls.
Goes to prove there is something to regular maintenance.

 

[1998Exp]

I agree. I think it wasn't getting fuel or air either one. Fuel pressure Saturday was 29.5 and went to 40 when I pulled the vacuum line off the regulator. Fuel trim levels are good, meaning no vacuum leaks. That 29.5 reading just screams clogged fuel filter.

Someone correct me if that's wrong, but fuel pressure going up by 10 psi when the vacuum line is disconnected seems perfectly normal to me. The purpose of that connection is to adjust the fuel pressure to a certain value above the manifold pressure (since the fuel is injected into the manifold). At idle the manifold has about 20 inches of vacuum, which translates to about 10 psi. When you pull out the vacuum line, the regulator "thinks" that the manifold vacuum is zero (a full throttle condition), so it increases the fuel pressure by 10 psi.

 

[shadow460]

Yep, it's normal. Pulling the vacuum line tests the regulator. If there's no change or if you get squirted with fuel, the regulator is bad. The result I got indicates the regulator is good.

 

[shadow460]

I'm going to call this case closed. The vehicle does still try to stall occasionally at low rpm. It died in the driveway yesterday when I backed it up and turned hard out of my parking spot. It didn't have the terrible loping problem this time, it just died when the transmission engaged into first year. I saw the tach hit zero while I was backing up the hill into the driveway but the engine didn't die.
I pulled codes again at home, nothing this time except I/M monitors incomplete. Remember I can't see the body codes on my Bosch 1200 but my mechanic said he couldn't clear the engine disabled PCM code that I was seeing, now that code is gone. I think he actually did pull the battery cable at some point.
I think once the drive cycle monitors are complete the idle will clean up, or, eventually a PCM code will be set and I'll go from there. I half expect to find a vacuum leak but that'll be confirmed by seeing P0171 and P0174 somewhere down the road.
Anyway I'm fairly certain this is NOT a Pats 2 problem and never was, although the system did show that some non essential work needs done.
I don't want someone finding this thread five years from now and thinking that changing a mass air flow or idle air controller will get their truck running when the anti theft light is flashing... it won't.
The initial problem was horrible idle and acceleration with no codes, my response was first read the PCM codes, then check throttle position sensor with the scanner, check fuel pressure, check actual mass air flow using the scanner and MAF sensor, then change the air and fuel filters (and fix a flat). I went from the horrible idle and acceleration to excellent acceleration and mostly stable idle (500 to 650 rpm) with one actual stall in the last week.

 

[shadow460]

By the way, when I checked, fuel pressure was 29.5 psi and mass air flow was .3 lb/min. The actual mass air flow value is bad, it is now between .7 and .9 and the sensor is doing its job.