What controls the injectors? | Ford Explorer Forums - Serious Explorations

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What controls the injectors?


March 15, 2015
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Year, Model & Trim Level
2002 Explorer
Alright, so after battling with my '02 Explorer XLS for ~6 weeks, and having the head gasket and all timing assemblies replaced (and timed), I think I've got it narrowed down to what the problem is.
Right now it will turn over all day long but won't even attempt to fire.

I've got fuel; tested with a fuel pressure gauge.
I've got spark; tested it by pulling a plug and grounding it etc.
I've got compression; did a compression test today.

When I spray starter fluid into the throttle body, it starts up immediately (then dies, obviously).

So, I've got fuel coming to the fuel rail, and seeing as I doubt ALL the injectors went bad at once, it must be whatever controls the injectors that is faulty.

So what would I replace?
I tried swapping the ignition relay (the gray relay) and that didn't do it.

Any help is greatly appreciated,

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On my 2000 Sport when anti-theft is active the PCM disables the fuel injectors. Many members have problems starting their vehicle when they have a defective after market alarm system, after market remote start system or a key not recognized by the PCM. Have you disturbed either of the first two since the last time the engine ran? Are you using a known good PATS key?

Before I had all this work done, it would run; very poorly, but would run.
And now that I think about it, it hasn't run since I ripped out the stupid aftermarket alarm it had in it.
Veeerrrryyyyy interesting.

So how do you remedy that? I've only one key to the car, and I have no idea what type of key it is (PATS, etc.)

PATS key

My PATS key has "Ford" inside an oval embossed on both sides of the key. The key has black plastic about 1/4 inch thick at the key ring end that contains a microchip. Is your THEFT light flashing rapidly?

I'm not familiar with aftermarket alarm systems. You'll probably have to figure out how to restore the stock start capability. Do you have electrical wiring diagrams?

PATS wiring diagram

2002 Explorer PATS related wiring diagram:


Oh god, I get irritated just looking at that diagram... I hate wiring.

What I did was rip out the aftermarket alarm because the key fob that I got from the previous owner was missing the buttons, and nothing even had a company logo on it, so I just wanted to return it to the stock keyless system so I ripped out everything aftermarket and bought two keyless fobs from Amazon and programmed them, and now the car locks and unlocks just like factory (even beeps the horn and stuff when you lock it).
Luckily they just spliced into the factory wiring and didn't cut anything, so it's all back to original now.

My key is a plastic key with the Ford Emblem inside an oval, but I have the feeling the aftermarket system altered the key to recognize it rather than the factory PCM.

So basically, I have an Explorer with a stock alarm/keyless system, and I need to get keys programmed for the car to recognize so it will start... correct?
It can't be that hard; what if you were the original owner back in 2002 and you lost your keys? Surely you wouldn't have to do a bunch of wiring.

A quick google search makes it sound like you can just buy something that disables the PATS system from Amazon. Anything wrong with going that route?

PATS disable

The only way I know to disable PATS is by getting a custom tune that turns it off in the PCM. If it was easy to disable it wouldn't be an effective theft deterrent. Some owners tape a PATS recognized key near the PATS receiver which allows any key cut for the ignition lock to start the engine. Anyone that purchases a PATS vehicle should demand a minimum of two keys or reduce the price $200. It takes two keys to program another key without a special machine. I always have three keys so if I lose one I can program another without going to the dealer or a PATS qualified locksmith. It takes about 10 to 15 minutes to program each of the first two keys with the special machine. It only takes about a minute to program a third key using the first two keys.

Are you sure that you have a PATS problem? Do you have an owner's manual to learn about the Theft display?

Well I have an SCT tuner for my Focus ST; I just emailed my tuner to see if he can do a bypass.

This is seriously blowing my mind that it's this big of a deal, and that there's not a cheap way around it if you don't have any PATS keys like myself. I can't drive my damn car!

What is my cheapest option so that I can start the car? Do I need to buy two PATS keys from Ebay or Amazon and call an automotive locksmith?

And no, I do not have an owner's manual.

Imagine that you just have an Explorer that is in fine running condition, but don't have a PATS key... that's where I'm at. What would you do?

SCT programmer

If your SCT programmer is like mine then you have to restore your Focus to the stock tune before you can use the programmer on another vehicle. If you get a custom tune for your Explorer with PATS disabled then you can't use the programmer on your Focus until you restore the Explorer to a stock tune.

Many locksmiths will not program keys they don't furnish because of potential problems with aftermarket keys. Also, a dealer or locksmith may be hesitant to work on your modified vehicle. Since you have a code reader why not try reading your DTCs to see if the PCM "thinks" there is a PATS problem?

Hmmm, okay.
Unfortunately my tuner has been at SCT for like 6 weeks after suffering a broken LED screen... I should have it back this week though.

If I were to have it towed to a dealership, could I buy new new keys and have them program them? And how much would something like that cost?
If it's like $150 or something it's not that big of a deal. But if we're talking like $500+, I'll have to look into other solutions, because that's just not an option.

Also, you asked whether or not I KNOW I have a PATS problem... no, I suppose I don't, but it makes perfect sense.

I have fuel, air, spark and compression.
The car recently had the motor removed and all the timing assemblies replaced and timed.
It will turn over happily, but will not even cough. Yet when I spray starter fluid, it fires up instantly.
I know that fuel is getting to the rail, and at a respectable pressure; so really all that's left is injectors. I replaced the ignition relay and have swapped around basically every relay and checked all the fuses to no success.
I DID pull out an aftermarket alarm that included a rectangular box, which judging by the pictures of them I've seen, is some sort of anti-theft bypass module, and now that someone mentioned it I've realized that the car has not run since.

Seems to be a logical conclusion at this point, right? Unless ALL the injectors failed at once, it's nearly impossible for an engine with compression, spark and fuel not to do SOMETHING.

PATS description

I agree that since your engine runs briefly on starting fluid and that you have "disturbed" the alarm system that you may have a PATS problem. It would probably be cheaper to have a PATS qualified locksmith come to your house than pay to have your vehicle towed to a dealer and have them diagnose the problem. However, neither may take responsibility for the configuration of the alarm system removal and will probably charge you by the hour to investigate it. I still suggest that you try to determine (rather than just guess) if you have a PATS issue by checking the Theft flashes. Here's a description of PATS for your 2002:

The passive anti-theft system (PATS) contains the following components:
theft indicator
encoded ignition key
PATS transceiver module
powertrain control module (PCM)
standard corporate protocol (SCP) communication network

Principles of Operation
The PATS uses a specially encoded ignition key. Each encoded ignition key contains a permanently installed electronic device called a transponder. Each transponder contains a unique electronic identification code out of over 18 billion, billion combinations. The passive anti-theft system (PATS), also known as SecuriLock(R), uses radio frequency identification technology to deter a drive-away theft. This system is known as SecuriLock(R) in North America, Safeguard(R) in the U.K., and PATS in Continental Europe. Passive means that it does not require any activity from the user. The SecuriLockr System (PATS) is not compatible with aftermarket remote start systems, which allow the vehicle to be started from outside the vehicle. These systems may reduce the vehicle security level, and also may cause no-start issues. If equipped the remote start system must be removed before investigation of PATS related, no-start issues. Each encoded ignition key must be programmed into the vehicle's powertrain control (PCM) before it can be used to start the engine. There are special diagnostic repair procedures described in this section that must be carried out if a new encoded ignition key is necessary.

This system contains a new feature named Unlimited Key Mode. This feature allows a customer to program more than eight keys to the vehicle if they request it. Each vehicle in Unlimited Key Mode is set up with a special Unlimited Transponder Security Key. This allows all the customer vehicles to share the same keys, but no other keys from outside can be used to operate the vehicles. For an individual customer, any randomly selected Security Key is acceptable.

The PATS transceiver module communicates with the encoded ignition key. The module is located behind the steering column shroud and contains an antenna connected to a small electronics module. During each vehicle start sequence, the transceiver module reads the encoded ignition key identification code and sends data to the PCM. The control functions are contained in the PCM. This module carries out all of the PATS functions, such as receiving the identification code from the encoded ignition key and controlling the engine enable. The PCM initiates the key interrogation sequence when the vehicle ignition switch is turned to RUN or START. All elements of the PATS must be functional before the engine is allowed to start. If any of the components are not working correctly, the vehicle will not start. The PATS uses a visual theft indicator. The indicator will prove out for three seconds when the ignition switch is turned to RUN or START under normal operation. If there is a PATS concern, this indicator will either flash rapidly or glow steadily when the ignition switch is turned to RUN or START. The PATS system also flashes the theft indicator every two seconds at ignition OFF to act as a visual deterrent.

The PATS will be activated and will disable the vehicle from starting if there is a:
incorrectly encoded ignition key
damaged encoded ignition key
unprogrammed key
non-encoded key (key has no electronics)
damaged wiring
damaged transceiver
damaged PCM

NOTE: The PCM disables the engine for 20 seconds every time DTC B1601 is set. The
ignition must remain in the run position for at least 20 seconds before an
attempt is made to start the vehicle with any encoded ignition key. Check the
PCM PID ANTISCAN for this unprogrammed key timeout status.

NOTE: Large metallic objects, electronic devices on the key chain that can be used to
purchase gasoline or similar items, or a second key on the same key ring as the
PATS ignition key may cause vehicle starting problems and record DTCs under
certain conditions. If a fault cannot be identified, examine the customer's key
ring for such objects or devices. If present, inform the customer that they need
to keep these objects from touching the PATS ignition key while starting the
engine. These objects and devices cannot damage the PATS ignition key, but
can cause a momentary concern if they are too close to the key during engine
start. If a concern occurs, turn ignition OFF and restart the engine with all other
objects on the key ring held away from the ignition key. Check to make sure the
encoded ignition key used by the customer is a Ford approved encoded ignition
key (Rotunda is the only approved encoded ignition key).

Great info, thanks!
I spoke to a mobile locksmith today, and I need to see if there is an anti theft light at all; I can't remember and the car isn't with me.

If there isn't a light, does that necessarily rule out a PATS problem? I just don't know what else could be causing it not to start.

fuel pressure?

You really need to get a copy of the Owner's Guide so you have some idea how things are supposed to work in your vehicle. There are usually some available free online. Try searching.

When the ignition switch is switched from off to run the lights on the instrument panel should display. If they don't you may not have power to the PCM.

You posted that your fuel pressure was good. Did you measure while the starter was cranking the engine? The fuel pump is energized for a couple seconds when the ignition is switched on. It is also energized when the PCM determines the crankshaft is rotating via the crankshaft position (CKP) sensor. If the CPK sensor is not functional the PCM disables the fuel pump for safety reasons. You might try cycling the ignition key from off to on to off a couple times before cranking the starter. If the engine starts but doesn't continue running then clean the CKP sensor connector by disconnecting/reconnecting the connector a few times.

How old is the fuel in the tank? If the fuel has been in the tank for more than a year and you did not add fuel stabilizer it may no longer be combustible.

Have you pulled a spark plug after cranking the starter to see if it is wet from fuel?

So I went to go check the anti-theft light, and lo and behold, for reasons I cannot explain, it started, and has continued to start ever since. Hopefully the trend continues.
Had to fix a few things, but now it purrs like a kitten!

However, unfortunately now I've got an oil coming from the exhaust issue to deal with :(
When I performed a compression test, one of the cylinders was ~85psi and shot up to ~150 when I squirted oil into it (all others were 140+ dry and 160+ with oil), so I know I've got worn rings and probably one REALLY worn ring, but the amount of oil coming out was way more than I'd expect from just worn rings... gonna replace the PCV valve tomorrow, hoping that helps.
I know this truck has been BADLY neglected, probably for it's whole 140k mile life, so I wouldn't be at all surprised if the PCV valve is completely faulty, and it's one of the few basic parts I haven't replaced.

The PATS system is in the instrument cluster, not the PCM. Aftermarket tuners will not be able to bypass it. If you have the old alarm system, look to see if there may be a key taped in a box or taped to the harness. Also if you have another programmed key you can tape it to the column near the ignition lock cylinder to bypass needing to program keys.

PATS disable

The PATS system is in the instrument cluster, not the PCM. Aftermarket tuners will not be able to bypass it. . .

I don't know yet about your 2002 but on my 2000 with strategy CDE4 I can disable PATS with my SCT Advantage III software package and my X3 PowerFlash programmer.