PCM fault, injector turned on when shouldn't

[tripletdaddy]

Hi. I have a 95 Windstar with the 3.8 L engine. I have narrowed my problem of the #6 cylinder flooding and not firing, to the #6 injector being grounded to fire all the time by the PCM. It grounds the injector to fire at KOEO, keeping it open all the time draining off all of the pressure. If I turn the key on and off real quickly, I can keep the pressure up. Disconnecting the battery or the PCM eliminates the grounding, so I'm certain the grounding isn't caused by a wire to wire or a wire to metal type grounding due to some sort of wire damage. So, any suggestions as to what do I do to solve this? How do I read and fix the PCM without costing a lot? Would I be better off getting a used PCM?
Thanks

[shorod]

In some of our earlier conversations I didn't trigger on the fact that disconnecting the battery will cause the short to ground to go away. Likewise, the switching the key off to on rapidly doesn't always result in a ground condition. This means the driver transistor in the PCM isn't shorted, but still able to turn on and off normally. Maybe you should try unplugging the camshaft position sensor to make sure it isn't somehow stuck and telling the PCM to fire the injector. I'm not sure what other sensors would come in to play for base injector firing.

-Rod

[tripletdaddy]

Anyone know for certain if I buy a used PCM for my 95 van it will need to be reprogrammed or flashed or not? And what about a "new" one, like a reman, the same? The van does NOT have PATS, keyless entry, or a remote. If it does need reprogramming, is there anywhere or way that I can have that done without going to the dealer or paying the dealer's rate for this? Can it be done from your own pc?
Thanks

[tripletdaddy]

I have an exact replacement PCM as my original, number for number. I would think it should work as it is since it worked as it is in an identical van to mine. So........., can I safely assume I can just plug her in and go?

[shorod]

If you have it in hand, give it a try. If it starts, you're probably fine. If it doesn't start or it runs REALLY poorly, then you might be looking at needing reprogramming. It probably will run somewhat roughly at first as the computer relearns various parameters specific to your engine (fuel trims, etc.) similar to what happens after the PCM is reset.

Since you don't have PATS or another anti-theft system that gets programmed to the PCM, you will probably be fine.

-Rod

[tripletdaddy]

Thanks Rod. My feelings were already to go with it and my logic said it would be ok too. If anyone wondered, I won't have to worry about the IMRC since the Windstars didn't have that until 96. Just to be clear for everyone's benefit, I also was able to prove that the old PCM is the cause of the incorrect firing of and signal to the 6 injector. So my confidence is very high that the PCM problem is solved, just not sure if it really needs programming for whatever inane reason. I fully expect the rough "break-in" period simply because I had to disconnect the battery in the first place. Wish me luck. It goes in today!!!

[tripletdaddy]

A valid point Rod had made much earlier on this was what caused the #6 cylinder driver in the PCM to croak. So, I've been trying to track down any possible culprits. Unfortunately, there are quite a few things that are connected to the PCM, so that means checking the wiring to each, voltage to and from each and whatever tests to check the components. He thought the CMP is most likely the only sensor that might cause this short failure to the drivers, but I wonder about the CKP, too. I also wonder if the ICM is ok. Anbody have any suggestions? Ways to test the ICM? I have a Haynes and the Ford CD-ROM Service Manual, which isn't particularly user friendly, which annoyingly has you do procedures as if you are equipped with all of Ford's service equipment like a dealer.
Thanks in advance.

[searcherrr]

My newly discovered situation is nearly identical to your first post (including same year, make, model) with the exception of this:
"Disconnecting the battery or the PCM eliminates the grounding," - I bolded the PCM part because thats what I never did try, but I'm very confident the PCM is the problem.

I have the same annoying Ford CD-ROM too.

Flashing the PCM - There are certain Scan Tool type devices that do this. When ordering yourself or if the shop does it, they should Flash it before its shipped. I actually contacted Ford and they sent my request to their research department. My request was to obtain my specific vehicle Engine Calibration Code as it has worn off the sticker on the front valve cover. I was able to obtain the code, but I have not yet been able to find a OBDII scanning program that will show me what code my PCM is using. I might have to have a more advanced scan tool than just my ELM interface and free EasyOBDII software.

In any case its extremely important the engine is flashed with the right information so that the PCM knows its in a 95 3.8L Windstar and not a 98 3.8L Mustang or some other make.

As far as how many flavors of "flash" there are for the 95 3.8L Windstar (Mine's a GL and Fed Spec emissions) according to a company called SMPCORP.com who reman's PCM's there are 3 flavors. In particular their part number for my van (and probably yours too) is EM10104 and this part number (remanned PCM) covers all 3 flavors of flash type for 95 3.8L Windstar Fed Spec. Obviously other engine sizes and Cali emissions will change the "flash" flavor and SMPCORP.com's part number.

Only theory I could offer you is that at some point someone who did repairs in your engine bay mis-routed the PCM wiring such that it later needed to be repaired or maybe still needs to be. This was/is the case in my engine as someone had routed the PCM wiring harness over the EGR pipe and between the valve cover. This in turn re-merged/re-melted PCM wires over and over and over again till I found it myself when I decided to get to the bottom of this since the shop couldn't.

This is my 2nd PCM. The melted wiring by the EGR (I suggest you check your routing too, main harness should be UNDER the EGR pipe & off to the right NOT ABOVE the EGR pipe and off to the right) is what I am sure caused the 1st Original PCM to blow out, but the shop didn't know it at the time.

Given this problem you really cannot troubleshoot ANYTHING electrical reliably I feel beyond just plain resistance tests. After my 1st PCM blew, the IAC blew & the MAF blew out immediately and I was lucky I didn't lose a lot more. I figure I didn't lose more simply because the harness had become stationary after service.

Due to the unstable nature of "A BUNCH OF SHORTS" there is no telling what else connected may have been damaged so you just hope for a code or not hope for a code.

I too have wondered about the ICM and CKP as they are both the originals. To make matters worse the CMP was installed backwards on the exhaust stroke, a bad alternator was installed, caused the battery to go bad & ran like this for a while... simultaneously while injector 6 and others (2,3, and 5 intermittently; testing blew fuse "S") for a while were squirting constant liquid fuel into the engine.

I just looked up the CKP installation instructions and there doesn't appear to be a special way to install it, so it would come down to resistance testing it and doing whatever other tests are in the PinPoint tests list for Ignition on the Ford Cd-ROM.

If you are curious check out page's 14, 13, and as far back as you want in my current thread: http://www.automotiveforums.com/vbul...85#post5980085

I know you have fixed this (hopefully), but I'd be curious to know what CITY/HWY MPG you are seeing now and what your fuel pressure drop rate is after the engine is turned off.

I ask about the drop rate because I'm wondering if the excessive voltage to #6 somehow ruined the "NEW" injector I just put in and/or yours too. I have a theory, that due to prolonged durations of voltage that if the injector heated up enough it would be in an overheated state while the spring with the magnet inside the injector is held up top. So I'm thinking it may also get hot enough to stretch-bend in the upwards ("more open") position and then once it cools it may stay that way effectively ruining the spring.

The only problem with this theory is that I don't know how hot the injector would have to get to ignite the fuel flowing threw it.... IE: Get really really hot, but not ignite the fuel, but hot enough to stretch-bend or re-tension the spring into a more open position.

Its a theory of my own and have not seen discussed anywhere else. It may likely be impossible to occur, but I thought I'd bring it up because I disconnected all 6 injectors from the PCM at the main injector harness connector that feeds all 6 and then did a KOEO to build pressure.

Afterwards with all injectors disconnected I observed the following:

Fuel Pressure Drop rate: 2lbs every 6 seconds above 30lbs
Fuel Pressure Drop rate: 2lbs every 15 seconds between 20 and 30lbs

In addition, pressure drops sharply to zero within 1-2 seconds at KOEO and I would guess maybe also while the battery is connected AT ALL even if the Key isn't on.

Having previously observed the pressure drop rate of my old injectors, the rate was much slower at least over a period of 15 - 30 minutes till it got to nearly zero PSI. The rates above are with brand new injectors and are a lot faster.... though perhaps this is because the new injectors are cleaner and better flowing???

As far as testing the ICM or CKP you'd have to go into the PCED section of your Ford CD-ROM and go to PinPoint Tests and go to the Ignition tests. Browse through them to find the CKP and ICM stuff.

Until I have the situation with the injector(s) resolved I will refrain from any further testing cause I think the PCM needs to go and can only hope the melted wiring harness issues were fully resolved when found.