PCM/ECU swap help

harold · Sun Nov 25, 2007 3:16 pm

My wife's ZX3 is running on 3 cylinders and based on the troubleshooting in the manual I need a new computer. I did the troubleshooting steps outlined and also swapped out the injectors for known good ones just for good measure.

1) Do I need a computer with exactly the same box code or can I get any computer from a Zetec Focus? I know that in EEC-IV Fords there were ECUs with different box codes that were interchangable.
2) Are the key codes stored in the computer or in an external box like the keyless entry? If it's in the computer itself, what do I need to do to make the computer work with the existing key?

I tried swapping the PCM from my 2000 ZX3 into hers and vice versa to verify that was the source of the problem, but neither car would start with the PCM from the other. I don't know if this is because of the key codes or because the box codes are incompatible. Anybody willing to help me out, here? We're down to 1 car and I have to drive all over the place for work, so it makes it hard to carpool.

harold · Sun Nov 25, 2007 7:43 pm

I've talked to Al and he's got a computer with a cylinder and key I can buy (and the number of a guy who will reprogram), but I just need to know if the computers are pin-compatible. It'll be from the same 5sp 4-door my new engine came from (I don't recall if it's a 2000 or 2001) and it's going into a 2000 ZX3. If I have the computer and the key with a matching cylinder, is there anything else I'd need to have it start up right away? I'd like to be able to swap this stuff in tomorrow afternoon if it'll work so my wife can drive her car again.

zurno · Mon Nov 26, 2007 5:21 am

sounds like a good plan

and I am sure the mismatched pats on thos ekeys is why swapping with yours didnt work

also, you might be able to swap out the pats thing from the key you get from al into one of your spare keys so that it wouild work in your current ignition cylinder, but I would be careful if you did. I have 1 key (an aftermarket one I think) that the cover came off that covered the pats on the key. I was able to remove that from it, so you may be able to do the same.

Redlineracer12 · Mon Nov 26, 2007 5:13 pm

Like zurno said I'd guess the PATS is whats giving you problems. You could try having the good key (programmed for the pcm you're putting in the car) real close to the ignition cylinder and then just using a non chipped key to turn the ignition cylinder. I've heard of that working, something about the computer just needs to find a valid key and close to the ignition is good enough. Otherwise if you could bypass the PATS temporarily you could try that.

I know with the Contours the PCM code changed every year and it was pretty important on those to have the correct one, they also changed a lot of crap though so I'm not sure it's relevant to your situation.

How about more information on the problem? Like more things about how its running? Are you only getting fuel in three cylinders? How do you know it's running on three cylinders? I'm just curious as to how you got to replacing the PCM. I did(still do) think the one in my Contour is bad but that was after an electrical short

zurno · Mon Nov 26, 2007 5:35 pm

another note is that if you get a non chipped key make sure it is exactly the same as the normal ignition key. I have a non chipped key that I think I got with my car and it is missing a feature cut into it lengthwise (a line) and I think that made it so it wouldn't turn the ignition cylinder.

harold · Mon Nov 26, 2007 6:02 pm

Redlineracer12 wrote:Like zurno said I'd guess the PATS is whats giving you problems. You could try having the good key (programmed for the pcm you're putting in the car) real close to the ignition cylinder and then just using a non chipped key to turn the ignition cylinder. I've heard of that working, something about the computer just needs to find a valid key and close to the ignition is good enough.

I don't really feel like getting a non-chip key cut for this, but I might do so just in case of emergency.

Redlineracer12 wrote: How about more information on the problem? Like more things about how its running? Are you only getting fuel in three cylinders? How do you know it's running on three cylinders? I'm just curious as to how you got to replacing the PCM. I did(still do) think the one in my Contour is bad but that was after an electrical short

It runs like shit and will die if you let off the throttle. It tosses a P0201 (which I asked about several weeks ago with my car and got no replies) and I followed the troubleshooting steps in the manual. The first step is to measure the resistance of the injector circuit that's tossing the fault. If that checks out, it's the injector driver. The circuit was fine and I even tossed the injectors from my old engine in there just to make sure it wasn't clogged or something, but it ran exactly the same way.

I picked up the computer and the ignition key and cylinder from Al tonight and I'm going to head out and do some swapping after dinner. I'll report back then.

Redlineracer12 · Mon Nov 26, 2007 8:44 pm

Good luck

harold · Mon Nov 26, 2007 9:03 pm

Well, I forgot the 1st rule of reading codes: reset and see if they come back. I reset them, but I didn't give it long enough to see if they came back. I'm thinking whatever made it toss that code was a transient. After swapping computers and starting it up, it ran the same for a few minutes and then cleared up a bit. I swapped the computers again and it ran the same. I reseated all the plug wires and now it runs how it did before all this. I thought I pulled the plug wires before to see if I had a dead cylinder, but the long day must have been getting to me.

On the upside, I got some other stuff from Al I'd been wanting to pick up and just hadn't gotten around to getting. And now I have a spare good ECU (which came with an SCT chip with unknown tunes on it) with a matching key and cylinder. The wife is happy, but I still feel a little dumb.

Thanks for your input, guys.

zurno · Tue Nov 27, 2007 5:09 am

glad to hear you got it fixed

Redlineracer12 · Tue Nov 27, 2007 9:14 am

Hey now you just send the chip in and have it re-flashed for your own tunes

I just got myself an SCT chip last friday.

Glad to hear it's running well again, that's all that matters.

harold · Tue Nov 27, 2007 4:15 pm

I've actually got an XCal2 (that I've never used). Now I could have both cars running different tunes if I really wanted. Both of them are daily drivers, though. I got the XCal thinking I'd be able to do tuning myself. I didn't realize at the time I'd need to spend almost $400 on the software to do real tuning.

I decided to take the wife's car to work today just in case something popped up. On the way in, the throttle cable started sticking, but only once. When I was looking at it last night I noticed the TB end was in trouble, so I know the next thing I get to replace on that car. I'm going to be in the garage tonight putting a clutch in a Merkur, though, so that'll have to wait for another day.

soul_hammer · Wed Nov 28, 2007 9:37 am

ohhh i want the merkur i love those cars. got any pics?

harold · Wed Nov 28, 2007 11:29 am

I don't really have any good pics. I've got 2 XRs in my garage right now, though.

soul_hammer · Wed Nov 28, 2007 1:43 pm

well ill take one and you can keep one then we can take this site over as MNMERKUR.com

lol

harold · Wed Nov 28, 2007 2:19 pm

soul_hammer wrote:well ill take one and you can keep one then we can take this site over as MNMERKUR.com

Sorry, the one I'm putting the clutch in is going to my brother-in-law in Eau Claire for his winter beater. Last October I was t-boned in that one and that's what prompted me to get the Focus. I'd done some upgrades on it (mainly the transmission), so I need to swap those into the one I just bought before he gets it. So I've got 2 XRs on stands without transmissions in them. I think I'm about ready to put the tranny back in the one that's going away.

Steve was razzing me about it when I pulled up in it to grab some parts. The old one looks and runs like shit, but the new one is in great shape. I can't wait to get some real mods going with that one.

Also, we've already got a group. :)