Not for the Faint of Heart! Fresh Engine Swap Troubleshooting!

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MojotronGT

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So. I can tell you myself that I'm in over my head, so please don't tell me to take it somewhere. I'm tantalizingly close to victory with this thing..

1993 Mark VIII engine, rebuilt by the book and installed into a 1994 Towncar.
Immediate issue: No Spark. (continue reading)

Current state of the swap: Engine is in place, but not bolted down to the mounts because the exhaust manifold on the driver side will hit the chassis. That said, my setup is essentially replicating an engine on a stand. No Exhaust hooked up yet other than the manifolds. This includes the O2 sensors- they aren't plugged into the engine harness yet either.

Full intake tube is not on the car, exposing one vacuum line and one crankcase vent tube.

Purge canister solenoid is not hooked up.

Oil level /temp sensor is not hooked up.

Currently running the Towncar sending unit, so there's no "Fuel pump monitor" or high speed fuel pump for when the IMRCs open (whenever I get it over 0 rpm...)

A/C pump & power steering pump are not attached, but they are plugged in.

No belt on yet (re: A/C, P/S) so alternator isn't turning when I key it.

When I turn the key, the car will light up, fuel pump charges and a very faint whine will come from the driver-side engine bay. I've got plenty of fuel pressure, and a test light shows the injector wires appear to be getting a pulsed-charge when it's cranking, which makes me think my cam/crank sensors are good. My spark tester showed a very weak (but still pulsing) glow in the bulb when cranking, so I pulled a plug (and grounded the socket part) to see the spark and there's nothing visible going on at all.

The wiring is good (according to Ford) between the ICM and the coils. Coils are new, ICM is new, plug wires are new, plugs are new.

My main concern at this point is whatever security protocols this car had. The Towncar has nothing in that vein, but I've read concerns about that with the Mark VIIIs.

I have to say I was expecting a sputter out of it, but like I said- there's just no spark.

Pointers?

Thanks a Ton!
 
@97MarkJA - The engine harness is MarkVIII, except for the Alt charging cable. I used the TC cable because the batt is on the passenger side. The Intermediate Harness (42 pin square connector) from the Engine to the PCM, ICM, relay box and TC chassis power has been re-wired to to accommodate the TC body. I can scan and post my re-wiring diagrams after work.

So, Mark VIII PCM, Mixed Towncar and MarkVIII Harness.
 
Hmm. It sounds like I should re-consult my manuals before I make myself seem any bigger a fool.

I didn't use a donor Mark to do this swap, I've been picking up components as I go. So no, there are no MarkVIII Security components in the car right now. When I was studying the PCM wiring, I didn't find any leads that indicated anti-theft was directly involved with the ignition. Again, I do have fuel pressure and it turns over with no problem.

If there is something that could cause a no-spark condition, I definitely would like to know what it is. Thanks for your interest!
 
@Snapperfire Not exactly- I know they're getting 12V in "run" but I haven't watched the voltmeter on either of the coil driver wires with the engine cranking. I'll check that ASAP after work, thanks.
 
The Mark VIII passive security only serves to disable power to the starter solenoid, nothing else.
 
Small update

driller said:
The Mark VIII passive security only serves to disable power to the starter solenoid, nothing else.
Click to expand...

Well, that's reassuring, as the car will crank 'til the cows come home.

Didn't get to do much tinkering this weekend, but this evening I went out to test the signal to the coils.

As I stated earlier, both coils have the proper 12V in the Run and Start ignition positions. Each of the individual coil driver wires read ~4.8V in the Run position, and vary from 4.8V to 5.6V when the engine is cranking. The readings were taken using the Original Motorcraft ICM from the TownCar. I've also tried a New ACDelco unit I have which made no difference with the spark generation.

I double checked the resistance between the ICM terminals and each wire at the coils, each read 0.

Swapped out the Mark VIII PCM for the original Towncar PCM, with no difference. (There are only 2 additional circuits for the MK8 vs TC PCMs: knock sensor intput & IMRC output)

I'm also wondering what the test method is (other than "Buy a new one and see if that works") for Cam and Crank sensors? I was under the impression they're just magnetic pickups; it's hard to imagine what exactly can go wrong in there.

I appreciate and will investigate any and all leads!
 
crank sensor will cause a no start, cam sensor just seems to set a CEL.
how is your fuel pressure? and are the injectors firing?
got a timing light? can you verify spark?
 
Fuel pressure has always been good, but I'm not 100% sure the injectors are firing. As stated in the original post, they appear to be getting a pulsed signal, but I have yet to get a buddy over here to crank the engine while I listen for the solenoids with my stethoscope. Also, I've got the #3 spark plug out of the engine, watching for spark. I expected to smell fuel from that open cylinder at least, but nothing so far as I can tell.

Would a bad crank sensor prevent both the firing of the injectors and the coils?

The Crank Sensor is original after all, and to my knowledge the engine had 90,000 miles on it when I picked it up.

Considering the hundreds of dollars in fasteners alone in this thing, maybe I should spring for a shiney new Crank Sensor.

I do have a timing light, but I'm failing to think of how that'll help me at this point. It's not that it's running poorly, I've just got no spark... and possibly no fuel.
 
timing light just verifies spark with the plugs installed.

crank sensor wiring is sometimes problematic. i had to replace the plug on my car recently. they do good bad though. i guess the heat and oil gets to them eventually.

the cam sensor times the fuel injectors, but the computer can guess without it. my car will start with it unplugged. (if older ford fuel injection systems were batch fire, an educated guess for a sfi system should be enough to get it to run.)

if you have fuel pressure and the injectors are firing, then it has to be spark related. you may have to try a new crank sensor and possibly wiring plug.
 
The crank sensor wiring simply being reversed will cause a no start.
 
Have you hooked up any of the ground cables to the block? Seeing that the engine mounts aren't even attached yet, I wouldn't be surprised if a poor/non-existent ground path was causing your issues.
 
racecougar said:
Have you hooked up any of the ground cables to the block?
Click to expand...

A valid point. I've got two ground straps hooked up to it, but I haven't thought to check the resistance between the block and the main ground cable. I'll add that to the list, thanks.
 
If the engine is cranking and you haven't burnt the car down yet the ground is sufficient. :p
 
I remember when I did my intake swap I had rebuilt injectors in the intake ready to go.

They were not ready to go however.

Two of the injectors were not firing and the car would not start. I swapped the old injectors in place of the rebuilt ones and the car fired up the first try afterwards.

Just a thought.
 
Project Hiatus

Thanks gents.

I've got someone coming over tomorrow so I'll be able to tell whether or not any of the injectors are firing while the engine cranks, but after that my main focus for the next week will be ramping up for a monster road trip out to the Bonneville Salt Flats for Speed Week, so the "4V TC" is gonna have to wait until the 17th to get any more attention from me. I'll update before I leave.

Obviously all hypotheses are still welcome while I'm gone.
 
I'm Baaaaaaacck!

I've been gone for a month and this build has been sitting in the garage for two, which is at least 4 weeks too much. This thing needs to run.

When I had someone else crank the engine for me, I listened to each of the injectors with my stethoscope to detect any solenoid actuation. Didn't hear a d@mn thing in any one of them, but there's more to that story.

During the build, I kept each of the injectors in individual bags in a container beneath a workbench. Little did I know a can of parts cleaner was leaking into the container, and obviously managed to eat its way through all the bags, so the injectors were soaked for at least a couple weeks. I sprayed them out with fresh carb cleaner, but it's possible the solenoids are all frozen.

The plan moving forward is to borrow the injectors off my TC engine which I know are properly functioning. I know they're lower flow but it's the fastest way I know to check if the Mark computer is sending any usable signal to the injectors. As I stated before, there is a pulsed charge at the injector connectors when the engine is cranked, but there is NO fuel getting into the cylinders.
 
if you have a pulsed signal, but no fuel, fuel injectors. put a working set in, see what happens!
 
Progress, Sort of

I've got gas!

In my cylinders that is. I removed and prepped the TC injectors for installation into the Mark engine, as I was testing the solenoids with some test leads to make sure they were all kicking, it occurred to me to do the same to the Mark injectors. So I did the right bank. The left bank remains to be done.
That was last Wednesday. Tonight I mounted the P/S and A/C pumps and installed the belt, in case the computer is looking for any voltage blips from the alternator.

So I cranked it over a few times and I now most certainly have fuel in at least the right bank! Since it was so late I didn't check the left bank yet, I'll do that asap. I'll also make sure and sniff for fuel before I test the left bank solenoids to make sure I'm not just smelling the gas from almost a week ago on the right bank ones.

Next I'd like to finish the intake tube. Right now I could be confusing the computer without it.

I still have no spark.
 
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