For 88-91 EEC open loop mode uses RPM and MAP doing direct lookups in tables which is why it runs so rich until it warms up. These tables are designed to operate whatever engine the EEC is tabled for with reasonable disregard for engine condition (worn rings, vaccum leaks, and so on).

CTS is used to determine if the vehicle is warmed up enough to make the decision to flip into closed loop mode with the assumption that the O2 sensor will provide a valid output once the engine is warmed up "a little".

While I often recommend staying away from lumpy cams with Ford speed density EFI for obvious reasons know that even with a lumpy cam the SD system will start and run the engine - just not very well - the lumpier the cam is the worse it will run, but it will start and run.

Based on what you've described thus far, something is leaking or plugged. Being that taking the spark plugs out "resets" the engine to allow it to start I think it's likely that an exhaust valve isn't opening enough or at all resulting in a hydraulic lock situation until you release the pressure by removing the plugs, or letting the thing leak naturally over an hour or a few.

Code 11 on your EEC just means the 88-91 computer found all the sensors and was able to measure something - it doesn't mean the sensors are any good. The diagnostics capability of the first EEC's on pickups were.. um.. crummy at best.

Don't be offended by my questions, I'm trying to rule things out and they're not questioning your mechanical ability or savvyness.

Have you done a vaccum test? What were the readings? Was the gauge steady up and down with engine RPMs or did it jitter all over the place?

Have you done a compression test? Results wet? dry?

If the results of both tests give reasonably good results, unplug the map sensor from it's vaccum line and plug the vaccum line (finger, pencil, etc) and start the truck and see what happens. Without the map sensor it should barely catch and immediately stumble and die in open loop mode.

Connect MAP back up, then unplug the CTS connector and repeat test. What should happen (if everything else is proper) is the truck should idle a bit high, light check engine and throw a code. But it should start, and idle.

IAC may be an issue as well - clean or replace.

Are you still using the 302 computer on the 351W? The 302 computer will run the 351W a bit lean but we can address that later - it should start and idle.

 

After looking at your question, we may both be at fault.

The injectors were disassembled, i.e. removed o-rings, fuel screens, spacers and pintle caps. They were then soaked in a T-T-T solution in an ultrasonic cleaner for about 8 hours. Reassembled with new parts. I took a connector from the old engine harness and made a test circuit. I then applied fuel to the inlet sides of each and pulsed the injectors to make sure they were opening and closing, holding pressure and checked for spray pattern.

The only change with throttle position is that it starts a bit faster with a slight amount of pedal pushed(about 1/4 travel). I've tried it fully closed and fully open. The only difference is how quicker it starts. I've even pumped it to see what happens(I know this has no effect but hey I tried).

 

As stated before, I have not done a Vacuum test. I guess when I get home I'll buy a tester and try that. Either it's that or I have a small enough leak that will not let it run but also will not let it start with the TB plugged off from air flow.

Compression was 70-80psi. I'm not sure what you mean by wet or dry. I did not put any oil in the cylinders to boost it if that's what you mean.

I have tried starting it with most of the sensors disconnected trying to isolate the problem. I'm sure I did the ECT. The MAP senor I didn't disconnect but I did try it with the 302 one.

After I tried starting the engine with the 302 computer and it didn't work, I put the 351W computer back in. I also tried using the IAC from the 302 and the whole TB.

Anyone's questions are not offensive at this point.
I'm at my wits end with this thing.

 

A small leak will not cause the wild run of RPMs then death. If it is a vaccum related issue, it's a big one, and why I am suggesting that it might be INSIDE the engine - valvetrain. If the vaccum gauge doesn't read very high (well, technically low - a vaccum) then you have a leak. If it pulsates then one cylinder (or more) is leaking, and the jitteryness will help you zero in on valve train issues - dropped valve, stuck valve, etc.

a dry compression test means you stick the tester into the spark plug hole and crank and take a reading.

A wet compression test means you squirt in a little oil first, then thread in the tester into the spark plug hole and take a reading.

If the delta between the two readings are very different, then you're having ring issues (blowby) as you're not getting a good seal. The oil (i.e. wet) helps make a temporary seal.

80-90 is low. Very low. The last compression test I did on my F350 (with well over 400K on the engine) all eight cylinders were in the 125-130 psi range. Mine is a tired engine for sure, and you're way below that. A new 351W with freshly honed cyl walls and new properly sized rings should yield about 180psi or thereabouts.

Make sure when you do the wet/dry compression test you do the leakdown test as well. If you're not familiar with this test after you crank your engine to produce the pressure you read on the gauge, you leave the gauge there and release the "hold" button and allow the gauge to decline in it's reading - based on the cylinder's leaking. If it drops instantly you're leaking badly and not retaining pressure, if it's very slow then you're okay. This is a rule of thumb and depends on a lot of factors which is why I've given you vague terms.

I should have focused more on this earlier - the 80-90psi compression is probably the biggest indicator of what's wrong. That's crazy low for an American V8. No compression in the cylinders means no vaccum in the intake, no vaccum in the intake, and the EEC has no idea what's going on and guesses - and runs the fuel rich, runs the idle upwards (trying to hunt) and then eventually chokes the engine to a stall.

The symptoms lead me onto the vaccum tracing route, but thinking about it more (with your response) I'm more inclined to think it's in the engine itself rather than external - at least the major problem.

Rings, valves stuck open or closed, bent pushrods, holes in piston tops, broken rods/wrist pins, bent valve rockers, bad lifter(s), frozen stem seals and so on can all influence/cause these kinds of problem.

 

I can understand the low compression for a New(no break in) engine. But there should be enough there for the engine to at least sustain momentum running. I've seen less but have poor power, burning oil and such but at least still run.

Keep in mind that this engine has never ran continuously since being rebuilt. Of all the time I've messed with it, I would venture to say it has about 5 minutes of total time with fuel and ignition going on at the same time. It has never ran long enough to get the plugs warm.

 

Did you actually order the pistons and rings or did the shop do it for you? Did you put them in yourself or did the shop do it for you? I've heard on here before that the machine shop had labeled a motor as a 302 and not a 351w. If that happened then there may be some seriously mis-sized stuff in there that although it fits in, it isn't quite the right size. I tend to lean toward what frederic is saying here. For giggles see if it will run on the 302 computer. If it does, then I would think you have some firing order/valve/cam timing issues. Like he said, get a degree wheel and check it.

 

All the machine shop did was the block work. I ordered all the parts myself. They did press in the piston pins but that was it. I also marked my block so I could tell for sure I was getting mine back. I have already done the computer swap and put the 351W back in. No change. And after tearing the engine down twice and installing 3 cams, I pretty much doubt I offset the timing or something would have change enough to show a difference.

Does anybody know if there is anything on the EFI system that would prevent an engine from starting via a sensor. I have heard before that if an engine overheats above 289 degrees or something like that, the ECT will break the ground to the computer and shut the engine down to prevent further damage. I have not been able to substantiate this in any documentation nor by looking at the schematics. I also disconnected it just to be sure. No Change.

Also, if timing was an issue from my past experience, if it was 180 out it would burp and pop and run like crap. This engine does not do that unless I throw it 180 out. When it starts, it revs up nice and smooth then dies.

 

It sounds like a fuel issue if it will start and run up to 2500 rpm then die then it has compression and spark try to start it with either if it starts give it another shot to see if you can run it on ether for a few seconds if this works you can eliminate compression and spark and quiet a few other things let me know what happens

 

I'd be to the point of calling an exorcist at this point if I were in your shoes...

No idea on the system shut down due to sensor readings.

Does your timing set have a multi-keyway on the crank gear?

 

try adjusting the fuel valves sounds like you are getting to much gas

 

Sounds more electrical, does your ignition have power in the "on" position. Maybe you just have fire in "start" position. Even when my FPR was bad it would still run ,just rich and ragged. Just a thought.

 

Does the motor have any spark?

 

For a status of what I've been doing to this truck, here is the link to the thread. I haven't updated it because there hasn't been any major advances.

Refurb Status

 

Had the exact same problem on an old john deere. It was always one of two things. The ECM would only allow it to run for a few minutes, then die. I swapped the ECM, and it ran fine, apparently overheating the ECM. I still use the old ECM for testing since it allows the engine to start, but always shuts off after a short time. Also, I have seen a similar situation where the fuel filter would allow enough fuel (after a time) to allow the engine to start, but to then shut off after the fuel was burned. Then you have to allow the fuel to trickle past the filter to allow another restart. Sooooo, is the fuel pressure staying up the entire time, or is it dropping then the engine dying? Also, maybe stick a noid light on the injector harness and watch it to see if it shuts off when the engine dies, or if it continues to fire (when cranking) after the engine is dead. Then you will immediately know if the computer is still on and/or injectors are still firing. Of course, if you still ahve a reference voltage of about 5 volts, you will also know if the computer is still on.

 

Just a thought Did you gap the rings before assembling the engine? If not I maybe wrong but it sounds like the engine is warming up the rings and locking up the engine. The time it takes to remove the plugs allows the cylinders and pistons to cool enough to allow movemnet again. Just a possibility had similar problem with a race car. As for the 2500 RPM is this just when it fires up for a few seconds? Or will it run like this for a while? Curious what you figure out

Luke