I deliberately submerged the intake with injectors in place to look for O-ring leaks and manifold cracks. Bad idea?

V6 now only idles (rough) with fuel pressure regulator off (vacuum control disconnected). Won't idle at all connected. (Yes I plugged the tree after pulling the line off.)

I can only get it to run at higher rpm by pulsing the throttle. When I do this I get popping (backfire) in the exhaust.

Could the injectors be water fouled?

 

You ruined them. They're electric solenoids, electricity and water don't work well together.

 

You'd be surprised. I've run a 120v open motor pedestal pump under 4 feet of water. Repeatedly. Looks like a vortex to hell!

It takes more than water to short a 12v circuit. Notice the exposed connections to your starter, exposed to salty slush in winter.

The only threat water poses to a 12v circuit is corrosion. They are more affected by corrosion than 120v cicuits. A couple days is not likely to open the circuits even if the water got inside the body of the injector. I did not see any bubbles so they must be sealed well enough.

What I'm worrying about is ingress from the tips since the back ends were still sealed by the plugged fuel rails.

Unless someone has a better idea, I'm going to remove and test the injectors. There are plastic covers over the tips that I think might be called baskets. Water might still be trapped in there.

 

It's not likely you damaged the injectors they are all but bullet proof, I'd more suspect you have the injector wiring mixed up.

 

I really wish that was possible, but of the 3 ways the harness can go, only one puts the main connector in front with the injector plugs aimed downward.

It behaves like the injectors are out of sequence, but that could happen if they are dribbling instead of spraying.

 

The distributor had to come off to remove the manifold. Could an erratic position signal from the distributor mess up the injector sequence? The spark timing is about 10 degrees BTC.

 

Looks like you've got it all figured out. Not sure why you posted the question then.

 

No parts on order. Not all figured out. Still in the testing/diagnostic phase.

Do you think fouled injectors is still the best idea?

 

Is the EEC-IV programmed to open all injectors simultaneously during quick acceleration? That would explain why it quits at steady open throttle, but runs fairly smooth when I pulse it a couple times per second. The rpm doesn't follow my foot.

 

So did you make sure piston #1 was at TDC of the compression stroke before reinstalling the distributor?

 

Yes. Thanks! Timing is good. Shows 10 BTC with the timing light.

I was relying on the MIL (aka CEL) to tell me if it threw any codes. Silly me!

I got 21 engine coolant temp, 22 mystery code, 24 intake air temperature, and 52 mystery code.

I disconnected the jumper to clear the codes, but only 21 clears. 21 comes back if I run the engine a little, but not up to temp. Disconnecting the battery for awhile and shorting the cables together only clears 21.

This makes sense if 22, 24, and 52 tests are performed everytime the scan is initiated.

Interestingly, I don't get code 19 (powertrain control voltage) after disconnecting the battery.

I previously tested both temp sensors. The intake sensor had smoothly varying resistance as I exhaled over it. The coolant sensor had 50 some kohms cold and 8kohms warm. The engine sped up when I pulled the plug off it.

 

Although I think my sensors are OK, tbere could still be a problem with the harness. The intake sensor plug comes off the injector harness.

 

Upon further review. Those codes just mean the engine was too cold to run the self test. The temp at the time was around freezing.

 

The injectors are sealed so water isn't an issue. To me it sounds more like the new intake gaskets aren't sealing fully. Have you put a vacuum gauge on it yet to see what it's reading.

 

That is always a possibility, but I really doubt it. The passenger side was leaking coolant before and now it's dry.
I tested for too much air by choking the intake with duct tape. I left about a half inch gap on one side. No help. I also removed the bypass valve and blocked the ports with an aluminum plate (and gasket). No help.
I have a vacuum gage on it, but I can't get a reading since I have to pulse the throttle to keep it running. Sometimes I can get it to idle very rough, but it falls on its face in less than a minute.

It really seems like a fuel delivery problem. My best guess is no position signal from the distributor. This is needed to sequence the injectors, but is not needed to sequence the spark. This could also result in loss of spark advance control, but that would be minor.

I want to test the injector timing. I hope Autozone has a kit so I don't have to make something.