Question: should all four injectors be firing at the same time during cold start? Mine puts out nice conical patterns but I'm thinking they should be firing at the proper firing order interval. Found nothing to help on FAQ.

Steve

The injectors fire all together, all of the time. None of that sequential nonsense going on there. New seals and back in the hole since you have a nice spray pattern. Good day, rcs

Tell it like it is RCS. Steve, you just learned the difference between multi port injection (MPI)which is what you have and sequential port injection (SPI).

Mark

I guess I did...sometimes I long for the days of carburetors and points. I have tried nearly everything to get the beast to start and it won't. Timing perfect, good spark, good injectors. Seems like the car should run.

I've had this exact problem on several occasions in various vehicles (belonging to friends of mine). After verifying that both the Ignition and Fuel Injection system are functioning propery, I discovered that the cylinders did not have any compression. A trip to Autozone for a $5 can of fogging oil, and 4 second spray into each cylinder did the trick (with the spark plug removed).

The reason why this occurs is that if you crank the engine with the fuel injection system running, but no ignition, the fuel will wash away the thin film of oil on the piston rings. Once this oil film is gone, the cylinder can't hold compression and the air and fuel push past the rings and into the crankcase (resulting in a dead cylinder). You won't even hear a cough or a pop like it's attempting to fire, since all the air and most of the fuel will be past the rings long before the spark plug fires.

This is much more common to occur in a neglected car or one that has more than average ring & cylinder wear. -however, it could happen on a brand new car too. Try squirting 4 seconds worth of fogging oil in each cylinder and see if she fires right up. If not, verify that your camshaft lobes are in the correct position when cylinder #1 is at top dead center (to make sure that the timing belt hasn't slipped). It would also be worth your time to take some sandpaper to the sparkplugs to clean up the electrodes where the spark jump occurs. A little bit of carbon buildup hear will cause fuel to saturate to the plugs tips and inhibit spark transfer.

I'm assuming that you've verified that your ignition system is indeed firing, -otherwise there are several other issues that it could be.

God bless,
Fitz Fitzgerald.
--
'87 Blue 240 Wagon, 255k miles.
'88 Black 780, PRV-6, 148k miles.

I'm willing to try anything at this point. As far as the cam lobes go, I lined up the timing marks, verified #1 on TDC, opened the oil filler hole and verified that both cam lobes were out to the sides, intake lob was a bit off the valve and the exhaust lob still had several degrees of rotation before contact. I believe that is the correct orientation.

I have to agree check the squeeze on the cylinders. You should have 150 pounds or so and if you do not you might want to consider a little oil in there to give you the seal you want. I have had motors wash down a cylinder or two but have never had to resort to oil them down but the theory is sound and it should work.


Mark