Can an intake leak (not properly set or torques) cause problems

[Boss 351]

My car isn't running right after the cobra intake install. Cylinder #7 runs flooded but it has spark and the injector is fine. However I didn't have a torque wrench so I only torqued down the intake by hand and maybe I didn't seat it properly (doubt it, but you never know). The engine was running 100% perfect with the stock intake and before I touched anything.

There's no check engine light and the engine starts up just fine. I'm going to remove the lower and put it back on using the "right" method using a torque wrench and the proper order of tighting the bolts. I'm doing this just to rule out the possibility of an improper lower intake install.

I have no clue what's going on, here are the things I checked:

- Vacuum leaks = none found

- Faulty injector = put a new on #7 and same problem, so I swapped with #8 and same problem still so it isn't the injector.

- Bad spark plug = swapped with another cylinder and still the #7 was wet

- No spark bad wire? = there is plenty of spark

- Air leak at the MAF/intake tube (rigged up) = sealed it off real good, problem not there

- Checked the voltage of the injector harness = 2.02 volts at #7 KO

When I get the lower off, I'll check to see if the injector leaks with the key on (pump primed), but I doubt it leaks though. I don't have the tools to do a leak down test so removing the intake is the best I can do and manualy visualize the injectors.



Any clues?

 

[jrichker]

My car isn't running right after the cobra intake install. Cylinder #7 runs flooded but it has spark and the injector is fine. However I didn't have a torque wrench so I only torqued down the intake by hand and maybe I didn't seat it properly (doubt it, but you never know). The engine was running 100% perfect with the stock intake and before I touched anything.

There's no check engine light and the engine starts up just fine. I'm going to remove the lower and put it back on using the "right" method using a torque wrench and the proper order of tighting the bolts. I'm doing this just to rule out the possibility of an improper lower intake install.

I have no clue what's going on, here are the things I checked:

- Vacuum leaks = none found

- Faulty injector = put a new on #7 and same problem, so I swapped with #8 and same problem still so it isn't the injector.

- Bad spark plug = swapped with another cylinder and still the #7 was wet

- No spark bad wire? = there is plenty of spark

- Air leak at the MAF/intake tube (rigged up) = sealed it off real good, problem not there

- Checked the voltage of the injector harness = 2.02 volts at #7 KO

When I get the lower off, I'll check to see if the injector leaks with the key on (pump primed), but I doubt it leaks though. I don't have the tools to do a leak down test so removing the intake is the best I can do and manualy visualize the injectors.



Any clues?

Did you run the cylinder balance test? What were the results? Did you go through all the leaking stuck injector tech note I posted?

Remember that the computer does not source power for any actuator or relay, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

The following tests will require you to probe the injector wiring from the rear of the injector connector with a safety pin. Do this while the injector wiring is still connected to the injector.

The injector red wire should read minimum of 12 volts anytime the key is in the Run position. The computer provides a ground to turn the injector on when the intake valve is open. The tan/orange wire (#7 inector to computer) goes to ground when the injector fires. It should have 12 volts on it unless the injector is firing.

Remove #7 spark plug, place you finger in the hole & crank unit you feel good compression. Then check both the red wire and the tan/orange wire for 12 volts. Since the spark plug is firing, the intake valve is closed & the injector should not be firing. Both wires should have 12 volts. If the tan/orange wire does not have 12 volts, the injector is bad, or the tan/orange wire has a short to ground or the computer has a bad injector driver.

A voltmeter will not catch the voltage change from 12 volts to ground when the injector fires unless it is one of the very expensive Fluke DVM’s. The computer pulses the tan/orange wire to ground for only a few milliseconds (thousands of a second).

A noid light available from Autozone, is one way to test the injector wiring. The light will flash briefly when the injector fires, but long enough to be easily seen. If it is on all the time, you have either a wiring problem or a bad computer.

The computer injector drivers are not replaceable unless you are a skilled electronics technician that does component level PC board level repair.